Solar usage in the USA
Solar usage in the USA is rapidly becoming cheaper and growing increasingly faster.
According to Bloomberg Energy Finance (BNEF), solar and wind reached 67% of new power capacity added in 2019. That of fossil fuels slid to 25%.
In 2004, the average price of an installed rooftop solar module was about US$3.50 per watt. The cost of solar in the USA is now plummeting. In the four years since 2016, solar modules prices have (in all USA markets) fallen. The drop was from US$ 0.63 per watt to about US$ 0.20 per watt.
Solar usage in the USA - higher solar cell efficiency
This fall in price is due mainly to higher solar cell efficiency. Until recently, most high-quality solar cells were about 18% efficient. In 2020, however, the global JinkoSolar raised that to 24.79%. The launch of those ultra-efficient modules lowered the USA’s domestic average cost of solar-produced electricity. It is now (late 2020) US$38 per megawatt-hour (MWh). This cost is similar to that of producing electricity from newly built coal-fired power plants. Currently, the most efficient solar projects in Chile, the Middle-East and China produce electricity for under US$30/MWh. Wind power projects in Brazil, the USA and India do likwise.
The rise in production capacity and efficiency is primarily in China. It is now the centre of global solar panel manufacturing. China's module production was 17% higher in early 2020 than in the same period of 2019. This despite exports falling slightly.
The implications of solar energy increase are immense. Overall emissions are substantially reduced. Apart from making, transporting and installing solar modules and associated electronics, it is zero thereon. Most solar modules last for at least 25 years. Meanwhile, appliance makers seek to reduce energy use.
Further solar growth
The USA’s solar energy market is forecast to increase. That increase is a likely (compounded) annual 17.3% throughout 2020-2025. Tax credits on renewable energy-related matters may expire in 2021. Solar power investors in solar power will expedite finishing projects. This trend may partly offset COVID-19 investment impacts.
A 30% tariff on solar module imports has already forced USA producers to become more competitive. Furthermore, to increase domestic manufacturing. Cost-effective battery energy storage technology is also needed. Significant developments are already well underway.
It is now all but sure that solar (and wind) power will continue to displace traditional base-load power sources. This will happen not just in the USA. It will be worldwide.
Battery charging quickly and deeply by a generator
Battery charging quickly and deeply by a generator is totally possible. You must, however, know how to do it. This article reveals all. It explains why and how. The article is valid for both 120-volt and 240-volt generators.
All such generators have a 12-volt DC socket. Some generator makers label it ‘Battery Charger’. This socket, however, is intended to power small 12-volt devices, such as a TV directly. Its output is a typically unregulated 13.6-volts. It drops under load (to 12.6-volts or less). That voltage is, nevertheless, fine for running 12-volt lights and appliances.
Battery charging quickly and deeply by a generator - lead acid and AGM batteries
A generator's typically unregulated 13.6-volts is far too low for full and speedy battery charging. It may half-charge a flat 100 amp-hour lead-acid or AGM battery within six or so hours. From there on, charging progressively reduces. It may take further 24 hours to charge it over 70%. And a week or more more to fully charge it.
The solution is simple and effective. Charge the battery via a 240-volt (or 120-volt) battery charger powered by the generator's 240-volt (or 120-volt) outlet. The size charger required (and its safe charging rates) varies with battery capacity and types. This is particularly so for LiFePO4 batteries.
As a general guide, most lead type batteries below 180-200 amp-hour typically have a recommended maximum charging current of less than 40 amps. For these a 25-amp charger is adequate.
Recommended maximum charging voltages for most AGM or gel batteries are around 14.6 volts,but always check the manufacturer’s recommendation.
For lead-acid and AGM batteries once fully charged, to avoid overcharging and to extend battery life, the charger should drop to about 13.2-13.3 volts.
Charging in high temperatures
Battery maker charging recommendations usually for an ambient temperature of 250 C. Regardless of battery type, if charged in a high-ambient temperature environment, such as an engine bay, check the battery manufacturer’s related recommendations. Some batteries (particularly AGMs) are not suitable for engine bay installation. Some battery warranties are void if installed in engine bay temperatures.
If there is no realistic way of relocating a battery in higher temperature environment, if feasible charge it a lower maximum voltage. The lowest setting is generally advisable.
It generally takes 40% of the total charging time to recharge the last 20% of a battery, this is the most important stage to help improve the battery’s service life and overall performance. Using a fast battery charger with pre-set absorption times on smart chargers may not provide enough time to fully charge the battery. Pic: Redarc.
The importance of battery specification
Upgrading an existing solar system
Upgrading an existing solar system has unexpected traps. It is often better to scrap, use elsewhere, or attempt to sell that existing, and install a new one. This is particularly so with grid-connect systems and doing so with stand-alone systems is still tricky.
The water pump for this 30,000 litre swimming pool is powered by four 100 watt solar modules. Pic. Solar Books.
Retaining or selling older solar modules is often possible. Good quality solar modules have a working life of 25-30 years (with only marginally less output). They are, however, likely to be incompatible with new ones. This is because solar module electrical characteristics have changed. It may be possible to overcome this - but too costly to be worthwhile. There can also be re problems with upgrading in that a number of legal (and Standards-related) requirements have changed. This relates also to the ways solar is installed.
A further reason for upgrading is that gas prices have escalated. It is now far cheaper to heat a home by using reverse-cycle air-conditioners in their heating mode. The top models now use only a quarter of the power of the same nominal wattage as an electric radiator or gas fire. This may seem impossible but is really so!
With grid-connect systems, in most areas, it now pays to install more solar than you use yourself. This increases feed-in rebates. It will also produce more power during times of lower solar input. Upgrading an existing solar system, however, has unexpected traps. There may, for example, be a limit on the excess amount. if so, the maximum is likely to be 6 -6.6 kW. Your installer can advise.
Using Existing Modules in a Separate (Stand-alone) System
Those familiar with electrical systems could consider using the original solar modules in an electrically separate stand-alone system. This can currently (in 2020) be self-done legally (in Australia and New Zealand) as long as those modules are connected in a manner (e.g. series-parallel) such that the maximum does not exceed 60 volts. But 48 volts dc is safer and more convenient.
An inverter may still be used to provide 230 volts. For Australia and New Zealand that inverter must be of the type that has inbuilt socket outlets. Appliances plug directly into those outlets (via a power board if required). Such inverters must not be connected to any fixed mains-voltage wiring.
The above could, for example, provide charging power for a small electric vehicle. Or via batteries, power 12/24 volt garden lighting, fountain water pumps etc. If at 48 volts it may readily power a dc brushless motor swimming pool pump such as the Badu range. If used only during the day, no batteries are required. (Our book Solar Success shows full details of how to do this – complete with our own actual example in Broome, WA.)
It is also feasible to retain that old system and have it paralleled to the new one – but that is strictly Certified Installer territory.
Our book Solar Success (now also in low priced eBook and Kindle format) has all you need to know to undertake this work. It is also readily feasible if you have a friend who knows his/her way around solar or systems of this voltage.
Charging your electric car at home
Charging your electric car at home or workplace is readily feasible.
Most electric vehicles have a charging unit inbuilt. Check with the vehicle maker for charging options available. This article about charging your electric car at home gives some indication of how many kilometres you can drive.
Typical electric vehicles have some form of inbuilt charger. You can plug into a 15 amp outlet socket. You save money, however, via an economy tariff for off peak charging overnight. To be on that tariff, however, you must have a dedicated EV charging point: a standard power point isn't permitted. This is because that’s otherwise a cheap source for other purposes!
Have an electrical contractor set up a dedicated electric charging point.You are also likely to need a meter for the car charging tariff.
Charging your electric car at home - set-up cost
Set-up cost varies. A very rough estimate is about $1,750 for the charging circuit wiring. Plus $100 - $150 for a standard electrical power point. An electric vehicle charging unit costs up to $500. A for a more advanced unit costs about $2500. A local licensed electrical contractor can advise.
Some electric car dealers include a home charging assessment price and/or a consultation with a licensed electrical contractor as part of the car’s purchase price.
Charging your electric car at home - energy usage
If used for typical commuting (e.g. 40-50 km a day), re-charging needs 2.5-5 kilowatt/hours. One kilowatt hour is that which many refer to as ‘one unit’. That currently typical is shown below.
Type Maximum charge (kW) km (per hour of charging)
BMW i3 7.4 25
Chevy Spark EV 3.3 11
Fiat 500e 6.6 22
Ford Focus Electric 6.6 22
Kia Soul EV 6.6 22
Mercedes B-Class Electric 10 29
Mitsubishi i-MieEV 3.3 11
Nissan Leaf 3.3 – 6.6 11 – 22
Smart Electric Drive 3.3 11
Tesla Models S & X 10 -20 29-58
Charging is readily done overnight. Excess solar captured during the day can be sold to the electricity supplier. It is then bought back at off-peak rates. Most of Australia's electricity suppliers charge 25 30 cents per kilowatt/hour for off-peak use. Some, however, offer better prices on a contract basis. It also often possible to obtain a better rate. You can often do this by obtaining a quote a rival supplier. If it is lower, seek that same price (or lower) from your existing supplier. You are likely to be offered a really low price for (say) a two-year contract.
Charging primarily from home solar
Charging from home solar and/or business solar is totally feasible. It has the added benefit of no CO2 emissions.(See Electric vehicles –solar charging at home).
By and large, a 6-6.6 kW solar system will be needed. This is the largest right now (mid 2020) that qualifies for rebates (and usually grid-connect systems). Solar however is now so cheap that it is worth seeking quotes for a dedicated solar car charging system. It is readily feasible to charge an electric or hybrid car from your home and/or business solar system This further reduces cost.
Charging from public outlets
An ever-increasing range of service station fast and super-fast chargers charge at rates as high as 135 kW. They readily recharge an EV battery in about 30 minutes. Owners use these mostly long drives. They rely on routine charging at home and whilst at work. Electric car vendors usually offer offer such charging..
While not yet adequate in many areas, there are fast charging facilities around Australia. These including right across the Nullabor. See: Charge Stations in Australia (https://myelectriccar.com.au/charge-stations-in-australia) or ChargePoint. Prices vary.
Many existing home grid-connect solar systems have excess capacity outside peak periods. Solar energy fed in during the day can be re-drawn during off-peak periods. This charges an electric car cheaply because many grid networks have excess capacity outside peak periods. Routine such charging extends battery life. All dislike ongoing deep discharges.
It is already totally feasible to charge cars from home and office solar. It is being done by many owners right now.
Electric vehicle batteries
Electric vehicles were commonly used from 1880 or so. Their increased use was limited by inefficent electric vehicle batteries. This also limited speed to only 35 km/h (22 mph). Their range was about 100 km (62 mph). It also awaited adequate control technology. (See also Electric Vehicle History)
Pic: Edison Battery Archives
From 1970 onward, technology improved dramatically. AGM batteries increased driving range slightly. Otherwise, electric vehicle batteries remained almost unchanged. Most provided about 33 watt-hours per kilogram.
In 1991, the USA launched its Advanced Battery Consortium. This resulted in the nickel hydride (NiMH) battery. This initially doubled energy - to 68 Wh/kg. That has since doubled.
Early nickel hydride (NiMH) battery. Pic: ecomento.com
While having greater energy density, NiMH’s have low charging efficiency. Moreover, they are costly. Furthermore, they tend to self-discharge. There is also hydrogen loss. Nevertheless, they still power hybrid vehicles. Honda and Toyota use them.
In 1996, Texas University conceived lithium batteries. They now store 140 Wh/kg. This is more energy than NiMH otherwise equivalents. Their charging rate is far higher. Furthermore, they can release huge energy.
As of 2020, these batteries provide 250-450 km. This is just adequate for commuter driving. Lithium batteries can be recharged overnight. This is feasible from solar or grid power. See Solar Charging Your Electric Car.
Lithium batteries have high energy density. They are, however, costly to make. It is far from emission-free.
Graphene is a break-through product. At one atom thick, it is virtually two-dimensional. The height of three million layers is 1.0 mm. Each layer consists of hexagonal honeycomb-like rings. Atoms strongly co-bond within the rings.
Graphene is ultra-strong. It has neglible electrical resistance. Furthermore, it conducts heat superbly. Graphene enables lithium batteries to increase capacity per kg. It's high conductivity enables electric vehicle batteries to charge faster. Graphene also increases their usable working life. Moreover, that of batteries generally. These batteries are not yet on sale. Research and development, however, is intensive.
A graphene lattice is one atom thick. Pic: Original source unknown
Ultracapacitors are an alternative to batteries. They store energy energy in an electric field: not a chemical reaction. Ultracapacitors release energy at ultra-high rates. This assists vehicle acceleration and hill-climbing. They also store regenerative braking energy
Ultracapacitors have other benefits in electric vehicles. Ultracapacitors have very little internal resistance. This enables them to release extremely high power. Furthermore, they are close to 100% efficient. They are lighter than batteries. Moreover, they contain no harmful chemicals or toxic metals.
Ultracapacitor have other plusses. This includes almost instant charging and discharging. They operate efficiently in extreme temperatures. They have high reliability and safety. Furthermore they work for 15 or more years. Moreover, they need no maintenance.
Batteries and ultracapacitors are complementary
Batteries provide energy for long term general use. Ultracapacitors are mainly used for secondary energy-storage. This is ideal for electric vehicles. Moreover, they help electrochemical batteries level load power.
An ultracapacitor. Pic: Maxwell Technologies
Alternative battery technologies
Piëch Automotive may have a possible breakthrough. It's electric car has an all-new battery. It is claimed to 80% recharge in under five minutes. The company claims ‘significantly higher currents can flow as the cell temperature rises only marginally'. Furthermore, fast charging 'reaches 80% in under five minutes'. Also claimed is reduced heat build-up enables battery cooling by air alone. Furthermore that 'such cooling saves weight'.
The vehicle has three electric motors. One front-axle asynchronous motor delivers 150 kW. Two rear-axle synchronous motors produce 150 kW each. Its range is claimed to be 500 km (about 310 miles).
Electric vehicle battery life
Sudden battery failure is now rare. Because of this, most battery makers quote 'usable recommended lifespan'. It is now of the charge/discharge cycles before original capacity fall to 80%. The battery may remain usable, but 20% capacity is lost.
Most electric car makers guarantee batteries for eight years. Nissan's guarantee is against defects for eight years or 160,000 km (100,000 miles). Also, against capacity loss for 5 years or 96,500 km (603,000 miles).
Aluminium has electrical potential. Phinergy (plus Alcoa) have developed a non-rechargeable alumiumium-based battery. It releases electricity in a process that, in effect, is the reverse of aluminium smelting.
The Phinergy Al-air battery uses air as the cathode. Being aluminum, the Al-air battery is lighter than a comparable lithium battery. Each Al-air ‘battery’ is claimed to extract 8.1 kilowatt-hours of energy. Of this, 50% is electricity and 50% heat per kg of aluminium. Fully depleted batteries are replaced. Each should enable over 1500 km (about 935 miles) for typical electric passenger vehicles. Far from all fuel stations may initially stock these batterries. A spare one is thus needed
Phinergy is associated with the Indian Oil Corporation and Ashok Leyland. Its concept is interesting, but will need global service for ongoing replacements.
The Phinergy ‘battery’. Pic: Phinergy
The aluminum-air battery market is likely to grow. The batteries are claimed cost-effective, recyclable and safe. If so proven, aluminum-air batteries may power electric and hybrid vehicles.
The market for quickly-rechargeable, light and compact batteries is huge. One or another battery will eventually evolve. When it does, electric-only vehicles are likely to have a range unthinkable using fossil-fuels. Moreover, in the meantime, hybrids are an excellent compromise. Furthermore, see also Electric Vehicles – Hybrids.
Charging your electric car at home or work.
Electric vehicle home charging for small electric cars is feasible at home or at work from a 15 amp power point. A power cable plugs into the car’s on-board charger. Most such vehicles have a charging unit inbuilt.
Some electric car dealers include a home charging assessment price and/or a consultation with a licensed electrical contractor as part of the car’s purchase price.
A typical electric of hybrid used for typical commuting (of 40-50 km a day) uses 2.5-5.0 kilowatt/hours. This, often called one 'unit’, usually costs less during off-peak periods .
This guide gives some indication of how many kilometres you can drive when charging typical electric cars from a home or similar supply at their maximum rate via that inbuilt charger.
Type: Maximum charge (kW). km per hour of charging
BMW i3 7.4 25
Chevy Spark EV 3.3 11
Fiat 500e 6.6 22
Ford Focus Electric 6.6 22
Kia Soul EV 6.6 22
Mercedes B-Class Elec. 10 29
Mitsubishi i-MieEV 3.3 11
Nissan Leaf 3.3 – 6.6 11 – 22
Smart Electric Drive 3.3 11
Tesla Models S & X 10 -20 29-58
Charging is readily done overnight but solar captured during the day can be sold to the electricity supplier.
Electric vehicle home charging - electricity costs (in 2020) across Australia.
Average prices (per kilowatt/hour) are:
Queensland: 22.72 cents
Victoria: 24.20 cents
New South Wales: 26.245 cents
South Australia: 36.223 cents
Tasmania 32.137 cents
Western Australia 28.8 cents
Most suppliers charge about 25 cents per kilowatt hour (off-peak). Even if not using solar it will cost only a dollar or two a day to travel the average daily 40-50 km to and from work. This is far less than for even small petrol-fuelled cars. Most use at least 5 litres per 100 km – typically costing (in mid 2020) about $7.
Meters for electric vehicle charging
You are likely to need an additional meter for a dedicated electric car charging tariff. It may also be necessary to have an electric charging point set up by your electrical contractor. You can save money if you switch to an economy tariff for off peak charging overnight. To be on an economy tariff, you must have a hard-wired dedicated EV charging point. A standard electrical power point isn't permitted as it does not take long to work out that’s a cheap source also for other purposes!
Electric vehicle home charging - charging from solar
If you charge from a home solar system you have added benefit of no CO2 emissions from this renewable energy source. That required will be the maximum 6.6 kW systems that currently enable rebates. Solar modules, however, are now so cheap that it is feasible to forgo that rebate.
Electric vehicle home charging - home charging set-up cost
The cost of home charging from grid power primarily varies with local electricity price tariff and charging options.
A Victorian electric vehicle report noted that installing a home charging outlet costs around $1,750 for the charging circuit wiring, plus <$100 for a standard electrical power point, up to $500 for a basic dedicated EV charging unit and up to $2500 for a more advanced such unit.
If your choice of charging rate exceeds the standard fuse or circuit breaker rating, those too must be upgraded – but that cost is not high. A licensed electrical contractor can advise re all this.
Before going too far check the varying electricity tariffs for electric vehicle charging, already offered by many electricity suppliers.
If solar power is to be used, in urban areas this is likely to best done by feeding into the grid and buying it back at off-peak rates. Here again – see Electric vehicles – solar charging.
Charging at public charging outlets
An ever-increasing range of service station fast and super-fast chargers charge at rates as high as 135 kW. They can already fully recharge an EV battery in around 30 minutes. In practice, owners will use these only during long drives – and rely on routine charging at home and whilst at work. Electric car vendors too offer this.
There are already fast charging facilities around Australia – including right across the Nullabor.
See: Charge Stations in Australia (https://myelectriccar.com.au/charge-stations-in-australia) or ChargePoint. Prices vary from state to state etc – much as does petrol right now.
Many existing home grid-connect solar systems have excess capacity outside peak periods. Solar energy fed in during the day can be re-drawn during off-peak periods, for much the same price, to charge an electric car. This is because many grid networks have excess capacity outside peak periods. Furthermore, such charging extends battery life: all dislike ongoing deep discharges.
