Abstract: For the photovoltaic system using inverter DC side negative grounding technology, we analyze the characteristics of the DC side of the photovoltaic system of positive and negative short-circuit and insulation faults occurring, put forward the leakage detection program, the grounding detection system to carry out technological transformation, to make up for the defects of the original system of grounding fault detection function is insufficient, and to improve the safety of operation of photovoltaic power station.