- Error code
- Riso
- Category
- PV generator insulation
- Manufacturer
- SMA
- Models
- Sunny Boy (SB)
1What the error means
The insulation resistance of the PV generator to earth is below the limit. The inverter does not start until the insulation is restored — it indicates a ground fault on the DC side.
2Possible causes
- Moisture in junction boxes, connectors or modules
- Damaged DC cables
- Faulty module
3What to do
- Note whether it appears after rain or early in the morning, when there is moisture.
- Measure the insulation resistance of each string.
- If the PV generator is fine, check the inverter's measuring circuit.
4Repair by Aineas
You send the inverter to our lab in Thessaloniki. We diagnose it, inform you of the fault and the cost, and the repair starts only after you approve it. Every inverter is tested under simulated operating conditions before delivery.