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Interconnecting batteries in series or parallel- here’s how and why

Updated 2020
Interconnecting Batteries

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.

batteries series (6-12 volt)

Series connection

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/

Parallel connection

Paralleled batteries (or paralleled strings of series connected batteries) must all be the same voltage. They may, however, be of varying capacity.batteries parallel 12 volts 2013

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.

Battery shed coconut well reduced jpg

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 caravans

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.

References

• 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 for RVs – here’s how you can use them

Updated May 2020

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, caravans 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.

solar regulator morningstarThis 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).

Outback Power MX60

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.

Further information

Full details of all this, plus a great deal more  is included in my books: Caravan & Motorhome ElectricsSolar 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

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 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.

Battery Technology

Mainly retarding electric-car development is ultra-slow improvement of rechargeable batteries. The first-known lead-acid was invented by Gaston Planté (in 1859). In 1881, Camille Alphonse Faure’s improved version (of a lead grid lattice and a lead oxide paste) enabled higher and flexible performance. It was also easier to mass-produce.

Sealed versions later enabled batteries to be used in different positions without failure or leakage. That apart, there were no significant developments until the AGM version. It was initially developed for the U.S. military around 1980.

The next major development was the lithium-ion battery. This reduced battery weight and volume by over three times. It enabled charging and discharging at far higher rates. But while a significant battery breakthrough, it’s energy storage of 0.5 MJ per kilogram is tiny. That of petrol and diesel’s is 45 M.J. per kilogram. Hydrogen’s is 142 MJ per kilogram.

The latest major development (late-2020) are graphene-based batteries. These can (potentially) provide up 750-800 km per full charge. Graphene is a one-atom-thick composition of carbon atoms. The atoms are tightly bound in a hexagonal or honeycomb-like structure. This virtually two-dimensional structure enables excellent electrical and thermal conductivity. It also has high flexibility and strength, and low weight.

Graphenano claims its graphene-based batteries can be fully charged in just a few minutes. Furthermore, that they can charge and discharge 33 times faster than lithium-ion. Another development, (Gelion), uses zinc-bromine chemistry in combination with advanced electrolytes. These can be all-liquid, liquid/ion gel or all-ion/gel.

Solid-state Batteries

Samsung’s Advanced Institute of Technology’s revolutionary solid-state battery may provide up to 1400 km (875 miles) range. They are about half the size of comparable batteries.The first commercial vehicles with such solid-state batteries are likely to be launched by 2025 or so.

SAIT is also studying lithium-air battery technology. It focuses on cathode technology, protective films for lithium metal anodes, and electrolytes for energy-density improvement, long-term reliability, and safety. This technology has the potential to provide a range of more than 800 km (500 miles) on a single charge.

Battery Prices

Battery prices, which were above $1,100 per kilowatt-hour in 2010, fell to $156 per kilowatt-hour in 2019. Research company BloombergNEF forecast that the average price will be close to $100/kWh by 2023.

Many other battery technologies are in hand – as are significant developments in fuel cells.

Electric and hybrid vehicles – hydrogen as a fuel

World-wide, hydrogen is being seriously considered to replace petroleum products. A major benefit is that its close to being emission-free. (A downside is that is very corrosive).

In terms of mass, hydrogen has nearly three times the energy content of petrol: 120 MJ/kg versus 44 MJ/kg for petrol. In terms of volume, however, liquified hydrogen’s density is 8 MJ/L. Petrol’s density is 32 MJ/L.

Work is in progress to highly compress stored gas. Fibre-reinforced composite pressure vessels are capable of withstanding about 700 times atmospheric pressure at lower cost than before. Other ways include cold or cryo-compressed hydrogen storage, and materials-based hydrogen storage technologies. These include sorbentschemical hydrogen storage materials, and metal hydrides.

Hydrogen can be used to power existing petrol-powered vehicles (and with only minor changes). Plans have already been drawn up to have fleets of hydrogen fuel-cell electric buses on routes in up to ten central hub locations across Australia.

Another approach (already by car makers) is electric vehicles fuelled by stored hydrogen that is converted to electricity by a fuel cell.

Hydrogen fuelling stations

California is leading the USA in building retail hydrogen fuelling stations. As of mid-2020, there were about 60. The state is providing up to US$20 million per year through 2024 until there are at least 100 operational stations. Vehicle makers are only offering fuel-cell-powered cars in regions that have hydrogen fuel stations.

