Ground Fault

What does 401 mean?

This status code indicates that a ground fault has been detected in the PV system or the Fronius Primo GEN24 208-240 inverter itself. This is a critical safety issue caused by an insulation breakdown between the PV conductors (PV+ or PV-) and ground, often due to moisture or physical damage in the PV cabling or modules.

• Insulation breakdown between PV+ or PV- conductors and the ground (GND) potential.
• Moisture ingress into the PV cabling, junction boxes, or solar modules.
• Physical damage to the insulation of DC cables or the backsheet of solar modules.

Click steps to track your progress.

1. 1

   Measure the insulation resistance of the entire PV system (PV+ to GND, PV- to GND) using a megohmmeter (e.g., at 500VDC). Expect values >1 MΩ.

2. 2

   Thoroughly inspect all DC cabling from the solar modules to the inverter for any signs of damage, cuts, abrasions, or evidence of moisture ingress.

3. 3

   Examine the solar modules for physical damage, such as cracks in the glass, tears in the backsheet, or compromised junction boxes.

4. 4

   De-energize the inverter (switch off AC and DC disconnects), wait for 5 minutes, then re-energize to reset. If the message persists, the inverter may require service.