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Solar battery storage UK — cost, savings & payback calculator
Solar battery storage UK: typical cost £3,000–£6,000 added to solar. Calculate combined savings from solar panels, home battery and EV charging. 15-year net benefit with live Ofgem rates.
Solar battery storage UK — cost and what to expect
A home battery added to an existing or new solar installation typically costs £3,000–£6,000 in the UK in 2026. The battery lifts solar self-consumption from ~35% to 60–70%, reducing what you export at the low SEG rate and increasing what you use at the full import rate — the key economic lever.
| Setup | Battery cost | Self-consumption lift | Extra annual saving | Combined payback |
|---|---|---|---|---|
| 4 kWp solar only | — | ~35% | — | 7–9 yrs |
| 4 kWp + 5 kWh battery | ~£3,500 | ~60% | +£250–350/yr | 10–12 yrs |
| 4 kWp + 10 kWh battery | ~£5,500 | ~68% | +£300–400/yr | 12–14 yrs |
| 4 kWp + 5 kWh + EV | ~£4,500 | ~70% | +£600–800/yr | 9–11 yrs |
The combined payback is longer than solar alone — but total 15-year savings are higher. A battery makes most sense when your SEG export rate is low (under 8p/kWh) or you have an EV to charge overnight on off-peak electricity. Use the calculator below to model your specific combination.
Looking for a battery without solar? See the standalone home battery payback calculator .
Interactive combined solar, battery and EV savings calculator
Worked example
A UK household with 4 kWp solar, a 5 kWh battery, and an EV doing ~8,000 miles/yr, on Octopus Agile with 85% of EV charging overnight:
- Year-1 total saving
- £1660
- Stack cost
- £12700
- Solar year-1
- £844
- Battery year-1
- £457
- EV year-1
- £359
- Payback on the whole stack
- 6.8 yrs
- 15-yr net benefit
- £20544
You'll probably want this next
Ready to model individual components in more depth?
The dedicated solar, battery-via-Agile and EV calculators each model their piece more thoroughly.
Open full solar calculator →Why the stack numbers matter
- Battery on its own rarely pays back. Pure-arbitrage payback is typically 10–20 years at current Agile spreads.
- Battery + solar is different. Lifts solar self-consumption from 35% to 65–70%, compressing solar payback by 2–3 years.
- EV + time-of-use tariff is where the real money is. An 8,000-mile EV saves £300–£500/yr on Octopus Go or Agile vs the flat Ofgem cap .
- Order matters. Install solar first, layer an EV, then a battery if the peak/cheap spread justifies it. This calculator lets you see the effect of each on the others.
Frequently asked questions
- Why model solar, battery and EV together?
- Because the savings interact. A battery on its own, bought purely for Agile arbitrage, typically takes 10–20 years to pay back. Stack it with solar and it dramatically lifts solar self-consumption (from 35% to 65–70%), shortening solar payback too. Add an EV that overwhelmingly charges overnight on off-peak, and the household's marginal electricity price drops to 8–12p/kWh blended — which is the real argument for the whole setup. Calculators that model each in isolation miss the compounding — for the deep-dive single-asset view use the [solar panel savings calculator and the [EV home charging cost calculator.
- How is battery arbitrage modelled?
- Simple but honest: one full cycle per day at 85% round-trip efficiency, discharging during your supplied peak window price and charging at the supplied cheap window price. Effective charge cost per useful kWh = cheap price ÷ 0.85. If that exceeds peak, the battery loses money and the savings clamp to zero. Real-world arbitrage can cycle 1.1–1.3× per day with smart software, and can also stack solar-surplus charging in summer — we don't model those uplifts in v1. For live half-hourly Agile pricing context, see the [Octopus Agile savings calculator.
- What counts as the 'peak' and 'cheap' window?
- If you're on a flat tariff, both are the same and battery arbitrage saves nothing — it only makes sense on a dynamic or time-of-use tariff. Sensible defaults: Octopus Agile 4–7pm averages 35–45p; overnight trough averages 10–14p. Octopus Go: 28.5p peak / 8.5p cheap. Octopus Cosy: three cheap windows around 13p. Put whatever your actual tariff shows.
- Is the payback realistic?
- Payback is on the total stack cost — solar install + battery install + EV charger install — against the combined year-1 saving, with your electricity-inflation assumption compounding. For a typical 4 kWp + 5 kWh + EV stack with a decent off-peak tariff, 8–11 years is typical. Much longer if you overspec the battery and pay flat tariff rates; much shorter if you layer Agile + a big EV driver. The SEG export rate is a big swing factor — check your best-paying supplier in the [UK SEG export tariff comparator.
- What's not in this v1?
