Power cut guide
Solar Panels and Home Batteries in a Power Cut
Quick answer: Most UK solar panel systems switch off automatically the moment the grid goes down, even on a sunny day. This is a deliberate safety feature that stops your panels sending electricity into lines that engineers may be repairing. Only a system with a battery that has been designed and installed to run in backup (often called EPS or island mode) can keep some of your circuits going, and even then usually only the ones it was wired to supply.
Is the power off where you are? See live power cuts from the network operators and reports from neighbours.
This guide is for households that already have solar panels or a home battery, or are thinking about getting them, and want to know what will actually happen in a power cut. It explains the safety rules in plain English, the different kinds of backup, and the questions worth asking an installer before you sign anything.
Why your solar panels go off when the grid does
A normal rooftop system is “grid-tied”. The panels make direct current (DC), an inverter turns it into the alternating current (AC) your home uses, and anything you don’t use flows out into the local network. The inverter constantly watches the grid’s voltage and frequency so that it can match them.
When the grid disappears, the inverter detects the loss and disconnects within a fraction of a second. Network operators describe this as stopping electricity “feeding back into the electricity network when engineers may be working on it”. Without that protection, a line that an engineer has switched off and believes is dead could be made live again by hundreds of homes’ solar systems. The technical name is anti-islanding or loss-of-mains protection: your house is prevented from becoming a little powered “island” connected to an otherwise dead network.
So if you have panels and no battery, a power cut on a bright afternoon looks exactly the same indoors as one at midnight. The panels are still producing energy, but nothing in the house can use it.
What G98 and G99 mean
You may see “G98” or “G99” on your installation paperwork. These are Engineering Recommendations published by the Energy Networks Association (ENA) and used by every network operator in Great Britain. They set the rules for connecting generation, including solar inverters and batteries, to the local network safely. Part of that is proving the inverter will trip off quickly when the grid fails.
| G98 | G99 | |
|---|---|---|
| Typical size | Up to 16 amps per phase (3.68kW on a normal single-phase home supply) | Anything larger, or several systems that add up to more |
| Process | Installer fits type-tested kit, then notifies the network operator (within 28 days of commissioning) | Installer applies to the network operator and gets agreement before connecting |
| Common in homes | Smaller solar arrays, some batteries | Larger arrays, solar plus a big battery, some export-limited systems |
The rating used is the inverter’s continuous output, not the total size of the panels. Your installer normally handles the paperwork, but it’s worth asking for a copy of the notification or approval for your records. If you ever sell the house, or the operator asks, you’ll have it to hand.
Batteries: why many still switch off
A common surprise is that adding a home battery does not automatically give you power in a power cut. Most batteries are installed to store cheap or solar electricity and use it later while the grid is on. Network operators say batteries usually shut down during a power cut “unless they are designed to operate in backup” mode, and that this capability “must be specifically designed and installed”.
In other words, three things need to be true before a battery can help you when the grid fails:
- The battery and inverter must support backup operation.
- The installation must include the extra hardware and wiring that safely separates your home, or part of it, from the grid.
- The circuits you want to keep running must be connected to the backup side.
If any of these is missing, the battery simply disconnects along with the panels, however full it is.
The main types of backup explained
Manufacturers use different names, but most home backup set-ups fall into one of the groups below. The words matter less than what is physically connected.
| Set-up | What it does in a power cut | Things to bear in mind |
|---|---|---|
| No backup (standard grid-tied) | Panels and battery switch off | Most common arrangement; nothing works until the grid returns |
| EPS socket | A single dedicated socket on or near the inverter stays live | Good for a fridge, phone chargers or a router via an extension lead; limited power |
| Partial backup (essential circuits) | A small sub-board keeps chosen circuits on, such as lights, the fridge and a few sockets | You decide which circuits at the design stage; there may be a short gap while it switches |
| Whole-home backup | An isolation switch disconnects the house from the grid and the battery supplies everything it can | Big loads (electric shower, oven, kettle) can drain or overload the battery quickly |
With any of these, the system still disconnects your home from the grid first. That separation is what keeps line workers safe. A backup system that skipped this step would not be allowed to connect.
Will the panels keep charging the battery?
Some backup systems let the panels keep topping up the battery while you’re cut off from the grid; others only run from what’s already stored. This makes a big difference in a long daytime cut, especially in summer. Ask the installer directly, and ask whether it works in winter when generation is low.
Tip: Work out roughly how long your stored energy will last by adding up the wattage of the things you’d want to run. Our battery backup calculator does the sums for you.
What will and won’t work in practice
Say your power goes off at 7pm on a winter evening and you have a partial backup system with a half-full battery. Lights, the fridge, the router and phone chargers on the backup circuits use relatively little power, so they could run for many hours. An electric oven or a 9kW shower would use the same stored energy far faster, and a battery’s maximum output may not even be enough to start them.
Heating is the one people often forget. A gas boiler still needs electricity for its controls and pump, and a heat pump needs a lot more. Whether either can run from a battery depends on how the system was wired and how big the inverter is. Our guide to boilers and heat pumps after a power cut covers what to expect from your heating.
- Usually fine on backup: LED lighting, fridge or freezer, broadband router, phone and laptop charging, TV.
- Possible, depends on size: gas boiler controls and pump, microwave, kettle for short bursts.
