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Problem diagnosis · Huawei

Huawei SPS Backup Not Working — Backup Box & Off-Grid Mode Diagnosis

The power went out and your Huawei battery didn't kick in? SPS (backup power) requires a Backup Box, the correct FusionSolar settings, and enough stored charge. Many systems are installed without backup capability even though they have a LUNA2000 battery. This guide explains what is needed and what to check.
  • Backup Box B0 (single-phase) / B1 (three-phase)
  • Off-grid mode must be enabled in FusionSolar
  • Battery SOC reserve for backup
Need backup power configured or fixed?

Backup Box installed but not switching, SOC reserve not holding, or loads tripping the off-grid output? We diagnose and configure Huawei backup systems remotely.

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5.0
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

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
ℹ️

A LUNA2000 battery does not automatically provide backup power. Unlike some other battery systems, Huawei requires a separate Backup Box to be installed between the inverter and your consumer unit. Without this hardware, the inverter and battery shut down during a grid outage — exactly like a system without a battery. If you do not have a Backup Box, start at step 1.

Diagnostics

6-step SPS backup diagnosis

Start with the hardware check (step 1). If you have a Backup Box, verify software settings (steps 2–3). If settings are correct but backup still failed, check battery charge and load issues (steps 4–6).

1

Check whether a Backup Box is installed

SPS backup power requires a Backup Box — a separate hardware device installed between the inverter and your consumer unit. Without it, the system has no backup capability regardless of how much battery you have.

Backup Box-B0

For single-phase SUN2000 L1 series inverters (SUN2000-2/3/3.68/4/4.6/5/6KTL-L1). Wall-mounted unit near the consumer unit.

Backup Box-B1

For three-phase SUN2000 M1 series inverters (SUN2000-3/4/5/6/8/10KTL-M1). Larger unit with three-phase switching.

If you do not have a Backup Box, one can usually be retrofitted. This requires a qualified installer for both the hardware installation and FusionSolar configuration.

2

Verify that off-grid mode is enabled in FusionSolar

The Backup Box hardware must be paired with the correct software setting. Even with a Backup Box installed, backup won't activate unless the software is configured.

1. Open FusionSolar and log in as installer (default password: 00000a)
2. Go to Settings → Feature parameters
3. Check the ESS mode — it must be set to "Grid-tied and Off-grid ESS"

If it is set to "Grid-tied ESS" only, the Backup Box will not activate during a power cut. The system will behave as if the Backup Box is not installed.

This setting requires installer-level FusionSolar access. If you cannot change it yourself, contact your installer or book a remote diagnostic.

3

Check the Backup Power SOC reserve setting

The Backup Power SOC setting reserves a percentage of battery capacity exclusively for backup. This charge is held back and not used for daily self-consumption.

Where to find it: FusionSolar → Settings → Grid connection settings → Backup Power SOC
Set too low (0–10%): The battery may be empty when a power cut occurs because it has already discharged for normal use. Little or no backup available.
Recommended (20–30%): Ensures meaningful backup capacity is always available. A 10kWh battery with 30% reserve holds 3kWh for backup — enough for lighting, fridge, and router for several hours.
Set very high (80–100%): Maximum backup protection but very little battery capacity available for daily self-consumption. The battery barely participates in normal energy management.

The right balance depends on your priorities — maximum backup security vs maximum self-consumption savings. Most homeowners find 20–30% is a reasonable compromise.

4

Check whether the battery had enough charge when the outage occurred

Even with correct settings, backup power only works if the battery has charge. Check the FusionSolar history to see the battery SOC at the time of the outage.

Outage in the evening after a cloudy day: The battery may have discharged through normal self-consumption with insufficient solar to recharge it. Only the Backup Power SOC reserve remains.
Outage after a sunny day: The battery should have been fully charged. If it was still empty, investigate why it didn't charge — see our battery not charging guide.
Outage overnight on TOU tariff: If the battery charged from the grid overnight and discharged during the evening peak, it may be at the Backup Power SOC minimum by the time an overnight outage occurs.

During an outage, the battery will discharge to 0% powering the backup loads. When it is fully depleted, the backup circuit loses power until either the grid returns or the sun rises and the panels begin generating again.

5

Review the loads connected to the backup circuit

The Backup Box powers only the circuits wired to its off-grid output — not the entire house. If the loads on this circuit are too high, the Backup Box will trip or fail to start.

