Error 304 on a Growatt inverter: AC F Outrange - utility grid frequency out of permissible range
Short answer
On a Growatt inverter, Error 304 means: AC F Outrange - utility grid frequency out of permissible range. The inverter stops until the fault clears or is reset. The wording differs by model range — each is shown below.
Reviewed 24 September 2026 · 2 sources
What it means
On the MIN 2500-6000TL-X
The manual says: AC F Outrange - utility grid frequency out of permissible range.
Part involved: AC grid protection (frequency).
Likely causes:
- Grid frequency.
On the SPH 3000-6000TL BL-UP (48 V battery hybrid)
The manual says: AC F Outrange - grid frequency fault.
Part involved: AC grid protection (frequency).
Likely causes:
- grid frequency fault.
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 - reconnects when frequency is back within limits.
Manual reset: no.
What you can check
- Read and note the exact code and time from the inverter display or app (screenshot).
- Usually a brief grid disturbance; no action if it clears the same day.
- Check the solar/battery AC isolator and the consumer-unit breaker/RCD are ON (do not reset a breaker that trips again immediately).
- Growatt's manual says 'restart inverter'. A homeowner can switch the inverter off and on at its AC isolator/breaker; leave DC switching to the installer unless the manual step says to switch DC off immediately (Error 202).
What the engineer will check
- Verify country/grid code (UK G98/G99).
- Log grid frequency.
- Check for unstable supply (e.g. generator/backup operation).
Who to ask for: PV installer.
Certification: Usually none (grid-side event). If persistent: installer/electrician to measure supply voltage and check settings; DNO investigates supply voltage (G98/G99 protection settings must not be changed without DNO agreement).
What you might notice
Sources
- Growatt MIN 2500-6000TL-X Installation & Operation (User) Manual, general EN 2022-06 ↗ · EN 202206 · page PDF p.22 · Reviewed 24 September 2026
- Growatt SPH 3000-6000TL BL-UP User Manual EN 202512 ↗ · EN 202512 · page PDF p.63 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026