Insulation resistance on PV side has fallen below protection threshold during isolation check. Safety-critical fault.
Common causes
Short circuit or damaged insulation on PV string cablesMoisture ingress into connectors or cable runsPanel frame or racking contacting live conductor
What to check
STEP 1
SAFETY: Do NOT disconnect DC switch while DC current above 0.5 A. Wait for low-irradiance conditions. Then disconnect DC switch and inspect PV cables and connectors for insulation damage or moisture.
STEP 2
Repair or replace any damaged components. Do not reconnect until grounding fault fully cleared.
Escalate if
No visible damage found or fault cannot be isolated — contact Sungrow support
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