The Ofgem price cap doesn’t actually cap your total bill – it caps the unit rate and standing charge suppliers can charge on a standard variable tariff. When these capped unit rates are high, every kWh you avoid buying from the grid is more valuable. That makes solar panels and home batteries more attractive.

As of recent price cap periods, many households still pay around 25–30p per kWh for electricity (exact rates vary by region and tariff). A solar battery lets you:

• Store cheap or free solar energy to use after dark
• Buy electricity when it’s cheaper (off-peak) and use it when prices are higher
• Reduce the impact of future price cap rises

Prices vary by brand, capacity and installer, but for guidance:

• 3–5 kWh battery (small flat or low use) — roughly £2,500–£4,000 installed
• 5–10 kWh battery (typical 3-bed house) — roughly £4,000–£7,000 installed
• 10–15 kWh+ battery (large home / EV / heat pump) — roughly £7,000–£10,000+ installed

If you add a battery with a new solar PV system, overall costs per kWh of storage are usually lower than retrofitting a battery later. A typical 4 kWp solar + 5–7 kWh battery package might cost from £8,000–£12,000, depending on equipment and roof.

Solar batteries save you money in three main ways:

1. Maximising your solar self-consumption
2. Time-shifting cheap grid electricity
3. Exporting at higher rates on smart tariffs

1. Use more of your own solar power

Without a battery, a typical UK solar home may use only 30–50% of the power generated. The rest is exported to the grid, often at a low export rate. With a correctly sized battery, self-consumption can rise to 70–90%, cutting the amount you buy at the capped unit rate.

2. Charge off-peak, use at peak

Time-of-use tariffs (like Economy 7, or smart tariffs with cheaper overnight rates) let you charge your battery when electricity is cheap and use it when the price is high. This works even without solar panels.

For example, if you charge at 10p per kWh off-peak and avoid paying 28p per kWh in the peak period, the saving is 18p per kWh cycled through the battery. Over a year, this can be substantial.

3. Smarter exporting

Some smart tariffs pay more for exported electricity at peak times. With the right setup, you can charge your battery cheaply and export when prices are higher, further improving payback. This requires careful tariff selection and system configuration.

Every home is different, but these simple scenarios show how a battery can pay for itself under current UK price cap levels.

Scenario 1: 3-bed home with 4 kWp solar + 7 kWh battery

• Annual electricity use: 3,800 kWh
• Solar generation: around 3,600 kWh per year
• Battery capacity: 7 kWh
• Installed battery cost: about £5,000 (as part of a bundle)

With a battery, the home may reduce grid imports by an extra 1,200–1,800 kWh per year compared to solar alone.

If the capped unit rate is around 28p per kWh, this could save approximately:

• Savings: £336–£504 per year from reduced imports alone

Ignoring export benefits and tariff optimisation, the simple payback on the battery portion is around 10–15 years. With smart tariffs and careful use, many homeowners see faster payback.

Scenario 2: No solar, battery only on a smart tariff

• Annual use: 4,000 kWh
• Off-peak rate: 10p per kWh
• Peak rate: 28p per kWh
• Battery capacity: 10 kWh, usable cycle of 9 kWh
• Installed battery cost: about £6,000

If you cycle 9 kWh every day by charging off-peak and using that energy during peak hours:

• Daily saving: (28p - 10p) × 9 kWh = £1.62
• Annual saving: around £591

This gives a simple payback of around 10 years, assuming consistent use and stable price differences. Future price rises could shorten this.

If you already have rooftop solar, adding a battery is often the next logical step, especially if:

• You export a lot of solar during the day while the house is empty
• Your evening electricity usage is high (cooking, TV, EV charging)
• You’re on or can switch to a smart tariff

Typical UK solar households without batteries might use around 40% of their solar. With a well-sized battery, this may rise to 75% or more, significantly increasing your return on the solar panels you already own.

Yes, a battery-only system can make sense under the price cap if you:

• Have access to cheap off-peak tariffs
• Use a lot of energy during peak hours
• Cannot install solar (e.g. shaded roof, listed building, rented property with permission only for internal works)

This strategy is sometimes called load shifting or energy arbitrage. You charge your battery when the grid is cheapest and discharge when it’s most expensive, reducing the impact of the price cap on your bills.

The UK price cap is reviewed regularly. While rates fell from their peak, they remain much higher than pre-2021 levels, and future changes are uncertain.

Batteries give you flexibility:

• If prices rise, the value of every stored kWh increases
• If time-of-use price differences widen, off-peak charging becomes more attractive
• If smart export tariffs improve, you have more ways to monetise your system

Instead of being fully exposed to future price cap changes, a home battery lets you take more control of when and how you buy grid power.

The best battery size depends on how you use energy, your solar array (if you have one), and your budget. As a guide:

• Flats / low usage homes: 3–5 kWh
• Typical 2–3 bed homes: 5–10 kWh
• High usage homes, EVs, heat pumps: 10–15+ kWh

A professional installer will look at:

• Your half-hourly usage (if you have a smart meter)
• Solar generation profile (if applicable)
• Tariff structure and export options
• Your priorities: maximum savings, backup power, or fastest payback

Modern lithium-ion home batteries are designed for many years of daily use. Typical specifications include:

• Warranty: usually 10 years, often with a guaranteed number of cycles
• Performance: batteries typically retain around 60–80% of their original capacity by the end of the warranty period
• Maintenance: minimal day-to-day maintenance, with remote monitoring via apps

Even after the warranty ends, many batteries continue to operate, just with reduced usable capacity. This is usually factored into professional payback models.

A solar battery is most likely to be worth it if you:

• Have or plan to install solar panels
• Are on (or can move to) a time-of-use or smart export tariff
• Use more energy in the mornings and evenings than mid-day
• Plan to stay in your home for at least 7–10 years

It may be less suitable if you:

• Use very little electricity
• Cannot access competitive tariffs
• Expect to move home within the next few years

No two homes are identical. To understand whether a battery is really worth it under the current and future price caps, you need a personalised assessment of costs, savings and payback.