Electric and hybrid vehicles – fuel cells

Fuel cell electric vehicles are fuelled by stored hydrogen that is converted to electricity by the fuel cell. They are more efficient than conventional internal combustion engine vehicles. They are almost silent. Furthermore, they produce no harmful emissions: only very-pure water vapour and warm air.

These vehicles and the infrastructure to fuel them are in the early stages of  being implemented. As with conventional vehicles, they take under five minutes to refuel. Currently, most have a range of about 500 km (300 miles). Fuel cell electric vehicles also have regenerative braking systems. These capture the energy lost during braking and store it in a battery.

The Hyundai Nexo hydrogen-powered SUV.

Higher Weight – a Benefit for Towing

Lighter and more energy-compact batteries are evolving. Without a truly major change in battery technology, however, vehicles suitable for caravan towing are likely to be heavier than now (late 2020). This weight, however, is a bonus. For towing stability, the tow vehicle needs to outweigh the caravan.

The secondary source of electrical energy for RV and domestic use may well be via fuel cells, of which there is significant and ongoing international development.

Electric motor drive is ideal for caravan towing

Fossil-fuelled vehicle engines only develop their maximum torque (i.e. turning power) at relatively high engine speed. The types of electric motor used in electric and hybrids, however, develop maximum torque at zero and low speed. This characteristic is ideal for caravan towing.

Electrical and hybrid vehicles suitable for caravan towing

Many hybrid SUVs and serious off-road 4WDs are available in Australia. These include the Land Rover and Range Rover, Lexus NX and R.X, the Mercedes GLE, the Mitsubishi Outlander, Nissan Pathfinder, Porsche Cayenne and Volvo X160 and X190.

For truly serious off-road going the Rivian XIT and RIS are worth considering. Scheduled for sale in 2022, each has four electric motors (totalling 750 hp). The claimed range is over 640 km (400 miles). Why anyone needs such power, however, is unclear. One U.S. magazine suggests the Rivian ‘looks like a Ford F-150 on a gym-and-yoga regime’.

The Toyota Land Cruiser is already being converted to all-electric drive (for mining applications) by the Dutch company Tembo. The Hilux too, may follow. A local company is also planning to sell electric-only LandCruisers for normal use. Toyota may offer a petrol/electric hybrid Land Cruiser in Australia. The company launched one in the USA. Sales, however, did not exceed 8000 or so.

The iconic Jeep Wrangler is to be sold in a hybrid form – probably by 2022. Full details have not yet been released.

The prospects for caravanners are generally good. There is seemingly no downsides apart (and initially) a need to ensure charging facilities are available in remote areas. That, however, is cheaper and simpler than for petrol or diesel. It also offers opportunities for landowners to build solar arrays and install rapid chargers

Feasible from solar

For those with ample home or business solar, it is readily feasible to charge the battery (or fuel cells) from solar. Such charging of electric and hybrid vehicles can even be done overnight by selling daytime solar energy to a grid supplier and repurchasing it (often at low agreed off-peak rates) at night. Or, to have ample solar energy where the car is during the day.

Electric vehicle charging stations

In the Australian government’s Infrastructure Priority List 2020 (a guide to the investments required to ‘secure a sustainable and prosperous future’) – the independent advisory body (Infrastructure Australia) identified the development of a fast-charging network for electric cars as one of Australia’s highest national priorities over the next five years. Infrastructure Australia, however cited a lack of access to charging stations as a major hindrance to the uptake of electric cars.

Furthermore, data from the Electric Vehicle Council of Australia (EVC) states that Australia currently has less than 2000 public charging stations and only 250 of those are fast charging stations. The EVC likewise cites lack of charging stations in Australia as hindering the uptake of electric vehicles. Moreover, data shows that two-thirds of drivers regard access to charging stations as a major barrier to buying an electric vehicle.

(Those currently existing in late 2020 are listed at https://myelectriccar.com.au/charge-stations-in-australia/red)

Infrastructure Australia has called for the Australian government to, over the next five years, ‘develop a network of fast-charging stations on, or in proximity to, the national highway network to provide national connectivity’: and ‘developing policies and regulation to support charging technology adoption’.

