All Solar House
We self-built our all solar house in Australia’s far north. It is beautiful and practicable. Living with solar alone is 100% possible. Here’s how and why.
The upper third of the 10 acre block. The solar array for our all solar house is bottom left of the photograph. Pic: solarbooks.com.au
Apart from bore water, the 10 acres (of Cable Beach frontage) had no services. Using hi-tech materials and techniques, however, enabled a beautiful and totally practicable living space. Plus extensive irrigation.
The land at Ngungnunkurukan (locally known as Coconut Well), is 21 kilometres north of Broome – one of the world’s most isolated towns. Its nearest cities, (Darwin and Perth), are over 2000 km away. The 12,000 or so population is 50% indigenous.
The land directly adjoins the route of one of three major Aboriginal song lines traversing Australia. Moreover, it also has major rock formations significant to the local Gularabulu community.
Original bush and sand dunes front directly onto a tidal lagoon. Furthermore the Indian Ocean is a mere 400 metres away.
Protecting the culture
Knowing the significance, we consequently followed the traditional owners’ wish to protect rocks and significant trees. And, at the same time, to restrict access to a sacred part of the site. That part was welcomed! It’s a breeding area for King Browns.
We attempted, also, to avoid heavy earth moving machinery being close to that area. In addition, Broome Shire and the local fire authority allowed obligatory fire trails to detour around such areas.
All solar house – Cyclone Rosita
We moved onto the land in April 2000. Cyclone Rosita struck ten days later. We buried our ultra-strong OKA off-road truck to its chassis and also strapped a table across its windscreen. This gave shelter against the subsequent 180 km/h plus wind.
Whilst scary, that cyclone 160 km/h wind specifically caused us to rethink the engineering. Furthermore, we added an almost indestructible cyclone shelter. It’s rarely needed, but provides visitors with a truly strong bedroom.
All solar house – our main requirements
Our main requirements were light and space. And visually, to link the ocean in front, to the virgin bush at sides and rear.
The original concept was good. Nevertheless, as an engineer myself, it was clear the designer’s structure was inadequate. It was subsequently and brilliantly re-designed by Garry Bartlett of B&J Building Consultants (in Broome). B&J also fabricated the massive main frame.
Despite its complexity the all steel framework was erected in one (12 hour) day. The diagonal steel tubes add strength. They also double as water drainage for the gutters. The Pindan soil really is this colour. Pic: solarbooks.com.au
All solar house – bridge like construction
The house’s superstructure is closer to an arched steel bridge than a house. It’s structural engineering – not traditional building. It is almost entirely concrete, steel and glass. There is not a single mud brick, straw bale, or any but non-structural timber in it!
The main area – looking north. Pic: solarbooks.com.au
It is also rare in having a ceiling 4.3 metres high at its centre. Apart from its roof, the exterior is almost entirely cyclone-proof toughened glass sliding doors. Each has slide-open stainless steel security mesh. There are no full height internal walls, only a couple of 2.0 metre high partitions.
Double curvature roof
The all solar house’s main strength is its double curvature roof! This is fabricated from heavy gauge Colorbond steel. It is secured by 14 gauge Tek screws. In addition it has cyclone washers at every channel. Furthermore, the purlins are welded to massive curved RSJs (rolled steel joists). A similar Colorbond ceiling likewise attaches directly to the purlins’ undersides. The whole forms an immensely strong, but nevertheless light, beam.
The roof is tied down by forty steel posts. Each is 100 by 100 mm square. The posts are bolted to a 600 by 600 mm reinforced concrete perimeter beam. Diagonally located 150 mm diameter (and 20 mm thick) steel tubes provide further support. They also double as rain water down pipes.
The RSJs sections (each over 2000 kg) were rolled to the desired double curvature in Perth. They were then trucked the 2100 km to Broome and welded into complete sections. Then trucked 4200 km to Perth and back for galvanizing. Roofing sections were rolled to the same curvature.
The all-steel structure demanded tolerances of only a few millimetres. This is closer to watch-making than builders’ typical plus or minus a centimetre. Or three. The 400 mm perimeter (40) beam’s needed placing within two to three millimetres. Surprisingly, it worked. Furthermore, the 150 m² structure is within five mm² across diagonals.
Assembling the all solar house
We had contractors pour the 300 mm thick concrete floor. B&J assembled the huge steel frame – assisted by a 200-tonne crane. Even at that capacity the crane consequently worked hard. It had to position the massive steel beams at its full extension of over 40 metres. We had contractors install the Colorbond roof and ceiling. Likewise, internal plumbing and 230 volt ac wiring.
All else was done by myself and my psychologist wife (Maarit). She acquired Welding and Production Engineering Certificates at Broome TAFE. Maarit also became a certified venomous snake handler!
We also had invaluable aid from a local with a building background.
Building started building in earnest in August 2000. We moved into the (semi-completed) but already all solar house by Christmas.
There are no full height internal walls.The floor is ochre-coloured polished concrete. Pic: solarbooks.com.au
Powering the all solar house
To enable mainly solar to power the construction, I built that first. I used 2000 watt of solar modules that I located on the roof of an existing shed.
