475 on a Fronius International GmbH Fronius SnapINverter: Solar module ground, insulation fault (connection between solar module and earth)
Short answer
On a Fronius International GmbH inverter, 475 means: Solar module ground, insulation fault (connection between solar module and earth). The inverter stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Solar module ground, insulation fault (connection between solar module and earth).
Part involved: insulation / earth fault.
When it shows: Class 4 status code.
Likely causes:
- Inverter not feeding in (474/475); if recurring contact your system engineer.
Is it safe?
| Does the inverter stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: See engineer checks.
What you can check
- Read the state code on the inverter display or in Fronius Solar.web and note date/time for your installer.
- Do not touch panels, DC cables or the inverter - an insulation (earth) fault may be present. Contact your installer (Fronius UK support: 'contact your installer to check the system').
What the engineer will check
- Insulation-resistance test of PV strings (per string), inspect DC cabling/connectors for damage/water ingress; check neutral connection (448).
Who to ask for: Fronius-trained PV installer / Fronius Service Partner.
Certification: Qualified electrician (BS 7671; MCS-certified PV installer for work on the PV array/DC side).
What you might notice
Sources
- Fronius Primo 3.0-1 - 8.2-1 Operating Instructions (HTML) ↗ · 42,0410,2165 online edition · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026