Building residential micro-grid of DC power supply need to determine the appropriate DC voltage. Too high or too low of the voltage can cause many problems. Based on the household appliance energy use efficiency in typical home, we make detailed analysis of the electric power supply modules. Simplifying and classified all kinds of appliances, building energy loss functions are done. Then we get the relationship between energy consumption and DC voltage level. We find that setting the voltage of 110V DC is more economical in DC micro grid.

hybrid microgrid; voltage level; residential electricity; energy loss