Problem diagnosis · Huawei

Huawei SUN2000 AFCI Fault — DC Arc Detection Alarm & Safe Reset

Your SUN2000 inverter has detected a possible DC arc fault and shut down as a safety precaution. A single trip may be a nuisance event — but repeated AFCI alarms indicate a real wiring issue that must be inspected before resetting. This guide explains what to check and when it is safe to clear the alarm.

Start diagnosis

Safety-critical — do not bypass AFCI
5-trip lockout within 24 hours
MC4 and DC cabling inspection guide

AFCI alarm keeps returning?

Repeated arc fault trips need professional diagnosis. We can identify the likely fault location remotely using FusionSolar string data before an engineer attends site.

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13 Trustpilot reviews

Trustpilot Google

I have a GivEnergy system consisting of two batteries, two inverters and a controlling EMS (Energy Management System) which has not worked since Nov 2025. After six months I discovered Solar Tech Support, reached out to them and Ron phoned me back – how often do you get that service? Could not be more helpful – worked directly with me over the phone, outside what I would call normal working hours. Lucid explanations and we were able to discuss the issues and history using camera and email history. As this was a very rare setup, Ron was able to access an EMS expert in the field to confirm the solution. One sunny day in, I am now only paying for standing charge and a few pence for spikes in grid consumption while battery catches up with house demand.

Ian · May 2026 Trustpilot

When my GivEnergy system had an issue, I was completely left without support and had honestly lost all hope. Thankfully, I searched online and found Ron, which completely turned things around. After sending him a message, he responded incredibly fast and called me to assure me that he would get the problem fixed. I really admire his dedicated, supportive nature and his determination to find a solution. With this kind of outstanding attitude and customer service, he has absolutely secured a future customer in me.

Sree · May 2026 Trustpilot

Ron want out of is way to help, nothing was to much. He was very thorough in what he did Very knowledgeable I would highly recommend Ron and his company He did a fantastic job for me. if you have any problems, he'll do his best to help you out and resolve your problem. I wouldn't hesitate to recommend them

Dennis Brown · May 2026 Trustpilot

Ron took me through a diagnostic to confirm my GivEnergy Inverter had a fault. A common one as it turns out with the AC Inverter. As GivEnergy is defunct there is no immediate fix, aside from sourcing 2nd hand replacement. It may be that a fix becomes available over the summer which would make a lot of GivEnergy customers happy (Again)

Tony Deacon · May 2026 Trustpilot

Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone

Phill · May 2026 Trustpilot

I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues

michael fairhurst · May 2026 Trustpilot

Contacted Solar Tech Support in desperation. After explaining the issues I had with my system a diagnosis was made and a solution proposed. Fantastic service, even contacted a manufacturer to arrange replacement parts for me. Great communications, explained all they were doing and what I had to do, clearly and precisly. Followed up to confirm all was ok. Excellent service.

Mr Machin · May 2026 Trustpilot

After GivEnergy went into liquidation, just my luck, my battery started playing up (internal board crashed). Contacted my installer - not interested! Found Solar tech support on a Google search. Sooo glad I found this company! Ron is extremely helpful and has plenty of experience. He soon confirmed what the fault was, and helped me to get my system up and running again. Now moved my GivEnergy account to Solar tech support, and will definitely use again if I have more issues. Unusual to find such a helpful company in these times, no morons reading scripts, just direct contact with the engineer.

Keith Ballard · Apr 2026 Trustpilot

Contacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.

Hugh Speirs · Apr 2026 Trustpilot

Ron is a super star. Two months ago my GivEnergy battery failed a firmware upgrade leaving it a brick. My installer couldn't/wouldn't fix it. GivEnergy couldn't/wouldn't fix it. Then they went into administration and all hope was lost. A flurry of emails later and Ron had diagnosed the fault (failed USB flash drive, something I'd suspected) and talked me through resolving it. Two months of nothing resolved in about 3 hours. It's great to work with someone who pays attention to the details, knows that they're doing (not just following a script) and gets stuff sorted without a fuss or up-charging.

