Disclaimer: This content is for informational and educational purposes only. The diagnostic steps described are suggestions, not an official service manual.
Phenomenon: The inverter displays Error 203 on the screen, typically during startup or morning hours. Fault LED illuminated; inverter does not connect to grid.
Technical Causes:
- Low PV insulation resistance due to moisture (dew, rain) on panels or cables causing temporary leakage current.
- Damaged PV cables, connectors, or modules leading to ground fault.
- Water ingress in junction boxes or DC isolators.
Diagnostic Procedure:
- Note time of occurrence: If limited to mornings and clears later, likely moisture-related.
- Disconnect DC inputs; measure insulation resistance PV+ to ground and PV- to ground (>500 kΩ required in dry conditions).
- Inspect PV strings for damaged cables, wet connectors, or cracked modules.
Resolution:
- Allow system to dry naturally if moisture-related; error often self-clears.
- Repair or replace damaged components; ensure proper sealing of junctions.
- Restart inverter after resistance returns to normal.
WARNING: Maintenance and repair of PV systems, high-voltage DC, and AC components must only be performed by certified professionals with valid electrical qualifications (e.g., SEP/G1 in Poland, or local European equivalents). Unauthorized opening of the inverter housing will void the warranty and carries a risk of electric shock or fire.
In case of persistent hardware failure, the only authorized path for repair is contacting the official Growatt Service Department.