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 300 on the screen or app, with the fault LED illuminated. The inverter disconnects from the grid and enters reconnection delay.
Technical Causes:
- Grid voltage exceeds the permissible range defined by the selected safety standard.
- Voltage rise due to high export and AC cable impedance.
- Incorrect safety standard configuration.
Diagnostic Procedure:
- Measure AC voltage at inverter terminals during the fault.
- Compare against limits of the active safety standard.
- Check for grid fluctuations or local impedance issues.
Resolution:
- Wait for grid voltage stabilization.
- Adjust safety standard or voltage limits if allowed by regulations.
- Optimize AC cabling or reduce export if impedance-related.
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.