If you have solar panels or plan to fit them, the question of adding a battery comes up fast. A domestic solar battery stores the electricity your panels make during the day. You then use it after the sun goes down. Otherwise you send it to the grid for a small payment and buy power back at a higher price in the evening.
This guide covers how the technology works and what a combined system costs. It also shows how the sums shift and who benefits most. It should help you decide whether a battery belongs in your plans.
How does a solar battery work
Think of a battery as a reservoir for your daytime sunshine. Sometimes your panels make more power than your home uses at that moment. Perhaps the kettle, washing machine and dishwasher are all off. The surplus then charges the battery. Later the panels stop, but you switch on the TV, lights or oven. The battery then discharges to meet that demand.
You draw from the grid only when the battery is empty. In contrast, any excess goes out under the Smart Export Guarantee only when the battery is full.
Most UK systems use lithium-ion cells, like the battery in an electric car but sized for a house. The unit is usually wall-mounted in a garage, utility room or loft. It links to your consumer unit through an inverter. The inverter converts between the battery's direct current and your home's alternating current. Because the system runs itself, you do not need to switch anything on or off.
Solar panels with battery: what the combined system looks like
A typical 4kWp solar array on a three-bedroom home costs around £6,000–£8,000 fully installed. Adding battery storage brings the total to roughly £10,000–£14,000 installed. That figure includes the battery unit, the extra inverter work, mounting, wiring and commissioning. It also includes the VAT saving that applies to both panels and batteries until 31 March 2027.
Zero-rate VAT on domestic installations can save roughly £1,000–£3,000 on a typical installed price. The quoted range already reflects that saving.
Battery capacity for a 4kWp system usually falls between 5kWh and 10kWh of usable storage. A smaller battery covers the evening peak for a lower upfront cost. While a larger one costs more, it stretches further into the night. It can also capture more on long summer days. The right size depends on your evening usage pattern, which a survey will assess.
Domestic solar battery cost: what drives the price
The battery unit itself is the largest single cost. The hybrid inverter (or a separate battery inverter) comes next, with the labour to fit it all safely. Brand, chemistry, warranty length and smart features all affect the final figure. One example is time-of-use optimisation.
Because each roof, consumer unit and usage pattern differs, installers quote per project. They do not publish a fixed menu. A free, no-obligation survey is the only way to get an accurate number for your address.
Does adding a battery increase savings
Yes — but the size of the increase depends on how much of your daytime generation you export now. Suppose you are at home during the day running appliances. You already use a large share of your solar output. Because of this, a battery adds less extra self-consumption.
However, the house may be empty until early evening. Then you export most of your generation at SEG rates that average around 13p per kWh on standard tariffs. You then buy evening power back at a higher import rate. A battery flips that equation. You keep the energy you made and avoid the higher import price.
The trade-off is that each kilowatt-hour you store in the battery is a kilowatt-hour you do not export. As a result, you forgo the SEG payment on that unit. A good survey models both sides. It weighs extra self-consumption savings against lost export income. It then shows the net effect on your annual bill.
Payback and the 10 to 15 year horizon
Most UK homes see panels pay for themselves in roughly 10–15 years, depending on daytime usage and the SEG rate you secure. Adding a battery extends the payback period, because the upfront cost rises faster than the extra yearly saving in many cases. Still, the battery also shields you from future price rises. This covers the share you shift from grid import to stored solar.
If you value that protection, the sums can look better. The same goes if you can use a time-of-use tariff. Such a tariff charges the battery cheaply overnight in winter.
Panels are typically guaranteed for 25 years and keep producing well beyond that, losing under 1% output a year. In contrast, battery warranties are usually around 10 years with a throughput or capacity guarantee. Over the full life of the panels, you may replace the battery once. Factor this into your long-term plans.
Who benefits most from solar panels and battery storage
Households at home in the evenings that use a lot of power after dark tend to see the strongest return. Think of cooking, electric vehicle charging, heat pump running and entertainment. Families with high baseload overnight also capture more value. Examples are fridge-freezers, always-on networking gear and medical equipment.
Homes with an electric vehicle gain a double benefit if the battery can top up the car from stored solar. Still, the car's own battery is usually much larger than the home unit.
Suppose you are out all day and use little power after 6pm. A battery may then take a long time to earn its keep. In that case, push for a good SEG rate and use timers to run appliances during peak generation. This often delivers better value per pound spent.
Best battery for solar panels: what to look for
There is no single "best" battery for all homes. Still, a short checklist helps you compare quotes. A free survey from an MCS-certified installer will then match these specifications to your usage data and roof output.
- Usable capacity — quoted in kilowatt-hours you can actually draw, not the headline cell capacity.
- Power rating — the maximum kilowatts the battery can deliver at once; this matters if you run several heavy loads together.
- Warranty terms — years, cycle count or throughput limit, and the guaranteed end-of-life capacity percentage.
- Chemistry and safety — lithium iron phosphate (LFP) is now common for its thermal stability and long cycle life.
- Smart features — ability to charge from the grid on cheap overnight rates, integrate with time-of-use tariffs, and participate in future grid services.
- Installer certification — MCS certification is required for SEG registration and most grant routes, so always confirm your installer holds it.
Solar panels and battery storage: the SEG interaction
The Smart Export Guarantee means licensed suppliers must pay you for exported solar power. Rates vary widely. They run roughly 1p–15p per kWh on standard tariffs, with some installer-exclusive or time-of-use deals paying more. The market average is around 13p per kWh.
When you add a battery, you export less because you keep more. That is usually a good trade, since you avoid buying at the import rate. That rate is typically higher than the export rate. Still, the exact crossover point depends on your tariff pair.
Some modern tariffs reward you for exporting at peak grid times (early evening) while charging little overnight. You can programme a smart battery to discharge to the grid in those high-price export windows. It then recharges from cheap overnight power, effectively arbitraging the difference. This only works with compatible tariffs and hardware, so raise it at survey stage.
Grants and support that can include batteries
The ECO4 scheme can fund 100% of a solar installation, typically worth £5,000–£8,000. It is for households on certain means-tested benefits with a lower EPC rating (D to G). It runs via energy suppliers or Local Authority Flexibility routes. It is due to run to the end of 2026.
While ECO4 primarily targets insulation and heating, some delivery routes include solar PV. A few also include battery storage where it improves the overall energy performance score. Eligibility depends on your household. Ask your surveyor whether your circumstances open any funded options.
Are solar batteries worth it
For many homes, the answer is yes. The reason is not purely a simple payback sum. It is the broader value of using more of your own clean energy. You also cut your exposure to price spikes and gain some backup power. However, most UK batteries do not provide off-grid power during a power cut without extra switching gear.
The financial case strengthens if you have high evening usage, a favourable time-of-use tariff, or access to grant funding. It weakens if your daytime self-consumption is already high. It also weakens if your export rate is unusually generous.
The only way to know for your address is to model it with real usage data, roof direction, shading and your current tariff. A free, no-obligation survey provides exactly that.
Next steps: get a quote that includes a battery option
Maya Solar covers England, Scotland and Wales with a network of MCS-certified installers. We do not sell or install ourselves. Instead, we arrange a free survey. We share your details only with vetted professionals, and you receive quotes directly. Since there is no phone line, everything starts with our online form.
When you request a survey, ask to see a battery option alongside the panel-only quote. The installer will model both scenarios. You can then compare the extra cost, the extra savings, the changed payback, and the SEG impact side by side. You are under no obligation to proceed, but you will have the numbers you need to decide with confidence.
Solar battery storage turns daytime generation into evening freedom. If that matches the rhythm of your home, the numbers are worth checking.