Solar Battery Storage UK: Costs, Savings & Is It Worth It?
Is battery storage worth it with solar panels?
A home battery (typically 5kWh) costs £2,500–£5,000 and increases your solar self-consumption from around 50% to 80%. This adds roughly £150–£250 per year in extra savings. The battery's own payback is typically 12–18 years, which means it may not pay for itself purely on savings alone. However, batteries offer additional benefits: resilience during power cuts, compatibility with time-of-use tariffs, and greater energy independence.
£2,500–£5,000
Battery cost (5kWh)
2026 installed price
50% → 80%
Self-consumption boost
£150–£250/yr
Extra annual savings
10 years
Typical battery warranty
Battery storage is one of the most asked-about topics in home solar. The idea is straightforward: instead of exporting surplus solar electricity to the grid for 4.5p/kWh, you store it in a battery and use it in the evening when you would otherwise buy from the grid at 24.5p/kWh. The 20p per kWh difference is where the savings come from.
But the question is whether those savings justify the upfront cost. Let us look at the numbers honestly.
Solar panels without battery
| System Size | Panels | Cost | Annual Saving | Payback |
|---|---|---|---|---|
| 3kW | 8 | £4,500–£6,500 | £400–£550 | 9–12 years |
| 4kW | 10 | £5,500–£8,000 | £500–£700 | 8–12 years |
| 5kW | 13 | £6,500–£9,500 | £620–£850 | 8–11 years |
Solar panels with battery
| System Size | Panels | Cost | Annual Saving | Payback |
|---|---|---|---|---|
| 3kW + 5kWh | 8 | £7,000–£11,500 | £560–£770 | 10–15 years |
| 4kW + 5kWh | 10 | £8,000–£13,000 | £680–£930 | 9–14 years |
| 5kW + 10kWh | 13 | £10,500–£16,500 | £840–£1,150 | 10–14 years |
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How home batteries work with solar
During the day, your solar panels generate electricity. Your home uses what it needs first. Without a battery, any surplus is exported to the grid. With a battery, surplus electricity charges the battery instead. In the evening, when your panels stop generating, the battery discharges to power your home — reducing how much you buy from the grid.
A typical 5kWh battery stores enough electricity for an average household's evening and overnight needs (roughly 5–7 hours of typical usage). It charges fully from solar on most days between April and September, and partially during the winter months.
What size battery do I need?
The right battery size depends on your solar system size and electricity usage patterns:
- 3kW solar system: A 3–5kWh battery is usually sufficient. A 3kW system generates less surplus, so a smaller battery avoids paying for capacity you rarely fill.
- 4kW solar system: A 5kWh battery is the sweet spot for most 3-bed homes. It captures most of your daily surplus without being oversized.
- 5–6kW solar system: A 5–10kWh battery makes sense. Larger systems generate more surplus, and a bigger battery lets you store more for evening use.
As a rule of thumb, your battery capacity in kWh should be roughly 1–1.5 times your solar system size in kW. An oversized battery will rarely charge fully and represents wasted spending.
Battery cost breakdown
Battery costs depend on capacity and whether they are installed alongside or after solar panels:
- 3kWh battery: £2,000–£3,500 installed
- 5kWh battery: £2,500–£5,000 installed
- 10kWh battery: £4,500–£8,000 installed
- Retrofit (adding to existing solar): Add £300–£500 for the additional labour and wiring
All residential battery installations benefit from 0% VAT when installed with or after solar panels. The battery must be installed alongside an electricity generating system (such as solar panels) to qualify for the VAT exemption.
Additional battery benefits
Power cut resilience
Some battery systems (when paired with a hybrid inverter) can provide backup power during grid outages. Not all systems offer this feature, so check with your installer if this is important to you. Most standard setups shut down during a power cut for safety reasons.
Time-of-use tariffs
Some energy tariffs charge different rates at different times of day. With a battery, you can charge from the grid during cheap overnight periods (as low as 7–10p/kWh on some tariffs) and discharge during expensive peak hours (30p+ per kWh). This can improve the battery's financial return significantly, even in winter when solar generation is low.
Energy independence
A solar-plus-battery system lets you generate and consume 70–80% of your own electricity. For many homeowners, the peace of mind that comes from reduced reliance on the grid — and protection against future price rises — is a significant benefit beyond the pure financial return.
Frequently asked questions
Related guides
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