SolarEdge arc fault detected — what to do right now
Your SolarEdge system is showing "Arc Fault Detected" or fault code P700/P701 in SolarEdge Go or the MySolarEdge portal. This is a safety event — not a nuisance alarm. Isolate the system, do not attempt to reset, and follow this guide before calling an engineer.
If your SolarEdge shows "Arc Fault Detected" or P700/P701, do these three things before reading any further:
No buttons, no power cycling, no restarting.
Usually on the wall next to or below the inverter.
Solar circuit breaker in your consumer unit (fuse board).
Not affiliated with SolarEdge Technologies. Independent solar support.
Unlike grid faults or communication errors, AFCI events must not be reset and walked away from. An arc fault means the inverter has detected current patterns associated with an electrical arc on the DC wiring — a potential fire hazard. The correct immediate response is full isolation of both DC and AC sides, followed by inspection by a qualified engineer. Do not touch any DC wiring, connectors, or open the inverter enclosure.
What to do right now — 5 steps
Work through these in order. The first two steps take less than a minute and make the system safe to leave.
Check SolarEdge Go or MySolarEdge — confirm the fault code
Before you do anything else, confirm exactly what the system is reporting. Open SolarEdge Go on your phone via Bluetooth (stand within 3–4 metres of the inverter) or log in to monitoring.solaredge.com. Navigate to the Alerts or Status section. You should see one of the following:
SolarEdge Go will also show which optimiser position the fault is attributed to. Take a screenshot — this is important information for the engineer. Do not dismiss or acknowledge the alert.
If you see a different code (G70–G99 grid faults, P404 communication loss) — see the red light guide for those fault types. This page covers AFCI only.
Do NOT reset — do not touch any buttons or cycle power
This is the most important instruction on this page. Do not press any reset button on the inverter. Do not switch the AC isolator off and on. Do not try to clear the fault code in SolarEdge Go. Resetting an AFCI fault without fixing the underlying cause has two outcomes — both bad:
The system powers back up with a live arc fault in the DC wiring. The AFCI will likely trip again — but in the interim, the arc can cause further insulation damage or generate enough heat to start a fire.
The system appears normal — but the fault is still present. It will return, possibly days later. You've lost the original fault log data that would have helped locate the cause.
The only exception is a single isolated trip following a confirmed direct lightning strike to the property or a significant power surge — but even then, an engineer should verify this before recommissioning.
Switch off the DC isolator
Find the DC isolator switch. On most SolarEdge installations it is mounted on the wall immediately adjacent to or below the inverter, inside the property (often in the loft or utility room). It is usually a red or yellow rotary switch or a large toggle labelled "DC" or "String Isolator". Turn it to the OFF position.
SolarEdge uses SafeDC — a built-in safety feature where the power optimisers on each panel automatically reduce DC output to approximately 1 volt per panel when the system shuts down or loses communication with the inverter. By the time the AFCI has tripped and you locate the DC isolator, SafeDC is already active. Switching the DC isolator off completes the isolation. The cabling is safe to be near, but still should not be touched or disturbed.
If you cannot find the DC isolator, do not continue looking near the inverter. Proceed to Step 4 (AC isolation) and ask the engineer to locate and switch the DC isolator when they arrive.
Switch off the AC isolator at the consumer unit
Go to your electrical consumer unit (fuse board / distribution board). Find the solar PV circuit breaker — it is usually labelled "Solar PV", "SolarEdge", "PV Inverter", or "Generation". Switch it to the OFF position. This disconnects the inverter from your household AC wiring and the grid export connection.
The system is now fully isolated — DC side down via the isolator, AC side down via the consumer unit. You can leave it in this state safely until an engineer attends.
Contact a qualified solar engineer with the fault details
Get in touch with a qualified solar PV engineer. When you call, tell them:
Do not attempt to investigate the DC wiring, connectors, or roof fixings yourself. Do not open the inverter enclosure. These tasks require specialist equipment and training.
What causes SolarEdge arc fault detection to trip?
AFCI trips in SolarEdge systems fall into three categories. Understanding which type you're dealing with helps the engineer plan their investigation.
MC4 connector failures — the most common cause
MC4 connectors are the snap-fit waterproof connectors used throughout SolarEdge systems — on every panel, every optimiser, and along the string cable. Over time they can develop problems:
Cable insulation damage
DC string cables run from the roof, through the roof structure, and down to the inverter. The insulation can be damaged in several ways:
Failed or degraded optimiser
SolarEdge power optimisers are fitted to every panel. Optimiser failures can trigger AFCI in two ways:
The advantage of SolarEdge is that SolarEdge Go can identify which optimiser position the P700 fault originated from — which narrows the physical inspection to a specific panel or the short section of cable between adjacent optimisers.
Using SolarEdge Go to identify which optimiser triggered the fault
SolarEdge Go (available free on iOS and Android) connects to the inverter via Bluetooth. It can show the AFCI event log and which optimiser position the fault was detected on. This information is valuable for the engineer — it narrows a whole-roof inspection down to a specific panel or short cable section.
Search "SolarEdge Go" in the App Store or Google Play. Open the app. Earlier documentation may refer to this as SetApp — SolarEdge Go supersedes SetApp with the same Bluetooth functionality. Stand within 3–4 metres of the inverter.
SolarEdge Go connects to the inverter directly via Bluetooth — no WiFi or internet connection needed. Once connected, navigate to the Status or Alerts section. You will see the active P700/P701 fault with a timestamp and — critically — the optimiser serial number or position identifier attributed to the fault.