It is already totally feasible to charge cars from home and office solar. Moreover, it is being done by many owners right now.
Electric vehicle history
Electric vehicles have existed for longer than most people think. They long pre-date petrol and diesel. This electric vehicle history by Collyn Rivers is an overview.
The first dc electric motor (1866). Pic: Siemens UK.
The electric battery was invented by Allessandro Volta in 1800. In 1820, Christian Oersted showed electricity could produce a magnetic field. William Sturgeon, (in 1825) invented the electromagnet. Inventors worldwide sought to build an electric motor. They used two main approaches. These were: rotating, or reciprocating (i.e. like early steam engines).
In 1834, Moritz Jacobi invented the first (realistically powerful) electric motor. By 1838 it was improved. It propelled a 14-passenger boat. Meanwhile (1835), Sibrandus Stratingh and Christopher Becker developed an electric motor. It drove a small model carriage. The first electric motor patent was granted to USA’s Thomas Davenport. Many US sources credit Davenport as ‘inventing’ the electric car. It was, however, only a small model. It had negligible power. In 1866, Werner von Siemens developed the basic DC motor. It was this that enabled the first electric cars. DC motors are used to this day.
Electric vehicles were also hampered by lack of stored energy. The only realistic source required constantly supplied diluted acid. These ‘batteries’ were like today's fuel cells. They combined hydrogen and oxygen to produce electricity. Such batteries worked. There is no record, however, of their powering electric vehicles.
The first lead-acid batteries
In 1859, Gaston Plante developed practical lead-acid batteries. They were bulky and heavy. Nevertheless, they made electric vehicles practical. Their first known usage (1897) was in New York's electrically-powered taxis.
The first electric powered taxi – New York late 1890s. Pic: taxifarefinder.com
Electric cars’ original acceptance was thus near the end of the 1800s. Most were quieter and smoother than early petrol-fueled cars. Electric cars started instantly. They needed no ‘warming. No gear changing was required. There were even hybrids. In 1916, the Woods Motor Vehicle Company developed a car with both petrol and electrical engines. See Electric Vehicles – Hybrids.
The electric vehicle market was primarily the USA. There was, however, some usage in Europe. London had electrically-powered taxis from 1897. They became known as ‘Hummingbirds’ – due their curious sound.
A London Hummingbird electric taxi – in use from 1897 for many years. They were designed by Walter Bersey.
End of an era
Electric vehicles of that era lacked adequate control technology. This limited speed to about 30 km/h (about 19 mph).
By 1920 or so, road structures (particularly the USA's) had massively increased. This was particularly inter-city. This required a vehicle range beyond that from batteries. These, however, remained similar in weight and size as 80 years before. Moreover, recharging facilities were inadequate beyond urban areas.
Meanwhile petroleum became increasingly plentiful. This enabled it to power vehicles cheaper and further than electrically. Furthermore, mass production made them affordable. The result was Henry Ford’s (1908) mass-produced model-T. It killed sales of electric cars. Thereon, electric vehicles were used only where limited range was required. It was nearly 40 years before electric cars re-appeared.
In the late 1950s, Henney Coachworks and Exide Batteries developed an electrically-powered Renault Dauphine. It attracted some sales. It could not, however, compete in price with conventional cars. Production ceased in 1961.
General Motors EV1
In 1990 California's Air Resources Board briefly re-ignited interest in electric cars. Its mandate required U.S. major vehicle makers to have 2% of their products totally emissions-free if used in California. This resulted in General Motors producing its EV1. It was an electric-ony car.
Early EV1s had 16.5–18.7 kWh lead-acid batteries. Later EV1s had 26.4 kWh Nickel Metal Hydride (NiMH) batteries. The car was produced from 1996 to 1999. It was the first mass-produced and purpose-designed electric vehicle of the modern era.
Usage was by leasing only. Customers liked the EV1, but General Motors saw electric vehicles as unprofitable. It sought to cease production. In 2002 EV1 usage was ceased. General Motors repossessed all of them. Most were crushed. A few were given to museums, but with deactivated motors. The Smithsonian Institution has the only intact EV1.
Major US car makers then legally questioned California's emissions requirement. This resulted in relaxed obligations. That, in turn, enabled developing and producing low emissions vehicles. These included natural gas and hybrid engines, but not (then) electric-only.
The General Motors EV1. Pic: Wikipedia
The right concept at the wrong time
The electric car (and truck) back then was the right concept. But at the wrong time. It awaited control technology, and lighter and smaller batteries.
Control technology then improved dramatically. That of rechargeable batteries, however, did not. Moreover, the size, weight and energy stored in lead-acid batteries remained much as 100 years before.
In 1996, the University of Texas conceived the lithium battery. These store three to four times the energy as lead-acid batteries the same size and weight. They charge quickly and can release huge amounts of energy over a short time.
Now (late 2020), lithium batteries enable electric-only cars to travel 350-550 km (about 220-345 miles) between charges. This is still borderline. It is inevitable, however it is inevitable that battery technology will advance. One thousand kilometres (625 miles) is now seen as feasible. Moreover, so too are electric off-road vehicles.
It is feasible to use home and other solar (with or without grid-connect) to charge electric cars. For details on using solar to charge electric cars click here. Furthermore, articles on all aspects of electrics cars are being progressively published on this website. Moreover, these will include ongoing details of technology and charging.
Electric vehicle motors
Electric vehicle motors use one or other of the two main kinds of electricity: alternating current and direct current. Both are effective as electric vehicle motors.
Alternating Current (AC) is where electric current constantly reverses its direction. It is that used in grid power supplies. In Australia and many other countries it cycles at 50 times a second. In America it cycles at 60 times a second.
Tesla Roadster AC motor. Pic: Tesla.
The AC induction motors used in a few electric vehicles have a stator (stationary coils of wire). When AC current flows through it, the stator generates a rotating magnetic field. That in turn causes a rotatable armature to revolve. It rotates at the rate of the AC current: i.e. at 50 or 60 times a second.
The relationship between AC voltage and its frequency enables changes in vehicle speed. The batteries' DC output is converted to AC by an ‘inverter’. All that required is an inverter that has variable frequency. This is effective, but not that efficient.
AC induction motors are often used in hybrid vehicles. These use electric drive for limited commuting. Efficiency and range are not seen as major factors. There is however an increasing trend to direct current (DC) motors for electric vehicles.
Electric Vehicle Motors - Direct Current (DC)
Direct current (DC) is a flow of electrons in one direction. Edison is often credited as conceiving it. It was, however, initially conceived (in 1800) by Alessandro Volta. The term 'Volt' commorates his name.
A basic DC motor has fixed external magnets. These surround a revolving armature that is an electromagnet. It also doubles as the drive shaft. Direct current is fed to this electromagnet via a commutator.
Electric Vehicle Motors - commutators & brushes
The commutator is a basic DC motor's weak point. It is a small ‘drum’ made of an electrically-insulating material. This drum has a number of copper segments. Carbon brushes, that conduct the DC current, are sprung against these segments.
The direct current is fed to the revolving armature via those brushes. This creates a magnetic field in the armature. The magnetic field causes the armature to spin through 180 degrees. A further mechanism causes the current fed to the brushes to reverse the DC’s polarity for the second 180 degrees. And so on.
While these motors work well, the carbon brushes sprung against rotating segments, wear out. They also constantly spark. This is a potential fire hazard. Moreover, it causes electrical 'noise' that must be suppressed.
A few electric vehicles use basic DC motors originally designed for other purposes. There are, however, many variants that combine the benefits of both AC and DC.
A DC electric motor’s commutator. One carbon brush is attached to the yellow lead. A second (out of sight) is on the left.
Brushless DC motors
A Brushless DC motor (BLDC), is in effect a DC motor turned inside out. It has permanent magnets on the rotor that generate a rotatable magnetic field on its outside. An electronic sensor monitors the angle of the rotor. Then, via high power transistors, it applies current to generate an external electromagnetic field. That field creates a turning force.
Brushless DC motor – Pic: original source unknown
Maximum torque at zero speed
Brushless DC motors develop maximum torque at zero speed. They are efficient electrically. Moreover, they have no brushes that wear out, and no need for internal cooling. Furthermore, this enables its internal bits and pieces to be free of contamination.
These motors produce far more torque than fossil-fuelled motors of comparable size and/or weight. They can rotate at far greater speed. They are relatively light and compact. Their available power is primarily limited by heat.
BLDC motors have minor downsides. They cost more to make than their brushed counterparts. Furthermore, d at present, the permanent magnets field strength is not adjustable. Work is in progress to make it so. Once achieved that will enable increasing maximum torque at low speeds when required. This is likely to be done by using neodymium (NdFeB) magnets.
Brushless DC motors cost more than most electric motors but are nevertheless proving commercially successful. They are used for Tesla’s Model 3. It seems likely they will dominate the market.
Electric Vehicle Efficiency & Emissions
This article, by Collyn Rivers, discusses electric vehicle efficiency and emissions. All road vehicles emit pollution (and are health issues). Emissions are in two main forms. One includes haze and particulate matter. The other are 'greenhouse gases’, These include carbon dioxide and methane.
Vehicle pollution – 2019. Pic: Original source unknown
Particulate matter from tyres
Tyres constantly shed particulate matter. It is mainly soot and styrene-butadiene. The smaller particulates are airborne. They are a minor cancer risk. https://ncbi.nlm.nih.gov/pmc/articles/PMC1567725/.
The larger particles are washed into lakes and rivers etc. Related data, however, is scarce. Sweden, calculates tyre particulates as about 150 tonnes yearly. Battery-electric vehicles are heavier than those fossil-fuelled. Their tyre emissions accordingly increase.
Particulate matter from brake linings
Brake linings cause particulate emissions. These were initially asbestos cadmium, copper, lead, and zinc. All are now banned. They are now fibres of glass, steel and plastic. There are also antimony compounds, brass chips and iron filings. Also steel wool to conduct heat. These particulates disperse directly into the air. Their antimony (Sb) content may increase cancer. Most electric vehicles reduce speed by regenerative braking. This reduces brake lining emissions.
Many hybrid and most electric cars have regenerative braking. When needing to slow or stop your car's drive motor acts as a generator. This charges the vehicle’s batteries.
Regenerative braking assists thermodynamic efficiency in all electric vehicles. Not just hybrids. It also reduces braking emissions.
Regenerative braking: whilst braking the drive motor acts as a generator, thereby charging the vehicle’s batteries. By doing so the vehicle’s kinetic energy is saved and stored for propulsive use. Pic: reworked from a concept of the Porter & Chester Institue, Connecticut, USA.
Electric vehicles produce negligable direct emissions. Hybrids produce no tailpipe emissions in electric mode. They have evaporative emissions, mainly during refueling. Their overall emissions are lower than those of 100% fossil-fuelled vehicles.
Indirect emissions from fossil-fuelled power stations
An Australian electricity power station. Pic: SMH.com.au.
Electric vehicles run from grid power must include power station emissions. Most of Australia’s power stations are fossil-fuelled. At an averaged 920 kg CO2-per megawatt/hour, ost are below average global efficiency. None rivals China's 670–800 kg per megawatt/hour. India has many inefficient fossil-fuelled power stations, but is the world-leader of large-scale solar power. No fossil-fuelled power station, however, converts more than 40% of heat into electricity.
Some 78% per cent of the electricity generated by Australia's power stations is from coal. Gas accounts for just under 10%. The remaining 12% or so is from hydro, wind and solar.
Due to Australia's power stations emissions, it seems pointless to use an electric car powered via the grid network. When battery capacity permits, however, it makes sense to go all electric. This particularly if charged via solar. Or possibly via hydrogen fuel cells.
Future power stations
Australia is unlikely to build efficient fossil-fuelled power stations. Even reducing their existing pollution is enormously costly. Their output will inevitably be undercut by renewable energy. Wind plus solar and hydro systems are cheaper and simpler. Furthermore, (once apart from manufacturing and erecting) wind, solar and hydro is pollution free.
Quantifying petrol vehicle emissions
Oil-well to vehicle emissions must include extracting, refining and distributing. Furthermore, fossil fuel powered vehicle engines are about 25% or so efficient. The remaining 75% of the energy is lost.
Overall, every litre of burned petrol causes in 3.15 kg of CO2 emissions. About 81% is caused in burning the petrol, 13% by extraction and transportation, and around 6% from refining. Burning petrol's released nitrous oxide has 300 times the global warming potential of CO2.
A typical fossil-fuelled Australian passenger car uses about 9.0 km/litre. Driving just one kilometre generates close to 350 grams of CO2 equivalent being emitted into the atmosphere. This is about 4.8 tonnes of CO2 equivalent emissions per car per year.
Some major European vehicle makers disgracefully concealed their diesel engine emissions. They included software that detected the vehicle's emission were being checked. That software changed the engine's operating mode accordingly to indicate reduced emissions.
Huge technical efforts have since been made to legimately limit fossil-fuel powered vehicle emissions. It is now, however, recognised it is not feasible to reduce them any further. This is particularly so of diesel. Reduced vehicle weight and performance assists but vehicle makers globally are now (2020) accepting their post-2030 products will be all-electric.
Current battery technology restricts range between charging. All-electric cars are fine for typical commuting to and from work. For general use right now however, hybrids make more sense.
Most cars are driven about 14,000 km/year. They emit about 4.8 tonne/year. The Toyota Prius hybrid averages just under 30 km/litre. It emits 31% CO2 (about 1.5 tonnes a year). That is 3.3 tonnes less than a comparable petrol-powered car.
Toyota Prius Hybrid. Pic: Toyota
An increasing possibility is that hydrogen may replace oil as a global source of fuel. It can and is already being produced from fossil fuel. It can be done (and on a large scale) by passing an electric current through water. This now includes sea water. This enables it to be produced via both solar, wind-power and wave-power.
A so-called fuel cell enables hydrogen to be re-converted to electricity stored in so-called fuel cells. The fuel cell can then power an electric vehicle. This is not just conjecture. Many such vehicles now exist - mainly in California and Norway.
Australia’s main power stations - ages and emissions
Those known in terms of year built, and kilograms of CO2 per megawatt/hour (MWh) actually produced.
Stanwell (1996): 969 kg per MWh.
Bluewaters (2009): 982 kg per MWh.
Muja CD (1985): 982 kg per MWh.
Mt Piper (1996): 997 kg per MWh.
Collie (1999): 1004 kg per MWh.
Eraring (1982): 1011 kg per MWh.
Vales Point (1979): 1018 kg per MWh.
Callide B (1989): 1019 kg per MWh.
Bayswater (1986): 1031 kg per MWh.
Gladstone (1976): 1052 kg per MWh.
Lidell (1973): 1066 kg per MWh.
Muja AB (1969): 1285 kg per MWh.
Worsley (1982): 1324 kg per MWh.
A few of the above have now been (or soon will be) closed down.
Electric vehicles energy use
Regardless of its type of fuel, the energy drawn by any road vehicle is a function of three main factors: air drag, accelerating and braking, and rolling resistance. Electric vehicles energy use is no exception.
The Tesla 3. Pic: Tesla
This relates to frontal area and aerodynamics, and particularly to speed. The reason speed so matters is that energy use rises with the cube of the speed). It is thus also affected by driving into prevailing wind. This is not usually a major factor in most countries. It is, however, very much so on Australia’s 1675 km (141 miles) Eyre Highway. Often called the Nullarbor, the highway links South and Western Australia. It is very close to the ocean for much of the way. That wind tends to be either from in front or behind, and can be as high as 30-40 km/h. If driving into the 30 km/h wind at 90 km/h, for electric cars that’s a battery flattening equivalent 120 km/h.
Wind resistance is a powerful reason for driving anticlockwise around Australia. One drives north around September, around the top during winter, then back down the west coast and to where one started in late summer. This should result in a following wind for the west and east crossings.
Electric-only vehicles of today are most suited to urban driving. As battery technology inevitably advances, and charging facilities increase, these will be decreasing issues.
The (2016) Chevrolet Voltec electric vehicle motor and transmission. Pic: Chevrolet.
Acceleration & braking
The energy involved in acceleration and braking relates substantially to the laden weight of the vehicle. Existing batteries are far heavier than their range-equivalent petrol or diesel. An electric vehicle motor and transmission, however, is simpler and lighter. Moreover, it is also 80% to 90% efficient (a fossil-fuelled engine is only 25%).
BMW i3 ultra-light carbon-fibre body shell saves weight. Pic: BMW.
Body shells can be made much lighter: BMW’s i3 electric car has an ultra-light carbon-fibre body shell. This cancels out much of the battery weight. That extra battery weight, however, is expected to be a short-term issue. As our article Electric Vehicle Batteries notes, huge efforts are in progress worldwide to reduce the weight of rechargeable batteries. This will also enable a longer range between recharging.
Rolling resistance is directly proportional to minor friction losses, minor heat loss due to tyre wall deflection (<3%), and speed. That of fossil-fuelled,and an electric vehicle’s rolling resistance, is thus the same. There is, however, one considerable energy advantage of electric (and hybrid) vehicle over internal-combustion engined vehicles. It of simple and effective regenerative braking. This recovers the kinetic energy that would be otherwise lost in heat-generating braking. It works by an electric car’s motor momentarily acting as a generator and charging the batteries.
Stop/starting in traffic
In recent years, petrol and diesel engine cars have a (usually optional) engine stop/starting system for use in congested traffic. Whilst this saves fuel, electrical energy is used for each restart. Moreover, electric cars will have a considerable edge as no energy is drawn whilst at rest, nor extra when restarting.
Electric vehicle hybrids
Electric vehicle hybrids are powered by either or both electricity and fossil fuel. They are far from new. In 1898, Ferdinand Porsche developed a hybrid car (the Lohner-Porsche). Its petrol engine ran a generator powering electric motors in its front wheels. The car had a range of 60 km (about 37 miles) from batteries alone.
The 1898 Lohner-Porsche- the first hybrid car. Pic: Original source not known.
In 1905, American H. Piper applied for a patent for a petrol-electric hybrid vehicle. It was claimed to reach 40 km/h (25 mph) in ten seconds. The patent took a long time before granting. By the time it was, petrol-fuelled vehicles achieved similar performance.
Woods Motor Company Dual Power
The best-known early hybrid is the Woods Dual Power Model 44 Coupe. It was made from 1917-1918. The vehicle had four-cylinder 10.5 kW petrol engine. This coupled to an electric motor. The motor was powered by 115 Ah lead-acid batteries. Below 24 km/h (15 mph) the car ran from electricity. Above that, the petrol engine took over. Maximum speed was about 55 km/h (34 mph). Much like today's hybrid cars, it had regenerative braking. Reversing was by causing the electric motor to run backwards.
The Woods petrol-electric hybrid. Pic: courtesy of Petersen Automotive Museum Archives
The Woods car was promoted as having unlimited mileage, adequate speed and great economy. Also that it was faster than most electric cars. It was very costly. Only a few hundred were sold.
The first era of electric cars was ending. Whilst quieter, none could compete with Ford’s petrol Model T. Furthermore, battery development was static. Moreover, there was thus little incentive to develop electric motive power.
Hybrid development re-arose in the USA and Japan. Due to increasing air pollution, in 1966 the U.S. Congress recommended electric-powered vehicles. One (in 1969) was General Motors’ experimental hybrid. It used electric power to 16 km/h (10 mph). It then used electric and petrol power until 21 km/h (about 13 mph). From thereon it ran on petrol. Its maximum speed was about 65 km/h (about 40 mph).
The Arab oil embargo (1973) increased interest in electric powered vehicles. One result was Volkswagen’s experimental petrol/ battery hybrid. It was not, however, mass-produced. Another was the US Postal Service trialled battery-powered vans.
