Grid voltage or frequency outside tolerance — system has disconnected.
Common causes
Grid undervoltage (<207 VAC single-phase)Grid overvoltage (>253 VAC single-phase) — common in summer near substationsGrid frequency outside 47–53 HzDNO planned outage or local faultLoose AC grid connector at power moduleThree-phase: phase imbalance or missing phase
What to check
STEP 1
Measure AC voltage at AC GRID port — should be 230 VAC ±10%
STEP 2
Measure grid frequency — should be 50 Hz ±3 Hz
Escalate if
Voltage consistently >253 VAC — report to DNO. Voltage in range but fault persists — contact Anker support
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