201 GoodWe — Ground Fault (GFDI / IMD)
At a glance
- Severity
- FAULT STOP
- Domain
- INVERTER_FV
- Reference standard
- IEC 62109-2 / IEC 61557-8 / CEI 64-8
- Product / context
- PV Insulation Resistance Low
What it means
The inverter detects a ground insulation fault on the DC side via the integrated Insulation Monitoring Device (IMD). The inverter shuts down for protection against electrocution and fire risk. Leakage current to ground exceeds the threshold (typically 300 mA).
Probable causes
- Water ingress into MC4 connectors or module junction boxes.
- Solar cable with damaged sheath in contact with the metallic support structure.
- PV module with cracked rear glass allowing moisture ingress.
- PID (Potential Induced Degradation) reducing insulation resistance.
- Faulty DC surge protector (SPD) with leakage path to ground.
Where to start
Turn off the inverter from the AC side (circuit breaker). Open the inverter DC disconnector. Wait 5 minutes for capacitor discharge. Disconnect all strings from the DC inputs of the inverter. Does the fault persist on the display?
Full guided diagnosis in the app
The diagnostic tree for this fault has 7 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the five IndexOS apps: free, works offline.
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