In 1976, the USA encouraged developing hybrid-electric components. Furthermore,Toyota built its first (experimental) hybrid. It used a gas-turbine generator to power an electric motor.
In 1980, lawn-mower maker Briggs and Stratton developed a hybrid car. It was driven by a twin cylinder 6 kW engine. It ran on ethanol, an electric motor, or both. Twin rear wheels bore 500 kg of batteries. It could travel 50 to 110 km (31-70 miles) in electric mode, and about 320 km in hybrid. The car was a promotion for the maker's lawn-mowers. To put it mildly, its adverse power/weight limited performance. Its reported time to reach 80 km/h (50 mph) in combined mode was 35 seconds. By comparison, even today's slowest cars need only a few seconds.
The Briggs and Stratton hybrid. Impressive visually –but seriously underpowered.
A battery boost
A major boost for hybrid vehicles was the USA’s (1991) ‘Advanced Battery Consortium’. It aimed at producing a compact battery. The US$90 million cost resulted in nickel hydride batteries. These had about three times the capacity of comparable lead-acid batteries. This was still less than needed. It did, however, enable a new generation of electric vehicles. Hybrid and otherwise.
Toyota’s ‘Earth Charter’
In 1992 Toyota outlined its ‘Earth Charter’. Its intention was to develop and market vehicles with minimal emissions. Also that year, the USA sought low emission cars. The aim was fuel usage under 3.0 litres/100 km. Three prototypes (all hybrids) resulted. For likely political reasons, Toyota was formally excluded.
That decision back-fired. It prompted Toyota to create the Prius. That car initially went on sale, in Japan, in December 1997.
The original (1997) model NHW10 Toyota Prius. This initial model was sold only in Japan. Some, however, were imported privately into many countries. Pic: Original source unknown.
The initial version’s petrol engine produced 43 kW. Its electric motor produced 29.4 kW. It was powered by nickel-metal hydride batteries. Torque (at zero rpm) was 305 Nm. Later models had a larger petrol engine. It produced 53 kW and 115 Nm torque.
The car was an instant success. Some buyers waited six months for delivery. The Toyota Prius was launched in Australia in 2001.
In 1997, Audi mass-produced a hybrid. It was powered by a 67 kW 1.9-litre turbo-diesel engine. It also had a 21.6 kW electric motor. This was powered by a lead-acid gel battery. The car, however, failed to attract buyers.
Audi's experience caused Europe to concentrate on reducing diesel emissions. Doing so, however, had 'limitations'. Because their emissions fell far short of EU requirements, some makers illegally disguised the true levels.
Meanwhile, most electric and hybrid development was in the USA and Asia. Progress in Europe was initially slow. Now, however, (2020) there are many European electric and hybrids.
Owned by BMW, the first Mini hybrid had a 1.5-litre three-cylinder petrol turbo engine. Its electric motor had 65 kW of power and 165Nm of torque. It was powered by a 7.6kWh lithium battery. BMW claims it can travel to 40 km (about 25 miles) on electric power. A later version has a claimed 47 km (29.3 miles) range. Fuel economy is claimed to be 2.1 litres/100km. CO2 emissions are claimed to be 49 g/km.
Mini hybrid –the Countryman S E ALL4. Pic: https://www.mini.co.uk
BMW’s own hybrid initially used a 0.65 litre petrol engine to charge the drive battery (if needed). The car has since been replaced by an all-electric version. The 42.2 kWh battery enables a claimed range of 310 km (194 miles).
Porsche has two hybrids. The 2019 Cayenne E-Hybrid has a 3-litre turbocharged petrol engine. It is claimed to produce 250 kW and 450 Nm torque. An electric motor adds an additional 100 kW. Plus 400 Nm torque.
The Porsche Panamera 4 (hybrid) is much as the Cayenne hybrid. Its Turbo S E-Hybrid has a twin-turbo 4.0-litre V8 petrol engine. It develops over 505 kW and 850 Nm. Its claimed all-electric range is 22.5 km (14 miles). Furthermore, it is claimed to use 4.9-litre of petrol per 100 km (62 miles).
Volvo's aim is to have either 'mild' hybrids, plug-in hybrids or battery electric cars by 2021. It plans to sell one million hybrids. Its V40 model will have a choice of engines, plus a rear axle-mounted electric motor.
Hybrid off-road vehicles
Hybrid drive works well off-road. The electric motor increases power. The fossil-fuelled motor extends range. Few however, meet 2020 Euro 7 emissions requirements. Fortunately, many have ample space for batteries. This eases their possibly legally required future conversion.
One example is the Lexus RX 450h. It retains its 3.5-litre V6, but has three electric motors energised by a 123 kW battery. This only marginally increases power (i.e. from 221 kW to 230 kW). It does, however, reduce fuel consumption. That claimed is from 9.6 litres/100 km (62 miles), to a commendable 5.7 litres/100 km.
Lexus 450h. Pic: Toyota
The Mitsubishi Outlander LS and Exceed have a two-litre petrol engine and twin electric motors. They can travel up to 55 km on their lithium batteries. Their claimed fuel usage is 1.7 litres per 100 km (62 miles).
Mitsubishi (2019 Outlander hybrid. Pic: MitsubisiNissan’s
The Nissan Pathfinder Hybrid is available in 2WD or 4WD. Each has a 2.5-litre cylinder supercharged petrol engine of 201 kW and 330 Nm. Its 12.3 kW electric motor is powered by lithium batteries. These are charged by the engine’s alternator, and regenerative braking. Fuel use is a claimed 8.6 litres per 100 km. The battery packs are under the forward-most part of the boot floor.
Subaru’s XV Hybrid uses a 2.0-litre, flat-four direct-injection petrol engine producing 110 kW of power (down from 115kW in the rest of the range) at 6000rpm and 196Nm of torque at 4000rpm. It has a lithium battery and electric motor to assist the petrol engine. It can be driven as electric only, electric motor assist or petrol engine only driving modes.
The Range Rover hybrid has all-new light alloy monocoque construction. It is unusual in being diesel-electric. The 2020 PHEV P400e's combined power is 297 kW. The maker claims a range of up to 48 km (30 miles) in electric mode. Regenerative braking assists charging.
The Range Rover Evoque hybrid. Pic: landrover.com
The Land Rover is (now) much the same vehicle. It is, however, marketed as a more serious 4WD. It is, however, not necessarily cheaper. A few models (e.g. the LR4 HSE LUX) are more costly than Range Rovers.
Hybrid vehicles and emissions
When comparing emissions, fossil-fuelled power station efficiency needs taking into account. Most convert about 38% of their fuel into usable energy. Petrol burned by cars converts only 25%.
Energy is also lost in producing petrol and diesel. It is also lost in conveying electricity from power station to electric outlets. Furthermore, in charging electric (and hybrid) car batteries.
The National Transport Commission report assesses CO2 emissions intensity of passenger cars and light commercial vehicles in Australia. The data shows average CO2 emissions of all new cars sold in Australia during 2019 was 180.5 g/km. This is far higher than for new passenger vehicles in Europe. There, (using provisional European data) it was 120.4 g/km. Moreover, corresponding figures in Japan and the USA were 114.6 g/km and 145.8 g/km, respectively, in 2017. As that if latest available data, such emissions are almost certainly now even lower.
The National Transport Commission report reveals that Australia’s result is largely due to the increased popularity of dual cab utes and SUVs. These are three largest CO2 contributing vehicle segments. Furthermore, there are also few Australian government incentives for lower emissions vehicles. Moreover, Australia's fuel prices are low compared with Europe.
In 2019 Suzuki is reported as having the lowest average emissions intensity (128 g/km). Ford is reported as having the highest (210 g/km). A Prius Hybrid emits 107 gram of CO2 per km.
Emissions: petrol versus diesel
On average, the CO2 emissions of diesel cars (127.0 g CO2/km) are now very close to those of petrol cars (127.6 g CO2/km). Moreover, that difference, of only 0.6 g CO2/km, was the lowest observed since the beginning of the monitoring. Diesel emissions, however, are more harmful. Furthermore, they are all-but impossible to reduce much further.
The majority of new SUVs registered are powered by petrol. Their average emissions are 134 g CO2/km. This is around 13 g per CO2/km higher than the average emissions of new petrol non-SUV passenger cars.
Solar-powered electric vehicles
If adequate solar energy is available an all-electric car is virtually non-polluting. There is a minor emission of rubber particles from the tyres. However, there is no equivalent of 'tailpipe' emissions.
Battery making, however, is seriously polluting. It is common to hybrid and all-electric cars – excepting that the latter have larger capacity batteries. See also Solar Charging Your Electric Car at Home.
An initially promising all-terrain electric car (the Tomcat) was designed and built in Australia in 2012. The first 100 sold out almost immediately. High manufacturing costs (and investor concerns) resulted in the company entering voluntary administration in February 2018.
The all-terrain electric Tomcat – sadly no more. Pic: Tomcat
The Electric Vehicle Series
This is a part of a series of articles about the history and technology involved in electric vehicles.
Fuel cells for homes and properties
Fuel cells for homes and properties provide clean silent electricity. High current prices hinder their acceptance, but this may soon change. Fuel cells enhance solar. Furthermore, they may all but eliminate our need for battery storage. Fuel cells hugely reduce harmful emissions.
Fuel cells for homes and properties provide clean quiet electricity. This article explains how, why and when they will be used. Fuel cells for homes and properties may all but eliminate battery storage. Moreover, fuel cells slash harmful emissions. This is a major bonus for all-electric cars.
The Panasonic fuel cell in the German Vitovalor product. Pic: Viessmann.
In 1839 Sir William Grove invented the first fuel cell. Petroleum was then found in abundance, resulting in fuel cells being overlooked. NASA later revived them.
Fuel cells for homes and properties - how fuel cells work
Fuel cells generate electricity. They do so via hydrogen reacting with oxygen. Heat, electricity and ultra-clean water-vapour results. Fuel cell chemistry is complex, but having no moving parts is a bonus. Fuel cells are easy to use, ultra-reliable and silent.
Hydrogen that fuel cells does not exist in free form. It can be produced from water, biomass, minerals and fossil fuels. Furthermore, it is readily produced from solar energy. Moreover, hydrogen is an energy multiplier and carrier. So, rather than using batteries, hydrogen can alternatively store energy. This is already being exploited (see below).
Fuel cells for homes and properties - hydrogen (how safe)
All fuels store energy. They have to be volatile. But unlike most fuels, hydrogen is not toxic. Furthermore, spilled hydrogen quickly evaporates. It leaves only tiny amounts of ultra-pure water.
Some quote the Hindenburg disaster. This airship used a huge volume of hydrogen contained within the airship's outer skin. That skin was cellulose nitrate plus aluminium flakes. Rocket fuel uses the same products. That of the Hindenburg's finally ignited.
Commercial hydrogen is stored in strong tanks. These are tested and certified accordingly. The risk is no higher than if containing any other fuel. read more...
Convert to your own all solar home
This vital easy to read guide shows you how to convert to your own all solar home at minimal cost. You can readily do this between 50-degree latitudes north/south. This easy to read article shows that to to convert to your own all solar home can save you thousands of dollars.
This article shows how to convert to your own all solar home. Do that and you can slash your power bills to virtually zero overnight. Our current home north of Sydney (Australia), when bought in 2000, drew over 35-kilowatt/hours a day. Whilst over twice that typical it did not worry us. We knew how to slash that by 30% or more overnight at zero cost. How you can do this too is outlined below. It is your first step to having your all solar home. It needs only a tiny, but vital, change in what you and your family do but it can save you thousands of dollars! From there you continue to reduce energy use - and only when that is done do you start thinking of how much solar you need.
The above is not how professional solar installers work. They may suggest a change to LEDs but otherwise calculate the energy you use, add a bit on top, and advise solar capacity accordingly. It is a quick and easy approach, but you will need a huge amount of solar to avoid paying power bills.
Convert to your own all solar home - wall warts suck!
Wall warts are those little grey or black boxes plugged into your power outlets. They enable you to turn off your lights, radio, TV etc by their remote controls. A typical home has 20 to 40 of them. Each draws only a tiny amount of power but do that day and night. Many draw far more power than whatever they control.
These wall warts typically suck a third or so of total electricity usage! Fixing the issue is simple. Turn off everything at all switch - never by the remote control alone.
Convert to your own all solar home - change the light globes
A further major energy user is incandescent light globes. They create a great deal of heat and some light. Many countries ban their sales. Fluorescent globes draw less, but the latest LEDs (Light Emitting Diodes) use only 20% or so of the energy of those incandescent globes and 50% of fluorescent globes. They cost more initially but have a far longer lifespan - typically many years. Many directly replace your existing globes. Almost all are available in warm white as well as the cooler light often used in kitchens. You can use some with existing wall dimmers. You can buy LEDs in Edison screw as well as for bayonet fittings.
This Philips 230 volt Edison screw LED produces 4-5 times more light than its incandescent predecessor.
Changing the light globes should be your next step when you convert to your own all solar home. You do need to spend money to do, but that which you saving over time is huge. Hint: You can often buy LED globes in bulk at a major discount.
Convert to your own all solar home - heating
Many homes have gas or electric radiator heating. It is far more efficient to heat your home by using reverse-cycle air-conditioners, using their heating cycle. By utilising so-called 'latent heat' this provides up to four times more heat for the same amount of electricity as electric radiators of the same nominal wattage.
Reverse-cycle air-conditioners vary in efficiency. All reveal their so-called CoP (coefficient of performance): in effect, the amount of cooling or heating (in watts) for the watts actually drawn. Top units (such as Daiken) have a CoP of about 4.0. The higher the CoP the more efficient it is.
If your home has heavy walls, heat it during the day (if/when solar is available). Reduce the heat setting during the evening. read more...
Updated November 2020
Hydrogen electric vehicles
It is increasingly realised (and accepted) it is impossible to eliminate CO2 emissions from fossil-fuelled engines. Some vehicle makers even used fraud to disguise this. Globally, governments progressively ban fossil-fuelled vehicles. Part fossil-fuel hybrids too will be phased out. Meanwhile, oil costs increasingly rise as supplies diminish. We are already seeing production of hydrogen-electric vehicles. Furthermore, it is increasingly probable our global economy will be hydrogen-based. Doing so needs major changes. We may, however, have little choice.
Hydrogen electric vehicles - not a new concept
The first known internal combustion engine was invented In 1806, by Francois Isaac de Rivaz. It ran on hydrogen and oxygen. In 1863, Étienne Lenoir developed a single cylinder hydrogen and oxygen powered car. Records show that 350-400 sold.
Interest in hydrogen power then waned until 1933 when Norsk Hydro power converted a truck to run on hydrogen from reformed ammonia. It used the existing internal combustion engine. While coal gas is not 100% hydrogen, vehicles ran on it during WW2.
Norway's Asko goods vehicles run on hydrogen generated by using solar energy to split water. This produces emissions-free hydrogen and oxygen. SINTEF (a major European research organisation) states Norway could have 10,000 heavy hydrogen-powered vehicles by 2030.
Hydrogen can be produced in many ways
Industry uses hydrogen on an industrial scale. Most however, is produced from fossil fuels. This causes substantial CO2 emissions. There are, however, no common international standards re producing and transporting hydrogen. Nor for tracing its environmental impacts.
Currently, heat and chemical reactions release hydrogen from organic materials. These include fossil fuels and biomass. An environmentally better alternative is via passing electric current through water. This splits water into hydrogen and oxygen. This technology is called 'electrolysis'. It is already well developed and now feasible using seawater via solar or wind generated energy.
Another way ('photolytic') uses energy from daylight. This too splits water into hydrogen and oxygen. It is at research stage. If feasible, it will produce hydrogen with low environmental impact.
Bacteria and microalgae too can produce hydrogen through biological reactions. They use sunlight or organic matter. These technologies are at an early research stage. They have the potential for sustainable, low-carbon hydrogen production.
Hydrogen is not always 'clean'
Hydrogen is a versatile energy carrier. It's cost, however, depends on how 'clean' it is.
Green Hydrogen has zero carbon emissions. It is produced via zero-emissions sources. Wind and solar powered electrolysis is preferred because splitting water releases no carbon. One 1 kilogram of green hydrogen's energy can produce about 33.3 kWh. In 2020 it costs 3.50 to 5 Euros.
Blue Hydrogen is produced without carbon emissions, or has such emissions captured and stored or reused. Synthetic Blue uses carbon capture and storage and carbon credits etc to achieve net-zero emissions.
Grey, Brown or Black hydrogen is typically produced from natural gas or brown coal. Generating electricity with hydrogen-from-coal will result in roughly the same greenhouse gas emissions as burning coal in a power station.
Global hydrogen energy plans
The USA was the first country to establish hydrogen (and fuel-cell) technology. It was part of its 1970s energy strategy. In 1990, the USA passed the 'Hydrogen Research, Development And Demonstration Act'. This formulated a five-year plan for hydrogen energy research and development. In 2002, its Department of Energy issued the national Hydrogen Energy Development Roadmap. Its guidelines coordinated hydrogen energy development.
In 2012, the US Congress rewrote the hydrogen fuel-cell policy. It increased tax credits for hydrogen refueling properties. It created tax credits for efficient fuel-cells. In 2014, the government promulgated an Energy Strategy. This clarified a leading role of hydrogen in transportation. The National Fuel Cell and Hydrogen Energy Association was formed in 2015.
The USA's hydrogen and fuel-cell research and development was led by the Department of Energy. It was also supplemented by universities and research institutes etc. All were allocated funds.
In 2019, the USA's Department of Energy announced intentions to spend up to US$31 million. This was for low cost hydrogen production, transport, storage and utilisation. It later launched a partnership with fuel-cell makers. All focussed on advancing hydrogen's infrastructure.
Hydrogen electric vehicles - fuel-cells
A fuel-cell is part generator and part battery. It converts a fuel's chemical energy into electricity. The cell is continuously supplied with fuel and air (or oxygen). The output is clean DC. The only emission is ultra-clean water.
Fuel-cells have long been used in space applications. Many are installed in hospitals, schools, hotels, office buildings and countless RVs. They can supply both main and backup power. Some are powered from methane produced by decomposing garbage. Smaller fuel cells are powered by ethanol or methanol.
The first fuel-cell powered vehicles (in 2002) were from Daimler-Benz, Ford, General Motors and Nissan. http://fsec.ucf.edu/en/publications/pdf/fsec-cr-1987-14.pdf.
The USA's take-up of fuel-cell powered cars is slow but steadily growing. In 2020 approximately 10,000 are used in coastal California. The California Fuel Cell Partnership has outlined targets for 1000 hydrogen refueling stations. Also, for about one million fuel-cell electric vehicles by 2030.
Hydrogen electric vehicles - European Union support
The European Union (EU) is pushing a vehicle hydrogen-program for aviation and heavy industry. The EU’s CO2 legislation for passenger vehicles includes SUVs. If fossil-fuelled, the EU requires average fuel consumption of 150 km (92 miles) per U.S. gallon (about 3.8 litres) by 2030. This is a serious engineering challenge. Vehicle makers thus welcome an alternative CO2-free fuel. Hydrogen is by far the favourite.
Producing hydrogen in Europe is not a problem. It can utilise excess capacity from wind-farm. There is ample such capacity in Germany, Denmark, the Netherlands and Scotland. There is ample hydro-electric power in Switzerland. In Germany, hydrogen is currently burned as waste.
The EU regulations virtually require new cars in 2030 to be battery or fuel-cell powered. The (global) Hydrogen Council estimates that by 2050, hydrogen will power over 400 million cars and SUVs. Furthermore, up to 20 million trucks and five million buses. Moreover, it forecasts that hydrogen will, by then, provide 18% of the world’s energy.
