A family of three in Austria has opted for a new solution for the heat supply of their detached house. The entire heating energy and hot water is provided by an electric boiler. This in turn uses surplus solar electricity from a photovoltaic system with an output of eleven kilowatts, which also serves as the building's roof covering. The solar power is initially used to power the consumers in the building. Once these are supplied, a power controller AC Thor from the Austrian manufacturer MyPV pushes the solar energy into the electric heating system. Only when the heat supply is also covered does any excess electricity flow into the grid.
6,700 kilowatt hours of surplus solar power
After a full year of operation, the first data is now available on how the system has proved its worth. The evaluation shows that between 1 May 2019 and 30 April 2020 the family pays 49 per cent less in electricity costs compared to a heat supply with a heat pump. This is because the boiler does not run exclusively on solar power. If too little solar energy is available, the family has to run the boiler with electricity from the grid. However, at 7,658 kilowatt hours, the electricity consumption was still reasonable. On the other hand, the family fed 6,700 kilowatt hours of surplus solar power into the grid.
Energy bill of 750 euros
As prescribed in Upper Austria, the family also has a non-electric heating system. In December and in January 2020 a Swedish stove provided extra comfort in the rooms of the house. The family paid about 80 euros for the fire wood (just under a solid cubic metre of beech wood). Together with the electricity from the grid, the energy bill came to a total of 750 euros. (su/mfo)
