Study on Sharing Electricity using Photovoltaic Panels and Storage Batteries in Housing Complexes

After the Great East Japan Earthquake, the household sector of public welfare is promoting the introduction of distributed energy systems by diversifying energy sources and applying local energy use as one of the energy supply measures in case of a disaster. This study introduced an energy-sharing system in the housing complexes to examine whether each house with different family composition and life patterns (i.e., different energy use patterns) could use energy more efficiently. The target energy in the housing complexes was set to electricity, which was generated by photovoltaic panels and stored in storage batteries. The strategy for stable electricity supply and profit generation was as follows: (1) electricity generated by photovoltaic panels is consumed first in the housing complexes; (2) the remaining electricity is stored in a large-capacity storage battery for the operation of the cooling and heating system; (3) afterward, electricity is sold directly to nearby housing complexes at a lower price than the supply price of electricity companies and at a higher price than when sold to electricity companies. The calculation results show that the profit from the sale of surplus electricity and the reduction rate of CO2 emissions were evaluated. The annual electricity purchase was 87 MWh, which decreased by 52% due to the introduction of the electricity-sharing system. Annual electricity sales were 433 MWh. The annual profit from selling surplus electricity directly to nearby houses was 1.14 times higher than selling to electricity companies. The CO2 emission reduction rate was 56.2%.