 

Have portable solar in your rented home

Updated February 2020

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 caravans 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.

My books Solar That Really Works! and Solar Success provides ample background for people considering this.

 

 

 

How to stop paying for electricity

Updated 2020

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).

Being virtually non-grid reliant has a ‘feel-good’ value. It has no price!  See also our article on the following: battery capacity required. 

Further information 

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

 

 

 

 

Solar regulators with current shunts – how to fix misleading readings

Updated 2020
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.

Our other books are the Caravan & Motorhome Book, the Camper Trailer Book. All are updated at least every second year. For information about the engineer/technical author please Click on Bio. 

Grid connect solar problems – what vendors may not reveal

Update 2020

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.

Q.Grid connect solar problems – is it true that most grid-connect system produce less than claimed?

My 2.4 kW grid-connect solar system has only produced the claimed input twice (for a few hours) within a now five years. The most I get is 2.2 kW. It’s often less. Should I ask for a rebate?

A.  Solar module reality is, to put it mildly, curious. It can only produce the promoted output under laboratory conditions. Such conditions do not replicate typical usage. The output you have is typical.

A solar module’s output in typical usage is shown in makers’ technical literature. It is even revealed on the back of most solar modules (but out of sight once installed.) It can be seen (below). The test laboratory claims (also use for promotion!) are in column 2. The ‘real-life’ output is that in the third column. Here, a nominally 120 watt module is shown as having a typical output of 87 watts.

Solar Warning

As seen in the above example, the most probable output of this solar module is ‘120 watt’ solar module is 87 watts. That 47 degrees C is not ambient temperature it is of the cells under hot glass.

I do not know of anyone taking legal action re this. But all installers I have discussed this with agree my statement is correct. Their installation reports (needed for rebate claims) often reveal that ‘true’ output. My own does.

Q. Grid connect solar problems – optimising tariff rebates

My 2.4 kW grid-connect solar system about 7 kW hours/day in winter, and about 15 kW hours/day in summer. Our home uses about 21 kW hours/day year round (we have gas heating). The rebate only cuts our electricity bill by about $100 a year! Is there anything I can do about this?

A. The enquirer and her partner are away from home all day. They currently pay 27 cents per kW hour during the day, and 67 cents per kW hour during the evening. They export almost all they generate for a few a unit, and pay 67 cents per unit for virtually all they use.

Most electricity companies, however have a flat rate. This is typically half the peak rate. Switching to that alone halves their bill. More can be saved by programming the dishwasher to run at about 11 am. Likewise the washing machine at about 1 pm. (See also below.)

Q. Grid connect solar problems – time shifting energy input

As I use most electricity at night, is it worth adding battery back-up to my grid-connect solar system.

A. Some grid-connect systems have in-built provision for this. If not it’s possible but costly.

Another approach is independent mini-systems, each of a small battery charger and battery, plus a stand-alone inverter.  This is legal in Australia providing the inverters are ‘stand-alone’ units with one or more outlet socket/s. Appliances plug directly into the inverter (via a multi-outlet power board if desired). Use only ‘electrically isolated’ inverters.

The grid acts as a ‘virtual battery’ for short term high current loads. Run these close to midday via their time switches. That enables them to run from solar power otherwise exported and paid for at a low price. My book Solar Success covers such issues in depth.

The electrically knowledgeable can legally do this themselves. No installation is required so cost is low.

Such inverters must absolutely NOT be connected in any way to 230 volt mains fixed wiring.

Inverter Jaycar MI5704 Appliances (230 volts ac) may be legally plugged directly into stand-alone inverters such as this 12 volt 800 watt unit from Jaycar. Pic: Jaycar.

Q. Taking grid-connect totally off-grid – is it worth doing?

I have a 3.6 kW grid-connect system. On most days I have more input than I use. Is it worth disconnecting from mains (grid) power so it becomes a stand-alone (battery) system?

A. You can do this, but it currently only makes financial sense if you are paying over $1.30 a unit (a unit is 1.0 kW hour). It also necessitates installing an inverter made for stand-alone use.

Right now it makes more financial sense to retain the mains (grid) supply for cooking and heating etc (as a virtual battery). Use use solar and a battery bank for semi-continuous and continuous light loads, like refrigeration, entertainment, computer, and LED lighting etc. The approach suggested above is a better solution financially for some years yet.

