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.
Huawei SPS Backup Not Working — Backup Box & Off-Grid Mode Diagnosis
- Backup Box B0 (single-phase) / B1 (three-phase)
- Off-grid mode must be enabled in FusionSolar
- Battery SOC reserve for backup
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.
Book your free remote diagnosticBack to Huawei hubIndependent — not affiliated with Huawei Technologies.
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.
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.
Solar Tech Support is an absolute lifesaver. My solar and battery system stopped working completely, but after one quick phone call, they fixed the problem straight away. The original provider, GivEnergy, has gone into administration, leaving me entirely without support from the original installers. It was a terrible situation on GivEnergy’s part, but thankfully, Solar Tech Support came to the rescue!
Ron is incredibly knowledgeable about solar installs in general but knows givenergy products inside out and the key personnel that worked there from the start to the end. My problem was spurious in its nature but Ron spotted it straight away when he understood the installation details. In essence the installers didn’t fit the correct trip switch. He also gave me hope that in the future hardware repairs could be possible but it’s still early days. This guy really is in the know and keen to sucas a business If you need help don’t hesitate
A superb service from Ron who went beyond the normal service received from other Tech support companies. I live abroad and was badly let down when my givenergy system failed (and the company went bankrupt) and the local supplier ran away from the problem. Ron sorted the problem and even accessed specialist coding for the inverter that would not be available for suppliers. Ron also ran a full diagnostic to insure that all was in good working order afterwards. Without Rons support and patient assistance I doubt I would ever have got the system back up and running. Well done and thankyou and you have a customer for the future.
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.
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).
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.
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.
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.
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.
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.
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.
The right balance depends on your priorities — maximum backup security vs maximum self-consumption savings. Most homeowners find 20–30% is a reasonable compromise.
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.
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.
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.
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.
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:
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.
SPS backup mode — common questions
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.
- No fix, no fee
- Backup Box and off-grid mode configuration
- SOC reserve and load management advice
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