Battery Storage Payback Calculator UK 2026

Home battery storage systems in the UK cost between £2,500 and £7,500 installed depending on capacity, with a 5 kWh unit suitable for a small home costing £2,500 to £3,500, a 10 kWh mid-range system at £4,500 to £6,500, and a Tesla Powerwall 2 (13.5 kWh) at £5,500 to £7,500. When paired with solar panels, a battery captures surplus daytime generation that would otherwise be exported to the grid at approximately 5p per kWh under the Smart Export Guarantee, allowing you to use that electricity in the evening when grid rates are 24.5p per kWh — a saving of roughly 19.5p for every kWh stored and used. A well-sized 10 kWh battery capturing 6 kWh of daily solar export saves approximately £427 per year, delivering payback in 12 to 15 years. Without solar, batteries can still save money through off-peak tariff arbitrage — charging at 7.5p overnight and discharging at peak rates. This calculator estimates your specific payback period and lifetime return.

How to Use This Calculator

Select your battery capacity — 5 kWh for small homes, 10 kWh for average, 13.5 kWh for large homes.

Indicate whether you have solar panels — batteries save most when storing surplus solar generation.

Enter your daily solar export (check your smart meter) and current electricity rate.

Review your payback period, annual saving, and 15-year net return on investment.