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.
Huawei Inverter AFCI 3003 — When the Arc-Fault Alarm Trips
Your Huawei SUN2000 has detected an electric arc somewhere in the DC wiring between your panels and the inverter — the event Huawei's documentation calls the “DC arc fault alarm”. Arcs are tiny lightning strikes inside damaged or loose connections; they generate intense heat and are one of the leading causes of rooftop solar fires. That is why the inverter stops producing power the moment one is detected. A single, isolated alarm that clears itself is the system working as designed. But repeated alarms are a red flag: if the AFCI alarm fires five or more times within 24 hours, the inverter locks itself for protection and will not restart until a qualified technician inspects the DC side and clears the alarm manually.
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?
Is your system producing power right now?
What this code means
Huawei's SUN2000 inverters include AFCI — arc-fault circuit interruption — as a standard, always-on safety function, designed to the UL 1699B-2018 arc-detection standard. The inverter continuously monitors the DC side for the electrical signature of an arc: the crackling, unstable current pattern produced when electricity jumps across a gap in a damaged or loose connection. The moment that signature is recognized, the inverter raises the DC arc fault alarm and shuts down so the arc cannot keep burning.
Huawei documents two behaviors you should know about. First, the AFCI function only works with Huawei optimizers or ordinary PV modules — it does not support third-party optimizers or so-called intelligent PV modules, and a mismatched setup can produce nuisance alarms. Second, the inverter has an automatic clearance mechanism: if the alarm triggers fewer than five times within 24 hours, the inverter clears it by itself and resumes operation. If it triggers five times or more within 24 hours, the inverter locks for protection and must be cleared manually — in the FusionSolar app under Device commissioning > Alarm management, or in the FusionSolar Smart PV Management System under Intelligent O&M > Alarm Management — and Huawei's procedure requires the DC side to be inspected first.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – 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 MC4 or DC connectors in a string — the single most common source of arcing
- Damaged, chafed or rodent-chewed cable insulation on the roof or inside conduit
- Corroded, overheated or poorly torqued DC terminals at the inverter or isolator
- A cracked panel backsheet or damaged junction box producing an intermittent arc
- Third-party optimizers or smart modules that Huawei's AFCI does not support, causing false trips
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
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 a qualified solar technician if the DC arc fault alarm has triggered five or more times in 24 hours (the inverter locks for protection), if alarms keep returning after auto-clearance, or if you see or smell any sign of burning. The manual procedure requires the DC side to be inspected for loose connections, damaged cables and hot terminals before the alarm is cleared in the app — clearing a locked AFCI alarm without inspection is dangerous. Never open the inverter enclosure and never handle DC wiring yourself; arc faults involve conductors that can strike again without warning.
Frequently asked questions
What exactly is the Huawei AFCI alarm?
It is the inverter's arc-fault protection firing. The AFCI circuit detected the electrical signature of an arc on the DC side — electricity jumping a gap in a loose or damaged connection — and shut the inverter down to prevent a fire. Huawei documents this as the “DC arc fault alarm”.
The alarm cleared by itself. Can I ignore it?
A single self-cleared alarm is the system working as designed, but do not ignore the pattern. Note the date and watch for repeats: five or more alarms within 24 hours lock the inverter, and a repeat offender needs a professional inspection of the DC wiring.
Can I clear a locked AFCI alarm myself in the app?
The clear button exists in the FusionSolar app, but Huawei's procedure requires the DC side to be inspected first — and that inspection is not homeowner work. Clearing the alarm without finding the arc source leaves the fire risk in place.
Why would a brand-new installation get AFCI alarms?
Usually a connector that was not fully seated during installation — MC4 connectors must click positively into place. Your installer should re-check every DC connection on the roof.
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 — Huawei SUN2000-(3KTL-10KTL)-M1 User Manual (solar.huawei.com), Section 7.2.2 AFCI — “The AFCI function involves the DC arc fault alarm”; automatic clearance <5 times/24h, lockout at ≥5 times/24h; Huawei Solar Inverter Modbus Interface Definitions V3.0 — Alarm ID 2002 “DC Arc Fault” (Major)