Suitable backup loads: LED lighting, fridge/freezer, broadband router, phone chargers, TV, small electronics.
Problematic loads: Electric motors (pumps, compressors) draw several times their rated power at startup and can exceed Backup Box limits. Immersion heaters, electric cookers, and EV chargers should not be on the backup circuit.

If the Backup Box contactor clicks repeatedly (switching on and off with an audible noise), the connected load is exceeding the off-grid output capacity. Reduce the load by disconnecting high-power appliances on the backup circuit.

The SUN2000 L1 series provides approximately 5kW off-grid output. The total backup load must stay below this at all times including startup surges.

6

Check for Backup Box alarms and wiring issues

In FusionSolar, check the alarm log for any Backup Box related alarms. Common wiring issues that prevent backup from working:

Reversed AC terminals: If the inverter AC output and grid AC terminal are swapped at the Backup Box, the device generates abnormal noises during switching and may fail to activate.
Off-grid output connected to the grid: If the off-grid output port is accidentally connected to the live mains, the Backup Box shuts down immediately to protect itself. This is a serious wiring error that needs professional correction.
Overload protection: High startup currents from motors or compressors trigger the overload protection. The Backup Box may trip repeatedly until the offending load is disconnected.

Backup Box wiring issues should only be investigated by a qualified electrician. If the system has never provided backup power since installation, the most likely cause is a configuration or wiring error during the original install.

How Huawei SPS backup power actually works

Huawei's SPS (Switch to off-grid Power Supply) mode is the system's backup power function. In normal operation, the SUN2000 inverter runs in grid-tied mode — solar charges the LUNA2000 battery and powers the house, with surplus exported to the grid. The Backup Box sits between the inverter and the consumer unit, monitoring the grid connection. When it detects a grid failure, it physically disconnects the house from the grid (to prevent back-feeding) and switches the inverter into off-grid mode within a few seconds.

In off-grid mode, the inverter and battery power only the circuits connected to the Backup Box's off-grid output — these are the "essential" or "backed up" circuits chosen during installation. The rest of the house remains without power. If solar panels are generating during the outage, they continue to charge the battery and power the backed-up loads. When the grid returns, the Backup Box automatically switches back to grid-tied mode and normal operation resumes.

The most common misconception is that having a battery means having backup power. On Huawei systems, this is not the case without the Backup Box hardware. Many UK installations include a LUNA2000 battery for self-consumption and tariff optimisation but were not fitted with a Backup Box — meaning they have no backup capability at all. If backup power is important to you and your system does not have a Backup Box, it can be retrofitted in most cases.

FAQ

SPS backup mode — common questions

SPS (Switch to off-grid Power Supply) is Huawei's backup power mode. When the grid fails, the Backup Box disconnects from the grid and the inverter switches to off-grid operation — the LUNA2000 battery powers essential household circuits. When the grid returns, the system automatically switches back. SPS requires a Backup Box (B0 for single-phase, B1 for three-phase) and off-grid mode enabled in FusionSolar.
The most common reasons: no Backup Box is installed (the battery alone cannot provide backup), FusionSolar is configured for grid-tied only instead of grid-tied and off-grid, the battery was empty when the outage occurred because the Backup Power SOC reserve was too low, or the loads on the backup circuit exceeded the off-grid output capacity. Many Huawei systems are installed without a Backup Box — meaning no backup even with a battery.
You need a Backup Box (B0 for single-phase, B1 for three-phase) physically installed between the inverter and consumer unit, and the FusionSolar setting changed to "Grid-tied and Off-grid ESS" under Settings → Feature parameters. Set the Backup Power SOC reserve to at least 20–30% so the battery retains enough charge. Both hardware installation and software configuration require a qualified installer with FusionSolar access.
Only circuits wired to the Backup Box off-grid output are powered — not the whole house. Typical backed-up loads include LED lighting, fridge/freezer, broadband router, and phone chargers. Avoid connecting electric motors (pumps, compressors), immersion heaters, cookers, or EV chargers as their power demands or startup surges can exceed the Backup Box limits and cause it to trip.
Yes, in most cases a Backup Box can be retrofitted. The B0 is for single-phase L1 inverters, the B1 for three-phase M1 inverters. Installation involves wiring the Backup Box between the inverter and consumer unit and connecting essential circuits to the off-grid output. This requires a qualified electrician and an installer with FusionSolar access. The Backup Box costs several hundred pounds plus installation labour.
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Backup power not working as expected?

Backup Box installed but not switching during outages, SOC reserve draining before a cut, or loads tripping the off-grid output? We diagnose and configure Huawei SPS systems remotely — including Backup Box settings, SOC reserve tuning, and load management.

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