Total load on BACK-UP port has exceeded inverter rated backup output power. Inverter shuts backup port to protect itself. Auto-restarts backup port once overload removed (up to 10 min delay if overload repeats). Displayed fault ID: 051.
Common causes
Too many loads or high-demand appliance on BACK-UP portSurge load from motor start-up exceeding inverter peak output
What to check
STEP 1
Reduce total load on BACK-UP port below rated backup power (check model spec). Disconnect any high-demand appliances from backup circuit.
STEP 2
Inverter will restart backup port automatically within 10 minutes of overload being cleared.
Escalate if
Load confirmed within limit but fault persists — contact Sungrow support
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