Battery without solar calculator
Can a battery pay for itself on tariff spread alone?
No panels involved. This estimates what you might save by charging a home battery on a cheap off-peak rate and using that electricity when power is expensive. Change every figure to match your own tariff and quote. Nothing is sent anywhere and nothing is stored.
Last reviewed: September 2026
Estimated results
- Delivered per day
- 5 kWh
- Bought to deliver it
- 5.56 kWh
- Lost to inefficiency
- 0.56 kWh
- Peak cost avoided per day
- £1.25
- Off-peak charging cost per day
- £0.44
- Estimated daily saving
- £0.81
- Estimated annual saving
- £266
- Simple payback
- 18.8 years
On these figures the price gap between your cheap and expensive rates is 17.0p per kWh, and the installed cost entered is £5,000. If the payback looks longer than you expected, the two figures worth testing first are the shiftable daily use and the tariff spread.
Important
This is a simple estimate, not a quote and not financial or technical advice. It ignores battery degradation, tariff changes, standing charges, finance costs, maintenance, export or virtual power plant payments, the value of backup during a power cut, and any electrical or consumer-unit upgrade a battery installation might need. We publish no national average saving, and plenty of battery installations do not pay for themselves on tariff spread alone. Check your own quote and your own tariff terms before committing.
How the calculation works
Delivered energy per day is the smaller of your usable battery capacity and the expensive-period use you could realistically shift. There is no credit for capacity you never discharge.
Electricity bought to deliver that is the delivered figure divided by round-trip efficiency, so at 90 per cent you buy roughly 1.11 kWh for every 1 kWh you use. Those losses are paid for at the off-peak rate.
Gross avoided peak cost is delivered kilowatt hours multiplied by the expensive rate. Charging cost is bought kilowatt hours multiplied by the off-peak rate. The daily saving is the first minus the second, the annual saving multiplies it by your chosen number of days, and simple payback divides the installed cost by the annual saving whenever that saving is positive.
No degradation curve, no assumed energy price inflation, no discount rate. Simple payback ignores the time value of money, which flatters long paybacks rather than shortening them.
When this tends to work, and when it tends not to
Stronger case
- A wide, reliable gap between your cheap and expensive unit rates.
- Real evening or peak-time consumption that a battery can genuinely cover.
- A tariff you are happy to stay on, with terms you have actually read.
- A competitive installed price, with no major electrical upgrade needed.
- High round-trip efficiency and a warranty that covers daily cycling.
Weaker case
- A narrow price spread, where losses eat most of the margin.
- Low evening use, so much of the battery sits idle each day.
- A battery sized well above what you could ever shift in a day.
- An installed cost inflated by works the quote does not itemise.
- Buying mainly for backup, which this calculator deliberately values at zero.
Read before you buy
Battery storage without solar
The full decision guide behind this tool.
Home batteries
Capacity, cycles, warranties and tariffs.
Methodology
What our estimates include and exclude.
Adding panels later changes the arithmetic. The solar savings calculator covers that case, and the guides set out the trade-offs in longer form.