Ensuring Successful Solar Projects – first time and every time.
Here’s how we built our own.
Our all solar house was self-built in five months. Hi-tech construction resulted in a superb and workable waterfront home in Australia’s remote far north. It was even built using mainly solar energy. Here’s how we did it.
The site’s ten acres of natural bush at Ngungnunkurukan (known locally as ‘Coconut Well’), fronts directly onto a tidal lagoon with the Indian Ocean about 400 metres away. The land adjoins one of the three major Aboriginal song lines that traverse Australia. It has major rock formations significant to the local Aboriginal community. We left all significant rocks and trees untouched.
We moved onto the land in April 2000. Cyclone Rosita struck ten days later. We sheltered from the 180 km/h gusts by burying our OKA off-road (ex-mining) truck to its chassis and strapping a table over its windscreen. While scary, the 180 km/h cyclone was an invaluable introduction.
Successful Solar Project – the House’s Design
Our main requirements were for light and space. Moreover, the house should form a visual extension of the Indian ocean and dunes, and likewise of the bush behind us. The original design was good, but as an engineer myself, I was not surprised the council rejected the architect’s plans as having inadequate cyclone rating. They were subsequently and brilliantly re-done by Garry Bartlett of Broome’s B&J Building Consultants – who also added a cyclone shelter. This doubled as an ultra-strong spare bedroom.
The subsequent all solar house is a mix of aircraft and structural engineering. To most people’s surprise, its main strength is derived from the roof. It is in effect a curved beam formed of two layers of heavy gauge Colorbond steel. It is constructed much like an aircraft’s wing and attached to four massive 100 by 200 mm rolled steel I-beams rolled to the same double curvature.
The roof structure is tied down by both vertical hollow beams that bolt onto a massive concrete perimeter beam via steel tubes that double as water drainage for the inset gutters.
The domed ceiling is 4.1 metres high. There are no internal walls – only minor partitions about 1.8 metres high. There are next to outer walls either: instead, there are 14 siding toughened glass sliding doors, each protected by sliding prison-grade steel mesh doors.
The all-steel structure demanded dimensional tolerances of only 1-2 millimetres. This is closer to watch-making than many a builder’s pluses or minuses the Post Code – but surprisingly it was achieved.
Erected in one day
The steel suppliers erected the main structure assisted by a 200-tonne crane that positioned the 1100 kg steel beams from 50 metres away. It took just one day. A neighbour commented: ‘When I left for work there was a flat space. Eight hours later a big house was there’.
We used contractors only for concreting, roofing, internal plumbing and non-solar electrical work. But, apart from that, all else was done by my wife Maarit and myself with assistance from an ex-builder. We started in August 2000 and moved into the semi-completed house in late November. It took a further six months to complete.
The solar system
I designed and built the (initially 2.5 kW) solar system before starting construction. It supplied almost all of the power needed for building. That, even more than the house design, puzzled contractors. They knew the closest grid power was 20 km away – that there was a 230 volt supply. It was hard to persuade them our’s was from solar.
The original system had thirty, 80 watt 12 volt solar modules on a north-facing existing shed 200 metres from the house site. This system provided about 12 kW/day from the Kimberley’s ample sun. It charged 24 two volt wet cell batteries each of 1000 amp hour – via an 80 amp Outback Power solar regulator. The inverter was( and in 2019 still is) is a 3.8 kW SEA unit of 11 kW peak ability. This array was later moved closer to the house. To cope with irrigation, I added further solar capacity to bring the total to 3.4 kW (about 18 kWh/day in peak periods.
Our 45 kW/h battery capacity
Whilst less than two years old, the original batteries were sadly flogged to death by a caretaker who, unknown to us, had a huge drying oven that he ran all night. The batteries were replaced by sixteen 12 volt gel-cell units – each row of four thus provided 235 amp hour and connected in series-parallel to provide 940 amp hours. Each row thus provided 940 amp hours 11.28 kWh. The total from the four rows was about 45 kW/h.
The area’s hard but crystal clear bore water is possibly the purest in the world. It comes from the Leopold Ranges, some 700 km north-west of Broome, with nothing but untouched desert between the two. We used only 2% of our annual water allocation, the remainder pours into the Indian Ocean, a few hundred metres away.
Whilst wonderful for drinking and irrigation, the bore was too hard for washing etc. We thus collected water from the 280 square metre roof of the house and pumped (via solar) to a 100,000 litre main tank about 70 metres from the house.
An above-ground rendered concrete block 31, a 10000-litre swimming pool is attached to the house. This too runs only from solar. It was originally a unique way of operating but has frequently been copied.
Original quotes for the circulation system (all using 230 volts and requiring doubling our solar capacity) were $60,000-$70,000 plus that solar. Instead, I used a dedicated 480 watt solar array to drive (directly) a 48 volt brushless dc pump that draws 480 watts from a dedicated four by 120 watt solar modules. As it runs all day under the Kimberley’s reliable sun, there is thus no need for batteries. It cost a mere $7500 including the solar.
I arranged for fresh irrigation water to passes initially through the pool, replacing about 10% each day. It thus needs minimal chlorine. It cost $7500 in 2002. Full details are in Solar Success.
Sewerage is septic. We would have preferred a more ecologically sound system, but the (then) Shire regulations prevented it.
The total price for building the house and solar was about A$220,000.
Our all-solar house worked well for us for ten years. While there I wrote and published five books. I also spent four years at the tiny Broome campus of Notre Dame University – auditing the Aboriginal Studies course. Meanwhile, Maarit added a Counseling, and a Psychology degree to her original Arts B.A. And some Spanish and Mandarin to her existing (English, Finnish, German and Swedish) to her four languages.
As part of her art, Maarit does heavy blacksmithing and has MIG, TIG and arc welding certification (plus a production engineering certificate). She comfortably uses tools such as nine-inch angle grinders and did a lot of the heavy construction work.
With considerable regret, but primarily because our expanding family lived in Sydney, we sold the property in late 2010. Our new home (in Church Point – north of Sydney) not surprisingly became an all solar house too! And Maarit acquired her Master of Art Therapy.
Our constantly updated book Solar Success has all you’ll ever need to know to buy, design and install solar systems for homes and properties. Solar Success includes full details of this house and solar system. Solar That Really Works! is for cabins and RVs. Caravan & Motorhome Electrics explains every detail of that topic. It also bought by auto-electricians as a practical textbook in this area.