David Wenger of Wenger Engineering Gmbh organises seminars on 'fuel-cells being inevitable'. He emphasises that investors are embracing hydrogen. Also, that companies like Toyota and Hyundai lead the way. 'People are starting to wake up to the benefits of hydrogen as industry tries to fulfil obligations from the Paris Agreement on Climate Change. Investors are moving in to help improve the product and lower costs.
Should car buyers go for fuel-cells rather than battery electric?
It is still being argued that producing hydrogen traditionally uses as much carbon dioxide as saved by via the fuel-cell process. Also that the renewable capacity from wind, solar and hydro-electric to provide enough hydrogen competitively doesn’t exist. And even if was, distribution and storage costs would be prohibitive. Far from all agree with that.
A 2020 California Energy Commission, report outlines a plan for developing renewable hydrogen production. It predicts that future hydrogen demand and costs makes this worthwhile. The key findings are: 'the dispensed price of hydrogen is likely to meet an interim target based on fuel economy-adjusted price parity with gasoline of $6.00 to $8.50 per kilogram by 2025.'
Fuel-cell car and other electric vehicle buying cost
Apart from lacking an adequate fuelling network, fuel-cell cars are expensive. The few currently for sale cost around US $60,000. That’s almost twice as much as comparable electric or hybrid vehicles. In California, however, fuel-cell powered vehicles attract up to $10,000 tax savings, and a $15,000 fuel card.
In addition to small volumes (large-scale fuel-cell vehicle production is yet to be industrialised) there’s also a need for the precious metal, platinum, which acts as a catalyst during power generation. The amount of platinum needed for vehicle fuel-cells has already been greatly reduced. 'The general goal is to bring down the price of hydrogen-powered cars to a similar level to that of other electric cars,' explains Rücker.
One reason why hydrogen fuel-cell cars are costly is their large size: their hydrogen tank(s) take up a lot of space. The motor for a 100% battery-driven electric vehicle, however, fits into small cars. That’s why electric cars are made in all vehicle classes.
Fuel-cell car and other electric vehicle running cost
A fuel-cell powered electric vehicle typically travels about 28 miles (45 km) on 1 lb (0.45 kg) of hydrogen. Currently, 1 lb (0.45 kg) of hydrogen costs around 14 $US in the U.S. In Germany, a joint venture (H2 Mobility Partners) will provide nationwide hydrogen refueling stations. The H2 Mobility's agreed price for 0.45 kg is the equivalent of 4.8 $US.
The cost per mile of running hydrogen cars in the USA is currently almost twice as high as that of battery-powered vehicles charged at home. BMW’s expert Axel Rücker expects these operating costs to converge: 'If the demand for hydrogen increases, the price could drop to around USD 2.50/lb (USD 5.60/kg) by 2030 forecasts Axel Rücker.
The cost of hydrogen fuel-cell vehicles has to include that of transporting and storing hydrogen. The gas can be in compressed liquid or gaseous form. The trend is towards compressed liquid. Either way, transporting and storing hydrogen is more complex and energy-intensive than for petrol and diesel.
Hydrogen electric vehicles - driving a fuel-cell powered vehicle
A fuel-cell car's propulsion is purely electrical. Driving one is similar to driving an electric car. There is virtually no engine noise. Furthermore, all accelerate well. This is because electric motors provide full torque at low speeds.
Another fuel-cell car's advantage is quick charging time. Depending on the charging station and battery capacity, fully electric vehicles currently require between 30 minutes and several hours for a full charge. The hydrogen tanks of fuel cell cars are refilled in less than five minutes: much as with refuelling a conventional car.
For the time being, hydrogen cars have a longer range than purely electric cars. A full hydrogen tank will last around 300 miles (approx. 480 kilometres). Typical plug-in electric cars travel about 160 km (about 100 miles) on a single charge. This range can be extended by having more battery capacity – but that increases vehicle weight and charging times. Fuel-cell vehicles, however travel 480 to 640 km (300 to 400 miles) per fill-up.
Hydrogen electric vehicles - summary
Hydrogen fuel cell technology can make ecologically sustainable travelling possible. This necessitates using renewable energy sources for hydrogen production. It also needs doing so in more places to shorten transporting.
In a recent (mid-2020 report) Bloomberg New Energy Finance, in alluding to the possibilities of a hydrogen economy, noted that it would take a global government subsidy of US$150 billion over 10 years to do so.
Electric Vehicle Series
This is a part of a series of articles about the history and technology involved in electric vehicles.
Interconnecting batteries in series or parallel is totally feasible. But its best to know how it works - and the limitations of each. Collyn Rivers explains.
Interconnecting batteries in series increases voltage. Current remains as before. Interconnecting batteries in parallel increases current. Voltage remains as before. No matter how connected, the stored energy remains the same.
A common need for series connection is that most batteries are two, six or twelve volt. Some vehicles, however, have 24 volt systems. These typically have two 12 volt batteries in series. Many stand-alone solar systems use 48 volt storage. These typically have four 12 volt batteries in series.
At common need for parallel connection is in systems above 100 amp-hour. A typical 12 volt deep-cycle 100 amp hour battery weighs about 32 kg. To ease handling it's common to parallel multiple such batteries. Lithium batteries of similar capcaity are one third the bulk and weight.
Interconnecting batteries in series or parallel - the pros and cons
Each way of interconnecting has its pros and cons. But not the same pros and cons. Nevertheless, if one needs over twelve volts, and/or substantial capacity, there's little choice. One must increase voltage or current. Or both.
A minus of series connection is that usage is limited by that of the 'weakest' cell. Series-connected batteries must thus be of identical type, capacity and condition. This is particularly so with LiFePO4 batteries. These also need monitoring to ensure all cells are at equal voltage.
Tapping 12 volts from one of two 12 volt series connected batteries is a no-no! This is because the battery that is less drawn on becomes fully charged sooner. This inhibits the other fully charging. The only remedy is disconnect, then charge each separately.
Obtaining 12 volts from a series pair can be done. It, does however, requires either equalising units (e.g. Redarc and GSL Electrics). Or a 24 volt to 12 volts dc-dc converter. These systems are commonly used on boats. There, 24 volts is used for winches, but 12 volts for most else. See 12-volts-dc-from-24-volts-dc/
Batteries parallel connected
Battery makers rarely oppose parallel connection. Most show how to do it. General Electric says 'there are no major problems with parallel charging.' Exide, however, is a little more cautious. It advises 'up to ten batteries may be interconnected without problem as long as certain precautions are followed'.
Paralleled batteries have socialist tendencies. Each takes according to its needs. Each gives according to its means. If two unequally charged batteries are paralleled, that more highly charged slowly discharges into the less highly charged. That continues until voltage is equal.
There is no problem parallel charging batteries of the same type and voltage but different capacities. They look after themselves. 'Each draws a proportionate share of the available charge. All reach about the same level of charge at roughly the same time,' says Ample Power Company. They discharge much the same way.
Ample Power company emphasises to connect paralleled batteries via equal length and size cables.
For 24 or 48 volts it is fine to parallel connect series-connected 12 volt batteries. That shown above is a bank of 16 batteries (each of 12 volt). They connected in series/parallel to provide 48 volts at 960 amp hours. Pic: author's previous all-solar house north of Broome.
Interconnecting batteries in series or parallel - what happens when a battery fails?
Traditional starter batteries may fail instantly. The cause is active material shed from the lead plates piling up in the bottom of a cell. Battery capacity relates to the lead that's left. Shedding thus causes ongoing loss. That loss is rapid if the battery is regularly over-discharged. The battery is then replaced. If shed material rises high enough to short circuit the plates, the battery fails instantly.
If a deep cycle battery is long uncharged, dendrite (a crystalline structure) forms during recharge. This causes a virtual 'short cicuit' across the cell. It kills the battery instantly.
Such failure is the most common forum argument against paralleling batteries. 'Just imagine,' some say, 'what happens if a fully charged cell in a big battery shorts itself out.'
Shorted battery cells - what really happens
What really happens in say) a 100 amp hour battery is that current will flow in that cell at a probable 100 amps. This is not a huge amount of energy. It may nevertheless cause the electrolyte to boil. As that happens current flow slows. It eventually stops. Meanwhile, adjacent cells heat up. Furthermore, as their electrolyte boils away, they too stop conducting.
The argument may extend to: 'What happens with possibly fully charged batteries paralleled across one with a 'shorted cell'. This, however, is like applying 12.5 volts across a (now five-cell) 10 volt battery. It's like charging a 12 volt battery at 15 volts. The warm dead battery become a slightly warmer dead battery.
The main risk is that hydrogen is created. But as long as a battery compartment is ventilated, danger is remote. 'Since the early 1960s . . . we have witnessed no dangerous situation that resulted from a cell short,' says the Ample Power Company.
Summary - interconnecting batteries in series or parallel
Parallel connection is convenient for large-capacity systems. Parallel connected pairs of series-connected batteries are convenient for higher voltage large-capacity systems.
Many property stand-alone solar systems run at 48 volts. This is usually by paralle- connecting strings of four series-connected 12 volt batteries.
The above applies to all batteries: conventional lead acid, gel cell, AGM and LiFePO4.
See also Lithium batteries in travel trailers
Any combination of the same batteries will always result in the same amount of stored energy.
Interconnecting batteries in series or parallel - further information
If you liked this article you will like my books. Batteries and their charging is fully covered in Caravan & Motorhome Electrics. That for solar in cabins and RVs is in Solar That Really Works. That for home and property systems is in Solar Success. My other books are the Camper Trailer Book, and Caravan & Motorhome Book. For information about the author Click on Bio.
• Ample Power Company 1990. Parallel Batteries, Seattle, Washington.
• General Electric 1979. The Sealed Lead Battery Handbook, Publication BBD-OEM-237, GEC, Gainesville, Florida.
• Linden. D 1984. Handbook of Batteries and Fuel Cells, 2nd Ed McGraw-Hill, New York.
• Also used for general reassurance: Barak M 1980. Electrochemical Power Sources: Primary and Secondary Batteries, 1st ed. IEE UK and New York.
Grid-Connect Solar Modules
Using grid- connect solar modules for RVs is readily done but needs an MPPT regulator. This article by Collyn Rivers explains how and why to do it.
Grid-connect solar modules are often sold very cheaply. Most however produce optimum power at voltages that cannot be handled by the 12-24 volt solar regulators used in most RVs. Using grid-connect solar modules for RVs is however readily done by using an MPPT (Multiple Power Point Tracking) solar regulator. These accept a much wider voltage range. Grid-connect solar modules for RVs can also be used in stand-alone solar systems. This article by Collyn Rivers (Solar Books) explains how and why.
Grid-connect modules are made in a huge range of voltages and sizes. Those of around 300-350 watts tend to be the best value for money. Most output about 50 volts at 6-7 amps.
Grid connect solar modules for RVs - juggling volts and amps
An MPPT solar regulator 'juggles' incoming volts and amps to produce whatever needed to charge your solar system's batteries deeply, speedily and safely. For RVs such as camper trailers, travel trailers and motorhomes this is usually a (nominal) 12 or 24 volts.
Care is needed when buying an MPPT solar regulator when using grid-connect solar modules for RVs. Some accept any input voltage from as low as 9.0 volts to often well over 100 volts. But some work only from 9-36 or so volts. Others have an upper limit of about 50 volts. This will be shown in the maker's literature.
This 400 watt Morningstar MPPT solar regulator is ideal for smaller systems. It will accept input from solar panels up to a nominal 36 volts. (The maker emphasises its use with grid-connect solar modules for RVs.) Pic: Morningstar.
MPPT regulator do not need prior setting for incoming solar voltage. They do need setting for the type and voltage of the battery/s used (e.g. lead acid, AGM, gel cell etc), and usually for the capacity (amp hours). This is usually easy to do. If in doubt ask the vendor (or most girls or boys from 9-35).
The Australian-designed (now US-made) Outback Power MPPT units will accept up to 110 volts or so at up to 80 amps - ideal for larger systems on motorhomes, converted coaches - and home stand-alone systems. Pic: Outback Power.
Can I legally install grid-connect solar modules for RVs myself?
In Australia, it is legal for non-electricians to install grid-connect solar modules etc, as long as the solar array's nominal voltage does not exceed about 60 volts DC. You are unlikely to experience other than a tingle up to 24 volts. Care is still needed, particularly if working on the RV's roof. Anything above 50 volts or so can give quite a shock. Unless experienced in electrical work have someone who is to assist you. If the modules produce or are series-connected to produce above 60 volts dc, you must use a licensed electrician.
Be aware that many (probably most) ultra-cheap solar regulators are claimed to be MPPT - when they are not. Stay only with known brands.
Full details of all this, plus a great deal more is included in my books: Caravan & Motorhome Electrics, Solar That Really Works! and (for bigger systems) Solar Success. See also related articles (under Power/Solar) on this website. My other books are the Camper Trailer Book and the all-new Caravan & Motorhome Book. For information about the author please Click on Bio.
Electric and Hybrid Vehicles
As of 2020 it is realised that reducing fossil-fuelled vehicle to a safe level is impossible. Hence the trend to electric and hybrid vehicles.
Many countries are already banning (or will ban soon) the sale of fossil-fuelled cars. These include France, Canada, Costa Rica, Denmark, Germany, Iceland, the Netherlands, Norway, Portugal, South Korea, Spain, Sweden and the U.K.
Twelve American states adhere to California's Zero-Emission Vehicle (ZEV) Program. The USA's Trump administration, however, eased the requirement - from the mandated 5% a year – to 1.5% a year. Unless Trump is (improbably) re-elected, this situation is likely to change. Environmental bodies led by California have challenged Trump's backward step.
Globally, there is move to electric vehicles. Apart from minor rubber tyre particles they are virtually emission free. They are also about 80% efficient. If, however, their electricity is from fossil-fuelled power stations, their emissions are similar to year-2020 petrol fuelled (or hybrid) vehicles.
Dirty Power Stations
Electricity vendors promote grid energy as 'clean'. At present, however, that applies only to its usage. It's generation is mostly filthy. As of 2020, 56% of Australia's electricity is from centralised, carbon-intensive coal-fired power stations.These generate about one–third of all Australia's carbon monoxide emissions. About 21% is from gas. Such power station emissions are similar worldwide. The remainder is from wind and solar.
Fully electrically-powered vehicles are virtually non-polluting. Most are over 80% energy efficient. If, however, the electricity they use is from most current power stations, their emissions are no lower than of a 2020 model petrol or hybrid vehicle. It thus makes little environmental sense to use an electric-only vehicle unless that electricity is wind or solar generated. This already possible in South Australia. It is also totally feasible (for commuting at least) to charge an electric vehicle by using solar energy at your home or place of work.
Electric and hybrid vehicles - the energy required
Urban-living Australians drive an average 38-40 kilometres each day. Most electric cars use about 1.0 kW/h to travel about 5 km. An electric vehicle (used as above) thus uses about 8 kWh of electricity/day. Grid electricity, on long-term contracts, costs about 20 cents per kW/h. If so the fuel cost is a mere $1.60 daily. However, as noted above, using grid power results in no overall fall in emissions.
Unless you can solar generate about 8 kW/h for daily commuting, it is (in 2020) better to use a hybrid. A typical hybrid generates less pollution than an electric-only vehicle run from current power stations. While hybrids are to be progressively be phased out in Australia from 2030, it is probable that the power station issues will have then been resolved.
Electrical and hybrid vehicles - charging from home solar
For those with ample home or business solar, it is readily feasible to charge the battery (or fuel cells) from that source. Such charging can even be done overnight by selling daytime solar energy to a grid supplier. You then repurchase it (often at low off-peak rates) at night. Or, to have ample solar energy available where the vehicle is parked during the day. Where ample sun access is available, there is a business opportunity for parking stations to provide vehicle battery charging. read more...
Have portable solar in your rented home
You can easily have portable solar in your rented home. Here’s how to do it simply, safely, legally and cheaply using readily bought parts.
You can easily have portable solar in your rented home. Here's how to do it simply, safely, legally and cheaply using readily bought parts. Doing so requires space that faces the sun for some daylight hours year-round. It works best within 50 degrees latitude north or south. Use high efficiency (plus 20%) solar modules to maximise input. You must not connect the system to any fixed mains wiring. This precludes using existing lighting. Use portable light fittings instead. Also, slash lighting cost by fitting LEDs. You take all that when you leave.
Have portable solar in your rented home - here's how
Group electrical units that you use at much the same time. Examples include a home office, child's study or entertainment centre. Depending on individual needs, make-up one or more systems, each accepting solar input. You can do this by using readily available portable inverter/chargers and battery packs. Grouped electrical devices connect to a multiple power board that can switch each socket individually. The solar unit then powers that board. If solar is adequate it can be used to power a second or more system.
Where and what you can use
Top solar modules produce about 180-200 watts a square metre. In most cases, your solar input is thus limited to about 500 watts. This will be a probable 1500 - 3000-watt hours/day if north facing. This runs computer systems plus LED lights, and good LED TVs up to 60 cm or so. It will not run air con, nor heating/cooking appliances.
All that's needed is stocked by solar equipment suppliers. The parts needed are used also in travel trailers and motorhomes. They readily interconnect. As pictured above, inverter-chargers combine all required apart from the battery. They are often buyable secondhand at bargain prices.
How to stop paying for electricity
How to stop paying for electricity is easy. This article shows how. Going almost totally off-grid is more affordable than ever. Now the electricity provider pays us. You can do the same - here's how.
Solar is now cheap
We always wanted to stop paying for electricity, and now we virtually have. It is getting easier to free yourself from dependence on the grid.
Many governments subsidise home solar. Most buyers, however, purchase only small systems: typically 1.5 or 2.4 kW (kilowatts). These, in Australia in early 2019 cost A$2500 -A$3000 installed. This helps reduce existing bills, but increasing solar capacity is truly worth considering.
Our (NSW government) subsidised 6 kW system cost us A$4350. It produces an average of 25-40 kilowatt hours a day. We initially paid the electricity supplier A$ 0.27 per kW/h for about three hours each night. We sold the daytime surplus (of an averaged 17 kWh/day) for a contracted 20 cents per kilowatt-hour for two years. This brought in about A$1200 a year. The initial cost of installation was A$4500. The result was then free power plus an increasing yearly income inside four years.
How to stop paying for electricity - adding battery backup to our solar array
As with many others, we prefer not to totally rely on grid-power - even as a back-up. Having self-built our own 3.8 kW stand-alone system in Australia's Kimberley, we knew that do this is totally feasible. But unless electricity exceeds about $1 a kilowatt/hour it is currently not a money-saving thing to do. Whilst going totally off-grid still appeals we settled on a compromise that is proving very satisfying.
We added a 14 kW/h Telsa battery bank that supplies our typical three/four kilowatt/hour early morning and evening energy draw, and copes with periods of overcast sky. As with any large solar array, even that still results in some solar input. The grid-connection has been retained - but mainly for selling our still considerable surplus. The grid acts now mainly as a 'belts and braces' back-up in the event of solar failure. It is occasionally drawn on to top up the Tesla battery bank - but rarely for more than about five hours a week (in early winter).
Our related book Solar Success explains and illustrates in detail how to a great deal of money when doing all of the above. Tens of thousands of people worldwide have bought it. We promise to return your full purchase price at any time if not totally satisfied. The digital version is downloadable right now by clicking on Solar Success. The print version is stocked by all Jaycar stores in Australia and New Zealand. It is also stocked by many bookshops in both countries - and can be ordered through them if not stocked. The book can also be bought by email (from anywhere in the world) from booktopia.com.au
Connecting Travel Trailer Batteries
Connecting travel trailer batteries is often misunderstood. This article explains what's possible, and why and how to do it successfully.
