Sungrow SG110 / SG250 Error Code E35

Fault 35 — PV Grounding Fault — means that the inverter has detected leakage to ground on the direct current (DC) side and has stopped feeding in for safety reasons. In practice we see it on the SG250HX model; on the SG110 / SG250 series it appears as E35 with sub-codes E35-1601 to E35-1611, which indicate where the leakage was detected.

The cause is almost always in the installation and not in the inverter: moisture or damaged insulation somewhere in the PV generator. When, however, the generator measures clean and the fault persists, the fault lies in the measurement circuit of the inverter itself.

• Moisture in junction boxes, MC4 connectors or the module junction boxes
• Damaged or worn insulation on DC cables, often where they pass over metal edges
• Defective module or corrosion in its junction box
• Missing or interrupted grounding of the mounting structure and the inverter
• Fault in the insulation measurement circuit or the leakage sensor of the inverter

All eleven sub-codes indicate the same fault — a ground fault or leakage on the DC side. The number shows at which stage of the check it was detected.

Besides fault 35, on the SG110, SG250 and SG350 models we also repair:

• Fault 38 — Permanent Relay Fault, a permanent fault in the grid connection relays
• Fault 71 — System Alarm, a general system alarm