Low insulation resistance detected between PV strings and earth. Safety shutdown triggered.
Common causes
Damaged or degraded DC cable insulationMoisture ingress at DC connectors or junction boxPanel frame not earthed correctlyPV connector not fully clicked in
What to check
STEP 1
Disconnect all strings and test each string in turn with an insulation resistance tester (500 V DC). Any string below 1 MΩ (wet) or below spec (dry) is faulty
STEP 2
Inspect all MC4 connectors and junction boxes for moisture or mechanical damage. Check panel frame earth continuity
Escalate if
Faulty string identified — replace affected cable or connector. If no string isolated as cause, escalate
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