How do I fix Grid Frequency Out of Range on a FoxESS?

Check frequency reading in Fox ESS app or on inverter display. Log frequency over time Then: If frequency excursions are brief and self-clearing, no action needed. Check G99 frequency response settings if applicable

FoxESS

Error 27

Grid Frequency Out of Range

Grid frequency is outside the permitted window (47–52 Hz for G98). Inverter disconnects until frequency recovers.

Common causes

Grid instabilityLocal generation overload on weak grid

What to check

STEP 1

Check frequency reading in Fox ESS app or on inverter display. Log frequency over time

STEP 2

If frequency excursions are brief and self-clearing, no action needed. Check G99 frequency response settings if applicable

Escalate if

Frequency is persistently out of range — notify DNO

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More FoxESS fault codes

Grid Lost

Error 26

Grid Voltage Out of Range

Error 28

10-Minute Average Voltage Fault

Over Load

Inverter Overload

Error 3

Isolation Fault (ISO Fault)