SolarEdge › PV strings and DC wiring
Isolation fault stops production, wet mornings or persistent
reported in the field
Symptoms
- The inverter flags an isolation fault (18X86 on a screened unit, 'DC current leakage to ground has been detected by the inverter' or 'Isolation Error' in the app or on the display) and stops producing. In the moisture-driven form it appears on a sunny morning and clears by midday with no action taken, or returns every time it rains (string impedance below the inverter's 600 kOhm shutdown threshold when wet, over 5 MOhm dry) and persisted on one 51-panel array after SolarEdge had replaced every optimizer. In the persistent form it does not clear on its own
- Ohming the disconnected string shows negative-to-ground continuity while positive-to-ground and positive-to-negative read clean, or the string does not ohm out to a clean short and the fault only returns when that string is reconnected and powered up
Alerts and codes
DC current leakage to ground has been detected by the inverterIsolation Errorisolation fault / ground fault18X86 isolation error
The cause and the fix
Subscribers see the cause, the fixes that worked and who did them, part numbers and recent prices when a part is involved, and the field reports behind this entry.