A typical travel trailer has an ongoing need for energy. And an occasional need for (high) power. Knowing the difference between energy and power truly assists.
Energy is the ability to perform work. It was originally estimated that a brewery horse could typically lift 33,000 pounds one foot in one minute. That amount of energy was thus called one horsepower. This now mostly expressed in watts. (About 750 watts is one horsepower).
Power is the rate at which energy is used to perform work. If that 750 watts is drawn for one hour, it's expressed as 750 watt hours.
That brewery horse's one-minute lifting is equalled, in a few hours, by a child. Horse and child exert equal energy. But the horse needs far more power.
Battery usage is similar. A starter battery is thus horse-like. It can exert high power. Starting a car engine however takes only two/three seconds. The energy expended is tiny. It's about that used by a 12 watt LED in ten minutes.
A deep cycle battery, contrarily, is akin to a marathon runner. Less 'power' but energy can be expended far longer.
Connecting travel trailer batteries - ensuring enough energy and power
As explained above - most RV batteries have two main (but different) requirements.
1. Enough power to cope with high peak loads.
2. Enough energy to cope whilst away from 230 volts etc.
This can be addressed in two main (but different) ways.
Different batteries - different characteristics
Increasing battery capacity increases available power. And, virtually by definition, more energy. There are, however, downsides. You must, for example, have the ability to recharge them. That charging must be both deep and fast.
Lead acid deep cycle batteries are heavy. Twelve volt versions weigh about 25 kg/100 amp hour. Their life is greatly reduced by frequent deep discharging.Their plus side is (relatively) low price. Plus ready availability.
AGM batteries are a compromise. They are physically rugged - thus suited to off-road use. AGMs can supply higher power than conventional batteries. They maintain charge far longer (12 months plus in cool climates). AGMs, however, are even heavier than conventional batteries. Discharge needs limiting to about 50%. If exceeded, their life is thereby curtailed. And they cost a lot more. (Gel cell batteries are similar - but less often used.)
Any 12 volt LiFePO4 battery above 18 amp hour supplies RVs peak power with ease. The energy capacity needed, however. is slightly less. This is because they can be routinely discharged to 10%-20% remaining. Another benefit is that (in RV use) they rarely drop below about 12.9 volts. They are about 35% of the weight and bulk. On the downside they cost far more. They must also have effective individual cell management. Buy only from vendors who truly understand them. These are, however, rare.
In practice, a 300 plus amp hour AGM will provide the peak power required for any RV. It also has ample energy capacity. AGM batteries are thus a good choice if space and weight permits
Connecting travel trailer batteries
To ease handling, (or obtain higher voltage, or higher current) batteries can be connected together. There are two main ways of doing so.
Series: consecutively positive to negative. Total battery voltage is the sum of each individual battery voltage. Total current is that of the battery that produces the least current. For example, were all batteries 100 amp hour, but one 50 amp hour, the total output would be 50 amp hour.
Parallel: positive to positive, and negative to negative.
Here, all batteries must be the same voltage, but can be of widely different capacity. The available current and capacity is the sum of each individual's current and capacity.
When connecting travel trailer batteries in parallel, it is, for example, just fine to parallel a 12 volt 10 amp hour battery across a 12 volt 500 amp hour battery bank. The result is a 12 volt 510 amp hour battery bank.
This battery bank (at the author’s previous all-solar powered property outside Broome, WA) had 16 batteries, each 12 volts and 235 amp hour. Each level has four such batteries in series. All four rows are parallel connected.The output is thus 48 volts and 950 amp hour. That's 45,120 watt hours (45.12 kW/h). Pic: solarbooks.com.au
Parallel connecting batteries is safe
Contrary to common belief, this is safe. Like good socialists each (battery) will thus take according to its need, and supply according to its capacity. See Interconnecting batteries in series or parallel re advised limits.
To increase both voltage and current, you parallel identical strings of series connected batteries. Here, the voltage is that of any one string. The amp hour capacity is the sum of all the batteries' capacity. Doing so, furthermore, is routine in large solar systems. They are typically 48 volts upwards.
Connecting batteries in series (end-to-end) thus increases total voltage. Connecting batteries in parallel increases total current.
In every case their total energy (i.e. watt hours) is the sum of each battery's energy so connected.
There is no magic way of increasing it.
Connecting travel trailer batteries - 6 volts or 12 volts?
Most travel trailers and motorhomes have 12 volt systems. As batteries are heavy, some owners prefer 6 volt batteries. To obtain 12 volts they are series-connected (positive to negative) as below. This results in the same current (as each 6-volt battery) but twice the voltage.
Series connection. If each 6 volt battery is 100 amp hour (600 watt hour) two series-connected such batteries hold 100 amp hour at 12 volts (1200 watt hour). Pic: solarbooks.com.au
If more capacity is required, further pairs of so-connected batteries are then wired in parallel as shown below.
Here, four 6 volt 100 amp hour batteries can hold 200 amp hour at 12 volts (2400 watt hours). Similar connection (but using 12 volt batteries) are used to obtain 24 volts in converted coaches with 24 volt alternators. Pic: solarbooks.com.au
A few travel trailers have only one 12 volt battery. Most, however, have two 12 volt, 100 amp hour batteries. The result is 200 amp hours (2400 watt hours.)
If four batteries, each of 100 amp hour are parallel connected, total capacity is thus 400 amp hours (4800 watt hours).
Ttypical battery bank for a largish RV. Four 12 volt 100 amp hour batteries store 400 amp hour at 12 volts (4800 watt hours). Pic: solarbooks.com.au
For most RVs, the highest (domestic) power need is likely to be a microwave oven. They draw about 130 amps for 5-15 minutes, typically via an inverter.
Any LiFePO4 battery used as the main RV supply will cope with ease. Such power can just be met by a 12 volt 200 amp hour AGM battery. But 300 plus amp hour is preferable. Some owners attempt this with 200 or so amp hour deep cycle lead acid batteries. They will supply such power for a short time, but doing so repeatedly shortens their life.
Connecting travel trailer batteries - Summary
The best way to increase available power for the same energy capacity is via batteries capable of doing so.
Conventional lead acid deep cycle batteries are the least so-capable. AGMs are better. If bulk and weight does not handicap, a 300-400 amp hour AGM bank readily provides RV power typically needed.
The highest power (by far) is from lithium-ion (LiFePo4). Any such battery will have ample power to drive whatever you wish. They also have more available energy capacity.They are however costly. Furthermore, they need specialised installation and charging.
Connecting travel trailer batteries - further information
Batteries and their charging are complex subjects. Caravan & Motorhome Electrics explains battery charging in depth.
If you liked this article you will like my books. They are technically accurate - yet in plain English. Other books are the Caravan & Motorhome Book, the Camper Trailer Book, Solar That Really Works (for RVs), and Solar Success (for homes and properties).
Solar Regulators with Current Shunts
If connected incorrectly, solar regulators with current shunts may register twice the true solar input. Here's why - and how to fix it.
An RV magazine article once described a solution to a non-existent problem. That Australia's sun can produce excess output that overheats solar regulators. It quoted a Plasmatronics PL 20 amp regulator as indicating 36 amps. And that from an 18 amp solar array. The article advised adding a cooling fan, That, it claimed, enabled the regulator to cope.
In reality the system's was producing 16-18 amps. That current, however, was being registered twice. Once as it flows through the PL 20 regulator. And again as it flows through the associated current shunt. Forum members sometimes post similar examples. And equally mistaken 'solutions'.
Ocasionally, your solar modules may briefly produce over their normal voltage. Their output current, is however, automatically limited. Your modules are thus not damaged by excess current. Your solar regulator likewise blocks excess current flow. There is thus no risk of overvoltage battery charging.
A cooling fan has merit in tropical areas. It may be advisable if air flow over the solar regulator is not feasible. A fan is otherwise not needed. Nor will a fan assist to increase your output.
Solar regulators with current shunts - return battery connection
When installing solar regulators with inbuilt monitoring, you must have the battery return path go directly to that battery. Furthermore, if a current shunt is used, it must by-pass that shunt. Moreover, details vary between solar regulators.
It is not feasible to show how do this in article form. Full details however are in Solar That Really Works! (for cabins and RVs). They are in Solar Success (for home and property systems). The issue is also covered in Caravan & Motorhome Electrics.
Inverters for Homes and Properties
How to choose inverters for homes and properties. Inverters convert the solar battery output into 110 or 230-volt alternating current. It is all-but-essential to use one. Using only 12-48 volts is too limiting for all but basic cabins.
Two Outback Power inverters are interconnected. Pic: Outback Power
User only inverters marketed as sine-wave (not modified sine wave etc). High-quality sine-wave inverters produce electricity that is 'cleaner' than the average grid supply. Other types do not. They may wreck sensitive electronics. There are two main types of sine-wave inverter:
Those transformer-based are bulky and heavy. This is rarely an issue for homes and properties. Their major plus is inherent overload capacity. Tools and domestic appliances draw two/three times they're running current whilst starting. Transformer units handle this with ease. Some produce twice or more their output rating for 30 minutes or so.
Transformer-based inverters up to 1500 watts will run from 12 volts. Those for up to 3000 watts require a 24-volt inverter. Anything over that needs 48 volts.
Only a few (e.g. Outback Power units) can be parallel-connected to increase output. This ability is uncommon. If you need, obtain written assurance of feasibility.
Switch-mode inverters are smaller and lighter. Few, however, have overload capacity. Most only sustain their rated output for a few seconds. The better quality units sustain 80% (of rated output) for constant use. Some, however, may only sustain 50%. Switch-mode inverters work best for loads that draw no excess starting energy. These are rare. Air-compressors draw many times they're running current whilst starting.
In Solar Books opinion, the best inverters for home and properties are those transformer-based.
Inverters involve complex technology. Our book, Solar Success explains inverters for homes and properties. Solar That Really Works! does likewise for boats, cabins and RVs. The top-selling Caravan & Motorhome Electrics covers inverters in detail. All our books are in digital or print versions. Digital ones can be bought right now. Click on a title (above). Print versions are stocked by all Jaycar stores in Australia and New Zealand and most Australian book shops. They are also available via email (and post) from booktopia.com.au
Grid connect solar problems
Grid connect solar problems include, false promotion and vendor claims, incompetent installation etc. Here's what vendors may not tell you.
Q. Must solar panels be at an exact angle?
A local installer says my existing 1.5 kW system's modules must be at exactly the same angle as my latitude. They are only a few degrees out). He say he can fix them for $1000 - so most days they’ll produce a lot more. Is this a scam?
A. Yes. He’s after your money!. In most areas plus/minus 5º makes less than 1% or so change. It may, however, result in a bit more in summer than winter - or vice versa. Less than that will make next to no change. It is, however, desirable to have them face more or less into the sun around midday. But, here again a few degrees does not matter.
Q Grid connect solar problems - do I need after-sales service?
My installer seeks $250 a year for ‘servicing and tuning’ my 1.5 kW grid connect system. Do I really need that?
A. This too is a scam. Installed solar needs no servicing, let alone ‘tuning’. Unless the modules are truly dirty, there is likewise no need to clean them. Occasional rain does the job. Our own grid connect systems (north of Sydney) remains unwashed since 2010. There is no measurable loss.
Q. Grid connect solar problems - do I need a tracking system?
I live in the south of Australia where the sun is much ‘lower in the sky’ in winter. My installer advise using a $5000 (plus $1000 installation) tracking system for my proposed 1.5 kW grid-connect system. He claims it will save the amount of solar capacity otherwise needed by about 30%. Is this true?
A. What he claims is true. But what he has not revealed is a lot!
Tracking systems are costly and need ongoing servicing. It is hugely cheaper to accept that loss. You can add another 450 watts more solar capacity for a probable $1250! And zero maintenance. Find another installer.
Q. Grid connect solar problems - how do I work out the grid-connect size I need?
I’d like to install enough grid-connect solar to halve my existing power bill. Installers say they need to calculate how much electricity is used and quote accordingly. Is there any way I can tell if they are selling me more than I need.
A. This is routine practice. The best way to start, however, is to reduce existing usage. We slashed the previous owner’s 31 kWh a day to 4.1 kWh a day summer and 6 kWh in winter.
It costs some money up front, however, savings are huge over time. That alone will fix that ‘halving’ you seek. Adding solar then - and only then, will drop it yet further. It is not feasible to explain how in an article. The first third of my book Solar Success shows exactly how to do it. It includes actual examples (including our own). Unless you do this, the installer will scale the system to existing usage. read more...
RV Solar and Alternator Charging
You can make RV solar and alternator charging work. It is complex on post-2014 vehicles. This ongoingly updated article explains how.
How RV solar and alternator charging works
A caravan or motorhome battery charges by connecting it across it a source that has a voltage that is higher than that battery has at the time. That battery neither knows nor cares whether that charge is from one source or several. Those sources must all be of closely similar voltage. Ideally, they are identical. If not, the battery will draw mostly from that with the highest voltage. Charging becomes complicated, however, once the battery/s approach full charge.
What happens then is that the controllers associated with each charging source mistake each other’s voltage for the battery. This may cause damaging overcharging. This is particularly so with AGM and LiFePO4 batteries. This applies also to simultaneous solar and generator charging. Do not attempt to do this yourself unless you know how. This explained in our book Caravan & Motorhome Electrics.
Suitable controllers for RV solar and alternator charging.
Most controllers sold for both solar and alternator charging, monitor both solar and alternator input but do not combine them. They switch to whichever has the higher input at the time. Solar Books recommends RV solar users to do likewise. This is particularly so with most vehicles made since 2010 or so and virtually all since 2014.
Issues with post-2014 RV solar and alternator charging
Prior to 2014 or so, vehicle alternators produced about 14.2 volts for some minutes after engine starting. This dropped to a more or less fixed 13.6 volts thereon. This, by and large, presented no issues for RV battery charging. Such alternators had a high enough voltage to charge a secondary battery in the vehicle to a usable level for leisure or auxiliary use. Ongoing emissions regulations however require minimising power usage. This (in 2014) extended yet further - to vehicle alternators of variable voltage. read more...
Solar shadowing - reducing the losses is like you partially unblocking a water pipe. Partial solar shadowing reduces your losses proportionally. Except in extreme clouding, however, solar modules produce some output. During daylight it's rare for you to have none.
Solar Shadowing - reducing the losses - bypass diodes partially assist
Most 12-volt solar modules have 60 cells. Each cell is connected in a string. A totally shadowed cell produces no current. Blocking one affects all.
Basic modules supply the current of the least producing cell. To limit this, good quality modules have three strings. Each string has 20 cells. Furthermore, each string has a so-called 'diode'. If activated, it carries current from unshaded strings. This assists, but is not a perfect solution. With only one cell shaded, output is slashed one-third. Furthermore, diodes are not reliable. One diode failing will prevent associated strings working.
A typical bypass diode. Pic: Original source unknown.
The ideal is a diode across each cell. Doing so, however, is costly. Worse, diodes fail more often than cells. Reliability is reduced.
Solar Shadowing - reducing the losses - the more effective ways
In basic systems, the lowest cell output limits your overall output. With multiple modules, shadowing one limits output of all. The loss is confined to the area shaded.
Power optimisers attach to existing solar modules. They maximise energy. Power optimisers also eliminate power mismatch. They decrease shadowing losses. Such optimisers can be built into solar modules. Or fitted separately. The concept works well.
Pic: Enphase micro-inverter (power optimiser)
Solar Shadowing - reducing the losses
Our books cover shadowing issues in depth. Solar That Really Works! is for cabins and RVs. Solar Success is for homes and properties. Caravan & Motorhome Electrics covers RV solar and general electrics. All are available in digital or print form. Moreover, our books also cover legal issues. Furthermore, you can download our digital versions right now. Click on the books' title (above). Print versions are stocked by all Jaycar stores. You can also buy them (from anywhere) from booktopia.com.au/
Solar Modules for Homes and Properties
This article shows how to know power output from solar modules for homes and properties. It shows how to optimise it for winter or summer.
Top quality solar modules catch 18% to 20% of the solar energy available. This is typically 140 watts-180 watts per square metre in full sun from about 10 am to 2 pm. Input tapers off before and after. Such modules are priced accordingly. Buy only top quality unless you have ample space for those cheaper but less efficient.
Solar modules for homes and properties - which way to face?
For maximum daily input, solar modules should face directly into the sun at mid-day: due North or due South. This is not always feasible, but the loss is not appreciable. Even if facing away from the sun at midday, you will still have worthwhile input. If in such situations (and you have room) simply add more solar modules. Their cost now is so low it will not cost much more.
Solar modules for homes and properties - at what vertical angle?
Most books and articles advise to tilt them at the same angle as your latitude (e.g about 33 degrees for Sydney, Australia). Errors of 10 or so degrees, however, make little difference in the yearly total. It is possible to increase winter input (at the expense of summer input) by tilting the modules more upright. Likewise, increasing summer input by having them closer to flat. At one time some people had them adjustable - but this is rarely feasible (or safe) if roof-mounted. But here again, if space is available, simply add solar capacity. This may require a larger solar regulator - it cannot 'overload' the existing regulator but it blocks current input in excess of its maximum rating.
Solar modules - shadowing losses
Another issue with solar modules for homes and properties is a loss of input when your solar modules are shadowed. Some loss is inevitable. The losses, however, with up-market modules is far less. Attempts to save money by buying cheap solar modules is counter-productive. There are also solar modules that each has a mini-inverter. With these, shadowing losses are reduced.
Solar modules for homes and properties - solar module types
There are two main types of solar modules for homes and properties: polycrystalline and monocrystalline. Until recently the latter produced more per square metre and priced accordingly. The best polycrystalline solar modules are now (2020) of similar efficiency and price. This is not an area in which to seek bargains. By and large, you pay dollars per actual watt. Not marketing watts!
Solar modules - the capacity you need
The minimum capacity you need varies according to your energy usage, your location and the time of year. See our article How much solar energy -where and when
How much solar capacity do I need
This article answers how much solar capacity do I need. It's valid anywhere in the world that has enough sun. It can save you a lot of money.
The map below shows the amount you typically have available in Australia. Generally, solar is readily feasible where the daily amount exceeds 3.5. It is still feasible below that but needs a lot more solar capacity. The map shows the amount of sunlight in kilowatt/hours per day per square metre. This refers to any unshaded horizontal surface.
The solar industry, however, in its non-technical publications refers to one kilowatt/hour per day per square metre as 1 Peak Sun Hour. This is usually abbreviated to 1 PSH. The concept is akin to measuring rainfall in a rain gauge.
Solar irradiation in Australia. The units are kilowatt/hours per day per square metre. They are more commonly referred to as Peak Sun Hours.
How much solar capacity do I need - solar module alignment
Ideally, solar modules face due north (in the southern hemisphere) and due south (in the northern hemisphere). You do not need to take this too seriously. If you are more than 20 or so degrees out, adding about 10% more solar capacity (per every extra 10 degrees will compensate).
In terms of tilt, having the solar modules at your latitude angle results in the maximum yearly average. If you need more input in summer than winter, tilt them closer to horizontal. If you need more in winter than summer, tilt them more steeply.
How much solar capacity do I need - assessing current energy use
Your next stage is to assess how much electricity you need per day (and also of any rare peaks loads). You can simply look at your electricity bill and see. Then consider what you can do to reduce the draw.
Almost any existing home has 30 or more so-called wall warts. These are the little black boxes that enable you to switch appliances remotely. Many made prior to 2014 (and all cheap ones still) draw 3-6 watts even when the related appliance is switched off. That may not seem much. If, however, you 30 of them (some homes have more) that's at least 90 to 180 watts, twenty-four hours a day (i.e. 2.16 to 4.32 kilowatt/hours a day. Worse, are items like 230 volt doorbells. One, personally experienced, drew a constant 40 watts, almost 350 kilowatt/hours a year. Yet activated a few times a week for a few seconds each time. Many a TV left on 'standby' all day draws far more a day than whilst being watched.
