039 Sungrow — Low Insulation Resistance (Riso Low)
At a glance
- Severity
- FAULT STOP
- Domain
- DC_SIDE
- Reference standard
- IEC 62446-1
- Product / context
- Low System Insulation Resistance
What it means
The inverter detects an insulation resistance to ground on the DC side below the safety threshold (e.g. < 1 MΩ).
Probable causes
- Water ingress into MC4 connectors.
- Solar cables mechanically damaged or crushed against mounting structures.
- Moisture penetration into PV modules (PID).
Reference values
| pv insulation | {"test":"1000 VDC (EN 62446-1)","system_minimum":"≥ 1 MΩ","healthy_string_typical":"> 40 MΩ","nota":"Measure per polarity and per string, inverter disconnected."} |
|---|
Where to start
Turn off the inverter (AC side) and open all DC disconnectors. Is the fault still displayed?
Full guided diagnosis in the app
The diagnostic tree for this fault has 5 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the four IndexOS apps: free, works offline.
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