Our all solar house was built in just five months (in 2000). It used (then) hi-tech materials and techniques resulting in a pleasant and very workable living space in a stunningly beautiful site in Western Australia’s far north Kimberley.
The site at Ngungnunkurukan (locally known as Coconut Well), 21 kilometres north of Broome, is a very special place. The site adjoins one of the three major Aboriginal song lines that traverse Australia. It has major rock formations significant to the Gularabulu people, whose community is a kilometre or two south. The land’s ten acres of natural bush fronts directly onto a tidal lagoon and then the Indian Ocean about 400 metres to the west.
It was agreed with the traditional owners that all rocks and significant trees be left untouched and that no access be allowed onto an exceptionally sacred part of the site. Also, as far as possible, to avoid having heavy earth moving machinery close to that area. The Shire and FESA allowed the obligatory fire trails to detour away from these areas.
The upper half of the 10 acre block at Coconut Well.
We moved onto the land in April 2000. Cyclone Rosita struck ten days later. We sheltered from the 160 km/h gusts by burying our OKA off-road truck to its chassis and strapping a table over its windscreen. Whilst scary, the plus 160 km/h wind was an invaluable introduction. As the site is high up and totally exposed to cyclonic winds it caused us to rethink the engineering – so as to cope with up to 240 km/h.
Our main requirements were for light and space, plus a home that would form a natural extension of the Indian ocean and dunes to our west, and the untouched bush behind us. The original concept was good but, as an engineer myself, it was no surprise that the structure was twice rejected (by Broome Shire) as having inadequate cyclone protection. It was subsequently and brilliantly re-done by Garry Bartlett of B&J Building Consultants (in Broome).
The resultant all solar house (of steel and glass) has a structure that is closer to a steel bridge than a house. It is a hi-tech design using structural engineering rather than building techniques. There is not a single mud brick, straw bale or piece of timber in it! It is also rare in having a ceiling 4.3 metres high at its centre..
The all-steel structure. Despite its size and apparent complexity it was erected in one 12 hour day. The diagonal steel tubes add strength and double as water drainage for the gutters. The gutters (not yet added) are protected from cyclones by being between the upper and lower Colorbond roof layers. The Pindan soil really is this colour.
The all solar house’s main strength is a double curvature roof. It is fabricated from heavy gauge Colorbond steel. This is secured by 14 gauge Tek screws and cyclone washers at every channel into purlins that are welded to four similarly double curved rolled steel joists. A similar gauge terracotta-coloured Colorbond ceiling is attached directly to the underside of the purlins. This (in effect massive but light beam) is tied down by forty 100 by 100 mm square hollow steel posts embedded into a 600 by 600 mm concrete perimeter beam.
Diagonally located 150-mm, 20 mm thick, steel tubes provide further support and double as water down pipes. The remainder of the house is almost entirely cyclone-proof toughened glass sliding doors. Each has slide-open stainless steel security mesh. There are no internal walls as such. The floor is ochre-coloured polished concrete.
The first major building problem was having the originally planned 100 by 200 mm rolled steel section roof supports formed to the necessary double curvature without buckling. This proved not possible so the design was changed to similar sized rolled steel joists. These were rolled up in Perth, trucked the 2100 km to Broome, welded up into complete end sections and then trucked the 4200 km round journey to and from Perth for galvanizing. The roofing sections were rolled to the same curvature.
The all-steel structure demanded dimensional tolerances of only a few millimetres: closer to watch making than builders’ typical plus or minus a centimetre or two. The 600 mm perimeter beam has over 40 beam tie downs, all of which needed placing within two to three millimetres in all planes. Surprisingly, it worked: the finished 150-square-metre main structure was within five millimetres across the diagonals.
The steel suppliers erected the steel structure — assisted by a 200-tonne crane ‘borrowed’ for the day. Even at that capacity the crane worked hard. It had to position 1100 kg steel beams at its full extension of close to 50 metres. Contractors were used for concreting, roofing and internal plumbing but, apart from that, all the work was done by ourselves,with the invaluable assistance of an ex builder who was living locally at the time.
Power for building was supplied almost entirely by solar. I built a 28-module system prior to starting the main construction. This provided 4 kW, and up to 11 kW surge. It could readily drive a nine-inch angle grinder. This, even more than the house design, tossed the contractors. They knew there was no mains power – yet here was 230 volts at considerable wattage. It was hard to persuade them it really was solar.
The solar system
The original solar system was designed and built just prior to starting work on the house. It had 24 by 80 watt Uni-Solar solar panels located on the north facing roof of an existing shed, about 200 metres from the house site. These were wired in series-parallel to provide about 32 amps at a nominal 48 volts (about 9 kW/day). These charged a bank of twenty four 2.0 volt wet cell batteries – each of 675 amp hour via a Plasmatronic PL 40 solar regulator.
