In the Swiss canton of Valais, at an altitude of 1,200 metres lies a passive house which is completely energy self-sufficient from the public electricity supply. After three years of trials, off-grid electricity generation using 100% renewable energy has become possible. "I have tried several complimentary systems that keep the supply going throughout the year", said owner Stefan Market, project manager for renewable energy to Soltop AG, explaining its sophisticated concept.
Thermal solar collectors to supply hot water and support the heating of the house have been built into the façade. A photovoltaic system in the south-facing garden produces electricity for the 150 square metre family house with a nominal capacity of 3 kWp. An additional PV system with 1 kWp capacity was built into the façade under the balcony, and a small wind turbine fixed to the roof provides power in case the PV system gets covered in snow during the winter. The surrounding environmental conditions are ideal for this self-sufficient house: clean mountain air, hardly any fog, over 300 days of sunshine a year and the reflection of solar rays off the snow in winter combine to guarantee high energy yields. A battery block in the basement stores generated power, with storage and output regulated by a sophisticated control system, designed like a miniature electrical plant. Energy use is further minimized by controlled ventilation and exhaust with heat recovery.