In recent years, energy conservation of houses has become one of the important issues to reduce global warming gas emissions, and ZEH could be an attractive solution. As renewable energy source, the spread of photovoltaic system is greatly expanding. The generated electric power by photovoltaic system is DC power, and it can be said that the DC power supply system would be suitable because it does not require conversion to AC. In this report, we analyze energy conservation effect by introducing DC power supply system quantitatively and clarify the difference of introduction effect due to regional difference.
