Home Battery Storage
Store your solar energy and use it when you need it most
Why Add Battery Storage?
Without a battery, a typical solar panel system only uses around 30 to 50 per cent of the electricity it generates. The rest is exported to the grid — often at a fraction of what you pay to import it back in the evening. A home battery changes this equation dramatically, allowing you to store surplus solar energy during the day and use it when electricity is most expensive.
80%+ Self-Consumption
Adding a correctly sized battery increases your solar self-consumption from a typical 30–50% to over 80%. That means the vast majority of the electricity your panels generate is used in your own home, rather than being exported at a low rate and bought back at a high one.
Peak-Time Power
Electricity demand — and prices — peak between 4pm and 9pm, precisely when solar generation drops off. Your battery discharges stored energy during these expensive hours, so you avoid importing costly peak-rate electricity from the grid.
Smart Export Earnings
With a battery, you can choose when to export surplus electricity. Rather than exporting automatically during the day at low rates, your battery stores energy and exports at times when SEG tariffs or agile export rates are at their highest, maximising your earnings.
Emergency Backup
Many modern battery systems offer backup power in the event of a grid outage. While standard solar panels shut down during a power cut for safety reasons, a battery with backup functionality can keep your essential circuits running until the grid is restored.
How Home Batteries Work
The principle behind home battery storage is refreshingly simple. During daylight hours, your solar panels generate electricity. Any energy your home doesn't use immediately flows into your battery, charging it up. When the sun goes down or your household demand exceeds what your panels are producing, the battery discharges its stored energy to power your home. Only when the battery is fully depleted does your home draw electricity from the national grid.
There are two main ways to connect a battery to your solar system: DC coupling and AC coupling. With DC coupling, the battery is connected directly to the solar panels before the inverter, resulting in slightly higher efficiency as energy is only converted once. AC coupling connects the battery on the household side of the inverter, making it the more flexible option for retrofitting a battery to an existing solar installation. Our surveyors will recommend the best approach for your specific setup, taking into account your existing equipment and future plans.
Modern home batteries are fully automated. Once installed and configured, the system intelligently manages the flow of energy between your panels, battery, home, and the grid without any intervention from you. Most systems also come with a smartphone app that lets you monitor energy flows in real time and review your generation and consumption history.
Battery Technology
All the batteries we install use Lithium Iron Phosphate (LFP) chemistry. LFP represents the safest and most durable battery technology available for residential energy storage today, and there are several compelling reasons why we have standardised on this chemistry.
First, safety. Unlike older lithium-ion chemistries such as NMC (Nickel Manganese Cobalt), LFP cells are inherently resistant to thermal runaway — the chain reaction that can cause lithium-ion batteries to overheat or catch fire. LFP's chemical structure is far more thermally stable, making it the safest option for installation inside your home.
Second, longevity. LFP batteries typically deliver 6,000 or more charge-discharge cycles before reaching 80% of their original capacity. In practical terms, that means your battery can cycle once per day for over 16 years before any noticeable reduction in performance. Older NMC batteries typically manage only 3,000 to 4,000 cycles, giving LFP a significant advantage in long-term value.
Third, environmental credentials. LFP batteries contain no cobalt — a mineral associated with environmentally damaging and ethically problematic mining practices. By choosing LFP, you can be confident that your home energy storage system aligns with the environmental values that led you to solar energy in the first place.
Our Battery Partners
We work with six leading battery manufacturers to offer a solution for every home and budget. Each brand has been selected for proven reliability, strong warranty support, and excellent real-world performance in UK installations.
Tesla Powerwall
The most recognised name in home energy storage. The Tesla Powerwall offers 13.5kWh of usable capacity with an integrated inverter, seamless app control, and the ability to stack multiple units for larger homes. Its sleek design and proven reliability make it a popular choice for homeowners who want a premium, all-in-one solution.
