Do solar panels work during a power cut in the UK? For the vast majority of homes, the honest answer is no — and if you have a battery, the same rule applies unless it was specifically set up with backup capability. Here's exactly why, and what it takes to change that.
Why do solar panels shut off during a power cut?
It seems counterintuitive. The sun is shining, your panels are generating electricity, yet the moment the grid goes down, everything stops. When a power cut happens, your solar system automatically shuts down. This is a safety feature known as anti-islanding — it protects engineers who may be working on power lines nearby.
When the grid fails, every grid-connected solar inverter in the UK is legally required to shut down within milliseconds. This is true regardless of whether your battery is fully charged. The reason is a safety rule called anti-islanding.
In the UK, all grid-connected solar systems must comply with strict electrical standards, including G98/G99 regulations and BS 7671 wiring rules. These rules require systems to shut down automatically when the grid fails. It isn't a design flaw — it's there to keep people safe.
The result? During a blackout, your panels stop, your inverter goes dark, and your house is exactly as powered as your neighbour's without solar. That's a surprise for most people, and it's worth knowing before you buy.
Will my solar battery keep the lights on in a blackout?
Not automatically — and this is where most homeowners get caught out. A battery on its own is not the same as a backup system. Not all batteries provide power during an outage. To enable this feature, your system must include a backup or emergency power supply function.
The default sequence without backup wiring is: grid fails → inverter detects loss of grid voltage → anti-islanding trips → inverter shuts down completely → battery sits idle → your house has no power until the grid returns. This is the default state of most UK solar battery systems.
Even if your solar panels are generating power and your battery is full, your system will shut down without backup equipment. That's the detail that catches people out — a full battery is irrelevant if the system isn't wired to use it during a grid outage.
Can solar panels power my home if the grid goes down — and how?
Yes, but only with the right equipment, properly installed from the start. The solution is a feature called Emergency Power Supply (EPS) or, in more comprehensive systems, whole-home backup. A battery with backup capability — sometimes called EPS or whole-home backup — detects the grid outage and physically isolates your home from the network using an automatic transfer switch, then continues running your essential circuits (or your whole home, depending on the system) from the battery, with the solar panels topping it back up during daylight.
What makes backup work is a combination of a compatible hybrid inverter, EPS-specific wiring between the inverter and your protected circuits, and the EPS mode being enabled in the inverter software. It is not something you can add with a firmware update — it needs to be built into the installation.
Most backup systems are designed around essential loads rather than whole-house coverage. In practice, that usually means keeping your lights, fridge, broadband router, and a few sockets running — not your electric shower or oven.
What does solar battery backup actually cost in the UK?
There are two levels, and the price difference is meaningful.
- Essential circuit backup (EPS): Essential circuit backup, where a gateway powers a small set of circuits such as lights, fridge, broadband, and a couple of sockets, has a typical installed cost of £600 to £1,000 on top of your battery installation.
- Whole-home backup: Whole-home backup, where the gateway powers the whole consumer unit, needs a larger battery, a higher-rated inverter, and an automatic transfer switch. Typical installed cost is £1,000 to £2,500 on top of the battery.
The battery itself is the bigger outlay. A medium battery of 5 to 10 kWh installed costs £4,500 to £7,000 — the sweet spot for a typical three-bedroom semi or terrace. For a fuller breakdown of what battery storage costs and whether it's worth it on its own terms, see our guide to solar battery storage: do you actually need one?
One important note: if you are installing a new battery system, adding EPS capability from the outset is significantly cheaper and simpler than retrofitting later. If backup matters to you, tell the installer before they design the system — not afterwards.
Is backup power actually worth paying for in a typical UK home?
This is the honest question, and the honest answer is: probably not for most people, but it depends on your circumstances.
According to Ofgem, power cuts generally last around 95 minutes on average and only happen once every two and a half years per area. While the UK has one of the most reliable power networks in the world, outages do still happen due to weather, maintenance work, or faults on the grid.
