Solar Battery Cost Calculator
Battery pricing is set by usable capacity, not headline capacity — and by whether it goes in with your panels or on its own visit later. Four questions, real 2026 installed prices.
Open the calculator →Estimate your battery cost in 30 seconds
4 steps. Covers the battery, the hybrid inverter where one is needed, fitting and the 0% VAT relief that runs to 31 March 2027.
How this calculator works
The calculator prices the battery on usable capacity, because that is what actually shifts your bill — a 5 kWh nameplate unit with 90% depth of discharge gives you 4.5 kWh a night, not 5. It then adds the two things that most often surprise people: a second visit if you are retrofitting, and a hybrid inverter if your existing string inverter cannot accept a battery. Those two lines are where retrofit quotes diverge most, so if you already have panels it is worth telling the installer the make of your current inverter up front: whether it is battery-ready or needs swapping for a hybrid unit moves the total by more than the battery choice itself.
Every figure is the installed price with 0% VAT, the relief on domestic energy-storage that runs to 31 March 2027. Regional multipliers reflect installer day rates, from London at +22% down to Wales at −6% against the Midlands baseline. Worth settling before you compare quotes: a battery earns its keep by storing cheap or self-generated power for use at peak, so the payback leans heavily on your tariff. Pair one with a cheap overnight rate and it charges from the grid when power is cheapest, not just from spare solar, which changes the sums considerably. If you have not added panels yet, it is worth checking what help is on offer in our solar panel grants guide, and where there is no room for more storage a solar diverter is the cheaper way to put surplus generation to use.
Solar battery costs by capacity (2026)
| Usable capacity | Typical 2026 cost | Notes |
|---|---|---|
| 5 kWh | £2,500–£4,000 | Evening cover for a small household |
| 8–10 kWh | £4,000–£6,500 | The most common UK choice |
| 13.5 kWh (e.g. Powerwall 3) | £8,500–£10,500 | Single large unit, whole-day cover |
| 15–20 kWh (stacked) | £9,000–£14,000 | High usage, EV charging, going fully off-peak |
| Hybrid inverter, if retrofitting | £1,200–£2,000 | Only when the existing inverter cannot take a battery |
| Retrofit visit (labour) | £300–£600 | Avoided if fitted alongside panels |
Figures match the ranges published on our solar battery cost guide and include 0% VAT. Warranty terms are quoted in cycles or total throughput as well as years — compare those, not just the headline figure.
Solar battery calculator FAQs
Yes, usually by £300–£600. One visit, one set of electrical testing and one sign-off instead of two. If a battery is likely within a few years, specifying a hybrid inverter at the panel install saves considerably more again — replacing a string inverter later costs £1,200–£2,000.
Yes. Since February 2024 the relief covers retrofit and standalone domestic battery storage, not only batteries installed alongside panels. It runs until 31 March 2027, after which the rate is currently legislated to return to 20%.
Look at your evening and overnight consumption rather than your annual total. Most UK homes use 3–6 kWh between sunset and sunrise, which is why 8–10 kWh usable is the common landing point — it covers that with headroom for a dull day. Going much larger rarely pays on a standard import tariff, because a battery only saves money on the units it actually cycles; the exception is a time-of-use tariff, where a bigger battery lets you charge cheaply overnight and can change the sizing maths entirely.
Ten to fifteen years is the realistic range. Warranties are usually expressed in cycles or total throughput as well as years, so a battery you cycle hard daily may reach its warranty limit sooner than the calendar suggests. It is worth reading the warranty for a stated end-of-life capacity too: most guarantee around 70% of the original usable figure at the end of the term, so a battery sized tightly today can feel undersized well before it fails outright.
Related cost guides
- Solar battery cost guide — full 2026 pricing by capacity and brand
- Solar panel cost calculator — price the array and the battery together
- Solar panel costs — system sizes, payback and export rates
- Diverter vs battery — which is worth doing first
Get My 3 Free Solar Battery Quotes
60 seconds · No spam · No obligation