Advantages and challenges of DC microgrid for commercial building a case study from Xiamen university DC microgrid

This paper discussed the advantages and challenges of DC microgrid for commercial building. The data obtained from the DC microgrid constructed at Xiamen University shows that DC microgrid with rooftop solar system is an efficient way to power varies DC loads inside the building. The capacity of the solar system on the rooftop normally will be enough to power the LED light loads in commercial buildings, even for high rise buildings. In order to power heavy loads such as air conditioning and EV charging stations, extra power are required, which can be obtained from the BIPV on the sidewall, glass window, or adjacent parking lots. To ensure the stable bus voltage and continuous operation of the DC microgrid, a suitable energy storage unit and two way AC/DC invertors are needed. Therefore we believe to use the solar power only for the matched DC loads, and keep existing AC power in the building to power the rest loads (or an AC and DC hybrid microgrid) maybe a more viable solution. The economical analysis shows that installation cost of a DC microgrid system is about $2.2/W, which is becoming a marketable technology.