A: Possible causes:
1. The voltage from the transformer at the connection point is on the high side;
2. There are many photovoltaic power generation equipment on the line, but the line load can not absorb so much energy, and the grid voltage is gradually raised;
3. The cable used from the inverter to the parallel point is longer (L), the wire diameter is smaller (s), and the line resistance is large (r = ρ L / s). When the voltage of the grid point reaches the output of the inverter, the voltage increases △ u = I * r = I * ρ L / s;
4. Several photovoltaic power generation equipment are connected to the same line;

Solutions:
1. Rreducing the output voltage range of the transformer;
2. Reasonably selecting the line diameter and planning the routing path, and connecting the grid nearby to minimize the impact of line loss;
3. If there are more than one inverter equipped near the grid connection point, they can be incorporated into different power supply lines;