Christopher · Apr 2026 Trustpilot

I can add to the list of customers who had already 'given up' on GivEnergy due to their appalling customer service, and that was before they went into administration (their Trustpilot reviews don't lie!). So you can imagine my desperation when, having changed my ISP and my Inverter, predictably, proving to be the only device that didn't connect automatically to my new network, I found zero prospect of any customer support with GivEnergy having called in the administrators just five days earlier! The salvation came from Solar Tech Support. My IT advisor stumbled across their web site and some very helpful tips for beleaguered GivEnergy customers, as well as an offer to provide direct assistance. Nothing ventured, I decided to drop them an E-Mail, with very low expectations based on my experience of GivEnergy customer support. Within an hour Ron had responded with some pin point advice, and after a few exchanges of E-Mails he had nailed the problem, enabling the combined efforts of my IT advisor and solar installer to resolve it and reconnect my Inverter. Thank you Solar Tech Support, and Ron in particular, for coming to the aid of a deserted and despondent GivEnergy customer. Expert, razor sharp advice and first class customer service, even though I wasn't officially a customer.

customer · Apr 2026 Trustpilot

This company are a rare gem, I had a very unusual problem following a failed firmware upgrade on my GivEnergy kit. I then found out GivEnergy were in administration and had dismissed all their support staff! None of the usual fixes to try and restore my inverter comms would work, and I looked everywhere, forums, GivEnergy youtube support videos - even AI couldn't figure it out. My installer was talking about huge sums for system replacements, and being vague / evasive about if they'd even install replacement GivEnergy inverter. Enter Solar Tech Support, reassuring and knowledgeable from the very start, I've learnt loads about my solar system though the friendly chat while my engineer worked as he diagnosed the problem and figured out a fix procedure that I've not found anywhere else - amazing . If you need solar system repairs - especially if you like me have been left high and dry by GivEnergy, I cannot recommend this company enough. Give them a call.

Andy Thomas · Apr 2026 Trustpilot

I sent a message on their website regarding a problem I have on my Givenergy system. Although not supplied by Ronald, I thought it was worth an email. Within the hour on a Saturday, he phoned and we discussed the problem. He logged in remotely and gave excellent advice. I'm too far away for his on-site help but he did diagnose the problem and was happy also to chat through my thoughts about an upcoming solar/battery install I'm planning. Great bloke.... if only he was nearer!

Philip · Apr 2026 Trustpilot

Ian · May 2026 Trustpilot

Sree · May 2026 Trustpilot

Dennis Brown · May 2026 Trustpilot

Tony Deacon · May 2026 Trustpilot

Contacted Ron with a problem and he sorted it out quickly with no problems at all. Very knowledgeable on anything solar/ batteries. I would recommend him to anyone

Phill · May 2026 Trustpilot

I've spoken to Ron a couple of times with issues with my Givenergy installation. Such a friendly knowledge guy very highly recommended. Thank you very much for resolving my issues

michael fairhurst · May 2026 Trustpilot

Mr Machin · May 2026 Trustpilot

Keith Ballard · Apr 2026 Trustpilot

Contacted Solar Tech Support when trying to understand what my Givenergy inverter problem might be and what might be my options. Received good/honest advise which backed up my thoughts.

Hugh Speirs · Apr 2026 Trustpilot

Christopher · Apr 2026 Trustpilot

customer · Apr 2026 Trustpilot

Andy Thomas · Apr 2026 Trustpilot

Philip · Apr 2026 Trustpilot

⚠️

DC arc faults are a fire hazard. The AFCI system exists to detect arcing on DC solar panel wiring — the same type of fault that causes PV fires. If the alarm has triggered more than once, do not reset the inverter without inspecting the DC cabling first. If you see visible damage, smell burning, or notice discolouration around connectors, isolate the system at the consumer unit and call a qualified solar engineer.

