In this site's model, a home using 3,000 kWh a year with 4 kWp of solar on Octopus Flux saves between £511 and £623 a year with a 13.5 kWh Powerwall 3, depending on region. Against Octopus's installed price of £7,999 that is a simple payback of 12.8 years in Merseyside and North Wales to 15.7 years in South Scotland, and 14.1 years in London. With no solar, on Octopus Go, it is 14.7 to 17.2 years. The order of the regions follows the evening export rate more closely than it follows the sunshine.
Analysis · Published by SEO Dons Ltd · Updated 7 October 2026
The question, and how we ran it
Payback is the number most buyers ask for and the one least often shown with its workings. We ran this site’s one savings model, the same one behind the calculator, for a Powerwall 3 in each of the 14 electricity regions that Octopus publishes rates for. The inputs were the same everywhere so that only the region changed:
- The home: 3,000 kWh a year, with 4 kWp of solar panels in the Flux columns and none in the Go column.
- The battery: 13.5 kWh usable, which is what Tesla’s UK datasheet gives for one Powerwall 3.
- The tariffs: Octopus’s published rates for 26 September 2026 for each region. The Flux columns use Octopus Flux, and the no-solar column uses Octopus Go.
- The solar: PVGIS yields for a 4 kWp array facing south at a reference city in each region.
- The comparison: the same home with no battery on Octopus’s flat Flexible tariff, with exports paid at the flat Outgoing rate.
- The price: Octopus’s £7,999 for a battery-only installation (April 2026 prices), and, in the last column, the official median of £630 per kWh for batteries of 11 kWh or more, which is about £8,505 for 13.5 kWh.
Payback here is the simple kind: the price divided by one year’s saving. It ignores the battery losing capacity, which the model’s own assumption puts at an average of 90% of usable capacity over ten years, and it ignores the cost of borrowing.
The result, region by region
| Electricity region | Peak export rate on Flux | Solar yield, 4 kWp | Saving a year on Flux | Payback at £7,999 | Payback at £8,505 | Saving a year on Go, no solar | Payback at £7,999 |
|---|---|---|---|---|---|---|---|
| Merseyside and North Wales | 30.68p | 3,860 kWh | £623 | 12.8 years | 13.7 years | £542 | 14.7 years |
| South East England | 29.79p | 4,393 kWh | £607 | 13.2 years | 14.0 years | £513 | 15.6 years |
| Eastern England | 29.32p | 4,163 kWh | £591 | 13.5 years | 14.4 years | £504 | 15.9 years |
| South West England | 29.22p | 4,209 kWh | £589 | 13.6 years | 14.4 years | £504 | 15.9 years |
| South Wales | 29.35p | 4,167 kWh | £588 | 13.6 years | 14.5 years | £503 | 15.9 years |
| Southern England | 29.00p | 4,255 kWh | £584 | 13.7 years | 14.6 years | £505 | 15.8 years |
| London | 28.60p | 4,075 kWh | £569 | 14.1 years | 15.0 years | £503 | 15.9 years |
| North West England | 29.25p | 3,544 kWh | £568 | 14.1 years | 15.0 years | £497 | 16.1 years |
| North Scotland | 28.73p | 3,550 kWh | £555 | 14.4 years | 15.3 years | £505 | 15.8 years |
| West Midlands | 27.81p | 3,872 kWh | £537 | 14.9 years | 15.8 years | £473 | 16.9 years |
| East Midlands | 27.70p | 3,880 kWh | £533 | 15.0 years | 15.9 years | £466 | 17.2 years |
| North East England | 27.69p | 3,789 kWh | £531 | 15.1 years | 16.0 years | £469 | 17.0 years |
| Yorkshire and the Humber | 27.17p | 3,788 kWh | £518 | 15.4 years | 16.4 years | £472 | 17.0 years |
| South Scotland | 27.19p | 3,410 kWh | £511 | 15.7 years | 16.7 years | £488 | 16.4 years |
Modelled for a 3,000 kWh home, 13.5 kWh battery, Octopus rates for 26 September 2026 including 5% VAT on imported electricity. Sorted by the Flux saving.
The best region pays back about three years faster than the worst, on the same battery and the same price. Over ten years the model’s fade assumption turns £511 to £623 a year into about £4,600 to £5,600 saved, which is between 57% and 70% of the £7,999 price.
What the table says about where you live
The surprise in the table is that the regions with the least sun are not the slowest. North West England has the second-lowest solar yield of the 14, 3,544 kWh from 4 kWp, and still saves £568, within £1 of London. South Scotland has the lowest yield and the slowest payback, but Yorkshire is nearly as slow with 380 kWh more sunshine.
