Is home battery storage worth it?

Helpful video reference. We use Artisan Electrics' video "Is Battery Storage Actually Worth It In 2025?" as the video reference here. Artisan Electrics is a Cambridge-based firm with one of the larger UK electrical YouTube channels. Their cost analysis is honest about where the numbers work and where they do not - which lines up with what we see quoted locally in Kent.

1. What a battery does and does not do

A home battery stores electricity and releases it later. It does not generate electricity and it does not reduce how much your home consumes overall. What it can do is shift when you use electricity, so you use more of your own cheap or free generation and less expensive grid power.

There are two main use cases:

• Solar self-consumption. Your panels generate most during the middle of the day when you may not be home. Without a battery, surplus generation exports to the grid at the SEG rate (typically 4–15p/kWh depending on tariff). A battery stores that surplus and uses it in the evening when your demand is highest and grid electricity is most expensive.
• Time-of-use arbitrage. On tariffs like Octopus Intelligent or Agile, cheap off-peak electricity is available at 2–3 a.m. at rates as low as 7p/kWh. A battery charged at that rate and discharged during peak hours at 25–35p/kWh saves the difference. This works with or without solar panels.

2. What does it cost?

UK battery system prices in mid-2026, installed by a qualified electrician:

• Small AC-coupled battery (4.8–5 kWh) - £2,800–£3,500. These retrofit to an existing solar inverter without replacing it. Suitable for smaller households or where the existing solar system already handles much of the daytime load.
• Mid-size system (9–10 kWh) - £4,500–£6,500. The most popular range for a 3–4 bedroom house with 4–6 kWp of solar. Often AC-coupled with a GivEnergy or Solax battery.
• Larger system with hybrid inverter (10–15 kWh) - £6,500–£9,000. DC-coupled systems with a new hybrid inverter included. Better long-term efficiency but higher upfront cost, and only worth it if the existing inverter needs replacing anyway or for a new installation.

These are rough ranges. Get at least two quotes and check that the installer is registered with a Part P competent person scheme - not just MCS accredited for solar.

3. Measure what you currently export

Before modelling the saving, you need to know how much electricity your solar system currently exports. Your inverter app, a smart meter export reading, or your SEG invoice will give you this figure in kWh per year.

A typical 4 kWp solar system on a south-facing roof in Kent generates around 3,400–3,800 kWh per year. A household that uses most of their electricity in the evening (out during the day) might only self-consume 30–35% of that - so they are exporting 2,200–2,600 kWh per year at the SEG rate.

A battery will not capture all of that export - it can only hold so many kWh, and on winter days the panels may not even fill it. A realistic figure for additional self-consumption with a 9–10 kWh battery on the above scenario is around 1,200–1,800 kWh per year.

4. Calculate the self-consumption saving

Multiply the additional kWh you will self-consume by the difference between your import rate and your SEG rate.

Example: import rate 28p/kWh, SEG rate 7p/kWh, difference = 21p/kWh. Additional self-consumption = 1,500 kWh/year. Annual saving = 1,500 × £0.21 = £315 per year.

That is the self-consumption element of the saving. You will also export less, so your SEG income drops - in this example by 1,500 × 7p = £105 per year. The net annual benefit from self-consumption is therefore £315 minus £105 = £210 per year.

5. Time-of-use tariff savings

If you switch to a time-of-use tariff and charge your battery at off-peak rates, the saving is separate from the solar self-consumption calculation. The tariff arbitrage saving depends on:

• How cheap the off-peak rate is (typically 7–15p/kWh on the best tariffs)
• How expensive the peak rate is (typically 25–35p/kWh)
• How many kWh you cycle through the battery per night

On Octopus Intelligent with a 9 kWh battery cycling 6 kWh per night at a 20p/kWh spread, that is 6 × 0.20 × 365 = £438 per year. In practice most households achieve £200–£400 per year from tariff arbitrage, depending on usage and tariff.

Combined with solar self-consumption, the total annual saving for a well-matched system on a good tariff is typically £300–£700 per year.

6. Payback period

Simple payback = installed cost divided by net annual saving.

• £4,500 system saving £400/year: 11 years
• £4,500 system saving £600/year: 7.5 years
• £6,500 system saving £500/year: 13 years

Most battery warranties cover 10 years or a stated number of cycles (typically 4,000–6,000). After 10 years the battery capacity has usually degraded to 70–80% of its original figure. This means the payback period and the warranty period are close to the same - which is not the same as saying the battery pays for itself before it fails, but it does mean you should be seeing clear financial benefit by the time the warranty ends.

Rising electricity prices improve the numbers going forward. If import rates increase from 28p to 35p over the next decade, the annual saving rises with them.

7. When battery storage makes the most sense

A battery is most likely to be a sound financial decision if:

• You have solar panels and your export is high because your household uses little electricity during the day
• You are willing to switch to a time-of-use tariff and shift flexible loads (dishwasher, washing machine, EV charging) to off-peak hours
• You have an EV that you charge overnight - the battery and EV charger interact well with smart tariffs
• Import rates are high and your SEG rate is low, making the arbitrage value large

It is harder to justify on the numbers if you are home during the day and already self-consuming most of your solar output, or if your SEG rate is unusually good relative to your import rate.

Non-financial reasons - backup power during cuts, reducing grid dependence - can change the calculation for some households even when the payback period is long.

8. Installation: what to check before buying

Before you commit to a battery purchase, have a qualified electrician check:

• Whether your consumer unit has space for a battery inverter feed and the right protection devices
• Whether your existing solar inverter is compatible with the battery you are considering (for AC coupling)
• Whether DNO notification is required under G98 or G99 for your total connected generation and storage
• Whether your meter is a smart meter - you cannot benefit from export payments or time-of-use tariffs without one

Battery installation is notifiable under Part P. An electrical installation certificate must be issued and Building Control notified. This is not optional - a system fitted without certification could affect your insurance and any future property sale.

When to call us

Richard covers solar battery storage work in Sandwich, Deal, Dover and east Kent. He can assess whether your existing installation is suitable for a battery, advise on AC or DC coupling, and carry out the notifiable installation with full certification. He can also handle DNO notification under G98 for eligible systems and help you understand which tariffs work with which battery brands.