Diagnostics

6-step AFCI fault diagnosis

A single AFCI trip can be cleared with a power cycle (step 3). Repeated trips require a DC cabling inspection (step 4) before the alarm is cleared (step 5). Never bypass AFCI protection.

Check the alarm in FusionSolar and note the details

Open the FusionSolar app and check the alarm log. Look for a DC arc fault alarm. Note the time it triggered and — if shown — which PV string was involved. Check how many times the alarm has appeared in the last 24 hours.

Single trip

Likely a nuisance event. A power cycle (step 3) is a reasonable first response. Monitor for recurrence.

Multiple trips or lockout

A persistent fault on the DC wiring. Do not attempt a power cycle — go directly to step 4 for cabling inspection.

Understand the 5-trip lockout mechanism

The SUN2000 has a built-in AFCI auto-clearance system:

Fewer than 5 trips in 24 hours: The inverter automatically clears the alarm and restarts. No manual intervention is required — but you should still investigate if it trips more than once.

5 or more trips in 24 hours: The inverter locks for protection and will not restart automatically. The alarm must be cleared manually via the FusionSolar app or portal (step 5). The DC cabling must be inspected first (step 4).

Each power cycle that results in another trip counts toward the lockout. Do not repeatedly restart the inverter to "get past" the alarm — this worsens the situation and accelerates the lockout.

For a single trip — power cycle and monitor

If the alarm has triggered only once, a power cycle is appropriate:

1. Turn off the AC isolator

2. Turn off the DC isolator on the inverter

3. Wait 5 minutes — longer than a normal restart to ensure full discharge

4. Turn DC isolator back on, then AC isolator

Monitor the system for the rest of the day. If the alarm does not return, it was likely a nuisance trip caused by moisture on a connector, a transient electrical disturbance, or environmental interference.

Alarm returned? Do not power cycle again. The fault is persistent — proceed to step 4 for DC cabling inspection.

Inspect DC cabling and MC4 connectors

Repeated AFCI trips indicate a genuine DC arc fault. The wiring between the solar panels and the inverter must be physically inspected. This should be carried out by a qualified solar engineer with DC-safe PPE and insulated tools. Common fault locations:

MC4 connectors: Loose, partially disconnected, corroded, or with water ingress. These are the most common cause of DC arc faults on domestic solar installations.

Cable insulation damage: Cables rubbing against sharp roof edges, mounting rails, or tile hooks. Wind movement causes gradual chafing that eventually exposes conductors.

Junction boxes: Water ingress or heat damage to the junction box on the back of a panel. Check for discolouration or melting.

DC isolator switch: Corroded or damaged internal contacts. Rooftop isolators are exposed to weather and degrade over time.

Rodent damage: Squirrels, pigeons, and other wildlife can damage cable sheathing under panels. Look for gnaw marks or nesting material around cables.

If the affected string is identified in FusionSolar, focus the inspection on that string first. If not, all strings need checking.

Clear the AFCI alarm via the FusionSolar app

Once the DC cabling has been inspected and any faults repaired, clear the alarm:

1. Open the FusionSolar app → tap Me → Device commissioning

2. Connect to the inverter — scan the QR code on the inverter or enter the serial number

3. Log in with the installer account (default password: 00000a)

4. Tap Alarm management

5. Find the DC arc fault alarm and tap Clear

The inverter will restart and resume generation. Alternatively, the alarm can be cleared via the FusionSolar web portal under Maintenance → Alarm Management using a non-owner account.

If you do not have installer-level FusionSolar access, your installer can clear the alarm remotely or you can book an STS remote diagnostic.

