Sol-Ark › GEN port and two-wire generator start relay

Generator bogs or trips while charging battery

manufacturer says

Applies to: 5K-1P-N, 5K-2P-N, 8K-2P-N, 8K-2P-L, 12K (first generation, 2019 to 2021), 12K-2P-N, 12K-2P-LL Limitless, 15K-2P-N, 15K-2P-LV, 18K-2P-N, 18K-2P-LV, 30K-3P-208V, 60K-3P-480V

Symptoms

A generator on the GEN port is tripped or shut down once battery charging starts, or the inverter logs F18
Combined battery charge current and house load exceed what the generator can deliver

Alerts and codes

F18

The cause and the fix

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Manufacturer documents

15K Installation Manual Rev 13 16July2026