Free Tool
Battery Storage Savings Calculator
Find out how much you could save with a home battery, which size suits your home, and whether it's worth it for you.
Recommended: 9–10 kWh battery
A 9–10 kWh battery like the GivEnergy 9.5 or Tesla Powerwall 3 stores most of your surplus solar generation and covers your evening electricity use. This is the most popular size for 4kWp solar systems.
Honest note on battery payback
Battery storage has longer payback periods than solar panels — typically 8–14 years on savings alone. Most people add a battery for these reasons rather than pure financial return:
- →Energy independence — use your own solar power in the evenings instead of exporting it cheaply
- →Protection against power cuts — most home batteries provide backup power
- →Combine with Octopus Flux or similar tariff and charge cheaply overnight to sell back at peak rates
- →Battery prices are falling — a 9.5 kWh battery cost £8,000 in 2020, around £4,500 today
- →Future-proofing for EV charging and heat pump integration
Savings based on electricity at 27p/kWh, SEG export at 15p/kWh, overnight cheap rate 7p/kWh (time-of-use tariff). Solar self-consumption uplift assumes battery stores surplus daytime generation for evening use. Peak avoidance saving based on shifting 1–2 kWh per day from peak to off-peak. Install costs: budget £3,500–£5,000, mid-range £4,500–£7,000, premium £7,500–£12,000. Actual savings vary significantly by usage pattern, tariff, system size and battery brand. This tool provides estimates only and is not a quote.
📅 Rates last verified: June 2026 · Electricity 27p/kWh · SEG 15p/kWh · Battery prices updated 2026 · Check current Ofgem rates →
Estimates only — not a quote. Get a real quote free →