 Q. Can a grid-connect system produce peaks in excess of that claimed?

I have a home very close to the sea. Sometimes the output shown on the energy monitor jumps to way over the claimed system output (but only for a few minutes). How is that possible – and what causes it?

A. This can indeed happen. It is, as you say, usually for only a very short time. It adds only a little to the daily input and occurs where a nearby surface is reflective (as an expanse of water or light sand). Sunlight is received directly by the solar modules, but some is then reflected upward from that nearby surface. If there is light white scattered cloud, that cloud may then reflect that energy down again such that it is received again by the solar modules. The increase may be as high as 20%-35% but there is usually no real gain as the scattered cloud also reduces solar input from time to time.

SolarPanels The solar array (above) on the roof of the author’s home at Church Point, NSW, has the effect described above. Sunlight is reflected back up from Pittwater – about 50 metres away.

The issues raised here, plus many more, are covered in depth in the author’s book Solar Success. It sells globally and has literally saved buyers thousands of dollars on their installations. My book Solar That Really Works relates to solar for cabins and RVs. My other books are the all-new Caravan & Motorhome Book, Caravan & Motorhome Electrics, and the Camper Trailer Book. For information about the author please Click on Bio.

RV Solar and Alternator Charging

Updated 2020

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.

A sunset - background picture.

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.

Variable voltage alternators  

Variable voltage alternators have their output voltage and current be based on the vehicle’s operating conditions. This reduces the electrical load (and hence) fuel-consuming mechanical load on the engine by varying the alternator’s voltage and current. That voltage may vary from 15 volts (one reaches 15.4 volts) and typically a low of 12.5 volts. But a few go to zero volts. All are controlled by the vehicle’s central Engine Control Unit (ECU).

The main problem for RVs with variable voltage alternators is that their priority is to ensure the vehicle’s starter battery (now known as the ‘main’ battery) is fully charged. This is typically achieved within five minutes of starting.  At that point the ECU causes the alternator to drop to a typical 12.5 or so volts. This reduces the load on the engine and hence fuel consumption and vehicle emissions. That 12.5 volts is not only far too low for the RVs’ auxiliary battery to charge, but the voltage sensitive relay (VSR) disconnects that auxiliary battery anyway.

The reality is that a variable voltage alternator almost totally precludes using any previous battery charging systems from charging an RV auxiliary battery.

Variable voltage alternator chargers

Currently, a small number of major manufacturers produce specialised RV chargers that cope with variable voltage alternators. Virtually all also accept solar input. Googling ‘variable voltage alternator chargers will bring up details of many now such products. Be aware these are complex units and require expertise to install. The manufacturer will be able to advise a suitably qualified installer.

How to know if I have a variable voltage alternator?

Virtually all new vehicles now have variable voltage alternators. A simple way to know is to open the bonnet and look at the vehicle’s starter battery.

If the starter battery has a module mounted on (or close to) the battery terminal (usually the battery negative) it is all but certain that you have a variable voltage alternator. Pic: Redarc.

How to know more

Our books, Solar That Really Works! and Caravan & Motorhome Electrics explain all.

You can now buy our books in digital and print formats. You can buy the digital version (right now) from this website. Just click on Bookshop

Our print editions can be bought from all the 60 plus branches of Jaycar Electronics in Australia and New Zealand. They can also be ordered from any bookshop or bought via email from booktopia.com.au/

 

 

Solar Shadowing – reducing the losses

Updated 2020

Solar Shadowing

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.

Pic: solarbay.com.au

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

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

Updated 2020

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

Full details of all aspects of this and other related topics are in Solar Success. For solar in caravans and motorhomes see Solar That Really Works!

How much solar capacity do I need?

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. 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.

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 but if you are more than 20 or so degrees out, adding about 10% more solar capacity will compensate.

In terms of tilt, having them at your latitude angle gives you 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. A far better approach, however, is to see what can be done to reduce the draw.

Almost any existing home will have 30 or more so-called wall warts. These are little black boxes that enable you to turn run off appliances remotely. Many over a few years old (and all cheap ones still) draw 3-6 watts even when the related appliance is switched off. That may not seem much but if 30 of them (and some homes have more) that’s 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 powered doorbells. One, personally experienced, drew a constant 40 watts – almost 350 kilowatt/hours a year – yet rarely activated.