Items to replace - lighting
Replace all incandescent globes by LEDs. These provide better light at less than 25% of the same watts. LEDs last for many years: you recover far more their initially high cost over time. Be aware that 'wattage' no longer indicates light produced. Wattage is only a measure of the energy they draw. LEDs vary widely in this respect. Some are far more efficient than others. Their light output is shown in 'lumens'. Their efficiency is thus lumens per watt. Because of this, LEDs that are cheaper to buy are likely to use far more long-term energy.
Items to replace - appliances
Recently made high-quality refrigerators draw far less energy. Replacing any made prior to about 2014 will save you money, in terms of how much solar capacity you need.
Air-conditioners likewise vary considerably in the amount of energy they draw. Assess their efficiency by looking for, or asking for, their CoP (Coefficient of Performance). This is the ratio of energy draw and work done. The higher the CoP the better. By and large units from 1.5 - 2.5 kW have the highest CoP. They cost more initially, but you will save over time.
Generators for Home and Property Systems
A backup generator is close to essential for home and property stand-alone solar. You can choose to down without but doing so may triple the cost of that system.
Generators for home and property systems are often needed as it is rarely feasible to size such a system for a 100% reliable solar supply. It is rare to have no input, but there will be days when solar input alone cannot cope.
Having solar and battery capacity for 95% of the time is readily feasible but extending that to 98% may triple the cost! That 95%, however, still leaves about 18 days a year where solar will not cope. Having a generator also provides emotional comfort.
Generators for Home and Property Systems
The most-used approach is a back-up petrol or diesel generator, but LP gas versions are also available. You need one big enough to run a few essential items directly - but primarily for battery charging. You use the generator's 110 or 230 volts to drive a suitably scaled battery charger.
For homes and small properties, the larger Honda/Yamaha petrol-powered inverter generators used in up-market RVs are adequate for occasional use. For use to routinely charge batteries, the smaller diesel-power generators last far longer. Where noise is an issue with generators for home and property systems, Onan (Cummins) has a range of quiet units. These include generators that run on LP gas.
A few properties have a large diesel like the 25 kW Cummins Triton unit (below) scaled for massive (but rare) loads. Often essential for the larger outback properties areas but cheaper to hire a big mobile unit for a day or two for those with convenient city access.
Generators for Home and Property Systems - how to find out more
Full details of suitable petrol, diesel and LP gas generators are in our book Solar Success. This, as well as our other books: Solar That Really Works! (for boats, cabins and RVs), and Caravan & Motorhome Electrics for all aspects of the topic are now available in directly-downloadable digital form from our Bookshop. Print versions are available via all bookshops in Australia and many in New Zealand - and via email (right now) from booktopia.com.au.
Solar charging your electric car at home
Solar charging your electric car at home or work is totally feasible. This article explains how. Many people already do so. Small electric cars require only a 15 amp power point. The associated cable plugs into the car’s onboard charger.
Virtually all electric vehicles have a charging unit inbuilt. Consult the vendor about charging options.
If used for commuting 40-50 km a day, re-charging requires 2.5-5 kilowatt/hours. One kilowatt hour is often called ‘one unit'. During off-peak periods it may cost less.
Here’s a guide to how many kilometres you can drive before recharging.
Solar charging your electric car at home - how to do it
Solar charging your electric car at home or work is feasible. Many existing grid-connect solar systems have excess capacity. You capture solar during the day and sell the excess to the electricity supplier. Then charge the car at off-peak rates at night
Most Australian suppliers ask for about 25 cents per kilowatt-hour (off-peak). That is only slightly less than buying it back off-peak. It pays to shop around. All that's needed is a quote from one supplier. Armed with that, most existing suppliers will reduce that for a two-year contract. If not, change suppliers. Unlike most products, grid electricity is standardised.
Daytime solar can be re-drawn at night to charge at off-peak rates. Many owners do this. Such charging permits charging overnight, with top-ups as required. Furthermore, it also extends battery life. All dislike ongoing deep discharging.
Using grid power costs only a dollar or two to commute. This is far less than for petrol-fuelled cars. Most use about 7 litres per 100 km. That typically costs (in 2020) about $9/day.
Economy electricity tariffs
Electric cars can be charged on economy electricity tariffs. Charging this way requires a dedicated charging point. This costs about A$1,750. A basic electric car charging unit costs about A$500. More advanced units cost up to A$2500. A licensed electrical contractor will advise re this.
If your charging rate exceeds fuse or circuit breaker rating, they must be upgraded. The cost is not high. Moreover, you save money by switching to such tariffs for charging overnight. You need, however, to install a dedicated charging point. So-using a standard electrical power point is illegal.
Another meter may be needed for the charging tariff. If so, that can be set up by your electrical contractor. Dealers may include an electrician's advice in the car’s price.
You can reduce costs much further if you charge from a solar PV system. Furthermore, this also reduces carbon dioxide emission.
Charging at public outlets
Fast and super-fast chargers charge at up to 135 kW. They fully recharge an electric vehicle battery in 30 minutes. Owners use these only during long drives. They rely on routine charging at home and at work. Electric car vendors have charging services.
Fast charging facilities exist around Australia. They are even across the Nullabor Plain. See: Charge Stations in Australia (https://myelectriccar.com.au/charge-stations-in-australia). Or ChargePoint. Prices vary from state to state etc.
Electric Vehicle Battery Life
Battery technology is changing fast. Currently, most vehicle batteries' life depends on their routine depth of discharge. Fully charge the batteries each night and they will live longer.
Most electric and hybrid car makers guarantee batteries for eight years. Nissan allows for 160,000 km, and capacity loss for 5 years or 96,500 km. Australians typically drive 14,000 kilometres a year. This necessitates battery replacing after about eight years. Outright failure, however, is improbable.
It is already totally feasible to charge cars from home and office solar. Moreover, it is done by many owners right now.
RV Solar Basics
Until 2010, solar modules were so costly that intending users did complex sums to minimise the amount of solar input required. Those days have gone. Solar is now so cheap (<10% of that 2010 price) that the only limitation today is the space available for solar modules. It is not possible to have too much. Ample solar prolongs battery life. Following RV Solar Basics also ensures at least some output during overcast days. There is no risk of overcharging, nor overloading the associated solar regulator. The solar regulator blocks excess current.
RV Solar Basics - how much power will solar generate?
Excluding Australia’s mid-winter down south, expect about 140 watts per square metre of solar module area (over a typical 3-5 hours a day) most of summer. The solar irradiation of Sydney and north of Sydney may exceed 180 watts a square metre. Daily input varies – but for RVs used outside winter months, assume 80 watts a square metre for 3-5 hours. New Zealand (and Tasmania) has about 160 watts a square metre. period.
Solar input in tropical areas (when not raining) is, to many peoples' surprise, much the same as above - but most of the year round. This is because atmospheric humidity absorbs part of the irradiation. Furthermore, almost all solar modules dislike heat. As explained in greater detail below, they work best when very cold
A further issue in tropical areas is it also stays hot all night. Electric fridges only barely work in these areas because there is insufficient power to drive them. Moreover, warm beer on a hot Darwin night is unthinkable.
RV Solar Basics - solar module types
Solar modules convert light into electrical energy. A good quality 12 volt solar module has 36 cells. Each cell’s efficiency is 14% - 21%, but when all are interconnected, the resultant module’s overall efficiency is around 17% for poly-crystalline and about 19% for premium quality mono-crystalline modules (a few are now much the same). Despite this, most solar module makers claim that higher (cell) output.
Both types are heat sensitive: they lose about 5% for each 10 degrees C increase in ambient temperature. Amorphous cells are not heat sensitive but are less efficient, hence larger per watt. Most solar modules weigh about 1 kg per 10 watts but the latest hybrid modules weigh only a third of that.
Apart from claimed efficiency, due to heat and other losses, solar module output is usually 20%-30% less than claimed on the packing. The maximum output is revealed but in technical units.
Only a few solar cell makers assemble complete modules. A vast number of small companies assemble most from cells made by these companies. Quality can only be totally assured by buying a major brand product from any of the widely recognised top ten. They are - in alphabetical order:
Canadian Solar, EGing PV, Hareon Solar, JA Solar, Jinko Solar, ReneSola, Trina Solar, Suntech Solar, Tunto Solar and Yingli Solar. read more...
Solar battery breakthrough
An Australian development may make battery storage cheaper and safer.
Battery storage has long been the major cost of home, business and even caravan solar. Most new systems are now lithium-ion and costs about $1 per watt/hour (most home systems need 12,000-15,000 watt/hours).
This may well be slashed by a new Australian-developed battery (called Gelion) that uses zinc-bromide: a (claimed) much cheaper and safer technology than the lithium-ion batteries used now.
The zinc-bromide chemistry used by Gelion operates without the need for active cooling and enables 100% of the battery’s capacity to be used (most batteries are damaged or wrecked by that).
The Gelion company is based on work by Professor Thomas Maschmeyer, winner of the 2018 Eureka Prize for Leadership in Innovation and Science. The so called the Gelion Endure system is inexpensive, robust, safe, fully recyclable and scalable.
The company plans to launch the system into the $70 billion global energy storage market. It states that ‘the global battery market is currently valued at $60 billion to $70 billion and yet, if we were to take all current batteries produced in one year, they would only have the capability to store around The zinc-bromide chemistry used by Gelion operates without the need for active cooling and uses 100% of the battery’s capacity, the company says
Its electrode surfaces can be rejuvenated remotely using battery management systems, making it suitable for stationary energy storage applications in remote sites.
Top ten solar scams
Here, the top ten solar scams are exposed. Read this article and you will avoid them all. Our books explain even more. Some solar scams are widespread while others are rare. It's vital to keep yourself informed. Many have headlines such as shown throughout this article!
Number One - The Most Common of all Solar Scams – seeking a large deposit
Installers seek a 10% deposit with installation promised within four to six weeks. Don't pay more than that. A few ask for up to 50% - and then postpone installation as long as they can. If an installer seeks more than 10%, find another. It is one the most common of all solar scams
Number Two of the Top Ten Solar Scams – solar output is only 71% -80% of that claimed
This is another of the top ten solar scams.
The solar industry worldwide has two sets of scales. One, Standard Operating Conditions (SOC) is for development and selling. SOC is measured as if the solar module is horizontal on top of an equatorial mountain in mid-winter at midday but simulated in a laboratory. Fine for development - but it is not how solar modules are used.
Solar reality is NOCT (Nominal Operating Cell Temperature). It replicates more typical usage. The NOCT is typically 71% of sales claims. A typical '3.5 kW' system rarely exceeds 2.9 kW. The industry does reveals this - but only in its technical data. A data panel on the rear of almost all solar modules reveals both. To stave of lawyers there’s a photo of one here. (The NOCT output of this ‘120 watt module is shown as 85 watts).
Here, the actual typical output of this high quality '120 watt' solar module is disclosed (in the third column) as 87 watts. Pic: An actual solar module once owned by the author. Copyright: solarbooks.com.au
The industry 'excuses this extraordinary practice as being ‘historical' (but so is theft in the burglary trade).
Number Three of the top ten solar scams – oversized inverters
This is less common but nevertheless happens. A 6 kW inverter is specified and the system sold as being of 6 kW. But only (say) 4 kW of solar modules are installed.
Four – low output/low quality solar modules
The 2018 top ten solar module makers (in terms of sales) are JA Solar, Tongwei, Trina Solar, Hanwha Q-Cells, JinkoSolar, LONGi, Shunfeng (Wuxi Suntech), Canadian Solar, Aiko Solar, First Solar. None is cheap but unless the supplier uses one of these, buy elsewhere. These companies make their own solar cells and supply complete solar modules. Virtually all others buy cells and use cheap labour to hand-assemble the modules.
Five – ‘your roof needs fixing first’
This too is one of the top ten solar scams. It is often a joint scam with a roofing company. Have an independent roofer check and quote independently.
Six – maintenance contracts
In this top ten solar scam, an installer may offer a 'bargain contract' (up to 20 years) for yearly ‘maintenance’ and solar module cleaning. Solar modules either work or not. No ‘maintenance’ is needed. Rain adequately cleans them. read more...
Vital things about solar in the USA
Among vital things about solar in the USA, while the price of solar in the USA has fallen it still seems almost absurdly high. As of July 2020 the average cost is US$17,460 for a 6 kilowatt system. It is still US$12,920 after the 26% Federal ITC discount (not factoring in any additional state rebates or incentives).
Just why solar is so costly in the USA seems unclear. It's cost is well over twice that of the far smaller market in Australia. That same size (6 kilowatt) system in Australia is under A$6000 (US$4,300) including installation.
Throughout 2020, the USA's solar tax credit is equal to 26% of the cost to install a solar system, with no maximum credit amount. This reduces to 22% in 2021 and expires completely for residential installations in 2022. After 2021, however, businesses can receive a 10% tax credit. The solar tax credit can only be claimed if there is a tax liability in the year of installation. Furthermore claimants cannot take a credit that is larger than the amount of taxes owed. They can, however, claim the credit over more than one year, and carry any leftover amount forward to the next year.
The USA's Internal Revenue Service requires the system to be 'placed into service' by the end of the year to qualify for that year’s tax credit. It does not, however, define 'placed into service', but presumably means fully installed and working.
On the plus side, the majority of Americans live in states that have a renewable portfolio standard. This is a mandatory state government requirement that a certain percentage of the state’s electricity must come from renewable sources. Some states have aggressive goals. Hawaii has a target of 100% renewable energy by 2045. Maine's target is for 100% by 2050. California, the USA's largest state, is aiming for 60% as soon as 2030.
Our related books are Solar That Really Works (for boats, cabins, travel trailers, motorhomes, and small homes). Solar Success is for homes, businesses and properties. Either (or both) can be bought and downloaded right now. To order, click on the book title (above).
All our books are also in print form. Buy them from any Jaycar store in Australia and New Zealand. They are stocked by (or ordered from) all bookshops in Australia and New Zealand. They can also be obtained by email (from anywhere in the world) from booktopia.com.au
Fuel-cells for RVs
Fuel-cells for RVs provide electricity cleanly and silently. Their high price is still hindering acceptance. That may change as new types are developed. Most use hydrogen derived indirectly from methanol. They charge batteries - enabling them to provide far higher short-term power than the fuel-cell can instantly supply.
Efoy fuel-cell in a camper trailer. Pic: SFC.
Fuel-cells for RVs - how fuel-cells work
Fuel-cells convert chemical energy into electrical energy without burning the fuel. Instead, they use cells that contain anodes and cathodes plus an electrolyte solution. Electrons flow from anode to the cathode. As they do so, they produce electrical direct current (DC). A so-called catalyst oxidise the fuel. That fuel is typically hydrogen. It is currently derived from hydrogen-rich methanol. The only emissions are a little ultra-pure water and minor heat. There is also a very small amount of CO2. Hydrogen, however, be obtained indirectly from solar modules. It is done by splitting water into hydrogen and oxygen. The fuel-cell then also acts much like a battery. It is, however, totally non-toxic.
Fuel-cells for RVs - brief history
The fuel-cell was invented in 1839. The concept, however, was not pursued until the early 1950s. NASA then produced them. They were used as ultra-reliable power sources for space missions. A later market was covert military and other surveillance. For that, a fuel-cell's silent operation is invaluable.
The very first fuel-cell (for boats and RVs) surfaced in August 2004. It was developed by the Smart Fuel Cell (SFC) company and named the EFOY. There are three models. All use methanol fuel. Outputs are from 80 to 210 amp hours a day. They are usually used with a small battery bank. This enables them to provide much higher power for short periods, e.g, for a microwave oven. SFC also produce a Pro range for military and other heavy-duty use.
The very first RV fuel-cell. Pic: SFC.
Another fuel-cell is the Hydromax. Developed by Dynad (Netherlands) for boats and RVs, its fuel is malic acid (found in acidic fruit such as apples) and a saline solution dried to powder form. When used it is mixed with fresh water.
Apple-powered! - the Hydromax 150. Pic: Dynad.
Another interesting concept is from Mercedes. The company has produced a hydrogen fuel-cell powered RV that in camp, can also provide sufficient grid power to run heating, air conditioning and a refrigerator.
A very promising fuel-cell was developed by Truma. A huge amount of time and money was invested between 2004 and 2012. The so-called Truma Vega unit finally launched in 2012. It was diesel-powered and worked well. Sadly, its price (plus 12000 Euro) proved far too high for commercial success. Production ceased in early 2014.
Fuel-cells for RVs - the future
There is a huge potential market for this type of fuel-cell. It is needed also to provide power in villages in third-world countries. Most currently run on methanol - but that needs to be of exceptionally high quality. The fuel is priced accordingly. The most probable solution is likely to that solar electricity/hydrogen combination mentioned above.
Fuel-cells for RVs - the risks
The methanol fuel-cells produced so far present no more risk than from any other fossil-based fuel. That fuel is converted into hydrogen within the cell but of such tiny quantity it presents no known risks. The Mercedes concept mentioned above uses hydrogen directly, but not enough is currently known it to comment.
Fuel-cells for RVs - read more
Fuel-cells for RVs are covered in my books Solar That Really Works!, and Caravan & Motorhome Electrics. Digital versions can be purchased from our Book Shop. Print versions can be bought from almost all bookshops in Australia and New Zealand. Also on-line from booktopia.com.au/
Going off the electricity grid
RV Books recently upgraded our system. This was not for leaving the electricity grid. It was to produce three to four times more electricity than we use on almost all days. We are thus not entirely free of the grid, but only rarely draw from it. At night, (or when overcast) we run from battery power. During each typical day we sell 15-40 kWh (at a current 20 cents per kWh).
All-solar town (Frieburg - Germany).
Going off the electricity grid appeals to many. An alternative is to retain it. But have the supplier mainly pay you. This article explains all.
Going off the electricity grid - why do it?
If connected, going off the electricity grid makes no financial sense. Grid electricity pricest soared in 2018. This was due mainly to commercial greed. That rise is unlikely to continue. Consumption is falling as appliances become increasingly more efficient. Apart from rare peaks, many countries now have more generating capacity than needed. Rather than going off-grid, retain that grid connection and have the supplier pay you. RV Books has done since 2018.
Going off the electricity grid - reliability
A well designed and built solar system is ultra-reliable. We designed and self-built the system shown below in 2000. RV Books no longer owns that (Broome WA) property. It is now 2019, however, but it still works much as when new.
Our previously-owned (3.8 kW) solar array - north of Broome (Western Australia)
Going off the electricity grid - being free of Big Brother
Many consider going off the electricity grid to be free of Big Brother. That has a 'feel good factor' but comes at an extremely high price. We briefly considered doing so for our current home (in Sydney). Instead, we upgraded our system (from 2.4 kW) to 6 kW and added a Telsa 14 kW/h battery. The system produces three to four times more electricity than we use on almost all days. The battery supplies us at night and rare times of little solar input.
We are thus not entirely free of the grid - but only rarely draw from it. During most days we sell 15-30 kWh (at a current 20 cents per kWh). That is a 'feel good' factor.
Even when substantially overcast that 6 kW system still produces enough for our daily needs. The grid provides back-up in case of rare periods of little sun. It may rarely be used, but is far cheaper than any other way of generating your own.
Control centre and battery of our current system in Sydney. It is on-grid but the electricity company pays us.
Going off the electricity grid - is wind power worthwhile?
Small-scale wind-powered electricity generation has its supporters (but mainly from vendors selling it).
