Huawei SUN2000 Alarm 2002 — DC Arc Fault
⚠ DANGER — this fault involves lethal voltage. Do not attempt a DIY fix. Call a qualified technician.
What it means: The inverter's arc-fault detection has found an electrical arc on the DC side. Huawei grades it Major and gives the cause as PV string cables generating arcs or being in poor contact. An arc on a solar string is a sustained high-temperature discharge across a bad joint, and it is the failure mode that starts rooftop fires. The alarm ID carries a cause ID that identifies which MPPT input the arc was seen on — cause IDs 1 to n map to MPPT 1 to n. This alarm is never a software glitch to be cleared and forgotten.
Why does Huawei show 2002?
- Huawei's stated cause — the PV string cables are generating arcs or are in poor contact.
- A DC connector that was crimped with pliers instead of the proper tool, so the conductor never made full contact.
- Mixed-brand MC4 connectors mated together, which look identical but do not seat to the same tolerance.
- A terminal loosened by years of daily heat cycling on a hot roof.
- Water sitting in a junction box or an unsealed connector, corroding the contact.
- Cable damage from rodents, from rubbing on a roof edge, or from being walked on during cleaning.
The Pakistan factor
Almost every ingredient Huawei lists for this alarm is standard practice on a cheap Pakistani rooftop install. Connectors crimped with pliers, mismatched MC4s from whatever was in the van, junction boxes left unsealed against the monsoon, DC cable clipped to a hot metal structure or left lying on the roof sheet — each of them makes the high resistance joint that an arc needs. Then a 50-degree summer roof cycles that joint open and closed every day until it fails. Huawei's AFCI claims to cut a DC arc within about half a second, which is the reason a well-installed SUN2000 logs 2002 rather than catching fire. That protection has already done its job by the time you read the alarm. Silencing it, which is what an installer does when he clears the alarm and leaves, is the single most dangerous shortcut in local practice.
How to fix it
- Treat this as a fire warning. Do not go up on the roof, do not open the DC isolator, do not unplug or re-seat MC4 connectors, and do not open a junction box. A PV array is live in daylight and cannot be made safe from the ground, and pulling a DC connector that is carrying current is how people are badly burned.
- Do not clear the alarm to get the system running again. Huawei's manual-clear step comes after the fault has been found and rectified, not before. Clearing an unrepaired arc fault leaves the arc where it was and switches off the thing that told you about it. Never disable AFCI to stop the alarm returning.
- If there is a smell of burning, visible smoke, scorch marks, or a discoloured or melted connector, treat it as an emergency. Get people away, switch off the solar supply at the main board only if that can be done normally and safely from the front of the board, and call the fire service if there is any sign of fire. Do not go to the array to investigate.
- Otherwise, open FusionSolar and note the alarm cause ID before you call anyone. It tells the technician which MPPT input to inspect and saves an hour on the roof.
- Call your installer the same day and say the words "DC arc fault". This is not a next week job, and it is not one for a general electrician who does not work on PV.
- What the technician does, per Huawei — identify the abnormal MPPT from the cause ID, then inspect that MPPT's strings for traces of ignition, poor contact at the terminals, poorly crimped cables and cable damage, and rectify whatever is found. Damaged connectors get replaced, not re-seated. Only then is the alarm cleared manually.
- If the alarm comes back after a proper repair, Huawei's escalation is to export the inverter logs and contact technical support. Do not run the system in the meantime.