Solar · Error codes · Sunsynk
F48Sunsynk · ECCO single-phase hybrid SG05LP1
F48 on a Sunsynk ECCO single-phase hybrid SG05LP1: Grid under frequency fault
Short answer
On a Sunsynk inverter, F48 means: Grid under frequency fault. The inverter stops until the fault clears or is reset.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Grid under frequency fault.
Part involved: grid frequency.
When it shows: Frequency below limit.
Likely causes:
- Grid frequency below range; generator frequency.
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: Check frequency; seek help.
What you can check
- Read the full code and message on the inverter screen or in the Sunsynk Connect 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
- Check grid/generator frequency and AC cabling.
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
- Fault Codes Causes & Solutions Version 1.0 ↗ · Version 1.0 · page 10 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026