Solar · Error codes · Sunsynk
F35Sunsynk · ECCO single-phase hybrid SG05LP1
F35 on a Sunsynk ECCO single-phase hybrid SG05LP1: No utility - grid lost
Short answer
On a Sunsynk inverter, F35 means: No utility - grid lost. The inverter keeps running with some functions stopped.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: No utility - grid lost.
Part involved: AC grid connection.
When it shows: No grid voltage detected.
Likely causes:
- Grid lost; grid connection or switch between inverter and grid off; in no-battery mode reported during grid-connected mode.
Is it safe?
| Does the inverter stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
The inverter keeps running with some functions stopped.
Resetting itself: yes.
Manual reset: Clears when grid returns.
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).
- Check for a power cut in the house/street.
- If the inverter's grid breaker has tripped, reset once; if it trips again call your installer.
What the engineer will check
- Check grid voltage/frequency at inverter; check AC switch and connections.
Who to ask for: Qualified electrician / MCS PV installer.
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 8 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026