The DC input from the PV strings is connected with reversed polarity.
CauseThe plus and minus conductors of a PV string are swapped at the inverter's DC input, so the inverter sees reverse polarity.
Recommended fixCheck the PV input polarity.
Source:065_BManual_SUN-7_7.5_8K-G02P1-EU-AM2_20260625_en_4466f08b.pdf· page 50032_BManual_SUN-9_10_10.5K-G02P1-EU-AM2_20260625_en_df0f2106.pdf· page 50