After the photovoltaic power station is connected to the grid, it is found that the faults caused by the grounding of the solar cable are the most. After the solar cable is grounded, the power generation will be lost in a small amount, and it will cause a fire in severe cases. In fact, most of the cable grounding faults are caused by construction, especially in severe weather, such as rain, which is even worse. The following are several problems that may cause ground faults:

1. The crimping is not firm, causing the cable core to loosen and grounding occurs.

2. The DC solar cable was damaged during the construction process, and it was grounded when it touched the metal bridge frame or the soil.

3. The influence of the intermediate joint on the circuit. In principle, it is not allowed to have intermediate joints during the construction process, but the actual situation is complicated and inevitably there will be intermediate joints.

In photovoltaic power plants, string and central inverters are usually installed. Among them, string inverters report low insulation resistance warning and stop operation, while centralized inverters report insulation resistance warning but do not stop operation, so the processing methods are also different. For string inverters, after stopping operation, unplug each mc4 connector of the branch and measure the voltage to ground in order. Under normal circumstances, the voltage is low and generally does not exceed plus or minus 10V. After it rains, the measurement will be higher at first, and the voltage will drop to the normal value with time. If the voltage to ground exceeds plus or minus 500V and does not change, the other end of the testing string should be basically zero, plus and minus ends. The voltage should be the normal value of about 700V. At this time, it can be determined that the solar cable with a ground voltage of about zero is grounded. For the centralized inverter, turn off the switches from the inverter side to the inverter from each DC combiner box in turn, measure the voltage to the ground) find the grounded combiner box, and then go down to find the branch for processing.