Usually, no. Standard grid-connected solar panels switch off when the mains fails, even on a bright day. This stops electricity travelling back into cables while engineers repair them. A home battery only supplies you during a cut if it has properly installed backup or “island mode”; it may serve selected circuits rather than the whole house. New compliant plug-in solar panels also stop when mains voltage disappears (SSEN, DESNZ specification).
The panels may still be in daylight, but a sunny disposition is not an electrical backup plan. The inverter and the way the system was installed decide what reaches your sockets.
Why does ordinary rooftop solar switch off?
Why can’t the panels power the house while the sun is out?
Most domestic solar is connected in parallel with the public electricity network. Its inverter turns the panels’ direct current into alternating current that works with your home and the grid. When the grid disappears, the inverter’s loss-of-mains protection shuts generation down. This is called anti-islanding.
The purpose is safety. If your panels kept energising local cables, engineers could meet electricity where they reasonably expected an isolated line. SSEN’s network guidance says solar automatically switches off during a cut to prevent export into the network.
Do not try to bypass the inverter, run a lead between sockets or alter the consumer unit. Backup supply needs equipment designed, protected and installed for that job.
Will the solar system come back by itself?
Usually, yes. SSEN says solar normally restarts after mains electricity returns, sometimes following a short safety delay. Check the inverter display or app once the supply has settled. If it shows a fault or stays off, follow the correct manual for your model or contact the installer. Do not remove covers or attempt electrical repairs yourself.
What changes if you have a home battery?
Does every solar battery provide power in a cut?
No. A battery can store energy and still be unable to supply the home during an outage. SSEN says batteries usually switch off with the grid unless they have a backup or island mode. That mode needs suitable switching and protection so your home is safely separated from the network.
Backup arrangements vary by model and installation. Yours may supply:
- one dedicated emergency socket;
- a small “essential loads” circuit for items such as the fridge, lights and router; or
- more of the house, within the inverter’s output and the battery’s available charge.
A battery’s energy capacity and its maximum output are different things. A large stored charge does not mean it can start every appliance at once. Do not assume an electric shower, oven, heat pump or EV charger is covered. Ask your installer which circuits are backed up, whether solar can recharge the battery while islanded, and what happens when the battery reaches its reserve level.
How should I test backup mode?
Use the installer’s approved test procedure, not the main switch as an experiment. Keep a paper note by the consumer unit showing which circuits should remain live and how to read the battery status. Check the manual for any maintenance test and ask the installer to demonstrate safe shutdown and restart. Behaviour varies by model, firmware and wiring.
What about plug-in solar panels?
Are plug-in or balcony panels legal in the UK now?
Compliant plug-in solar became legal to buy and use in Great Britain on 27 August 2026. The Government says current kits provide up to 800W and may be suitable for outdoor space or some balconies, although landlord, freeholder, planning or listed-building permission may still be required (DESNZ).
Buy only a product intended for the Great Britain scheme and follow its supplied instructions. The official specification covers solar kits with a grid-following inverter and manufacturer-supplied UK plug. It does not cover plug-in batteries or solar devices integrated with plug-in batteries.
Will a plug-in panel keep one socket live in a cut?
No. The current DESNZ product specification requires loss of voltage at the socket to remove voltage coming from the inverter. In plain English, a compliant unit stops output when the mains fails. Do not connect it to an extension lead, improvise a battery connection or treat its plug as an emergency outlet.
Before a power cut: know what you actually have
What should I ask my solar or battery installer?
Ask these questions while the lights are on:
- Does this installation have backup or island mode?
- Exactly which sockets and fixed circuits does it supply?
- What is the maximum backup output, and which appliances must stay off?
- Can the panels recharge the battery during a grid cut?
- How do I see remaining charge without broadband?
- What is the approved test and restart procedure?
- Who do I call if the system does not recover?
Keep the answers, model numbers and installer contact details on paper. Your broadband router and digital landline normally need mains power; Ofcom advises people who rely on their landline for emergency calls to ask their provider about a free backup solution (Ofcom).