What sorts the regions is the price Octopus Flux pays for the electricity the battery exports between 4pm and 7pm. It runs from 27.17p per kWh in Yorkshire to 30.68p in Merseyside and North Wales, and the 14 modelled savings follow it with a correlation of 0.98, against 0.64 for solar yield. A battery on Flux earns most by buying at the 2am to 5am rate and selling at the peak, so the peak rate matters more than how much sun filled the battery in summer.
Why Go without solar is slower
With no panels the battery can only move cheap night-rate electricity into the day. On Octopus Go, in the same model, that is worth £466 to £542 a year and a payback of 14.7 to 17.2 years, slower than the Flux column in every region. The gap is smallest in South Scotland, where Flux earns least: the Go home saves £488 against £511 on Flux. Our guide to the best tariff for a home battery sets out who can join each tariff, since Flux needs solar panels.
Go itself needs an electric car. The home battery without solar page lists which tariffs a battery-only home can use, including British Gas’s Charge Power, and tests Agile against 12 months of real prices.
What moves the answer more than the region
- The price you pay. Four suppliers publish installed Powerwall 3 prices: E.ON Next from £7,795, EDF from £7,995, Octopus at £7,999 and Costco’s Fresh Solar installation at £8,499.99. Against the cheapest, every payback in the table is about 0.3 to 0.4 years shorter; against the dearest, about 0.8 to 1.0 years longer.
- How much electricity the home uses. A 6,000 kWh home, such as one with a heat pump, uses more of the battery every day. In London on Flux with 6 kWp of solar, the model puts the saving at £524 a year with 13.5 kWh and £931 with a second unit, which changes whether the second unit is worth buying.
- Which tariff you can join. The Flux columns assume the home can join Octopus Flux, which needs solar panels, a home battery, a smart meter, an export meter number and the MCS certificate for the panels.
- VAT on electricity. The rates include 5% VAT on imported electricity as at 26 September. From 1 October 2026 to 31 March 2027, household electricity carries no VAT, which lowers the import-side saving by up to about 5%.
What the model leaves out
The model counts one thing: how much less the home pays for electricity. It puts no value on a Powerwall 3’s built-in solar inverter, which saves buying a separate one when fitting solar panels and a battery together, or on backup power in a cut, which needs Tesla’s Backup Gateway 2. It does not price a battery’s lifetime beyond the 90% average-capacity assumption, it holds tariffs at today’s rates, and it caps exports at what a 3.68 kW connection can send in the three-hour Flux peak. A Powerwall 3 configured for more output needs a network application before the installation, and in the model a 13.5 kWh battery gains nothing from a higher limit because it empties inside the lower one.
Export is the largest omission for homes with solar: what each export tariff pays ranges from 4.1p to about 31p a unit depending on the tariff and the hour.
How to use this
Treat the table as a range, not a quote. Pick your region, adjust for what you would actually pay, and then run your own usage in the calculator, which uses the same model. When you compare prices, put the supplier figures side by side with the official median: our page on the Tesla Powerwall 3 price sets out the four installed prices, what each includes and what Tesla’s list price leaves out. If a single 13.5 kWh unit looks too big or too small for your home, the 13.5kWh battery page and our analysis of whether a bigger battery saves more show where the saving flattens, and you can get battery storage quotes to compare against Octopus’s published prices.
The rates behind the Flux columns are Octopus’s 26 September rates; the 7 October rates, which carry no VAT on import, are on the Octopus Flux rates page.
Questions people ask
How long does a Tesla Powerwall 3 take to pay back in the UK?
About 13 to 16 years on the battery's bill saving alone in this site's model. A home using 3,000 kWh a year with 4 kWp of solar on Octopus Flux saves £511 to £623 a year depending on region, which repays Octopus's £7,999 installed price in 12.8 to 15.7 years. That ignores the battery losing capacity over time and puts no value on the built-in solar inverter or backup.
Why does the payback differ between regions?
Mainly because Octopus Flux pays a different rate for the electricity a battery exports in the 4pm to 7pm peak in each region. Across the 14 regions the modelled saving tracks that export rate (a correlation of 0.98) much more closely than it tracks solar yield (0.64). The peak export rate runs from 27.17p per kWh in Yorkshire to 30.68p in Merseyside and North Wales.
Does the Powerwall 3 pay back faster without solar panels?
No. With no solar, on Octopus Go, the modelled saving is £466 to £542 a year and the payback 14.7 to 17.2 years, slower than with 4 kWp of solar on Flux in every region. Without panels the battery can only shift cheap night-rate electricity into the day, which earns less than also selling it at the evening peak.
Do prices from E.ON Next, EDF or Costco change the payback?
Slightly. Using the lowest published installed price, E.ON Next's from £7,795, shortens each payback by about 0.3 to 0.4 years; using Costco's £8,499.99 lengthens it by about 0.8 to 1.0 years. The regional order does not change.