Take a screenshot of the alert including the optimiser ID. If you have access to the layout map in the monitoring portal (the visual panel layout view), you can cross-reference the optimiser ID to a physical position on the roof. Pass this to the engineer — it tells them which panel to start their physical inspection at.
In SolarEdge Go's event log or the MySolarEdge portal's Events tab, check whether this is the first AFCI trip or whether previous events were recorded. Multiple trips over days or weeks — particularly from the same optimiser — strongly indicate a real wiring fault at that location rather than a one-off transient event.
The optimiser ID from SolarEdge Go tells the engineer which panel to start with. They will perform an insulation resistance (IR) test on the DC string from that point — measuring the resistance between the cable and earth at various points along the string to locate where insulation has broken down. MC4 connectors in the identified section will be inspected and tested individually. If the optimiser itself is suspect, its output characteristics can be measured. The combination of SolarEdge's digital fault localisation and traditional electrical test methods makes SolarEdge arc fault diagnosis significantly faster than on brands without optimiser-level monitoring.
Can a SolarEdge AFCI trip be a false positive?
Very rarely — and this assessment must only be made by a qualified engineer, never by the homeowner. Here is the full picture.
Even in false positive scenarios, an engineer must verify the system before recommissioning. This requires insulation resistance testing of the DC string — you cannot determine a fault's presence or absence by eye, and SolarEdge Go cannot perform IR testing. The engineer's IR test gives a definitive answer: if the insulation resistance is within specification, the fault was a transient and the system can be safely restarted. If not, the fault is real and must be repaired.
A genuine AFCI trip that is "cleared" by cycling power and then left without inspection is the most dangerous scenario — the system appears to recover but the arc fault source remains in the wiring.
How SolarEdge AFCI works — and why it is different from every other fault
SolarEdge includes Arc Fault Circuit Interrupter (AFCI) protection as a standard feature on all HD-Wave inverters sold in markets with AFCI requirements, including the UK. It is built into the inverter hardware and cannot be disabled by configuration. It monitors the DC current waveform from the panel strings and applies signal processing algorithms to detect the irregular, high-frequency current patterns associated with electrical arcing.
AFCI is categorically different from every other SolarEdge fault type. Grid faults (G-codes) are safe external events — the grid is briefly out of specification and the inverter disconnects to protect itself. Optimiser communication faults (P404) are connectivity issues — the optimiser is physically intact but not communicating. An AFCI trip is the inverter reporting that it has detected a potential electrical hazard in the DC wiring — wiring that, on a typical UK installation, runs across the roof, through the roof structure, and down through the property.
The SafeDC feature works in conjunction with AFCI. When the inverter shuts down — whether due to an AFCI trip or any other reason — the power optimisers automatically reduce their DC output to approximately 1 volt per panel. This means the DC string voltage drops from its operating level (typically 200–500V depending on system size) to a safe low voltage. SafeDC activates automatically without any action from the homeowner, and the system maintains this safe state even if the inverter is powered down. It does not substitute for full isolation, but it significantly reduces the DC hazard during the period between the trip and isolation.
For the homeowner, the practical distinction is simple: arc fault events require isolation and engineer investigation before any restart. This is non-negotiable regardless of whether the system appears to restart successfully — a successful restart after an AFCI trip without investigation means the hazard is still present in the wiring.
SolarEdge arc fault questions
Arc Fault Detected (P700 or P701) means the inverter's AFCI has detected abnormal current patterns on the DC string consistent with an electrical arc — a partial discharge in the wiring from a damaged or degraded connection. Common causes include damaged cable insulation, corroded MC4 connectors, a failing optimiser, or a wiring fault at a junction point. The inverter shuts down and optimisers drop to SafeDC voltage (approximately 1V per panel) to prevent further hazard.
Yes — an AFCI trip should be treated as a genuine safety event. Electrical arcs in DC wiring generate intense heat and can cause fires, particularly in roof spaces where wiring runs through insulation. The system has tripped because it has done its job correctly. The system must be fully isolated (DC isolator off, AC isolator off) and must not be recommissioned until a qualified engineer has identified and corrected the physical cause.
No. Unlike grid faults or communication errors, arc fault events should not be reset by the homeowner. Resetting an AFCI fault without identifying the cause allows the underlying wiring fault to continue — and if a genuine arc is present, repeated resets increase the risk of fire. The correct procedure is to isolate the DC and AC switches and contact a qualified solar engineer who will investigate with SolarEdge Go to identify which optimiser triggered the fault.
The most common causes are damaged or degraded cable insulation on DC string wiring (particularly from pest damage or pinching), corroded or inadequately locked MC4 connectors, a failing optimiser creating a resistance fault, and wiring faults at penetration points or junction boxes. Very occasionally, a single AFCI trip after a lightning strike or severe power surge can be a false positive — but this should only be assessed by a qualified engineer.
The engineer will use SolarEdge Go via Bluetooth to review the event log and identify which optimiser or string position triggered the P700/P701 fault. They will then perform insulation resistance and DC string continuity tests to locate the precise fault. All MC4 connectors on the affected string will be inspected. If a failed optimiser is identified, it will be replaced. The system will only be recommissioned once test results are confirmed clear.
SolarEdge arc fault — we can investigate and fix it.
We handle SolarEdge AFCI investigations using SolarEdge Go for fault localisation, followed by insulation resistance testing and physical inspection of the affected string. Most arc fault sources are identified and repaired in a single visit.
This is a brand-specific version of our general inverter red light guide, which covers all brands.