PV Insulation Fault: Causes and Solutions

A PV insulation fault is a common DC system issue where the insulation resistance between solar panel DC circuits and the ground drops below the standard threshold. It triggers inverter alarms, stops power generation, and even brings electric leakage and fire risks, seriously threatening the safe and stable operation of photovoltaic systems.
This fault mainly stems from several practical reasons. First, harsh outdoor environments play a key role. Long-term exposure to rain, high humidity, dust and UV rays ages and degrades cable insulation and module surfaces. Water infiltration into connectors and combiner boxes further reduces insulation performance. Second, mechanical damage happens during installation or daily operation, such as scratched cable skins, broken module glass, and wires gnawed by rodents. Third, unstandardized wiring, loose connectors and aging system components also lead to decreased insulation resistance.
Targeted solutions can effectively fix this problem. First, conduct a comprehensive manual inspection to locate faulty modules, damaged cables and damp junction boxes, then replace broken parts and drain residual water. Second, clean dirty connectors and fasten loose wiring to ensure stable circuit connection. Third, enhance daily protection: seal combiner boxes tightly, protect cables from mechanical friction and animal damage, and replace aging equipment regularly. Timely troubleshooting and routine maintenance can eliminate insulation faults and extend the PV system’s service life.