Problem diagnosis · Huawei

Huawei LUNA2000 Battery Not Charging — Working Mode, BMS & Charge Schedule Fix

LUNA2000 battery stuck at the same SOC all day? The most common cause is the FusionSolar working mode — if it is set to "Fully Fed to Grid", the battery is completely bypassed. This guide covers working mode settings, BMS faults, charge schedules, and cold-weather heating behaviour.

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LUNA2000 5–30 kWh systems
SUN2000 hybrid inverters
FusionSolar app settings walkthrough

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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

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Your solar panels are probably still generating. A battery not charging does not mean the rest of the system has stopped. The SUN2000 inverter will continue converting solar power and exporting to the grid even if the LUNA2000 battery is not accepting charge. What you lose is the ability to store excess generation for later use — meaning more export and higher grid dependence in the evening.

Diagnostics

6-step battery charging diagnosis

Start with the FusionSolar app (steps 1–3) — most battery charging issues are caused by a wrong working mode or missing charge schedule. If settings look correct, check the hardware (steps 4–6).

Check battery status and alarms in FusionSolar

Open the FusionSolar app or web portal. On the plant overview screen, check three things: the current battery SOC (state of charge), the power flow direction (is power going to or from the battery?), and whether any alarms are active.

SOC at 100%

The battery is full — it will not charge further until it discharges. This is normal. Check again in the evening after household loads have drawn it down.

Alarms present

Note the alarm code. BMS communication faults are the most common — see step 4. Over-temperature or abnormal voltage alarms need professional investigation.

If the SOC is low and no alarms are present, the battery should be charging but isn't. This points to a settings issue — continue to step 2.

Verify the working mode in FusionSolar settings

This is the single most common cause. In the FusionSolar app, go to Settings → Grid connection settings → Working mode. There are three options:

Maximum Self-Consumption: The battery charges from excess solar during the day and discharges to cover household load in the evening. This is the correct mode for most UK homes with a battery.

Time of Use (TOU): The battery charges and discharges according to time windows you configure. Used with cheap overnight tariffs like Octopus Go or Economy 7. Requires charge periods to be set up correctly (see step 3).

Fully Fed to Grid: All solar is sent directly to the grid. The battery is completely bypassed — it will never charge in this mode. If this is selected, that is your problem.

Some working mode changes require installer-level FusionSolar access. If you cannot change the setting yourself, contact your installer or book a remote diagnostic.

Check the charge schedule and discharge SOC limits

If the working mode is Time of Use (TOU), the battery only charges during configured time windows. Go to Settings → Grid connection settings → Time-of-Use periods and check:

Charge periods: Are charge windows set during the hours you expect the battery to charge? For overnight grid charging, a typical window is 00:30–04:30.

End of Discharge SOC: If this is set very high (e.g. 90%), the battery stops discharging early and may appear permanently full. A typical value is 10–20%.

Backup Power SOC: This reserves a percentage of battery capacity for backup use. If set to 100%, the battery will not discharge at all. Check this is set to a sensible value (typically 10–20%).

If you are on Maximum Self-Consumption mode, charge schedules do not apply — the battery charges automatically from excess solar. If it still won't charge, move to step 4.

Check for BMS communication faults and battery module hardware

A BMS (Battery Management System) communication fault means the SUN2000 inverter has lost contact with one or more LUNA2000 battery modules. This is a hardware-level issue rather than a settings problem.

Battery DC switch: Each LUNA2000 module has a DC switch — check it is turned on.

Power and communication cables: Inspect the cables between battery modules and between the top module and the inverter. These must be firmly seated at both ends.

Module LED: Each LUNA2000 module has a status LED. Solid green means normal operation. Red indicates a fault. No light means the module is powered off or disconnected.

Multi-module stacks: If you have two or three LUNA2000 modules stacked together (10–15 kWh), a loose cable between any two modules disconnects every module below the break.

If a BMS fault clears after reseating cables, monitor for recurrence. Persistent BMS faults may indicate a failing module or damaged cable harness.

Consider cold weather — the battery may be heating itself

The LUNA2000 has an internal heating system that activates when the battery temperature drops below the safe charging threshold. During heating:

The battery draws approximately 300W — but this energy goes to the heating element, not to charging the cells.

The SOC does not change during heating. This is normal and not a fault.

Heating can last 30 minutes or longer depending on ambient temperature — common in unheated garages, lofts, and outdoor installations during winter.