Growatt
Growatt offers excellent value across a range of capacities, from compact 5kWh units to larger 10kWh+ systems. Their hybrid inverters are particularly well-regarded, combining solar inverter and battery management in a single unit. Growatt systems are known for reliable performance and an intuitive monitoring app.
SigEnergy
A newer entrant to the UK market, SigEnergy has quickly earned a strong reputation for innovative, modular battery systems. Their stackable design allows homeowners to start with a smaller capacity and add more modules later as their energy needs grow, making them an excellent future-proof option.
SolaX
SolaX provides a comprehensive range of hybrid inverters and battery storage solutions. Their systems are particularly well-suited to retrofit installations, where a battery is being added to an existing solar panel system. SolaX offers strong monitoring capabilities and competitive pricing.
Fox ESS
Fox ESS has become one of the UK’s most popular battery brands thanks to strong performance, competitive pricing, and excellent installer support. Their hybrid inverter and battery combinations offer a reliable, cost-effective route into home energy storage.
Solis
Solis is one of the world’s largest inverter manufacturers, with millions of units deployed globally. Their hybrid storage solutions are built on decades of inverter expertise, offering outstanding reliability and efficiency at a competitive price point.
Sizing Your Battery
Choosing the right battery capacity is crucial to getting the best return on your investment. A battery that's too small will leave surplus solar energy with nowhere to go, while an oversized battery will rarely charge fully, meaning you've paid for capacity you don't need.
The typical UK home uses between 8 and 12 kWh of electricity per day. However, the amount of energy you need to store depends on when you use that electricity. If most of your consumption happens in the evening — as is the case for most working households — then a battery in the 5 to 13 kWh range is usually appropriate. This allows you to store enough daytime solar generation to cover your evening peak usage.
Several factors influence the ideal battery size for your home. Your daily electricity consumption is the starting point, but we also consider the size of your solar array (a larger array generates more surplus to store), whether you have or plan to get an electric vehicle (EV charging can significantly increase your evening electricity demand), and your lifestyle patterns. A household where someone works from home, for example, will use more electricity during the day and may need a smaller battery than a household where everyone is out until 6pm.
During your free survey, our surveyor will analyse your energy usage patterns and solar generation potential to recommend the optimal battery size. We'd rather sell you the right system than the biggest one — correctly sizing your battery is one of the most important factors in achieving a good payback period.
Smart Export Guarantee
The Smart Export Guarantee (SEG) is a government-backed scheme that requires large energy suppliers to pay you for surplus electricity you export to the national grid. Without a battery, your solar panels automatically export surplus during the day when rates tend to be lower. With a battery, you gain control over when you export.
Some energy suppliers now offer agile or time-of-use export tariffs, where the rate you're paid varies throughout the day. A battery allows you to hold your surplus solar energy and export it during higher-rate periods, significantly increasing your SEG income compared to a solar-only system. Combined with the money you save by using stored energy instead of importing from the grid, a battery maximises the financial return from every kilowatt-hour your panels generate.
To be eligible for the SEG, your installation must be carried out by an MCS-certified installer — which Lunar Solar is. We handle the MCS registration and help you choose the best SEG tariff for your circumstances as part of our handover process.
Cost & Payback
Home battery storage systems typically cost between £3,000 and £8,000, depending on the capacity and brand you choose. A compact 5kWh battery sits at the lower end, while a larger 13kWh+ system or a premium brand like Tesla Powerwall will be towards the higher end of the range. All battery installations benefit from the current 0% VAT rate when installed alongside or as an addition to a solar panel system.
When combined with solar panels, a battery system typically achieves a payback period of around seven years. The exact timeline depends on your electricity usage, the size of your solar array, your battery capacity, and how effectively the system is sized to your household's patterns. After payback, your combined solar and battery system continues to deliver savings for many years to come.
All batteries we install carry a minimum 10-year manufacturer warranty, with most warranted to retain at least 70% of their original capacity at the end of the warranty period. Given that LFP batteries typically last well beyond their warranty, your battery is likely to continue performing for 15 to 20 years or more.
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