Also keep a torch, power bank, battery or wind-up radio, water and food that needs no cooking together. Those are the practical basics in the public GOV.UK Prepare checklist.
The first 10 minutes of a cut
What should I do when the grid goes down?
- Check whether neighbours or street lights are also off.
- In England, Scotland and Wales, report the cut online or call 105. In Northern Ireland, call 03457 643643 (Prepare).
- Use a torch, not candles.
- Switch off ovens, hobs, irons, electric fires and fryers. Unplug sensitive electronics.
- Look at the solar and battery status without touching wiring or removing covers.
- Leave one ordinary light switched on so you know when mains electricity returns.
If backup has started, confirm that only the expected circuits are live. Reduce unnecessary loads early. That leaves more stored energy for lighting, communications, refrigeration and any equipment your household genuinely needs.
If the cut lasts longer
How do I make battery power last?
Follow the battery display and installer’s priority list. Turn off high-demand loads that are not essential. Use a power bank for phones where practical rather than keeping a large backup circuit busy. Solar recharging during the outage is possible only on systems designed to do it, and output changes with daylight, weather, shading and the system itself.
Gas boilers, heat pumps and home internet normally need electricity. Even if a backed-up socket is available, do not connect fixed heating equipment with improvised leads. Prepare advises layered clothing, blankets, closed curtains and shutting unused rooms if the home cools. With fuel-burning heating, keep a working audible carbon monoxide alarm and never improvise indoor combustion (Prepare: cold weather).
People who need extra help
If anyone relies on powered medical equipment, agree an outage plan with their clinical team and equipment provider before a cut. Battery runtime and changeover vary by device. The free Priority Services Register can provide advance notice of planned cuts and extra emergency support, but it does not guarantee uninterrupted power. Contact both your supplier and network operator (Prepare, Ofgem). Check telecare, stairlifts and digital landlines as complete systems, including their router and batteries.
If you live in Northern Ireland, Scotland or Wales
Scotland and Wales: the Great Britain solar, battery and plug-in-solar points above apply; call 105 for a network cut. Northern Ireland: call NIE Networks on 03457 643643. The July 2026 plug-in-solar specification says its application to Northern Ireland remains subject to separate consideration and may need amendment, so do not assume a Great Britain product or connection route applies. Check current NIE Networks requirements before buying or connecting one (DESNZ specification, Prepare).
After power returns
Wait for the supply to settle, then check the inverter, battery and any backed-up circuits. Solar and heat pumps usually restart automatically; smart systems may need a check or reset. Follow the manual or installer’s advice if a fault remains. Recharge power banks, restore your battery reserve if appropriate, and update your paper instructions with anything you learned.
We’re putting together an Essentials Kit: the non-food essentials from the Prepare list in one bag, with a card saying exactly which water and tins to add. Join the list to hear when it’s ready.
Sources
- SSEN, planned power cuts and low-carbon technology: https://www.ssen.co.uk/power-cuts-emergencies/planned-power-cuts/
- GOV.UK Prepare, power cuts: https://prepare.campaign.gov.uk/be-informed-about-hazards/power-cuts/
- GOV.UK Prepare, cold weather: https://prepare.campaign.gov.uk/be-informed-about-hazards/cold-weather-snow-ice/
- GOV.UK Prepare, emergency supplies: https://prepare.campaign.gov.uk/get-prepared-for-emergencies/
- DESNZ, plug-in solar comes to market: https://www.gov.uk/government/news/households-can-save-as-plug-in-solar-panels-come-to-market
- DESNZ, final plug-in solar interim product specification: https://assets.publishing.service.gov.uk/media/6a60a03c47af652afa0c89f5/plug-in-solar-final-_interim-product-specification.pdf
- Ofgem, Priority Services Register: https://www.ofgem.gov.uk/your-energy-supply/how-manage-your-energy-supply/join-your-suppliers-priority-services-register
- Ofcom, digital landlines: https://www.ofcom.org.uk/phones-and-broadband/landline-phones/future-of-landline-calls