A: In the photovoltaic system, the flow direction of energy is photovoltaic inverter→ load→grid, while in the grid system, the flow direction of energy is grid→load. If it is inconsistent with it, it is reverse. The anti-reverse of photovoltaic system we often say includes two aspects: one is to prevent the current backflow of other solar panel from causing unnecessary damage or accidents in case of short circuit or grounding fault of DC system; Second, in some places, only photovoltaic power generation is allowed for self use to prevent electricity from flowing to the power grid.