The array was later expanded and moved closer. It now provides a reliable 3.4 kW – and about 18 kWh/day most year round. (It still works fine.)
The main solar array. A further bank (of six modules) was added just after this 2005 pic was taken. Pic: copyright solarbooks.com.au
The associated 48 volt, 80 amp SEA inverter coped with 11 kW surges. It readily drives big power tools. This truly puzzled contractors as they knew there was no mains power. Conversely, here was 230 volts at considerable wattage. It was nevertheless impossible to persuade them it was mostly solar.
This SAE 11 kW surge inverter installed in 2001 works well to this day. Pic: solarbooks.com.au
The original batteries were flogged to death by a caretaker. They were consequently replaced by sixteen 12 volt gel cell batteries. Each was 235 amp hour. An 80 amp Outback Power regulator controls charging.
Sixteen 12 volt (235 amp hour) gel cell batteries are connected in series-parallel. They provide 940 amp hours (45 kWh). Pic: solarbooks.com.au
All solar house – naturally cooled
Indian ocean cooled air is drawn into the house via the usually open doors. It’s subsequently extracted via roof vents. Air-conditioning was thus deemed unnecessary. A cool ocean breeze usually develops by midday year-around.
The property runs totally from the inverter’s 230 volts.
A very efficient Fisher & Paykel fridge copes well. Cooking is via LP gas (using 40 litre cylinders). Water heating is solar only. It even works well in winter.
As LEDs were not available back then, lighting was all via compact fluorescents. Ample power was available to drive them. Had we built later, however, we would have used LEDs throughout.
Air-conditioning was deemed unnecessary. Ocean cooled air is drawn into the house via its mainly open doors. It’s then extracted by roof vents.
All solar house – water
Despite excellent bore water, the house uses rainwater – even for toilet flushing. The 280 square metre roof has two deep and wide stainless steel gutters. These are inset between the roof and the ceiling for cyclone protection. Water flows via diagonal bracing tubes to sunken 200 mm pipes. These fill a 14,250 litre holding tank that captures torrential seasonal rain. The fall is so heavy the tank fills inside an hour. The water is then pumped to the main 100,000 litre tank.
Water is supplied to the house by a pressure pump and 500 litre water pressure tank. The pump replenishes the pressure tank once or twice daily. It is silent and efficient, moreover running only twice a day for a few minutes each time.
Swimming pool for an all solar house
Quotes for the pool’s circulation system were around $60,000. Finding them based on traditional technology, we designed and built our own. It cost a mere $7500 (in 2002.) This, as with all the house and property, runs from solar alone.
Lorentz Badu pump after seven years. It runs on 40 volts dc, pumping about 35,000 litres a day from four 120 watt solar modules. (The apparent rust is the Kimberley’s Pindan sand. It stains everything it touches.
A 480 watt solar array directly drives a Lorentz 48-volt brushless DC motor pump. No batteries are needed. The pump accepts a wide range of voltage, so no solar regulator is needed. As a result, water circulates all day under the Kimberley’s typical all-day sun.
No chloride is used. Irrigation water first passes through the pool. It effectively replaces about 10% each day.
Crystal clear water. A 48 volt dc is powered by four 120 watt solar modules seen here. It runs all-day. The house’s inset gutters can be seen here. The protruding section (left) is an ultra-strong cyclone shelter. (Full details of this pool are in Solar Success.) A (2020) visit showed that, while the batteries needed replacing, all systems are still working.
Crystal clear water
The crystal clear bore water is among the world’s purest. It comes from the King Leopold Ranges – 700 km north-west. The land between is totally untouched. We used only 2% of our allocation, 98% consequently pours into the ocean.
Sewerage is septic. We would have preferred a more ecologically viable system but, not withstanding, Shire regulations prevented it.
Broome Shire otherwise cooperated totally. It rejected the original plans as cyclone protection was inadequate. But that confirmation was nevertheless welcome. I’d thought that too.
Not all worked as hope. One downside, for example, was the kitchen. Built locally, it’s very poorly made. “Call yourself a cabinet maker” said Maarit to one, “you’re not even a half competent bush carpenter”.
Maarit in blacksmith mode. Pic: Broome TAFE
A time to move
The all solar house worked well for us for ten years. Whilst there I wrote and successfully published five books. I also spent four years at Broome’s tiny university campus, auditing the Aboriginal Studies course. Meanwhile, Maarit acquired two more university degrees. She subsequently obtained her Master’s degree.
We later needed to be closer to our rapidly expanding Sydney family. Reluctantly, we sold it in 2010.
Our home (in Church Point) has subsequently become an all solar house too!
A 2.4 kW solar system supplies all the three-story home’s needs. Pic: solarbooks.com.au.
Fuller details of the solar, swimming pool, water pumping are in my book Solar Success.
It is totally feasible to build an all solar house. That book shows specifically in detail how to get it right first time.
Solar That Really Works specifically cover cabins and all RVs. Caravan & Motorhome Electrics specifically covers this. Caravan & Motorhome Book gained excellent reviews. To quote Caravan World: ‘Collyn Rivers has put his encyclopedic knowledge into print . . . there is virtually no issue he hasn’t covered.’
See also our associated website: solarbooks.com.au