Demonstrative Research on DC Microgrids for Office Buildings

This paper reports the experimental study of a DC microgrid for an office building that is now being constructed in Obihiro City, Hokkaido, Japan. The objective of this study is to develop a self-sustained distributed energy system by combining distribution energies, batteries, and appliances with DC power. This new DC energy system not only reduces the environment load and improves energy efficiency but also forms a community energy system that can become independent from utility grids and resistant to natural disasters. We have found that compared with AC power supply, the DC system, which uses power generated by solar panels as is, increases the efficiency by 3.2 percent and decreases commercial power to be purchased by 4.2 percent.