If the alarm returns after clearing — do not reset again

If the AFCI alarm triggers again after clearing, the DC fault has not been fully resolved. Repeated arcing at the same location increases the risk of fire. At this point:

• Do not continue to clear and restart the inverter

• The fault location needs to be identified using string-level voltage and current testing

• Every connector, cable run, junction box, and isolator on the affected string needs individual testing

• Thermal imaging can help locate hot spots at degraded connections

STS can narrow down the likely fault location remotely using FusionSolar string performance data and alarm patterns before an engineer attends site — reducing time and cost.

What AFCI is and why it matters

AFCI (Arc Fault Circuit Interrupter) is a safety feature built into Huawei SUN2000 inverters that detects dangerous DC arc faults on solar panel wiring. A DC arc occurs when a connection is poor enough that electricity jumps across a gap — like a spark inside a loose connector. Unlike AC arcs that are interrupted every time the voltage crosses zero, DC arcs are continuous and self-sustaining, generating extreme heat at the fault point. This is why DC arc faults on solar installations are a leading cause of rooftop fires.

The SUN2000's AFCI system analyses the electrical noise pattern on each PV string to distinguish genuine arcs from normal electrical variation. When it detects an arc signature, it shuts down the affected string immediately. The system is enabled by default and under MIS 3002:2025 it must remain enabled — this is a mandatory requirement for UK solar installations, not an optional feature. AFCI works with standard PV modules and Huawei optimisers but does not support third-party optimisers or smart modules.

Nuisance trips do occur — moisture, transient interference, and certain environmental conditions can produce electrical patterns that resemble an arc. A single nuisance trip that clears after a power cycle and does not recur is not a concern. But any alarm that returns should be treated as a genuine fault until proven otherwise. The consequences of ignoring a real arc fault are severe.

AFCI arc fault — common questions

What causes an AFCI fault on a Huawei SUN2000 inverter?

The AFCI system detects DC arc faults on the solar panel wiring. Common causes include loose or partially disconnected MC4 connectors, water ingress into connectors or junction boxes, chafed cable insulation where cables rub against mounting rails, rodent damage, and corroded DC isolator contacts. A single trip can be a nuisance event caused by transient noise or moisture — these typically clear after a power cycle and do not recur.

How do I clear an AFCI alarm on a Huawei SUN2000?

Open the FusionSolar app, go to Me → Device commissioning, connect to the inverter, and log in with the installer account (default password: 00000a). Tap Alarm management and tap Clear next to the DC arc fault alarm. You can also clear it via the FusionSolar web portal under Maintenance → Alarm Management. Do not clear the alarm without inspecting the DC cabling if it has triggered multiple times — see step 4 above.

Why does my Huawei inverter keep tripping on AFCI?

Repeated AFCI trips indicate a persistent DC arc fault. The most likely cause is a degraded MC4 connector — loose, corroded, or with water ingress. Every connector, cable run, and junction box on the affected string needs inspecting. Do not continue to reset without investigation, as repeated arcing at the same location is a fire hazard. The SUN2000 locks after five trips in 24 hours to enforce this.

Can I disable AFCI on a Huawei SUN2000 inverter?

AFCI is enabled by default and should not be disabled. Under MIS 3002:2025, arc fault detection must be enabled where the inverter supports it — this is mandatory, not optional. Disabling AFCI removes a critical fire safety protection. If nuisance trips are occurring, the correct approach is to fix the wiring issue causing the false detection, not to disable the protection.

What does the Huawei SUN2000 5-trip AFCI lockout mean?

If the AFCI alarm triggers five or more times within 24 hours, the SUN2000 locks and will not restart automatically. This safety mechanism prevents repeated arcing. The lockout can only be cleared manually via the FusionSolar app (Me → Device commissioning → Alarm management → Clear) or the web portal. The DC cabling must be inspected and repaired before clearing. If the alarm triggers fewer than five times in 24 hours, the inverter clears automatically.

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AFCI alarm keeps returning?

Repeated arc fault trips need professional diagnosis. We can identify the likely fault location remotely using FusionSolar string performance data and alarm history — reducing the time and cost of an on-site visit. Most AFCI issues are traced to a single degraded connector.

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