Solar Battery Storage: Cost, Sizing & Value 2026
A home battery stores solar power, or cheap off-peak electricity, so you use more of it yourself and buy less at peak rates. Whether it pays depends on your usage, tariff and battery size. Here is what solar battery storage costs in 2026, how to size it, and how to choose.
How solar battery storage works
A home battery stores electricity — either surplus power from your solar panels or cheap units bought overnight on a time-of-use tariff — and releases it when you need it. That means you use more of your own generation and draw less from the grid at expensive peak times. Batteries can be added to an existing solar array or, increasingly, installed on their own to arbitrage a cheap night rate.
Solar battery cost and sizing 2026
As a guide for 2026, a 5 kWh battery costs around £2,500–£4,000 installed and a 10 kWh battery around £4,000–£6,000, with larger systems costing more. Size the battery to your evening and overnight usage, not your total consumption — a typical home is well served by 5–10 kWh. Oversizing rarely pays back, because the extra capacity sits unused.
Capacity and sizing figures are from our solar battery cost guide, which also breaks the quote down by component and by brand. Batteries are zero-rated for VAT until 31 March 2027.
Is a solar battery worth it?
A battery pays back fastest when you have enough solar to charge it, a good off-peak tariff, and high self-consumption in the evenings. Payback is often in the region of 8–12 years, so it depends on your usage, electricity prices and how long you stay. If your main goal is resilience or making the most of cheap night rates, the value case can be stronger.
Payback depends far more on the tariff than on the battery. A battery charged off-peak and discharged at peak earns its keep roughly twice as fast as the same battery on a flat-rate tariff, which is why a standalone battery with no solar takes longest to repay.
How to choose and compare quotes
1. Check your usage and tariff
Look at your evening and overnight usage and whether a time-of-use tariff is available to you.
2. Size the battery to your evening use
Match the kWh capacity to what you actually use after dark, rather than your whole daily total.
3. Use an MCS-certified installer
An MCS-certified installer ensures a safe, compliant installation and protects any available incentives.
4. Get three like-for-like quotes
Compare on the same battery capacity, brand and warranty so you judge value, not just headline price.
FAQs
Get 3 Free Solar Battery Quotes
BestBuilders matches you with up to 3 vetted UK solar and battery installers. Compare quotes — no cost, no obligation.