For most households, a 90-minute outage every couple of years is an inconvenience, not a crisis. Your fridge stays cold, your boiler can usually light manually, and a torch or phone charge will see you through.
But there are households where backup makes much more sense:
- You or a family member relies on medical equipment that needs continuous power.
- You work from home and a power cut costs you real money in lost work.
- You're in a rural area where outages tend to last longer and occur more often.
- You want peace of mind after a particularly bad storm knocked your power out for hours.
If you don't fall into one of those categories, a standard solar and battery combination — focused on saving money on your bills by storing your own generation — will almost certainly give you a better financial return than spending extra on backup wiring. Our guide on what size solar battery you need covers how to size for bill savings rather than backup.
It's also worth reading our honest look at solar panel payback time in 2026 before deciding how much to add to your overall budget.
Three things to sort out before you commit
1. Decide before you get quotes, not after. Backup-capable systems need different wiring and sometimes a different inverter. If staying powered during outages matters to you, confirm backup capability and which circuits it covers in writing before you sign.
2. Check the battery brand's EPS support. Not every battery offers it. The Tesla Powerwall 3 includes whole-home backup as standard. Most modular batteries offer EPS as an optional extra that typically powers a single essential circuit and needs additional hardware, adding around £300–£1,000.
3. Use an MCS-certified installer. Backup wiring must be done correctly — a mistake could create a safety hazard. MCS 012 is the battery storage standard, and an MCS-certified installer is required to register the system for the Smart Export Guarantee. You can find out how to check a certificate at MCS Certified. For more on spotting trustworthy installers, see our guide on how to check if a solar installer is MCS certified.
The bottom line
Standard solar panels — even paired with a battery — will not keep your lights on during a power cut unless the system includes specific EPS or backup wiring. That's not a flaw; it's a legal safety requirement that protects electricity workers. The good news is that adding backup capability is entirely possible, and it needn't cost a fortune if you plan for it upfront. Whether it's worth the extra spend depends on how often your area loses power, and what you genuinely can't afford to lose when it does.
If you're weighing up solar and battery options, the best starting point is a set of free, no-obligation quotes from vetted, MCS-certified local installers. Compare quotes through FairSolar — it costs nothing, and you're under no pressure to go ahead.
Frequently asked questions
Do solar panels work during a power cut in the UK?
No — for the vast majority of UK homes, solar panels automatically shut down the moment the grid goes down. This is a legal safety requirement called anti-islanding, designed to protect electricity network engineers. Your panels won't generate usable power in your home until the grid is restored, unless you have a battery with specific backup (EPS) wiring installed.
Will my solar battery keep the lights on in a blackout?
Only if it was installed with backup capability — often called EPS (Emergency Power Supply). A standard battery installation, even a full one, will shut down alongside the grid because it lacks the wiring and transfer switch needed to safely isolate your home. If backup matters to you, you need to specify this before installation, not after.
How much extra does solar battery backup cost in the UK?
Adding essential circuit backup (lights, fridge, broadband) typically costs £600–£1,000 on top of your battery installation. Whole-home backup — which keeps everything running seamlessly — costs roughly £1,000–£2,500 extra, and usually requires a larger battery and higher-rated inverter. Planning for backup from the start is significantly cheaper than retrofitting it later.
How often do UK homes actually lose power?
According to Ofgem, power cuts in most UK areas last around 95 minutes on average and occur roughly once every two and a half years. For most households, that's an inconvenience rather than a crisis — which is why many installers recommend prioritising bill savings over backup when sizing a battery system.
Can I add backup power to my existing solar and battery system?
Sometimes, but it depends on your current inverter and battery model. If your battery supports EPS as an option, an installer may be able to add the necessary wiring and transfer switch. However, if your inverter isn't backup-compatible, you may need to replace it — which significantly increases the cost. Always get a system assessment from an MCS-certified installer before assuming a retrofit is straightforward.