State 241
Fronius Solar Inverter
Severity:What Does This Error Mean?
Fronius State 241 is an earth fault (ground fault) trip — the inverter has detected unexpected current flowing to earth, which indicates a fault in the DC wiring, a panel, or the inverter's isolation monitoring circuit. Do not attempt to reset the inverter without investigating the cause first — earth faults can indicate damaged wiring or a safety hazard.
Affected Models
- Fronius Primo
- Fronius Symo
- Fronius Galvo
- Fronius SnapINverter Series
- Fronius GEN24 Plus
Common Causes
- Damaged DC cable with insulation worn through and contacting the frame or racking
- Water ingress into a junction box, conduit, or module connector
- Faulty or degraded solar panel with insulation breakdown
- Loose or incorrectly fitted MC4 connector creating a partial ground fault
- Residual current from a very large array — some large systems produce enough leakage current to trip isolation monitoring without an actual fault
How to Fix It
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Do not simply reset the inverter and restart.
An earth fault can indicate damaged wiring or a shock hazard. Restarting without investigation puts equipment and people at risk. The fault must be identified and corrected before the system is put back into operation.
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Check Solar.web for the fault timestamp and which MPPT input is affected.
Log into Solar.web and check the Events log. The Fronius Symo and GEN24 show which MPPT string triggered the fault. This narrows down which section of roof to inspect.
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Inspect DC cables and connectors visually.
Check all accessible MC4 connectors for correct mating, no sign of arcing (black marks), and no cracking or damage. Check DC cable conduit for any point where cables may have been pinched or abraded. Look for water in junction boxes.
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Perform an insulation resistance test.
A licensed electrician with a solar PV insulation tester (IR tester) can test each string's insulation resistance to earth. A value below 1 MΩ confirms an insulation fault. This is the definitive diagnostic step.
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Check for water ingress on the roof.
After rain, moisture in MC4 connectors or junction boxes causes ground faults that clear once the system dries out. If State 241 only appears after rain, water ingress is almost certainly the cause — seal or replace affected connectors.
When to Call a Professional
State 241 indicates a potential safety hazard. A licensed solar electrician must inspect the DC cabling, connectors, and panels before the system is restarted. Do not reset and ignore this event.
Frequently Asked Questions
Will Fronius State 241 clear itself after the fault dries out?
Sometimes — moisture-induced faults can clear once the system dries. However, water ingress means water has already reached the wiring and connectors, which will corrode over time. The source of ingress must be fixed regardless.
Is State 241 the same as an AFCI (arc fault) trip?
No. State 241 is a ground fault (earth fault) — current flowing to earth. Arc fault detection is a separate function in some Fronius models, typically reported with different state codes. Check your inverter's event description to confirm which fault occurred.