Insulation fault on PV generator

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.

• Insulation fault on PV generator.
• Water ingress into PV modules or junction boxes.
• Damaged PV cable insulation.

Click steps to track your progress.

1. 1

   Safely disconnect all PV arrays from the Fronius Primo GEN24 208-240 inverter using the DC disconnector and AC breaker.

2. 2

   Measure the insulation resistance of each PV string (PV1, PV2, etc.) to ground using a megohmmeter - expect >1 MΩ.

3. 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. 4

   Systematically check all junction boxes, combiner boxes, and cable conduits for moisture, corrosion, or loose connections.

5. 5

   Isolate PV strings or modules one by one and retest to identify the specific faulty component.