Small-scale wind power is only worthwhile close to the coast. Its rarely revealed downside is that when wind speed halves, output decreases eight times. Further, most such units develop their claimed maximum output just before wind forces blow them apart. The large systems are fine - but wind-power is not recommended for home systems. As Outback Power (in the USA) once commented re this: 'there are lies, damned lies - and wind generators'.
Going off the electricity grid - act as if you were now
Excepting that the cost is recovered inside (in Australia) about ten years, if a reliable grid supply is available, there is currently no financial gain. Unlike grid electricity, however, the cost of solar systems constantly falls. By 2030 it is almost certain to be financially worthwhile. As any good solar system (battery life apart) lasts for at least 25 years - it is thus viable right now.
Regardless of retaining or going off-grid or not, reduce energy usage. Slash heating costs by installing high-efficiency reverse cycle air conditioners used in the winter for heating. The top units produce up to four times the heat energy of the electricity drawn. Installing LEDs lights slashes energy cost four to five times. The latest washing machines work well on their cold water cycle and thus draw far less. A good quality 2019 TV draws under half that of its 2014 equivalent.
Replace any fridge made before 2000. Never have more than one fridge. Two of the same size will draw close to four times the energy (not twice).
Our current (Sydney) solar system produces many times the energy we use. That excess is sold to the grid.
Eliminate 'phantom loads' those little boxes (wall warts) that enable remote switching. All draw energy unless switched off at the wall socket outlet. Each draws only a small amount - but each for 24 hours a day. A typical three-bedroom home has over 30 of them. Each draws only a few watts (but 24/7). Collectively they typically account for a third of your usage.
Buy Solar Success. This totally up-to-date book explains all you need to know. It shows how to slash energy use by 30-50%. It will save you countless times its price. If not ask for your money back (no one has yet). You cannot lose - that offer is non-conditional.
Our books are now available in both digital and print format. The digital version can be bought and downloaded right now. Click on Solar Success to order. Our print versions are available from all branches of Jaycar in Australia and New Zealand or ordered from any bookshop in both countries. They may be bought via email from booktopia.com.au.
updated May 2019
Best Batteries for Stand-Alone Solar
Knowing the best batteries for stand-alone solar saves huge sums. This solarbooks.com guide explains how and why. It's all to do with having enough energy and having enough power. Energy and power, however, are different concepts. For stand-alone solar it is mostly energy, not power, that matters.
Author's previously-owned bank of sixteen Exide 12 volt gel cell batteries. Each is of 235 amp hour - about 45 kWh total. They are connected in series-parallel to provide 48 volts. Pic: solarbooks.com.au
Knowing the best batteries for stand-alone solar saves money. This solarbooks.com.au guide explains how and why. It's all to do with having enough energy and having enough power. Energy and power, however, are different concepts. For stand-alone domestic solar it is almost entirely energy, not power, that matters.
Energy and power explained
Energy enables work to be done.
Power relates to how fast energy is used. Starting a car engine needs high power but the energy used is tiny! It’s less than that needed to run a five watt LED light globe for an hour. It depletes the battery by about 2%. Another example is lifting 100 (1 kg) cans onto a shelf. A 10-year-old does this with ease. But were that 100 kg to be in one lump, hoisting it to that same shelf needs identical energy, but massively more power. Confusingly, however, even energy suppliers speak of grid-power!
A battery's stored energy measure is amp hours. An ideal 100 amp hour battery supplies one amp for 100 hours, ten amps for 10 hours or one hundred amps for 1 hour. It has both energy and power.
Knowing this difference ensures you buy only the batteries you need. Costly ones such as a 500 amp hour bank of lithium-ion (e.g. LiFePO4) batteries can deliver far more power than a domestic home will ever need, but only marginally more energy than a two-thirds cheaper bank of AGM batteries. Unless you truly need that LifePO4's power, buying them like buying an overhead crane to stack 1 kg soup cans. spacer height="20px"]
Batteries for stand-alone solar - lead acid
Lead acid batteries are totally known, relatively cheap, simple and affordable. They store ample energy but have limited power. Countless stand-alone solar systems use them because that power is more than ample anyway! They are bulky and heavy, but that too is rarely a problem. To ensure long life, use them in stand-alone systems(routinely) only from 100% to 70% of full charge. Unless essential, do not discharge them below 50%.
Batteries for stand-alone solar - AGM
AGM batteries too are bulky and heavy but hold their charge for a year or more. That ability is valued in standby systems that are left unattended for long periods. Virtually unused ones are often sold at very low prices.
Batteries for stand-alone solar - lithium-ion
Vendors promote lithium-ion batteries as having 'far more power'. The claim is true, but that power ONLY needed if you intend to do extensive arc welding etc. But for that, you need a great deal of energy as well. Here, a diesel generator makes more sense. No normal loads in a typical home or property stand-alone system need anything like even a small lithium-ion battery's power.
The main benefit of lithium-ion batteries is they are about one third the size and weight of lead acid and AGM batteries - but that rarely matters for most homes and properties. One benefit, however, is that more of their capacity can be used without overly shortening their life.
Conventional sealed lead acid, gel cell and AGM (Absorbed Glass Matt) battery banks are cheaper and simpler to install. They are also far more readily available. The one-time popular gel-cell batteries are still made but now only rarely used as they have no major advantage over lead acid or AGM. read more...
Lithium-iron batteries in RVs
Lithium-iron batteries in RVs - they are safe to use. They deliver a lot of energy and pack a lot of power but need specialised knowledge to use safely and reliably. Here's how and why for the LiFePO4 (lithium-iron) variety.
Pic: the lithium battery co.
There are two main types of rechargable lithium batteries. The so-called lithium-ion provides the most power. It is however less stable. The type generally used in RVs and home (LiFeP04) lithium-iron. The abbreviation 'LiFePO4' denotes their chemical make-up, i.e. it is not a trade-name. These batteries are very stable and safe to use.
Lithium-iron batteries - they are safe to use: energy and power
Energy enables work to be done. Power is a measure of the rate that energy is used. A child readily stacks 200 one kg cans (one or two at a time) on a shelf. An Olympic weight lifter heaves 200 kg that same height in a second or two. Both use the same energy but the weightlifter exerts hugely more power. Lithium-iron batteries in RVs have both energy and power.
There are good reasons to use lithium-iron batteries in RVs, but (for powering microwave ovens apart), an RV needs only minor power. Doing so is like having an Olympics weightlifter stack shelves in a supermarket. If weight is no issue, a 300 amp hour AGM battery bank is ample for RV loads and costs a fraction of lthium-iron price.
Safe to use: lighter and smaller
Lithium-iron batteries are re about one-third of the size and weight of conventional rechargeable batteries. This can of real value where space and weight are at a premium (as in most travel trailers). A converted coach, however, usually has space (and weight carrying ability) for a bank of far cheaper AGMs.
Chargeable very fast
Lithium-iron batteries can be charged at massively high current. One of 12 volt 100 amp-hour will readily accept a 300 amp charge. Most RV alternators supply about 70 amps so, if 50% discharged, that battery will fully charged in little over 30 minutes. Grid-voltage chargers that capacity are available - but cost over $1000. read more...
Solar and battery capacity required for cabins and RVs is usually limited. As with homes and properties, always have maximum solar capacity. Consider using LiFePO4 batteries as 80% of their nominal capacity is available. LiFePO4 batteries are also light and compact. Lead acid and AGMs, however, are fine for converted coaches. For those, size and weight are less critical.
The author's 2004 4.2 litre TD Nissan Patrol and TVan each had their own self-contained solar system. Pic: rvbooks.com.au/
Cabins and RVs should have the maximum solar capacity feasible. This ensures batteries will charge fast and deeply even with intermittent sun. The battery capacity required for cabins and RVs needs to cope for about three days. From thereon it is cheaper to charge via a grid-voltage charger. This can also be powered via a small inverter/generator. See: RV Solar and Alternator Charging.
As a rough guide, (and assuming a 12-volt system) do not allow battery capacity (in amp hours) to exceed 50% of your solar capacity (in watts). Unless you do, your batteries may not adequately charge. A 100 amp-hour battery thus needs at least 200 watts solar capacity. Seemingly excess solar capacity will assist charging during times of little sun. There is no risk of overcharging. The solar regulator automatically prevents that.
Dual solar system
AGM batteries are ideal for cabins and converted coaches, but their 33 kg per 100 amp-hour (for 12-volt units) is too heavy for small travel trailers. Where size and weight are critical use lithium-iron LiFePO4 batteries. They cost more, but as 80% of their nominal capacity is available, that cancels out their higher price. LiFePO4 batteries are also light and compact. They are about one-third the size and weight of AGMs. Another benefit is that unlike conventional lead-acid batteries, as long as first fully charged. AGMs can be left for up to a year without use. LiFePO4s can be left for evem longer.
If towing a camper trailer or travel trailer consider haing a self-contained solar system in each. This enables you to have one (charging) in the sun. The other can be in shade. You can readily interconnect the systems to share power and battery capacity.
Having two self-contained systems enables you to have a small fridge in the tow vehicle. This is very convenient when shopping. That vehicle too, can have a solar array on a roof rack and an associated battery.
Our 4.2-litre Nissan Patrol and TVan (shown above) were set up this way. Each had its own system. Moreover, they could be used separately or paralleled if desired. In over seven years, however, we never needed to do so.
It is also feasible to have alternator charging. :outlines how.
Ensuring Successful Solar
Our all solar house was self-built in five months. Hi-tech construction resulted in a superb and workable waterfront home in Australia's remote far north. It was even built using mainly solar energy. Here’s how we did it.
Ensuring Successful Solar - first time and every time.
Here's how we built our own.
Our all solar house was self-built in five months. Hi-tech construction resulted in a superb and workable waterfront home in Australia's remote far-north Kimberley. It was even built using mainly solar energy. Here’s how we did it.
The site's ten acres of natural bush at Ngungnunkurukan (known locally as 'Coconut Well'), fronts directly onto a tidal lagoon with the Indian Ocean about 400 metres away. The land adjoins one of the three major Aboriginal song lines that traverse Australia. It has major rock formations significant to the local Aboriginal community. We left all significant rocks and trees untouched.
We moved onto the land in April 2000. Cyclone Rosita struck ten days later. We sheltered from the 180 km/h gusts by burying our OKA off-road (ex-mining) truck to its chassis and strapping a table over its windscreen. While scary, the 180 km/h cyclone was an invaluable introduction.
Ensuring Successful Solar - the House's Design
Our main requirements were for light and space. Moreover, the house should form a visual extension of the Indian ocean and dunes, and likewise of the bush behind us. The original design was good, but as an engineer myself, I was not surprised the council rejected the architect's plans as having inadequate cyclone rating. They were subsequently and brilliantly re-done by Garry Bartlett of Broome’s B&J Building Consultants - who also added a cyclone shelter. This doubled as an ultra-strong spare bedroom.
The subsequent all solar house is a mix of aircraft and structural engineering. To most people’s surprise, its main strength is derived from the roof. It is in effect a curved beam formed of two layers of heavy gauge Colorbond steel. It is constructed much like an aircraft’s wing and attached to four massive 100 by 200 mm rolled steel I-beams rolled to the same double curvature.
The roof structure is tied down by both vertical hollow beams that bolt onto a massive concrete perimeter beam via steel tubes that double as water drainage for the inset gutters.
The domed ceiling is 4.1 metres high. There are no internal walls - only minor partitions about 1.8 metres high. There are next to outer walls either: instead, there are 14 siding toughened glass sliding doors, each protected by sliding prison-grade steel mesh doors.
The all-steel structure demanded dimensional tolerances of only 1-2 millimetres. This is closer to watch-making than many a builder's pluses or minuses the Post Code - but surprisingly it was achieved.
Erected in one day
The steel suppliers erected the main structure assisted by a 200-tonne crane that positioned the 1100 kg steel beams from 50 metres away. It took just one day. A neighbour commented: 'When I left for work there was a flat space. Eight hours later a big house was there'.
We used contractors only for concreting, roofing, internal plumbing and non-solar electrical work. But, apart from that, all else was done by my wife Maarit and myself with assistance from an ex-builder. We started in August 2000 and moved into the semi-completed house in late November. It took a further six months to complete.
Ensuring Successful Solar - the solar system
I designed and built the (initially 2.5 kW) solar system before starting construction. It supplied almost all of the power needed for building. That, even more than the house design, puzzled contractors. They knew the closest grid power was 20 km away – that there was a 230 volt supply. It was hard to persuade them our's was from solar.
The original system had thirty, 80 watt 12 volt solar modules on a north-facing existing shed 200 metres from the house site. This system provided about 12 kW/day from the Kimberley's ample sun. It charged 24 two volt wet cell batteries each of 1000 amp hour - via an 80 amp Outback Power solar regulator. The inverter was( and in 2019 still is) is a 3.8 kW SEA unit of 11 kW peak ability. This array was later moved closer to the house. To cope with irrigation, I added further solar capacity to bring the total to 3.4 kW (about 18 kWh/day in peak periods.
Our 45 kW/h battery capacity
Whilst less than two years old, the original batteries were sadly flogged to death by a caretaker who, unknown to us, had a huge drying oven that he ran all night. The batteries were replaced by sixteen 12 volt gel-cell units - each row of four thus provided 235 amp hour and connected in series-parallel to provide 940 amp hours. Each row thus provided 940 amp hours 11.28 kWh. The total from the four rows was about 45 kW/h.
Ensuring Successful Solar - Water
The area's hard but crystal clear bore water is possibly the purest in the world. It comes from the Leopold Ranges, some 700 km north-west of Broome, with nothing but untouched desert between the two. We used only 2% of our annual water allocation, the remainder pours into the Indian Ocean, a few hundred metres away.
Whilst wonderful for drinking and irrigation, the bore was too hard for washing etc. We thus collected water from the 280 square metre roof of the house and pumped (via solar) to a 100,000 litre main tank about 70 metres from the house.
An above-ground rendered concrete block 31, a 10000-litre swimming pool is attached to the house. This too runs only from solar. It was originally a unique way of operating but has frequently been copied.
Original quotes for the circulation system (all using 230 volts and requiring doubling our solar capacity) were $60,000-$70,000 plus that solar. Instead, I used a dedicated 480 watt solar array to drive (directly) a 48 volt brushless dc pump that draws 480 watts from a dedicated four by 120 watt solar modules. As it runs all day under the Kimberley's reliable sun, there is thus no need for batteries. It cost a mere $7500 including the solar.
I arranged for fresh irrigation water to passes initially through the pool, replacing about 10% each day. It thus needs minimal chlorine. It cost $7500 in 2002. Full details are in Solar Success.
Sewerage is septic. We would have preferred a more ecologically sound system, but the (then) Shire regulations prevented it.
The total price for building the house and solar was about A$220,000.
Our all-solar house worked well for us for ten years. While there I wrote and published five books. I also spent four years at the tiny Broome campus of Notre Dame University - auditing the Aboriginal Studies course. Meanwhile, Maarit added a Counseling, and a Psychology degree to her original Arts B.A. And some Spanish and Mandarin to her existing (English, Finnish, German and Swedish) to her four languages.
As part of her art, Maarit does heavy blacksmithing and has MIG, TIG and arc welding certification (plus a production engineering certificate). She comfortably uses tools such as nine-inch angle grinders and did a lot of the heavy construction work.
With considerable regret, but primarily because our expanding family lived in Sydney, we sold the property in late 2010. Our new home (in Church Point - north of Sydney) not surprisingly became an all solar house too! And Maarit acquired her Master of Art Therapy.
Our constantly updated book Solar Success has all you'll ever need to know to buy, design and install solar systems for homes and properties. Solar Success includes full details of this house and solar system. Solar That Really Works! is for cabins and RVs. Caravan & Motorhome Electrics explains every detail of that topic. It also bought by auto-electricians as a practical textbook in this area.
These digital books can be downloaded right now (as .pdfs) from the Bookshop on this site.
They are also available in print form from almost all bookshops in Australia and New Zealand, via email from booktopia.com.au.
If interested in all aspects of RVs, see our associated site - rvbooks.com.au
Our Solar Equipped RVs
This article describes our solar equipped RVs. Here's what we did, why and how well they worked and what would we do now to improve them.
Our solar equipped RVs (VW Kombi)
The first of our solar equipped RVs was a rare 1974 Westfalia VW Kombi. We added a single 80-watt Solarex solar module (that then cost $650!). It charged a 100 Ah lead acid deep cycle battery via a then basic solar regulator and alternator). This powered two 20 watt halogen lights, and a 40 watt Engel fridge. All proved to be mechanically and electrically reliable - despite being used mostly off-road. The electrics and the solar system worked well - but primarily because we travelled during spring and summer - when there was ample sun.
Were we to own it now, we would double the solar capacity and use a so-called MPPT solar regulator. Such regulators 'juggle' the incoming volts and amps so as to optimise charging voltage. The gain is about 10%-12%
The battery would be changed to a 110 Ah AGM. This is because they are more rugged. We'd update the fridge as current units are far more electrically efficient. The size would be 50 litres. Sixty litres would be better but takes too much of the limited space. Rather than using frozen food, we'd use freeze-dried. It is more convenient and enables space for more wine!
The Kombi was an excellent vehicle but, as we were then planning to travel extensively off-road and full-time for a year or more, we (reluctantly) sold it.
The 1974 VW Kombi - my wife (Maarit) is the foreground. Pic: solarbooks.com.au
Our solar equipped RVs (OKA)
Second of our solar equipped RVs was a one-year-old Australian-built OKA. These were specialist ultra-rugged 4WD trucks powered by basic four-cylinder (4-litre) Perkins turbo-diesel engines and made primarily for mining and quarry operations. Ours had been built with a coach type body and had been used to carry miners deep into the working areas. We had the original roof removed and installed a custom-made pop-top roof. The interior was designed such as to keep weight to the absolute minimum. We used white powder-coated aluminium and spruce timber.
The OKA in camp in the Kakadu National Park. Pic: solarbooks.com.au
The entire interior weighed under 100 kg. Keeping that weight low enabled the OKA to carry 400 litres each of water and diesel. Despite that mass of liquids the completed vehicle weighed 5.2 tonne. Most converted OKAs weight well over 6 tonne. We needed that fuel range as we were to travel Australia's truly off-road dirt tracks - where, in one instance, there was no fuel for over 2000 km. It also enabled us to refuel in areas where fuel was cheap.
The OKA crossing a crocodile-infested river near the tip of Cape York) - the dome on the roof is the satellite antenna. Pic: rvbooks.com.au
We installed a 120-watt solar module and upgraded to a Bosch 140 amp alternator. These amply powered our (then) huge Westinghouse satellite telephone (it was the size of a large suitcase and weighed about 15 kg!) and dome antenna plus water pumping and halogen lighting.
We drove the OKA over 150,000 km mostly on Australian dirt roads. This included over twelve return trips from our-then home in Broome, to and from the east coast via various routes - that mainly included Alice Springs.
The OKA was the third of our solar-equipped RVs and proved ultra-reliable. It was a wonderful machine for our then needs - but far too big for city use. It was sold in 2006. Despite that all OKAs are now over 20 years old, most now fetch huge prices - over A$100,000. Many have been refitted with larger engines.
Apart from replacing the original ten halogen globes by LEDs, there is little we would have changed. The huge satellite telephone stayed with the vehicle when sold - but was by then far larger than needed. Still big ( but hand-held) satellites units were by then readily available.
Our solar equipped RVs (Nissan PatroI)
The third of our solar equipped RVs was a new (2005) 4.2 litre TD Nissan Patrol -the last such to be made. As with the OKA, they were ultra-rugged and totally reliable. We used the Patrol to tow our also-new 2005 TVan - a part camper trailer/part mini-travel trailer made by Track Trailer for off-road use - it weighed about 1150 kg when loaded.