The batteries were connected in series parallel – thus providing 16,200 amp hour (about 32 kW/h). The inverter was a 3.8 kW SEA unit – that had a massive 11 kW peak ability. In 2014 (14 years later) it is apparently still working. The feed to the house was thus at 230 volts.
When the all solar house was completed, the solar array was moved closer to the house. To cope with irrigation needs it was expanded by adding further Kyocera 130 watt mono-crystalline solar panels, resulting in a total of 3.4 kW (about 18 kWh/day in peak periods).
The main solar array (a further bank of mono-crystalline solar panels were installed shortly after this photograph was taken (2005).
The original batteries were sadly flogged to death by a caretaker we employed for a time. They were replaced in 2007 by sixteen gel cell 12 volts batteries – each of 235 amp hour. The Plasmatronic regulator was replaced by an 80 amp Outback Power unit.
The 16 by 12 volt (235) amp hour gel cell battery was connected in series-parallel to provide 940 amp hours (45 kWh).
The SEA 48 volt dc -230 volt ac inverter has a peak capacity of 11 kW. An Outback Power 80 solar regulator can be partly seen (bottom left).The small unit under the SEA is a Xantrex energy monitor.
The all solar house runs totally on 230 volts from the inverter. All lighting was compact fluorescent (this was before the era of LEDs). A very efficient Fisher & Paykel fridge coped well in Broome’s hot periods. Cooking was via LP gas (using 40 litre cylinders). Water heating was solar only – and worked well even in winter.
The house design was such that cool air from the Indian ocean was cooled yet further by a full length pond and then drawn into the house via the many almost always open doors. It was then extracted by roof located vents. Air-conditioning was deemed unnecessary as a cool ocean breeze developed by midday almost year around.
My now-psychologist and somewhat feisty Finnish-born wife (Maarit) has a sculpting background. She acquired Welding and Production Engineering Certificates at Broome TAFE in anticipation of building. She is still comfortable using big power tools such as nine-inch angle grinders. It was and still is not a good idea for any tradesman or sales person to patronise her in local hardware stores!
We started building in earnest in August 2000 and moved into the semi-completed house but already all solar house just before Christmas.
Despite excellent bore water, the main house runs year-round on rainwater, even for toilet flushing. The 280 square metre roof has two 250 mm by 150 mm stainless steel gutters inset between the roof and the ceiling (for cyclone protection). Water flows via the (diagonal bracing) 150 mm steel tubes. These tee into sunken 200 mm pipes that run the full length of both sides of the house. They fill a 14,250 litre holding tank behind and north of the house that catches the torrential seasonal rain: in accompanying passing cyclones. The tank can fill in less than one hour. The water is then pumped up to a 100,000 litre tank 100 metres from the house. 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 a day. This is a very efficient and silent way of pumping water. The off-the shelf 0.75 kW pump runs just twice a day for about three minutes each time.
An above-ground rendered concrete block 31,000-litre swimming pool is attached to the house. This, as with all of the house and property, runs from solar alone. It has an interesting and originally unique way of operating. The pool has a dedicated 480 watt solar array that directly drives a Lorentz 48-volt brushless DC motor pump (there are no batteries). Rather than using chloride, the irrigation water input feed passes through the pool replacing about 10% each day.Swimming pool
Original quotes for the circulation system (all based on traditional 230 volt technology) were around $60,000. Ours cost $7500 in 2002. (Full details are in Solar Success)
The crystal clear water of the solar swimming pool – the circulating pump runs all day, driven from the four dedicated 120 watt solar modules seen here. The inset cyclone-protected gutters can be seen here.
The protruding section of house on the left is an ultra-strong cyclone shelter. (Full details of this pool are in Solar Success.)
That bore water is rare in being crystal clear. It is possibly the purest water in the world: it comes from the Leopold Ranges some 700 km north-west of Broome (with untouched land between the two). We used only 2% of our annual allocation. The unused remainder pours into the Indian Ocean.
Sewerage is septic. We would have preferred a more ecologically sound system but the (then) Shire regulations prevented this.
We had nothing but genuinely helpful cooperation from Broome Shire. They rejected the original engineering plans but as I already felt that cyclone protection was inadequate I welcomed their confirmation and requirements.
One downside was the kitchen. Built locally, it was very poorly made. “Call yourself a cabinet maker” said Maarit to one of them, “you’re are not even a half decent bush carpenter”.
The all solar house worked well for us for ten years. Whilst there I wrote and published five books. I also spent three years at Notre Dame University auditing the Aboriginal Studies course. Meanwhile Maarit acquired two university degrees, and added some Spanish and Mandarin to her existing four languages. With some regret, primarily that such large properties require ongoing major maintenance, but also as our expanding family lived mainly in Sydney, we sold the property in late 2010. Our home (in Church Point) has of course become an all-solar house too!
This article was originally published in Natural Home Builder. It was updated by Collyn Rivers in 2011 and 2014.