Items to replace – lighting

Replace all incandescent globes by LEDs. These provide better light at only 25% the same watts. They last for many years: you recover their initially high cost over time. Be aware that ‘watts’ no longer indicates light produced: it is only the energy they draw. LEDs vary in this respect. Some are far more efficient than others. The light output is shown in ‘lumens’. Their efficiency is thus lumens per watts. Because of this, LEDs that are cheaper to buy are likely to use far more energy.

Items to replace – appliances

Recently made high-quality refrigerators draw far less energy. Replacing any over (say) 12 years old will save you money in terms of how much solar capacity do I need.

Air-conditioners likewise vary 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 larger smaller units have a higher CoP.

Generators for Home and Property Systems

Updated 2020

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

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.

Type Maximum charge (kW) km/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

Solar charging your electric car at home – how to do it

Solar charging your electric car at home or work is feasible. You capture solar during the day and sell it to the electricity supplier. Then charge at off-peak rates at night. AGL (NSW) offers a 20 cents per kilowatt/hour two-year contract. That is only slightly less than buying it back off-peak.

Most Australian suppliers charge about 25 cents per kilowatt-hour (off-peak). Using grid power thus 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.

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. 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.

Footnote

Many existing grid-connect solar systems have excess capacity. Daytime solar can be re-drawn 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.

Summary

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

updated June 2020

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…

Battery Breakthrough

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

Top ten solar scams

Here, the top ten solar scams are exposed. Read this article and you will avoid the very worst. 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!

Solar Books - Top ten solar scams.

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 uses 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.

Seven – exact solar module alignment 

Installers may insist exact alignment of your solar modules is essential – requiring costly adjustable brackets etc. Having solar modules face due north (or in the southern hemisphere due south) maximises daily input. Errors of even ten degrees, however, do not matter. The difference is tiny.

Also, having them tilted at (your) latitude angle maximizes yearly input. This too is not critical. Errors of plus/minus ten degrees barely matter. You can use solar even on east or west facing roofs. The loss is still only 15% – 20% You can compensate this by having 15% – 20% more solar module capacity. This costs little for most systems.

Eight – pay over time at zero interest 

Paying over time is (usually) by far the most costly. The amount (otherwise charged as interest) is simply added to the payments. Such schemes are scams!

Nine – replacing solar modules at ultra-low cost (or free) 

This is an offer to replace your solar modules by ones claimed to have ultra-high output. This may be at very low cost, and even free. It is often offered to buyers of large recently installed systems. The scammers replace your likely high-quality solar modules by ultra-cheap ones of low output and reliability. The scammers re-sell your good modules.

Ten – save money by adding solar 

There are ample reasons to have solar power. Saving money is not one of them. Solar costs are falling and electricity prices are rising. In most countries, however, electricity latter needs to be about A$1.30 per kilowatt/hour to be equal. Thereon solar will be cheaper. Do however install it for environmental reasons.

HINT – how to truly reduce solar cost

Virtually all solar installers visit your home or business. They check your existing electrical consumption and quote accordingly.

It is far better to initially do all you can to reduce that usage. This is readily possible (and by as much as 50%) substantially at zero (or little) cost. And only then seek quotes.  Doing so can literally save you thousands of dollars. Our associated book $19.95 book Solar Success shows just how. If it does not we will refund that amount at any time – without questioning.

See also https://solarbooks.com.au/upgrading-an-existing-solar-system-has-unexpected-traps/

Convert to your own all solar home

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 in much of the world between 50-degree latitudes north/south. This easy to read article shows that doing so 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 as 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.

Our all-solar home in Church Point, NSW. Pic. solarbooks.com.au

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.

Convert to your own all solar home – refrigerators

Refrigerator efficiency improved considerably from 2000 onward – and in many cases dramatically around 2014. Consider replacing any made prior to 2014 and do replace if pre-2000.

Be aware that the larger the fridge the more efficient it is (pro rata its volume). For this reason, never have two small fridges. One of that same total volume will use only a quarter to a third more electricity – not twice.

