Critical What does this mean?

A safety-rated fault — there may be a risk of electric shock, fire, or equipment damage. Do not try to fix this yourself. Call a qualified electrician.

Fronius Inverter Code 241 — Arc Detected, and What Happens Next

Code 241 on a Fronius Symo, Primo, or Galvo means ArcContinuousFault: the inverter's arc-fault detector found an electric arc on the DC side, exhausted its automatic restarts within 24 hours, and has now disconnected from the grid for safety. Fronius is explicit — before you reset anything, the entire PV system must be inspected for damage. This one needs a qualified technician, not a button press.

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

An electric arc on the DC side of a solar system is one of the few faults that can genuinely start a fire. It happens when current jumps across a gap — a loose MC4 connector, a cracked cable, a corroded contact — and unlike AC arcs, DC arcs do not self-extinguish at a zero crossing. They sustain, they run extremely hot, and they can ignite surrounding material. That is why modern Fronius inverters carry integrated arc-fault detection (AFCI/AFPE) that listens for the electrical signature of arcing and acts within fractions of a second.

Code 241 sits in the middle of a defined sequence, and understanding the sequence explains why 241 is a hard stop rather than a hiccup. When the detector first senses an arc signature, the inverter logs code 240 (ArcContinuousFault) and begins its automatic restart attempts. If arcs keep being detected until the maximum number of automatic switch-ons within 24 hours is reached, the inverter escalates: code 241 is displayed directly after 240, and the inverter disconnects from the grid for safety reasons. It will not try again on its own.

Fronius attaches a formal CAUTION to this state, and it is worth taking literally: danger from damaged components of the photovoltaic system; before the 241 status is confirmed (reset), the entire PV system in question must be checked for possible damage, and damaged components must be repaired by qualified personnel. Only after that inspection may the code be reset by pressing the Enter key — at which point 242 appears and the inverter resumes feeding in.

The practical causes read like a maintenance checklist for an aging array: connectors that were never fully latched or have loosened with thermal cycling, cable insulation cracked by UV or chewed by rodents, corroded contacts in a combiner box, a damaged module junction box. Arcs need a gap and current; time and weather supply the gap.

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

Loose, poorly crimped, or never-fully-latched DC (MC4) connectors — the single most common arc source.
Aged, UV-cracked, or rodent-damaged DC cable insulation opening a gap in the conductor path.
Corroded or overheated contacts in connectors, combiner boxes, or disconnect switches.
A damaged module junction box or cracked backsheet arcing internally.
Years of thermal cycling loosening connections that were fine at installation.

Safe steps to try

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

Do NOT press Enter or otherwise reset code 241 until the system has been professionally inspected — Fronius's official remedy makes inspection the precondition, not an option.
From the ground, look for visible damage: discolored connectors, hanging or chafed cables, scorch marks. Do not go on the roof and do not touch any DC wiring.
Write down the code, the time, and whether code 240 appeared first — that history helps the technician.
If you smell burning or see smoke, treat it as a fire risk and call emergency services.
Contact your installer or a Fronius-trained service technician immediately and tell them you have a 241.

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

Immediately, with no intermediate steps. Arc faults are a fire risk, and Fronius's documented remedy requires the entire PV system to be checked for damage by qualified personnel before the inverter is reset. Never bypass, ignore, or repeatedly reset an arc fault — each reset without repair re-energizes the fault that caused it.

Frequently asked questions

What exactly is an arc fault?

An electric arc — current jumping across a small gap in a damaged or loose DC connection. DC arcs do not self-extinguish the way AC arcs do, so they can sustain, reach extreme temperatures, and ignite nearby material. That is why detection triggers an immediate, latched shutdown.

What is the difference between codes 240, 241, 242, and 244?

240 marks the arc event once the 24-hour automatic restart limit is reached; 241 is the latched state that follows, requiring inspection and a manual reset; 242 appears after you reset 241 and the inverter resumes feeding in; 244 is a single arc detection that needs no action and auto-recovers after about 10 minutes.

Can I just press Enter to clear 241?

Only after a qualified person has inspected the entire array and repaired any damage. Pressing Enter without that inspection is precisely what Fronius's CAUTION warns against — it re-energizes a system with a known arcing fault.

Is my house at risk while 241 is displayed?

The inverter has disconnected from the grid, removing the energy source — that is the safe response. The remaining risk sits in the damaged wiring itself, which is why professional inspection comes before any reset.

Need a professional?

This fault is a safety risk — do not attempt to fix it yourself. Contact a qualified solar electrician in your area.

Sources: meaning and troubleshooting verified against the manufacturer's documentation — Fronius Symo / Fronius Eco / Fronius Symo Advanced Operating Instructions (manuals.fronius.com) — Status diagnostics, Class 3 status codes: Code 241 'ArcContinuousFault — An arc was detected on the PV system.' Displayed directly after 240; the inverter disconnects from the grid for safety; remedy: before resetting, check the entire PV system for damage; reset by pressing the Enter key.