- Usually too much: electric shower, immersion heater, oven, electric car charging, tumble dryer.
Electric cars and vehicle-to-home
A standard electric car charge point cannot power your home. It has built-in protection that disconnects it during a power cut, and some units need a manual reset (usually off and on again) once power returns.
Vehicle-to-home (V2H) is different: it needs a car that supports two-way charging and a special bidirectional charger installed with the same grid-separation safety as a home battery. Only some vehicles and chargers support it, so if it interests you, check compatibility with both the car maker and an installer before buying anything. Never try to power a house from a car through improvised leads or adaptors.
Safer alternatives if you don’t have backup
If your system has no backup, you still have options for keeping essentials going. A portable power station can run a router, lamps and phone chargers and can be recharged from the mains or from portable solar panels. Our guide to choosing a portable power station explains capacity and safety.
Some people consider a petrol or diesel generator instead. These need much more care, both because of carbon monoxide and because they must never be plugged into your house wiring without a properly installed changeover switch. Read generator safety and sizing first.
Safety: Never connect a generator, inverter or battery to your home wiring by plugging it into a socket (“back-feeding”). It can make the street’s cables live and kill someone working on them. Any connection to your fixed wiring must go through a changeover switch fitted by a qualified electrician, and the network operator may need to be told.
What to ask an MCS installer
Most reputable solar and battery installers are certified under the Microgeneration Certification Scheme (MCS) and signed up to a consumer code such as the Renewable Energy Consumer Code (RECC) or HIES. You can check an installer on the MCS website. If backup matters to you, raise it at the very start, because it changes the equipment and the wiring.
- Will this system give me any power during a power cut? If yes, exactly which circuits or sockets?
- Is it an EPS socket, partial backup or whole-home backup?
- Does it switch over automatically, and how long is the gap?
- Can the panels recharge the battery while the grid is down?
- What is the maximum power the battery can deliver at once, in kW?
- How much of the battery can I keep in reserve for power cuts, and can I change that setting myself?
- Will the installation be notified or approved under G98 or G99, and will I get a copy?
- Is there an isolation switch, and how is the grid separated before backup starts?
- Is there a labelled diagram showing which circuits are on backup?
- Who do I call if backup fails to start, and is that covered by the warranty?
Get the answers in writing. A clear quote should spell out the backup arrangement rather than leaving it vague.
Before a storm or planned power cut
If your system does have backup, a little preparation helps you get the most out of it.
- Check the app or display shows backup is enabled, and raise the battery’s reserve level if you can.
- Let the battery charge fully before the expected cut, from solar or a cheap tariff.
- Know where the backup circuits are, and keep a torch somewhere you can find it in case the switchover fails.
- Learn how to reset the battery or charge point safely, following the manufacturer’s instructions.
- Check your postcode for planned work so you’re not caught out. You can check your postcode for live and planned power cuts.
Keep your emergency kit stocked too: backup systems can fail, and batteries run flat. Our power cut emergency kit guide lists the basics.
When the power comes back
Grid-tied solar should restart on its own after the grid returns, often after a short delay of around 20 seconds while the inverter checks that the supply is stable. Batteries and EV chargers may resume automatically or may need a reset. If an error message stays on the inverter display, follow the manufacturer’s guidance or contact your installer rather than opening any equipment yourself.
If power cuts in your area seem frequent, it can help to understand what causes them; our guide on why power cuts happen explains the usual culprits.
Frequently asked questions
Do solar panels work in a power cut in the UK?
Not on their own. Grid-tied solar panels switch off automatically when the grid fails, to protect engineers working on the lines. You need a battery with a backup or EPS function, designed and installed for that purpose, to use solar power during a cut.
Can I add backup to my existing solar battery?
Sometimes. It depends on whether your inverter and battery support backup and whether extra switchgear can be fitted. Ask an MCS-certified installer to check your exact model; some systems can be upgraded, while others would need a different inverter.
Is an EPS socket the same as whole-home backup?
No. An EPS socket is usually a single outlet with limited power, handy for a fridge or chargers. Whole-home backup separates the entire house from the grid and supplies all your circuits, within the battery’s limits.
Do I need to tell my network operator about a home battery?
Yes, if it can run in parallel with the grid. Batteries count as generation under the G98 and G99 rules, and your installer should notify or apply to the network operator. Ask for a copy of the paperwork.
Why didn’t my solar restart after a power cut?
Most systems restart automatically after a short delay. If yours hasn’t after several minutes, check the inverter display for an error and the isolator switches near it, then contact your installer. Don’t open the inverter or panel wiring yourself.
If you have solar or a battery, the most useful thing you can do today is find out whether it has backup at all, and which circuits it covers. Then check whether you qualify for the Priority Services Register, especially if anyone at home relies on powered medical equipment.
Sources
- UK Power Networks u2013 Power cuts, voltage issues and your low carbon technologies
- Electricity North West u2013 G98 micro-generation and storage connections
- Electricity North West u2013 G98 and G99 application guidance (PDF)
- SP Energy Networks u2013 Electrical energy storage
- Energy Saving Trust u2013 Consumer protection for home energy installations
Checked against these sources on 28 October 2026. Rules and amounts can change – your network operator or Ofgem has the final word. Spotted something out of date? Tell us.
More on being prepared: Power Cut Emergency Kit: What to Keep at Home · All power cut guides