Solar Battery Storage ROI Calculator
Find out how much a solar battery will save you each year, how long it takes to pay back, and whether it's worth the upfront cost for your home.
Quick-fill: popular UK batteries
How the Savings Break Down
Cumulative Value Over Time
| Year | Annual Saving | Cumulative | Net Position |
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💡 Ways to improve your battery ROI
- • Switch to a time-of-use tariff (Octopus Intelligent, Flux, Agile) — charge your battery cheap at night in winter
- • Increase your self-consumption — run dishwasher/washing machine during sunny midday hours
- • EV charging — use cheap stored solar to charge your EV instead of paying grid rates
- • Scotland homeowners — claim up to £1,500 cashback via Home Energy Scotland
Frequently Asked Questions
How does a solar battery save money?
Without a battery, solar energy generated while you're out during the day is exported to the grid at a low SEG rate (typically 7–20p/kWh). With a battery, that energy is stored and used in the evening when you'd otherwise import electricity at 24–28p/kWh. The saving is the difference between the import rate you avoid and the export rate you lose — typically 5–20p per kWh stored.
What is a realistic payback period for a solar battery in the UK?
For most UK homeowners adding a battery to existing solar, payback is currently 8–14 years. The main variables are: battery size and cost, the gap between your import rate and SEG export rate, and how much solar you currently export. On a time-of-use tariff (like Octopus Flux or Intelligent), where cheap night-rate electricity can charge the battery, payback can fall to 5–8 years.
What battery capacity do I need?
A good rule of thumb: match your battery capacity to your average evening electricity demand. A typical UK household uses 1.5–4 kWh per evening (after solar stops generating). A 5kWh battery covers most evenings for a small home; 10kWh suits larger households or those wanting multiple days of autonomy. Oversizing adds cost without proportional saving — unused capacity earns nothing.
Can a battery save money even without solar panels?
Yes — on a time-of-use tariff like Octopus Agile or Flux, a battery charges on cheap off-peak electricity (sometimes under 7p/kWh) and discharges during expensive peak hours (30–45p/kWh). This arbitrage strategy can save £300–£700/year with a 10kWh battery. However, this calculator is designed for households who already have solar and want to assess adding storage.
Does battery storage qualify for any UK grants or incentives?
Battery storage qualifies for 0% VAT (same as solar panels) since April 2022, saving 20% on the purchase price. The Warm Homes Plan (from 2025) is expected to include battery storage as an eligible measure for qualifying households. Home Energy Scotland offers a cashback of up to £1,500 on batteries for Scottish homeowners through the HES Grant and Loan scheme.
Which solar batteries are available in the UK?
Popular UK options include: Tesla Powerwall 3 (13.5kWh, ~£8,500–£10,000 installed), GivEnergy All-in-One (9.5kWh, ~£5,500–£7,000), SolarEdge Home Battery 10kWh (~£5,500–£7,500), Fox ESS ECS 5kWh (~£3,200–£4,500), and Sonnen eco (5–15kWh, premium pricing). Always get at least 2–3 quotes — installed prices vary significantly between installers.
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