|Cause ID 1: Warning|
- The PV string is shielded from sunlight for a long time.
- The PV string deteriorates or is damaged.
- Check whether the PV string current is obviously lower than the currents of other PV strings.
- If yes, check whether the PV string is shielded from sunlight.
- If the PV string is clean and not shielded from sunlight, check whether any PV module is faulty.