The Nissan Patrol and TVan wading a river-crossing - on the road to Mitchell Falls (Kimberley, West Australia). Pic: solarbooks.com.au
We used this rig experimentally to trial the concept of having two independent but connectable solar systems (one in the Nissan Patrol, the other in the TVan). The Nissan had a single 120 watt solar module (plus alternator if needed) that powered a 60 litre Engel fridge - handy for shopping. The battery was a 110 Ah AGM. We also used the rig to field trial the very first Redarc Battery Management System (BMS 1215). Clamped rigidly to a steel crash barrier it worked faultlessly for over three years. (Ten years later it controls our solar powered fountain and garden lighting!). The 60 litre Engel fridge was in the Nissan.
Our solar equipped RVs (TVan)
The TVan had a single 60-watt solar module plus a Plasmatronic PL20 solar regulator charging a 110 amp hour AGM battery. This powered our two PCs, three LED lights and a 12 volt electric blanket. The systems could be interconnected if found necessary - but we never found a need to do so. A major benefit of this arrangement is that it enabled the TVan to remain in the shade whilst camping, and the Nissan in the sun. It was used for three across-Australia and back trips.
The concept of two separate (but connectable) solar systems exceeded our own expectations. I thoroughly recommend it. All worked superbly. There is little (if anything) we would change except for more solar on the Nissan Patrol if we lived and/or travelled where there was less-reliable sun. All are fully described in my book Solar That Really Works!
Of our three solar equipped RVs, we experienced zero mechanical or electrical issues. This is remarkable as almost driving was over dirt tracks. It included 24 trips across the 1000 km Tanami track plus over 20 times along the plus 700 km Gibb River Road.
Travel Trailer and motorhome electrics generally are covered in our book of that name - Caravan and Motorhome Electrics
Refrigerators for cabins and RVs
How to pick the best refrigerators for cabins and RVs. Solar Books (Collyn Rivers) article outlines that now feasible and affordable, and can be run from solar.
Engel 60 litres slide-out fridge is powered by two 100 watt solar modules and a 110 amp hour AGM battery. Pic: solarbooks.com.au
Cabins usually have roof space for the 200-300 watts solar capacity required. Also feasible are portable solar modules placed outside when you use the cabin. RVs have less available space for solar modules. For these, buy only those that are 20% or more efficient. At one time these were monocrystalline modules, now the top polycrystalline have caught up.
Another and effective way you can do it is via a 12 volt (100 amp hour) battery. You can charge it via a 230 volt battery charger powered by a Honda/Yamaha inverter/generator. You will need to run the generator for only three or so hours a day. See article Generators for cabins and RVs.
Refrigerators for cabins and RVs - generator back-up
Twelve-volt electric fridges vary in efficiency. Buy only those known globally such as Engel, Waeco etc. Avoid the ultra-cheap look-alikes. Any saving in price is offset by far more energy needed to run them.
To cool efficiently you must install a fridge them correctly. Sadly, few installers do. Cold air must be able to pass over and through their cooling fins. That now-heated air must be able to escape to the outside. A few fridges have metal sides and top that dissipate the heat. These must have a 50 mm air-space at their top and sides. In addition, 12 volt fridges must have ample-sized connecting cable. Very few have. Our books (see below) explain why - and the sizes to use.
Refrigerators for cabins and RVs - three-way operation
Where solar is less feasible, consider a Dometic three-way fridge in its LP gas mode. This works well too for the smaller RVs that lack space for solar modules. However, be aware their energy draw is far too high for solar. Their major benefit is that there will adequate solar for other purposes!
Refrigerators for Home and Property Solar
Here's how to know the best refrigerators for home and property solar. All pump heat from inside them to where it does not matter. Some do it better than others.
Refrigerators circulate a gas (that becomes liquid when compressed) through finned tubes inside them. This gas 'captures' the heat. The (now liquified) gas is pumped out and the heat is dispersed via external finned tubes. Some refrigerators radiate the heat from their metal sides and top.
Refrigerators for home and property solar - improved efficiency
Refrigerators for home and property solar have improved in efficiency in recent years. You can make huge savings (by needing less solar/battery capacity) by replacing any made prior to about 2014. Further, big fridges use far less energy pro-rata their volume than small ones. This is because their major energy loss is via their outer skin. That skin's surface area decreases as a percentage of the refrigerator's volume. Two 300-litre fridges thus use at least three times the energy as one of 600 litres. This is particularly important with large properties. If essential have a few large ones - not multiple small ones.
Much of the refrigerator's energy draw is used for cooling the content initially. The energy required thereafter compensates for outside heat finding its way back in. This may be through too thin heat insulation, leaking door seals or the refrigerator being locating next to the oven!
It is vital that a refrigerator is installed correctly. Few are. That most important is to ensure that no sunlight can fall on it. It must also be located well away from any source of heat. Ideally, it should be in a location where cool air can be directed to its base and warm air escape to outside the home.
Refrigerators for home and property solar - free air flow is essential
All fridges rely on cool air being able to flow through cooling fins that are low down and at the rear of the fridge. That (then) warmed air must have some form of venting above refrigerator level and such that it can flow to the outside. If it cannot flow to the outside that heat needs to be directed such that it cannot heat up the refrigerator.
A few fridges for home and property solar have no fins. They rely on the heat being radiated from their metal sides and top. All such fridges must be installed such that they have a 50 mm (two inches) gap at the sides and rear. That essential is that space above the fridge top is adequately ventilated. (Remember that heat always rises.)
The choice and installation of refrigerators for homes and properties are covered in depth in Solar Success. Solar That Really Works! does likewise for boats, cabins and RVs. These books are in both digital and print format. You can download either or both (many readers buy both) right now. Do so by clicking on one or other of book titles (in blue) above. Print copies are stocked by all Jaycar stores in Australia and New Zealand. They can be ordered through any bookshop in Australia and New Zealand. They can also be bought directly (and worldwide) by email from booktopia.com.au.
Solar Regulators for Home and Property Systems
How to choose solar regulators for home and property systems fully explained. This article ensures you buy the right one first time.
The solar regulator's role is to manipulate the energy that solar modules produce to optimise charging. This ensures batteries are optimally charged. Most solar regulators for stand-alone systems accept a range of solar input voltage: typically 12-110 volts dc. Those for grid-connect solar work at a far higher voltage and will be specified by the system supplier.
Solar regulators in effect 'juggle' the solar voltage and current to that best required to charge your specific battery bank. That, for a 12-volt battery bank, is typically 12.8-14.4 or so volts. Varying types of batteries have varying needs. Most solar regulators are programmable for these. If you have LiFePO4 batteries it is absolutely essential. This is because they have specific needs that must be met.
Solar regulators vary in energy handling capacity. Because of this, choose one that accepts the maximum your solar array produces. Furthermore, you do not need to allow for rare overloads. Solar regulators for home and property systems protect against this too.
The nominal battery voltage you need is largely determined by your inverter's size, however it is likely to be 12, 24 or 48 volts.
The inverter converts that into 110 or 230 volts ac. See Inverters for home and property systems.
Finally, as with every aspect of solar - avoid 'bargains'. They rarely are! Buy only well-known and established brands. Moreover, if feasible buy all the bits and pieces from the same vendor. Unless you do this, each vendor may blame another if anything is wrong.
Solar Modules for Cabins and RVs
This solarbooks.com.au article explains solar modules for cabins and RVs. Space is often the major limitation so buy the most efficient modules.
With solar modules for small cabins and the smaller RVs, by far the greatest use is powering a compressor fridge below 220 litres. Never use two small (say 110 litre) fridges, rather than one larger. Their combined draw will be about that of a single one of 350 litres.
Again, for the smaller cabins and RVs, it is best to confine solar to lighting, water pumping, TV, laptop computer etc. Use LP gas (or diesel) for heating and cooking. If not done already use LEDs lighting only. Avoid the eBay cheapies - the more costly LEDs produce far more light per watt.
Solar Modules for cabins and RVs - what to buy?
Solar modules vary (from 12% to 20%) in their ability to turn sunlight into usable electrical power. Where space is at a premium, buy the most efficient solar modules on the market. They are likely to be monocrystalline but the very best polycrystalline solar modules are now equally efficient. Here too, it pays to buy the best: currently (mid-2019) they cost about A$2 per watt.
Flexible solar modules are convenient for RV with curved roofs - but typically produce only two/thirds of the output of the better quality rigid modules. Most rigid solar modules weigh about 10 kg per 100 watts, but there are rigid solar modules that weigh only 3 kg per 100 watts. Currently, however, most are very expensive.
Solar Modules for cabins and RVs - how much capacity?
Solar capacity in 2019 is less than 10% of its 2010 cost. Battery capacity, however, is only about 50% more. Always have the most solar that you can. This will not only ensure batteries charge much faster. It will enable charging even under light cloud. There is a zero risk of overcharging. The solar regulator will limit otherwise excess charge.
Full details of all aspects of this and all you need to know is in our books Solar That Really Works!, Solar Success and Caravan & Motorhome Electrics. They are now obtainable in digital form directly from this website (click on the book title above). They are also available in print form from all branches of Jaycar in Australia and New Zealand, they can be ordered from any bookshop in Australia or via email from booktopia.com.au.
Inverters for Cabins and RVs
This article explains how to choose the right inverters for cabins and RVs. They convert 12 or 24 volts dc to 110 or 230 volts ac.
This is a small transformer-based inverter. Pic:Jaycar.
Inverters for cabins and RVs
Care is need when purchasing inverters for cabins and RVs. There are substantial differences in price, but their range and quality reflect much what you pay.
There are two main types of inverter: transformer and switch-mode.
Transformer-type inverters are large and heavy, they can, however, supply several times their rated load. Some can do this for 10-30 minutes. This is a necessary requirement for many electrical devices that have electric motors. These draw two or three times their running current whilst starting. Air pumps and compressors, however, require even more as they start up on their full load. Small transformer-based inverters are still readily available. If weight is not critical they are often a better buy. Most produce twice or more their rated output for a few minutes. Some do so for up to half an hour.
Switch mode inverters are lighter and smaller. Most, however, can only sustain their rated output for a few seconds. That sustained output is typically 80% of that seemingly claimed, however, cheaper ones may struggle to maintain 50%. Because of this, switch-mode inverters for many usages may need to be rated to cope with high start-up loads. A suitable transformer-based inverter may actually be cheaper.
Connecting to inverters for cabins and RVs
Most small inverters have inbuilt socket outlets. You may plug appliances into those sockets (or via a multi-outlet power board). In many countries (like Australia) you must never connect their output to any fixed grid voltage wiring. Doing so bypasses all safety devices such as circuit breakers and RCDs. You may, however, plug in a multi-outlet power board (as that is not legally an 'appliance).
Inverters for cabins and RVs (and their installation) is covered in depth in our books, Solar That Really Works! , Solar Success and Caravan & Motorhome Electrics. These books are now available right now in downloadable digital form from our Bookshop. They are available in print form from all Australian bookshops - or by email worldwide from booktopia.com.au
RV electrical work - Victorian exception
A licence is required in Australia for electrical installations. Victoria claims for RV electrical work - a Victorian exemption. It states that RVs are not electrical installations and thus exempt. It accordingly classifies RVs (legally) as 'plug-in appliances'. Energy Safe Victoria confirmed the above in writing. Furthermore, it stated that licensing is outside its jurisdiction.
Your RV must meet Australian Standards AS/NZS3000:2018 & AS/NZS3001:2007. In Victoria, however, it need not be inspected. Nor need a Certificate of Electrical Compliance be provided.
In Solar Books opinion, this is not satisfactory. In 2018 a brand new Victorian-made RV was found (by us) to have so many electrical issues (including reversed polarity of its 230 volt socket outlets) it needed total rewiring. Solar Books makes no suggestion, nor implies that others are similar. Nevertheless, insist on a Certificate of Electrical Compliance. Furthermore, you need this anyway if re-registering interstate. This is particularly so in Queensland.
Legally Do it Yourself
You can legally install 0your own solar system, however, as long as no part exceeds the prescribed voltage limits. These are (in 2020) under 35.4 volts ac - and/or 60 volts dc. RV solar arrays are usually a nominal 12, 24 or 48 volts. Battery voltage is typically 12 volts dc up to 1.5 kW, 24 volts up to.2.5 KW and 48 volts there-on.
You can legally install a 'stand-alone' inverter that have integral outlet sockets as shown below.
This Powertech inverter accepts a single power cord. It is legal to alternatively plug in a multi-socket power board if required. It may not be connected to any fixed wiring. Pic: Jaycar.
You may plug an appliance directly into a stand-alone inverter's outlet socket (some have two) or several via a multi-output power board. You must not, however (in many countries) connect the inverter's output into any fixed wiring.
Electricity is dangerous
Do not attempt any such work unless you truly know how.
Energy and Power
This article explains that energy and power are different concepts. Confusing one for the other will mislead with solar & batteries and many other areas. Here's why and how.
Power is a measure of how quickly energy is used
Weightlifters like Svetlana Podobedova (above) readily lift huge weights. Doing so demands extreme power. A child can readily lift the same in smaller amounts. This needs little power but the energy used is the same.
Some batteries are promoted as producing massive power. They may well do so. But in say, [caravan],motorhome and solar use it's mostly energy, not power, that matters. Here's why, and how you can save a lot of money by knowing this.
How confusing these terms can matter
Energy relates to work done. Power relates to the speed at which energy is expended.
Surprisingly little energy or power is needed to hand start a car engine. Pic: reproduced here by courtesy of the Henry Ford Museum (copyright Henry Ford Museum).
Why confusing these terms can matter
Much of the time, confusing the two terms does not matter. Where it can do, however, is in battery advertising re travel trailers, motorhomes and solar. Many battery vendors either do not know the difference, or deliberately deceive. They promote their products' power in areas where power does not matter. For example, the only product in such areas that need a lot of power is a microwave oven. It typically needs 110 amps (at 12 volts). But any 12 volt battery bank over about 250 amp hour will do this.
Our books: Solar That Really Works cover cabins and RVs. Solar Success covers homes and properties. The associated Caravan & Motorhome Electrics covers every aspect of RVs in depth. Our all-new book - Why Caravans Rollover - and how to prevent that is rapidly becoming a top seller.
This article explains the battery capacity required for home and property solar during periods when there is no solar or other energy input. Solar capacity is now cheap. Battery capacity is increasingly costly. Quality solar modules produce usable energy even under light cloud. Install as much solar as you can. This ensures batteries fully charge quickly most of the time.
When determining the battery capacity required - never skimp on solar. Excess battery capacity is like having multiple bank accounts. It increases the cost of storage for no gain.
Battery capacity required for home and property solar
Battery capacity required for home and property solar is such that it is still 85% charged around dawn. Furthermore, it should reach 100% by midday. If not, add solar until it is. A 45 kW/h battery bank typically needs at least 5 kW hour solar. The amount depends on your location, however, more is always best. There is no risk of overcharging because the solar regulator prevents that.
Battery type depends partially on space available. If scarce, consider lithium-ion (LiFePO4). If ample, an AGM battery bank is initially far cheaper. AGM batteries are often sold secondhand. They are mostly ex-standby applications. Many are unused.
This battery bank has 16 by 230 amp hour gel cell batteries. Pic: solarbooks.com.au
For maximum input year-round, for home and property solar, tilt solar modules at your latitude angle. To increase summer input tilt them closer to horizontal. To increase winter input, tilt 10-15 degrees more than latitude angle.
Solar Regulators for RVs
This article explains solar regulators for RVs. Such regulators accept whatever output is produced by the RV's solar array. They optimise that output to whatever needed to optimise battery charging. Most also accept and monitor input from the RV’s alternator. They switch routinely to whichever is greater. The more upmarket RV solar regulators have Multiple Power Point Tracking (MPPT). This 'juggles' the solar module' amps and volts output. Doing so optimises battery charging. Ultra-cheap such regulators may claim to have MPPT. Few, however, do.
These regulators for RVs ensure RV batteries safely and fully charge. The regulator accepts the varying voltage from solar modules. It then converts that voltage to whatever it deems most suitable for charging the batteries used. Only a few, however, are suitable for charging LiFePO4 batteries. Be wary re this because RV owners increasingly use these batteries. For those, consult the battery maker.
Solar Regulators for RVs - dc-dc alternator chargers
Many vehicle dc-dc alternator chargers accept solar input. Apart from an energy monitor, that is all you need. Most good chargers, however, have such monitoring.
Solar regulators are made in various capacities. Yours must handle the maximum solar current or alternator charging current. You need not, however, allow for the two inputs combined. RV batteries charged by such regulators are charged automatically by whichever source has the higher output.
See also our article on solar and alternator charging.
Solar Basics You Need to Know
Solar basics you need to know to ensure your solar works first time. This article by Solar Books' Collyn Rivers explains all.
Solar Basics You Need to Know - is there enough sun?
Generalising, solar is feasible in most parts of the world between latitudes +/- 50 degrees. Solar input is typically quoted in PSH (Peak Sun Hours) per day. Google PSH and your closest town for the answer or contact your local met office.
Pic: In the above map PSH is the same thing as 'Daily sum'. Pic: solargis.
In most areas, PSH varies with time of year. You need at least 2.5 PSH/day, but 3.0 PSH is preferable. The minimum PSH determines the solar module capacity required. You then check there is non-shadowed space for that capacity.
The solar modules should face more or less north (in the southern hemisphere) and more or less south (in the northern hemisphere). For optimum year-round input, they tilt them at (your) latitude angle. To increase winter input tilt them more upright. Or less steeply for summer. Between 0 and 20 degrees north or south of the equator they can be more or less horizontal year-round.
Solar Basics You Need to Know - how much solar capacity do I need?
Most solar suppliers check your current usage - or use locally known averages. This, to put mildly, is not the way to go.
Your first step is to minimise usage. This is simple and easy, but you need to know how. Over a third of our book Solar Success devoted to just this. It shows how to (typically) slash usage by at least one third. Half is readily possible. Doing so will save you thousands of dollars in solar and (particularly) ongoing battery costs.
From there, you design the system to provide whatever percentage of the energy needed. It is possible to have 100% but settling for 95% will halve the cost!
Solar Basics You Need to Know - battery and generator back-up
Stand-alone solar systems typically have battery storage for two to three days of zero solar input. A generator and a large battery charger then recharge the system. Battery storage is however costly. It can be reduced if the generator is used more often.
Solar Basics You Need to Know - ongoing maintenance
Apart from cleaning the solar modules if they get dusty or muddy - they need no other attention. Do not get scammed into signing a yearly maintenance contract. Their useful life-span is 25-30 years. See our article Top Ten Solar Scams.:
The AGM or LIFePO4 batteries now used are usually maintenance free. Battery lifespan is typically 12-16 years. They may last longer but their capacity will be about 20% less than when new.
Solar Basics You Need to Know - can I build the system myself?
Many do but it does need some electrical experience. Unless you have, Solar Books advises seeking assistance. Much of the work, however, is mechanical. Framework for solar arrays is readily buyable. Huge savings can be made by constructing these yourself but you must allow for wind forces etc. Solar Success, however, shows that required. (It was built to withstand cyclones but is still far cheaper than standard commercial equivalents).
We strongly advise buying Solar That Really Works! (for boats, cabins and RVs). Buy Solar Success for homes and properties. Our book Caravan & Motorhome Electrics covers every aspect of that topic. All are routinely updated. Their content is globally valid.
All our books are now available in digital and print format. The digital books can be bought and downloaded right now from the Bookshop on this site. Click on the book title (above) to order, Our print versions can be ordered from any bookshop in Australia and New Zealand - or via email directly from booktopia.com.au