Battery Payback Calculator
The 30-second version
A battery pays back by shifting cheap energy into expensive hours — every usefully-cycled kWh saves you the gap between peak import (~26p) and what the stored energy cost (cheap-rate ~7–9p, or surplus solar). Cost ÷ annual saving = payback.
Unlike every installer calculator, this one has no lead form behind it. Move the sliders.
Battery payback calculator
No email, no signup — rough simple-payback maths you can sanity-check by hand.
Energy shifted / year
3,449 kWh
Annual saving
£586
Simple payback
14.5 yrs
Assumes every shifted kWh replaces peak-rate import with cheap-rate or surplus-solar charging. Real results depend on tariff, seasons and usage patterns — treat this as a sense-check, not a quote.
How to read the result
The single number that dominates payback is utilisation — what share of the battery's capacity you genuinely cycle daily. EV-charging and heat-pump households cycle hard and pay back fastest; a lightly-used 27kWh stack in a two-person house may never pay back. The tariff gap matters almost as much: pairing the battery with a time-of-use tariff (charging at ~7–9p overnight) roughly doubles the saving versus solar-surplus-only charging.
For current battery prices see solar battery storage costs and the Tesla Powerwall 3 cost breakdown; for the whole-system picture, run the solar cost calculator or start with the cost of solar panels in the UK. When you are ready to fit one, regional installers such as a Scottish battery installer or a home battery specialist can size a system to your usage; at business scale the maths shifts toward commercial battery storage.
Frequently asked questions
How is battery payback calculated?
Simple payback = installed cost ÷ annual saving. The saving is the gap between what you would have paid for peak-rate electricity and what the stored energy cost you (cheap-rate overnight charging or surplus solar), multiplied by every kWh the battery usefully shifts across the year.
What is a realistic battery payback period in the UK?
With a time-of-use tariff and good utilisation, 6–9 years is realistic in 2026 for a well-sized battery; poorly utilised or oversized batteries stretch well beyond 10. Solar-only charging without a smart tariff is usually the slowest route to payback.
Does a bigger battery pay back faster?
Usually not. Bigger batteries cost less per kWh but are harder to cycle fully — and unused capacity earns nothing. Sizing to your actual evening and overnight consumption beats maximising kWh.
Is this calculator really free?
Yes — no email, no signup, no lead form. The Cost of Solar takes no money from installers, so the calculator has nothing to sell you.