Once the battery reaches a safe internal temperature, normal charging resumes automatically. If you see 300W draw with a static SOC on a cold day, wait an hour before investigating further.

Power cycle the battery and inverter

If settings are correct, no alarms are present, and the battery is not in heating mode but still will not charge — power cycle the entire system:

1. Turn off the AC isolator

2. Turn off the DC isolator on the inverter

3. Turn off the DC switch on each LUNA2000 battery module

4. Wait 60 seconds

5. Turn battery module switches back on

6. Turn DC isolator back on, then AC isolator

Wait 5 minutes for the system to re-establish BMS communication and check FusionSolar for battery status.

Still not charging? The issue may be a module-level fault, a firmware problem, or an inverter configuration that requires installer-level access to change. Book a remote diagnostic for an engineer-level review.

Understanding LUNA2000 battery charging behaviour

The Huawei LUNA2000 battery system is tightly integrated with the SUN2000 hybrid inverter and controlled entirely through the FusionSolar app. Unlike some other battery systems that have their own independent management interface, the LUNA2000 relies on the inverter for all charge and discharge decisions. This means that nearly every charging issue traces back to either the FusionSolar settings or the communication link between the inverter and battery modules.

The working mode setting is the master switch. In Maximum Self-Consumption mode, the inverter automatically diverts excess solar to the battery and draws from the battery when solar generation is below household load. In Time of Use mode, the inverter follows a schedule — and if that schedule is not configured correctly, the battery may sit idle all day. "Fully Fed to Grid" mode is designed for systems without a battery or for testing purposes, and it disables all battery activity.

For homes on time-of-use tariffs like Octopus Go, Intelligent Octopus, or Economy 7, the TOU mode with correctly configured charge windows is essential. The battery should be set to charge from the grid during the cheap rate period and discharge during peak hours. If your installer set up the system but did not configure TOU periods, the battery may never charge from the grid even though the mode is technically correct. STS can review and configure these settings remotely.

LUNA2000 battery charging — common questions

Why is my Huawei LUNA2000 battery not charging from solar?

The most common cause is the FusionSolar working mode being set to "Fully Fed to Grid", which bypasses the battery entirely and sends all solar generation to the grid. Change the working mode to Maximum Self-Consumption or Time of Use in Settings → Grid connection settings. Other causes include a full battery (SOC at 100%), a BMS communication fault between the inverter and battery, or a grid code fault on the inverter.

How do I change the battery working mode in FusionSolar?

Open the FusionSolar app, go to Settings → Grid connection settings → Working mode. Select Maximum Self-Consumption to charge from excess solar during the day and discharge to loads in the evening. Select Time of Use to set specific charge and discharge windows — useful for cheap overnight tariffs. "Fully Fed to Grid" disables all battery activity. Some settings require installer-level access — your installer may need to adjust this remotely.

What does a BMS communication fault mean on a Huawei LUNA2000?

A BMS communication fault means the SUN2000 inverter has lost contact with one or more LUNA2000 battery modules. This is usually caused by a loose power or communication cable between modules, a battery DC switch being off, or a module-level fault. Check all module switches are on and cables are firmly seated. In a multi-module stack, a single loose cable can disconnect every module below it in the chain.

Why is my LUNA2000 battery showing 300W but not changing SOC?

This is the battery's internal heating system. When the LUNA2000 temperature drops below the safe charging threshold — common in cold garages, lofts, and outdoor installations during winter — the heating element activates at approximately 300W. During heating, the SOC remains static because the energy warms the cells rather than charging them. This is normal protective behaviour and resolves automatically once the battery reaches a safe internal temperature, typically within 30–60 minutes.

Can I force my Huawei LUNA2000 to charge from the grid?

Yes. Set the working mode to Time of Use in FusionSolar and configure a charge period during your cheap rate hours — for example 00:30–04:30 on Octopus Go or Economy 7. You also need to enable grid charging (sometimes called AC charging) in the battery settings. Some tariff-optimisation tools like Predbat can automate this based on energy prices. Installer-level FusionSolar access may be required to enable grid charging for the first time.

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LUNA2000 battery still not charging?

BMS alarm won't clear, battery SOC stuck, or settings locked behind installer access? We diagnose Huawei battery systems remotely using your FusionSolar data and can reconfigure working modes, charge schedules, and discharge limits in a single session.

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