Vimma Energy
// BATTERY SIZING

Sizing is a best fit.

Your battery only needs to cover the power you use outside the cheap overnight window. Match your yearly use to a size, then compare what each one costs and saves.

1
Find your size
Read across from your yearly use.

Find your yearly use along the bottom (it's on your bill), then read up to the battery we'd recommend. The lighter line shows the size that breaks even soonest.

8 kWh16 kWh24 kWh0£2002,000£7274,000£1,2536,000£1,7798,000£2,306kWh a yearTypical bill
8 kWh16 kWh24 kWh0£2004,000£1,2538,000£2,306kWh a year · Typical bill

Using more than 8,000 kWh a year? The larger sizes are in the cards below.

See the figures
Yearly use (kWh)RecommendedBreaks even soonest
0 to 3,3708 kWh8 kWh
3,380 to 3,89016 kWh8 kWh
3,900 to 5,97016 kWh16 kWh
5,980 to 7,24024 kWh16 kWh
7,250 to 8,68024 kWh24 kWh
8,690 to 10,63032 kWh24 kWh
10,640 to 11,10032 kWh32 kWh
11,110 to 13,28040 kWh32 kWh
13,290 to 13,62040 kWh40 kWh
13,630 to 16,26048 kWh40 kWh
16,270 to 16,62048 kWh48 kWh
16,630 to 18,59056 kWh48 kWh
18,600 to 22,89064 kWh48 kWh
22,900 and over64 kWh64 kWh
2
The sizes
Every system we offer, with what each one typically saves.
8 kWh
Price£3,999
Usage3,370 kWh/year
Benefit£526 a year
Breakeven7 yrs
Most popular
16 kWh
Price£5,749
Usage5,970 kWh/year
Benefit£1,051 a year
Breakeven5 yrs 2 mths
24 kWh
Price£7,499
Usage8,680 kWh/year
Benefit£1,562 a year
Breakeven4 yrs 7 mths
32 kWh
Price£9,499
Usage11,100 kWh/year
Benefit£1,998 a year
Breakeven4 yrs 5 mths
40 kWh
Price£11,249
Usage13,620 kWh/year
Benefit£2,452 a year
Breakeven4 yrs 3 mths
48 kWh
Price£12,999
Usage16,620 kWh/year
Benefit£2,992 a year
Breakeven4 yrs 1 mth
56 kWh
Price£15,499
Usage18,590 kWh/year
Benefit£3,346 a year
Breakeven4 yrs 3 mths
64 kWh
Price£17,249
Usage23,360 kWh/year
Benefit£4,205 a year
Breakeven3 yrs 11 mths
How we worked these out

Expected 15-year life. 10-yr battery & 15-yr inverter warranty.

Each card shows the usage at which that size breaks even soonest. Your Estimate uses your own figures.

These are projections, not guarantees. Your actual benefit depends on solar yield (where applicable), your import and export tariffs, and how you use energy.

3
How you save
Charge cheap, run the day on it, and bank the difference.
1
Charge cheap, overnight
The battery fills on cheap off-peak power, typically between midnight and 5am, while you sleep.
2
Run the day on it
Through the day your home runs on stored power, not peak-rate grid energy.
3
Bank the difference
You save the difference between the cheap rate you now pay and the peak rate previously paid. Every day.
BIGGER BATTERIES COST LESS PER KWH

Part of what you pay is the same whatever size you choose: the inverter, the installation and the paperwork. Spreading that across more kWh brings the cost per kWh down, so a larger battery is better value for each unit of storage it gives you.

8 kWh
£500
16 kWh
£359
24 kWh
£312
32 kWh
£297
40 kWh
£281
48 kWh
£271
56 kWh
£277
64 kWh
£270
How we work it out.We assume each unit (kWh) your battery moves to cheaper off-peak electricity saves 20p, rising 5% a year. Standing charges are not included. Only peak-time use can be shifted, so we size from your peak-time use, not your total. Batteries slowly hold less charge as they age. We factor for typical battery capacity degradation in the calculations. Recommended is the size that gives you the best return over 10 years; breakeven is when the benefit adds up to the price. Typical bills use the Ofgem price cap at the time of writing (October 2026). This is an Estimate. Your size, price and savings are confirmed at survey.

Ready to see a price? Build your system in the Estimator → Want solar too? See how much a panel array could earn.

Affordable payment options available
Tell us what you're interested in. No commitment.