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Home battery and solar back-up for power cuts (UK): costs, rules and installers

What a home battery does in a power cut, what the rules say, what one costs, and how to choose an MCS installer.

By the Civilian Survival Handbook editorial teamUpdated

What it is

A home battery stores electricity from solar panels or cheap-rate times. It only keeps your lights on in a power cut if it has a back-up or 'island mode' that powers chosen circuits on their own. Many systems switch off when the grid goes down, on purpose. Read why solar panels switch off in a power cut. If you mainly need phones, lights and the router, a portable power station costs far less.

UK planning and building rules

  • Solar panels on homes may be permitted development, but there are limits and conditions, and local rules can apply. Check with your council first (Planning Portal).
  • Electrical work in homes in England falls under the building regulations (Approved Document P). Use a registered installer who notifies the work (GOV.UK).
  • Generators: never plug one into a house socket. A qualified electrician must fit a proper changeover switch.
  • Listed buildings, conservation areas and flats have extra rules. Ask your council.

What it costs

  • Installed prices for a Tesla Powerwall 3 run from about £7,500 to £14,500 (installer price guides, from a search summary read 1 Nov 2026, so less certain).
  • Size, inverter, back-up wiring and whether you already have solar change the price. Get at least three written quotes.

How to choose an installer

  • Use an MCS certified installer (find one).
  • Ask in writing: will it work in a power cut, which circuits, for how long?
  • Ask who honours the warranty if the maker or installer stops trading.
  • Be wary of doorstep sales, pressure to sign the same day, or savings figures with no workings.
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Ask for help with a quote

Please read: we haven't signed up any installers yet. This form only sends your enquiry to us. We will reply ourselves. If we later suggest a company, we will tell you its name and ask your permission before we share any of your details with it.

Your permission

We keep enquiries for up to two years, then delete them, or sooner if you ask. They aren't added to any mailing list. See our privacy notice. If you rent, ask your landlord first.

Sources

  1. Planning Portal: solar panels (page, read 1 Nov 2026)
  2. GOV.UK: Approved Document P (page, read 1 Nov 2026)
  3. MCS: find an installer (page, read 1 Nov 2026)
  4. HSENI: portable generator safety (page, read 1 Nov 2026)

Frequently asked questions

Will a home battery keep my power on in a power cut?

Only if it is set up for back-up or 'island mode'. Many aren't. Ask the installer in writing what it will run and for how long.

Do I need planning permission?

Solar panels on houses are often permitted development, within limits. Listed buildings, conservation areas and flats differ. Ask your council.

Do you pass my details to installers?

Not at the moment. We have no installer partners yet. We reply ourselves, and we'd ask your permission, naming the company, before sharing anything.