Grid Freq Fault on a Fox ESS H1 G2 single-phase hybrid inverter: Grid frequency out of range
Short answer
On a Fox ESS inverter, Grid Freq Fault means: Grid frequency out of range. The inverter stops until the fault clears or is reset.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Grid frequency out of range.
Part involved: grid frequency protection.
When it shows: Measured frequency outside limits.
Likely causes:
- Grid frequency outside protection limits (grid disturbance, generator/backup scenario, wrong country setting).
Is it safe?
| Does the inverter stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
The inverter stops until the fault clears or is reset.
Resetting itself: yes.
Manual reset: System reconnects automatically when the utility is back to normal.
What you can check
- Read the full code and message on the inverter screen or in the FoxCloud app and note the date/time for your installer.
- Check the inverter's AC isolator next to the inverter and the solar/battery breaker in the consumer unit are ON (do not reset a breaker that trips again - call your installer).
What the engineer will check
- Verify grid code setting; check for local supply disturbances; review event log timing.
Who to ask for: Installer, with DNO (network operator) if grid supply is at fault.
Certification: None for homeowner checks; any grid-protection setting change needs installer and DNO consent (G98/G99).
What you might notice
Sources
- H1(G2)/AC1(G2) Series User Manual ↗ · V1.0.8 · page 47 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026