An Auckland company has developed what is believed to be NZ’s first “positive energy” house, which generates all its electricity from the sun and puts surplus power into the grid under a special deal with Contact Energy. The two-bedroom house at Kaiwaka in Northland has a combination of solar PV panels and solar hot water heating on the roof, using state-of-the-art solar technology from Europe. The company behind the project, Ewa-Tech, has an arrangement with Contact Energy, which has agreed to pay 18c for every kWh of electricity the house delivers to the grid.

Ewa-Tech’s founder, Eris Jansseune, who lives in the house, hopes it will be a model for similar solar-powered homes throughout NZ. His solar system has no battery; the power is fed directly into the grid. Jansseune says the solar hot water system provides about 75% of his hot water, with back up from gas-fired water heating in winter. The house also has a European-designed solar hot air heating system for use in winter.

Jansseune says the solar PV panels generate about 1800kWh a year, and the solar hot water system produces about 1960kWh annually, giving a total of 3760kWh/year. He estimates the house’s electricity demand at 3407kWh a year, which leaves a surplus of about 350kWh/year to put back into the grid. Jansseune expects to boost the solar PV output to 3600kWh within 12 months, by adding another row of panels to the roof. He explains the $10,000 cost of the extra panels is the reason for delaying their installation. But with an additional 1800kWh of power each year subsidised by Contact at 18c/kWh, it will help recoup the cost of the panels. The house is highly-insulated and uses LED lighting throughout and uses gas rather than electricity for cooking. All water is supplied by rainwater.

Jansseune hopes his house will be the beginning of a “solar revolution” in NZ. He adds, “Hopefully we can inspire architects, developers, councils and everybody involved in building industry to design more energy-efficient and solar-powered houses and buildings.”

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