Solar spectrum varies with seasons, time and weather depending on solar altitude and atmospheric condition. Because the solar cell efficiency is influenced by its spectral sensitivity, solar spectrum data is important to accurately estimate the output from photovoltaic systems. To this end, we observed spectral irradiance on horizontal and inclined surfaces for more than seven years at five stations in Japan with different solar radiation conditions. The observed data were compiled into a dataset. Using this dataset, we studied the influence of solar spectrum on the output from different photovoltaic modules.

To achieve net zero energy houses, it is necessary to install PV on the roof of houses. However, the electricity generated by photovoltaics have been required to be consumed in their houses. In this paper, we conducted an actual measurement survey of energy self-sufficient house installed with large-capacity storage batteries and daytime operation of heat pump water heater. Furthermore, we evaluated of electricity self-sufficiency rate on electricity sharing district which sharing electricity among multiple houses. As a result, the electricity self-sufficiency rate of energy self-sufficient house was 58%. In addition, the electricity self-sufficiency rate of electricity sharing district were 45-53%. These results cleared that half of the electricity consumption could be covered by photovoltaics generation.