- Heat pump load (model it separately with our [heat pump vs gas boiler calculator), regional PVGIS refinement by postcode (we use a UK-average yield you can override — try the [solar payback by postcode calculator for regional figures), solar-to-battery charging that doesn't hit the cheap/peak arbitrage model, and the battery's value during grid-outage backup. All on the v2 roadmap.
- How much does solar battery storage cost in the UK?
- A home battery added to a solar installation typically costs £3,000–£6,000 in the UK in 2026, depending on capacity. A 5 kWh battery (enough for most 3-bed homes) costs around £3,000–£4,000 installed alongside solar; a 10 kWh unit runs £5,000–£6,500. Installed as part of a new solar system, batteries are sometimes cheaper than retrofitting to existing panels — ask your installer for a combined quote. VAT is zero-rated on batteries installed at the same time as solar. For a battery without solar, see our [standalone home battery payback calculator.
- What is the best solar battery storage in the UK?
- The most widely installed systems in the UK in 2026 are the Tesla Powerwall 3 (13.5 kWh, ~£8,500 installed), Givenergy All-in-One (9.5 kWh, ~£5,500), Fox ESS H3 (10 kWh, ~£5,000), and Growatt ARK (5–10 kWh, ~£3,500–£5,500). For most UK homes the economics don't justify the Powerwall premium — a mid-range LiFePO4 unit delivers almost identical savings at 40–60% of the cost. The calculator above is brand-agnostic: enter your battery's kWh capacity and cost to see payback for any system.
- Is solar battery storage worth it in the UK?
- It depends on your SEG export rate and whether you have an EV. If you're getting 12–15p/kWh on Octopus Outgoing, exporting surplus solar is already well-paid and a battery adds relatively little. If you're on a 5p/kWh SEG, every kWh the battery captures and self-consumes saves 22p more than exporting — payback shortens significantly. With an EV, the battery also enables overnight off-peak charging, compounding the saving. Model your specific numbers in the calculator above.
How this calculator works
The stack calculator composes three calculations you'd normally do separately. For solar it reuses the same math as our Solar Panel Savings Calculator — annual generation from kWp × yield, self-consumption scaled by battery size, SEG export for the rest. For battery arbitrage it models one full daily cycle at 85% round-trip efficiency, with savings equal to cycled kWh × (peak price − cheap price ÷ 0.85); if that spread is negative the saving clamps to zero. For EV it splits annual EV kWh into an off-peak share (priced at your supplied off-peak rate) and the rest (priced at your flat tariff), and reports the gap against a flat-only baseline.
Payback is on the total stack cost (solar install + battery install + EV charger install) against the combined year-1 cashflow, with your electricity-inflation assumption compounding. The 15-year view applies the same inflation curve to the combined saving. That's more honest than the usual "each piece pays back separately" framing, because in real life you spend the money in one lump and the savings arrive in one lump.
What v1 doesn't model
- Heat pump load. Use our heat-pump calculator separately. Adding one would change the peak/cheap window allocation enough to deserve its own modelling path.
- Solar-to-battery direct charging. In summer, surplus solar charges the battery at zero marginal cost — we don't separately credit that yet, so sunny-summer numbers are conservative.
- Backup / outage value. A battery during an outage is genuinely valuable; we don't price it.
- Live regional yield. We take annual kWh/kWp as an input rather than looking it up by postcode. Our postcode solar calculator has regional precision for the solar piece.
When this isn't the right answer
If you don't have off-street parking, skip the EV piece — public-charger economics are completely different (see our EV charging calculator ). If you're on a flat tariff and unwilling to switch, skip the battery — arbitrage only works on a dynamic tariff like Agile . And if you're targeting MEES compliance as a landlord, start with the MEES calculator — solar usually isn't on the cheapest-first stack.
Related calculators
Ranked by topic overlap with this tool.
- Are solar panels worth it in the UK? Calculator + honest verdict — Full scenario comparison with battery modelling, SEG export income and 25-year stress tests.
- EV Home Charging Cost Calculator UK — Petrol-equivalent cost on UK time-of-use tariffs (Octopus Go, Intelligent Octopus, OVO, E.ON).
- Octopus Agile Savings Calculator UK — Agile vs flat-tariff savings by DNO region, with load-shift modelling and cheap-window detection.
- Solar Export Tariff Comparator UK — Compare UK SEG tariffs side-by-side — Octopus, E.ON, British Gas, EDF and more. See exactly what each pays for your export kWh.
- EV vs Petrol Running Cost Calculator UK — Pence-per-mile comparison: electric car vs petrol car on UK tariffs and pump prices. Home vs public charging split, post-April-2025 VED.