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 — with or without solar.

Your home setup
Do you have solar panels?
Solar system size
Annual electricity bill: £1,200
£400 £3,000
When are you mostly at home?
Are you on a time-of-use tariff? (e.g. Octopus Go, Agile)
Recommended battery size

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.

Popular batteries at this size
GivEnergy 9.5 kWh
9.5 kWh usable capacity
£3,500–£5,000
installed · most popular UK brand
Tesla Powerwall 3
13.5 kWh usable capacity
£7,500–£12,000
installed · premium option
SolarEdge Home Battery
9.7 kWh usable capacity
£4,000–£6,000
installed · good mid-range
Your estimated savings
Annual saving
£380
on your bills
Self-sufficiency
68%
of electricity from solar + battery
Typical install cost
£4,500
mid-range battery
Payback period
11.8 yrs
at current savings
Where your battery saving comes from
Solar self-use boost
£266

These figures assume your battery is cycled close to its full usable capacity most days. A battery that's often left partly full delivers proportionally less — see why this matters so much for the payback maths.

Honest note on battery payback

Battery storage has longer payback periods than solar panels — typically 8–12 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
  • →Grid balancing payments — schemes like Octopus Saving Sessions can pay £5–£15 per event on top of tariff savings, no solar needed. Not modelled in the figures above.
  • →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

Get free battery storage quotes

Whether you're adding a battery to existing solar or starting fresh, get matched with MCS-certified local installers.

Savings based on electricity at 26.32p/kWh (October 2026 Ofgem cap), SEG export at 15p/kWh, overnight cheap rate 7.5p/kWh (typical time-of-use tariff), with 90% round-trip battery efficiency applied to tariff-shift savings. Solar self-consumption uplift assumes battery stores surplus daytime generation for evening use. Tariff-shift savings are capped at your selected battery's usable capacity, so a bigger battery only shows more saving if there's realistically enough daily usage to fill it. Install costs: budget £2,500–£3,500, 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: 26 August 2026 · Electricity 26.32p/kWh · SEG 15p/kWh · Overnight rate 7.5p/kWh · Check current Ofgem rates →