Failure of the AC combiner box. Including power supply failures (such as power supply aging, damage, input voltage instability, etc.), remote communication abnormalities (such as communication module failure, interface damage, communication protocol abnormalities, etc.), backflow protection triggering (such as inverter failure, grid-connected voltage abnormality). There are also booster faults (such as internal damage to the inductor coil, insulating oil leakage, etc.), circuit breaker faults (such as solder joint blowing, contact deformation, poor sealing, etc.), and discharger faults (such as poor contact, short circuit of the line, insulation damage, etc.).