Swimming pool pumps

A typical swimming pool pump uses a huge amount of power. Here too, you can make truly major savings. If you have ample sun, consider installing a small stand-alone (48-volt dc) solar array directly running a 48-volt input dc brushless dc pump. You usually need no batteries as ample water is circulated whenever there is some sun. How to do this is explained in our book Solar Success.

Irrigation

You can save power used for pumping by knowing that water truly resists being pumped. Doubling pipe size costs little – but reduces the energy used by the pump no less than five times. This can make a huge difference even with small irrigation systems. Here again, see Solar Success.

Our present home

Our present home has 6 kilowatts of solar plus a 14 kilowatt/hour Tesla battery. The solar array produces 20 to 45 kilowatt/hours a day- and we currently use only 9-11 kilowatt/hours a day. The surplus is sold to the electricity grid (for 20 cents per kilowatt/hour – about A$730 a year). (We plan later to buy an all-electric Mercedes car and use that surplus to run it.)

See also: https://solarbooks.com.au/battery-capacity-required-for-home-and-property-solar/   Also https://solarbooks.com.au/ensuring-successful-solar/

See also: our previous -self-designed and built stand-alone system in Australia’s remote north-west Kimberley at https://solarbooks.com.au/ensuring-successful-solar/

About our books

All our books are updated at least yearly. They are Solar Success (for home and property systems), Solar That Really Works! (for boats, cabins, caravans and motorhomes), and Caravan & Motorhome Electrics (that covers all aspects in depth). They are available in both digital and printed form.

Digital: All or any can be purchased and downloaded right. To do so Click on the title/s (in blue) above.

Printed: Our print versions are stocked by all 60 plus Jaycar stores throughout Australia and New Zealand. They are stocked by major bookstores in Australia (but can be ordered via any). They are also available via email order (worldwide) from booktopia.com.au

Vital things about solar in the USA

Vital things about solar in the USA

Updated 2020

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 2045Maine’s target is for 100% by 2050. California, the USA’s largest state, is aiming for 60% as soon as 2030.

Further information

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

Fuel cells for RVs provide electricity cleanly and silently. Their high price is still hindering acceptance but that may well change as new types are being 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 and currently derived from the hydrogen-rich methanol. The only emissions are a little ultra-pure water and minor heat plus (for those methanol fuelled) a very small amount of CO2. That hydrogen can, however, be obtained indirectly from solar modules – by breaking down water into hydrogen and oxygen. The fuel cell then also acts much like a battery but is totally non-toxic.

Fuel cells for RVs – brief history

Whilst invented as far back as 1839, the fuel concept was pursued until the early 1950s. NASA then produced as a safe ultra-reliable power source for space missions. A later market was covert military and other surveillance where its silent operation was 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. Pix: 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 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 any from any other fossil-based fuel. That fuel is converted into hydrogen within the cell but of tiny quantity that it presents no known risks. The Mercedes concept uses hydrogen directly but not enough is currently known about the vehicle 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

Going off the electricity grid

We’ve recently upgraded our system, not entirely for going off the electricity grid, but 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 have yet to draw from it. At night, (or when overcast) we run from battery power. During each day we sell 15-30 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 pay you. This article explains all.

Going off the electricity grid – why do it?

If already connected, going off the electricity grid makes no financial sense. Its cost soared in 2018, but 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 have more generating capacity than needed. You can go off-grid – but a better way is to retain that grid connection and have the supplier pay you. We do that right now!

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. It is now 2019 – and 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. Whilst it has a ‘feel good factor’ that comes at an extremely high price.

We recently thought hard about doing this for our current home (in Sydney). Instead, we upgraded our system (from 2.4 kW) to 6 kW plus a Telsa 14 kW/h battery. This produces three to four times more electricity than we use on almost all days.

We are thus not entirely free of the grid – but have yet to draw from it. At night, (or when overcast) we run from battery power. During each day we sell 15-30 kWh (at a current 20 cents per kWh). That too is a ‘feel good’ factor.

Even when substantially overcast that 6 kW system still producs 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 (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.

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.

Further information

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.

 

 

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Upgrading an existing solar system has unexpected traps

updated 2019

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.

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 has unexpected traps in that there may be a limit on the excess amount. Your installer will 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 2019) 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 (ripple-free) dc output does not exceed 110 volts. In practice, this limits the solar array to 72 volts dc. 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 digital form) 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.