Insulation fault on PV generator
Fronius · Primo GEN24
What does 303 mean?
The Fronius Primo GEN24 208-240 inverter has detected a general insulation fault (ground fault) on the entire PV generator. This implies an unintended electrical path between the PV array's DC conductors and ground, which can be a safety risk and prevents inverter operation.
Common Causes
- Insulation fault on PV generator.
- Water ingress into PV modules or junction boxes.
- Damaged PV cable insulation.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Safely disconnect all PV arrays from the Fronius Primo GEN24 208-240 inverter using the DC disconnector and AC breaker.
- 2
Measure the insulation resistance of each PV string (PV1, PV2, etc.) to ground using a megohmmeter - expect >1 MΩ.
- 3
Conduct a thorough visual inspection of all PV modules, cables, and connectors in the entire PV system for signs of damage, moisture ingress, or degradation.
- 4
Systematically check all junction boxes, combiner boxes, and cable conduits for moisture, corrosion, or loose connections.
- 5
Isolate PV strings or modules one by one and retest to identify the specific faulty component.