F24 on a Sunsynk ECCO single-phase hybrid SG05LP1: PV isolation resistance is too low
Short answer
On a Sunsynk inverter, F24 means: PV isolation resistance is too low. The inverter stops until the fault clears or is reset.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: PV isolation resistance is too low.
Part involved: PV array insulation.
When it shows: Insulation resistance below threshold.
Likely causes:
- Earth fault on PV; + or - PV conductor touching ground.
Is it safe?
Switch the inverter off at its isolator and call an engineer.
| 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: Seek help if it does not return to normal.
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).
- Do not touch panels, DC cables or DC switch; call your installer if it recurs.
What the engineer will check
- Check PV-to-inverter connections; check inverter PE bonding; insulation-test each string.
Who to ask for: MCS-certified solar PV installer (DC/string work) or the original installer.
Certification: Work on DC strings and inverter enclosures: competent PV installer (MCS-certified installer for warranty/SEG continuity); electrical work notifiable under Part P (England & Wales) or equivalent.
What you might notice
Sources
- Fault Codes Causes & Solutions Version 1.0 ↗ · Version 1.0 · page 6 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026