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Persistent insulation resistance condition on Ring3 Inverter 1
Ring3 Inverter 1 has been underperforming since 1 February. The most likely cause is an insulation resistance problem. Estimated production loss is approximately 3.2 MWh.
Apollo2_New · Ring3_Inverter1 · Started 01 Feb 2025, 07:35
Estimated energy loss
3,204kWh
Estimated financial loss
€352
Current loss rate
22.6kW
Duration
31 days
Recommended action
Inspect DC cabling and connectors on the affected strings for moisture and damage
Why SOL detected this
- Production was 34% below comparable inverters during active daylight periods.
- The eleven other Apollo inverters were producing normally at the same timestamps.
- The device reported insulation resistance detection on 23 separate days.
- This device recorded 4.1 times more zero power records during daylight than the Apollo peer median.
- The condition returns most often in the first productive hour after sunrise.
Most likely cause
Insulation resistance fault on the DC side, most often caused by moisture ingress in cabling or connectors.
Other possible causes
- Water or moisture in a DC connector or junction box
- Damaged DC cable insulation
- Degraded grounding connection
- Moisture in a PV module junction box on an affected string
- Faulty insulation measurement circuit inside the inverter
Recommended inspection
These steps become the technician checklist
- 1Inspect DC cabling and connectors on the affected strings for moisture and damage
- 2Measure insulation resistance string by string with the inverter isolated
- 3Check grounding continuity and the earthing connection at the combiner
- 4Inspect module junction boxes on the affected strings
- 5Verify the inverter insulation measurement circuit if strings test clean
Actual against expected power
Peer comparison for a representative day
Expected against actual power
Units: kW by time of day
What to notice: The dashed line is what comparable inverters produced at the same time. The shaded area is the actual output.