Warning What does this mean?

Your system is down or running degraded, but this is not an immediate safety danger. Work through the safe steps below.

Fronius Inverter STATE 475 Error: Meaning, Causes & Safe Fix

STATE 475 means a ground fault on the solar panels — the inverter has detected an electrical connection between the panel wiring and earth (ground).

What should I do first?

Two quick questions — we'll point you to the right starting point.

Is this code still showing on your inverter's display?

What this code means

STATE 475 is a solar panel ground fault: the inverter's monitoring found a connection between the solar array wiring and ground. Like an insulation fault, it usually involves moisture, damaged panels, or compromised cabling. This is an error state — the inverter needs professional attention before it will operate normally.

What is this downtime costing you?

Rough estimate while your system isn't producing. Adjust the numbers to match your setup.

System size (kW) Peak sun hours / day Electricity rate ($/kWh)

–per day

–per week

–per 30 days

≈ – kWh of lost production per day.

Estimate only — assumes ~80% real-world output vs. nameplate. Actual losses depend on weather, shading, panel direction, and your tariff.

Common causes

A damaged panel or cracked backsheet creating a path to ground
Moisture in connectors, junction boxes, or DC isolators
Degraded or rodent-damaged DC cabling
Faulty grounding of the array or mounting hardware

Safe steps to try

Work top to bottom, ticking off each step as you complete it. 0 of 5 done.

Record the exact code and when it appeared
Do not touch the panels, DC wiring, or the inverter casing
From a safe distance, look for anything visibly wrong (fallen branches, storm damage)
You may try one documented restart: AC breaker off, DC disconnector to OFF, wait a few minutes, then back on
If the code persists, call your installer or Fronius Service Partner

Is your inverter still under warranty?

Before paying for a repair, check — your installer may fix this free.

Brand Year installed

Based on typical standard warranty terms — always confirm with your warranty card or installer paperwork, as terms vary by model, region, and purchase date.

When to call an electrician

Call your solar installer or a Fronius Service Partner promptly — ground faults need professional testing (insulation resistance measurement) to locate. Never touch array wiring yourself.

Frequently asked questions

What is the difference between STATE 475 and STATE 502?

Both relate to insulation and ground issues on the DC side. 475 specifically flags a ground fault on the panels (a connection between panel wiring and ground), while 502 is a broader insulation error. Treat both the same way: do not touch, call your installer.

Can I reset STATE 475 myself?

One documented restart is fine to try, but if the code returns, stop resetting it — repeated resets will not fix a ground fault, and the underlying issue needs professional diagnosis.

Is a ground fault dangerous?

It can be — that is why the inverter flags it and stops. Do not touch any part of the array or DC wiring; let a qualified professional handle it.

Need a professional?

This fault may need professional diagnosis. Contact a qualified solar electrician in your area.

Sources: meaning and troubleshooting verified against the manufacturer's documentation — Fronius Operating Instructions (Symo/Primo) — 'Status codes and remedy' / 'STATE CODES' tables (Fronius docs 42,0410,0192 & 42,0410,1909 series)