SolarEdge Arc Fault Detected: What It Means and What to Do
If your SolarEdge inverter displays an arc fault (error code 18xC), your system has detected dangerous electrical arcing. This is the most serious error code your inverter can display, and it requires immediate attention.
What Is an Arc Fault?
An electrical arc is a spark that jumps across a gap in a circuit. In solar systems, arcs can occur at loose wire connections, corroded terminals, or cracked conductors. They generate extreme heat — hot enough to ignite roofing materials or insulation.
SolarEdge inverters with AFCI (Arc Fault Circuit Interrupter) technology continuously monitor for the electrical signature of arcing. When detected, the inverter immediately shuts down to prevent fire.
Common Causes of Arc Faults
Loose connections at MC4 connectors, optimizer terminals, or the inverter's DC input are the most common cause. Over time, thermal cycling (heating and cooling) can loosen connections.
Corroded or damaged wiring from animal chewing, UV degradation, or poor initial installation can create gaps that generate arcs.
Water intrusion into connectors or junction boxes can cause intermittent arcing.
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Do not attempt to restart your inverter. An arc fault is a potential fire hazard, and restarting could recreate dangerous conditions.
- Leave the system shut down
- Call a certified solar technician or electrician immediately
- Do not go on your roof to inspect — leave this to professionals
- The technician will inspect all connections, wiring, and optimizers to find and repair the arc source
False Positives Do Happen
SolarEdge's AFCI technology is sensitive by design — it's better to have a false alarm than miss a real arc. Some appliances, power tools, or even certain types of electrical noise can trigger false arc fault detections. A qualified technician can determine if it was a real arc or a false positive.
Even false positives mean lost production time. SolarDoctor alerts you the moment your system stops producing, so you can get a technician out quickly — whether it's a real fault or a false alarm.
Frequently Asked Questions
What causes a SolarEdge arc fault?
Arc faults are caused by electrical arcing — sparks jumping across a gap in loose connectors, damaged wiring, or corroded contacts. The SolarEdge inverter detects the electrical signature of arcing and shuts down to prevent fire.
Is a SolarEdge arc fault dangerous?
Yes, arc faults can cause fires if left unaddressed. The arc fault detection system is a safety feature designed to prevent rooftop fires from electrical arcing in your solar system.
How do I reset a SolarEdge arc fault?
You cannot simply reset an arc fault — the underlying cause (loose connection, damaged wire, or corroded contact) must be found and repaired by a qualified solar technician before the system will operate safely.
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