Solar Battery Storage: Cost, Sizing & Value 2026

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.

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.

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

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