Is a solar battery worth it in the UK?
It depends less on the battery than on what it is told to do. We ran a full year of 20 homes with solar panels three ways: with no solar battery, with one left to itself, and with one Orza planned every half hour. Planned, a 9.5 kWh battery saved the average home £435 a year. Left to itself, £171. Over the 10 to 12 years a battery lasts, that is the difference between paying for itself and not.
Planned every half hour, a battery saved two and a half times as much.
The same homes, the same panels, the same year, three ways. Each on whichever of five Octopus tariffs suited it best: without a battery that was Agile with Outgoing Octopus’s fixed export rate; with one, the same or Flux.
| The average home’s year | No battery | Battery left to itself | Battery planned by Orza |
|---|---|---|---|
| 9.5 kWh battery, 4 kWp of panels | £438.82 | £267.82, saved £171 | £3.34, saved £435 |
| 13.5 kWh battery, 6 kWp of panels | £105.53 | −£85.35, saved £191 | −£441.76, saved £547 |
Average of 20 homes for each size, 1 October 2025 to 30 September 2026. The year’s energy cost: what the home paid for electricity, less what export paid it. A figure below zero is money earned. Standing charges are left out, and no limit was put on export.
- Left to itself, a battery stores spare sun and empties into the houseThat alone saved the typical home £129 to £242 a year. It never fills from the grid when power is cheap, and never holds charge for the hour that pays most.
- Planned, it saved £356 to £711, depending on the homeEvery one of the 20 homes saved at least twice as much planned as it did left alone. The ways to schedule a battery, compared.
- A bigger battery and roof saved more, but not in proportionHalf as much battery again, and half as much roof again, added about a quarter to the saving: £547 against £435.
Planned, a battery repays far more of what it costs.
The Energy Saving Trust puts a battery’s life at about 10 to 12 years, and its cost at £1,500 to £10,000 installed, around £4,600 for a 5 kWh system. A battery is worth it if what it saves over its life is more than it cost you. At this year’s prices, the average home would have saved:
Saved over 10 to 12 years, average home
- 9.5 kWh, planned: £4,350 to £5,230Left to itself: £1,710 to £2,050.
- 13.5 kWh, planned: £5,470 to £6,570Left to itself: £1,910 to £2,290.
- So a battery left to itself rarely pays for itselfUnless it cost under about £2,000. Planned, the same battery repays two and a half times as much.
If you have panels, get paid for export first. It costs nothing.
With no battery at all, the same homes on Agile went from being paid nothing for export to Outgoing Octopus’s fixed rate. Nothing else changed.
No battery, Agile, a year
- 4 kWp of panels: £846.40 down to £438.82£408 a year, for signing up to an export tariff.
- 6 kWp of panels: £797.46 down to £105.53£692 a year.
- Every battery figure on this page starts from thereWe compared a battery with a home that is already paid for export, not one that gives its spare sun away.
What moves the answer for your own home.
A year of modelled homes is strong evidence, not a quote. These are the things that would make your figures higher or lower than ours.
- How much you useThese homes used 3,400 to 13,000 kWh a year, half of them over 4,700, well above Ofgem’s typical home at 2,500. A home that uses much less has less for a battery to move, and may save less.
- Your export limitNo limit was put on export here. Most homes may send 3.68 kW to the grid, and a limit cuts what a battery can sell. On one real home it cost £13 in five weeks of autumn.
- Your sunThe panels face due south, and this was a sunny year: 4 kWp made 4,950 kWh. A roof facing east or west, or in shade, gives a battery less to store.
- The tariff, and what it pays for exportA battery earns most where prices move through the day and export is paid. How five Octopus tariffs compared over the same year.
- What you pay for itPrices for the same battery differ from one installer to the next. The Energy Saving Trust suggests at least three quotes from MCS certified installers.
Battery cost and life: the Energy Saving Trust’s battery storage advice, last updated 6 October 2026. Typical use: Ofgem’s typical domestic consumption value for electricity from 1 July 2026. Prices: as Octopus published them for North West England. Outgoing Octopus paid 15p a kWh to February 2026 and 12p from March.
Before you get a quote.
What people ask before buying a battery, answered from the same year where it can be.
All our guidesAre these real homes?
Their electricity use is: real households’ smart meter readings, from Low Carbon London (UK Power Networks, CC BY 4.0), moved to 2025 to 2026 a whole number of weeks so a Thursday stays a Thursday. The panels and batteries are modelled, on a south facing roof in London, with the weather that came. The prices are the ones Octopus published.
Is there VAT on a home battery?
Not until 31 March 2027. Batteries installed in homes are zero rated for VAT, whether fitted with solar panels, added to panels you already have, or on their own. From 1 April 2027 the reduced rate of 5% applies.
Can I have a battery without solar panels?
Yes. It fills when power is cheap and is used when it is dear. We didn’t model it here: every home on this page has panels.
Does a bigger battery always save more?
It saves more, but each kWh added saves less than the one before. In this year, half as much battery and roof again added about a quarter to the saving. The right size depends on how much you use in the evening and how much sun you have spare. Four sizes on the same homes.
Will the savings stay the same every year?
No. They move with prices, the weather and how much you use, and a battery holds a little less each year as it ages. These are one year’s figures, at that year’s prices. How the saving moved month by month.
What does Orza cost?
Nothing during the beta, and no card is needed to join. If you already have a battery, Orza plans it every half hour for your own tariff.
Already have a battery? Make it the planned one.
Free during the beta. Connect in a few minutes, and start in Monitor only.