Base on the DC microgrid in the College of Energy, Xiamen University, we through three different power supply modes to compare the energy efficiency. This paper introduces the distribution situations of three power supply modesin detail, including components and loads, and calculates and evaluates the Xiamen typical daily loads, typical daily and annual power generation of photovoltaic array. Taking the college offices as the research objects, we test the overall efficiency, the results show that dc power distribution has more advantages than ac power distribution. The overall efficiency can be improved by 6.5-7.9%. Finally, the line loss and voltage drop are analyzed, and the maximum length of cabling is calculated under 380V DC power supply.
Keywords Efficiency, photovoltaic power generation, loads, voltage drop