Battery storage allows you to capture electricity when it’s cheap – or free – to use later in the day or at night
Battery storage is normally combined with solar panels.
A solar panel system will generally produce more electricity than you need. If you don’t use it, the solar electricity flows off to the National Grid and is lost.
With battery storage, you can capture this surplus solar electricity.
You can then draw on it later in the day or at night, either to charge your electric car or power devices in your home.
Now, with smart electricity tariffs, battery storage can be installed even without solar panels. You can charge your battery at night at a very cheap rate, and then use the stored electricity during the day, to avoid paying high daytime rates.
New applications for storage are developing fast. For example, a few solutions now allow you to share your energy with a wider community and even help stabilise the grid.
Battery storage is also sometimes known as solar battery storage or just energy storage.
Do I need battery storage? Read our 4-step guide:
To help you decide whether you want or need battery storage, we have written a 4-step guide:
- Understand the technology: Find out how battery storage works
- See if it makes sense for you: Read our 10 reasons to install battery storage in your home
- Explore products: Compare and contrast products available in the UK
- Find a competent, local installer: Get easy access to local installers and ask for three quotes
1. How Battery Storage Works
It’s all in the name. Battery storage allows you to store electricity in a battery.
The question is: why on earth would you want to do that?
Why Do Battery Storage Products Exist?
A modern home battery is an active, intelligent hub for your home’s energy. It’s connected to the internet, watches the weather, and monitors the national grid. With smart tariffs, it can also earn you money by actively trading energy. Here’s why people invest in battery storage:
Reason 1: Maximising Free Solar Power
This is the simplest reason. The electricity you generate on your roof from solar panels is free. Without a battery, most of this energy (60-70%) is generated when you’re out. It gets exported back to the grid for a low rate, for example, a fixed export tariff of 15p per kWh via the Smart Export Guarantee (SEG).
With a battery, the system’s ‘smart brain’ sees this surplus, diverts that free energy, and stores it. In the evening, instead of importing from the grid at your normal rate, typically around 27p per kWh, your battery powers your home for free.
Every kWh from the battery is a kWh you didn’t have to buy.
Reason 2: Mastering Smart Tariffs
This is where the battery’s brain shines.
- Arbitrage tariffs: Tariffs like Intelligent Octopus Go – which you can get if you have an EV – offer ultra-cheap night rates (e.g. 7p per kWh). The battery can be programmed to automatically fill itself from the grid during this 7p window. For the rest of the day, it uses that 7p energy to shield your home from buying at the more expensive standard rate, allowing you to ‘bank’ the price difference.
- Trading tariffs: Other tariffs like Octopus Flux are designed for homes with both solar and a battery. They have different import and export prices that change throughout the day, including a high-priced export rate during the 4pm-7pm peak (roughly 37p per kWh). The battery’s brain will automatically store your free solar all day, then deliberately export all of it during the peak to earn the top rate, before refilling on a cheap c. 16p overnight rate.
Reason 3: Getting Paid to Support the Grid
Your battery is no longer just a personal device. It can be a community asset via the following schemes:
- Demand Flexibility Service (DFS): The National Energy System Operator (NESO) runs this scheme to prevent grid instability during peak times. During the 2024/2025 winter, nearly 2 million households and businesses were paid to reduce their energy use or, for battery owners, to export their stored energy back to the grid when it was needed most. You need a smart meter – talk to your energy provider to see if they offer this service.
- Virtual Power Plants (VPPs): This is the next level. A VPP is a network of thousands of home batteries, all grouped together by smart software to act as one giant, clean power station to help balance the grid. In July 2025, Tesla launched its UK VPP in partnership with Octopus Energy. Tesla stated participants could earn up to £300 a month for allowing their battery to be used in this way.
Reason 4: Resilience and The Future
After the energy crisis of the early 2020s, many are seeking ‘energy independence’ from volatile global prices. A battery, paired with solar, provides this. It also offers resilience, as many systems can keep your home’s lights on during a power cut – you need a battery for this and it depends on the model.
The next step is using the 50-100 kWh battery in your electric car. Vehicle-to-Home (V2H) and Vehicle-to-Grid (V2G) technologies, which allow your car to power your home or sell energy to the grid, are now emerging in the UK. In June 2025, Octopus Energy launched the UK’s first commercial V2G bundle.
The Basics of Battery Storage
Your home battery will probably be installed downstairs, perhaps in a garage or utility room, as they are heavy. Loft installations are possible, but usually for smaller, modular systems.
The storage will be mounted on the floor or wall. While most are installed indoors, some products like the Tesla Powerwall 3 and Sigenergy SigenStor are weatherproof and can be installed outside.
The battery then needs to be connected to your home’s electricity system. The method used usually depends on whether you already have solar panels.
How Batteries Connect: AC-Coupled vs. Hybrid Inverters
To understand this, you just need to know that your solar panels and battery use Direct Current (DC), but your home’s appliances use Alternating Current (AC). An Inverter is the ‘converter’ box that turns DC into AC.
The ‘Retrofit’ Option: The AC-Coupled Battery
This is the perfect solution if you already have a solar panel system. Your existing solar panels are already connected to their own solar inverter. An AC-coupled battery is a separate, self-contained box that has its own built-in inverter. It connects directly to your fuse board, on the ‘AC’ side of your home’s wiring. This makes it easy to add to any existing setup, but it is slightly less efficient as power has to be converted multiple times (solar DC to AC, then AC back to DC to store in the battery).
The All-in-One Solution: The Hybrid Inverter
This is the modern, streamlined solution you would probably choose if you are installing solar panels and a battery at the same time. A hybrid inverter is one single, smart box that replaces both the solar inverter and the battery inverter. The DC solar panels and the DC battery both connect directly to this single unit. This is often called a DC-coupled system and is more efficient (up to 98%) because the free solar DC power charges the DC battery directly without being converted to AC and back again.
Once the battery is connected (via either method), it can do two things:
- Receive electricity = charging, and
- Deliver electricity to the fuse board = discharging.
How Does a Battery Know when to Charge and when to Discharge?
A battery itself is dumb; it needs a ‘brain’ – a Battery Management System (BMS) or gateway. In a hybrid system, this brain is built right into the hybrid inverter itself.
The brain is connected via clamps (known as CT clamps) to your main grid cable and your solar cables. With the clamps in place, the brain can monitor all important electricity flows in real-time. This data, combined with an internet connection for tariff information and the weather, allows it to make intelligent decisions.
Charging your Battery with Solar Panels
This is the battery’s first and most important job.
In the day time, if there is more solar electricity than the house needs, the brain will sense this and divert the surplus solar electricity to charge the battery. The brain doesn’t let this excess solar electricity escape to the grid for a low price.
If, on the other hand, there is not enough solar electricity to power all the devices turned on in the house (for example, it’s a cloudy afternoon and you’ve just put the oven on), then the brain will tell the battery to discharge electricity to meet as much of the shortfall as possible. The battery will keep discharging when needed until it is almost empty, then wait for more surplus solar to recharge.
Charging your Battery with Cheap, Off-Peak Electricity
It’s also possible to charge your home battery with off-peak electricity. This is a crucial feature, especially in winter when you may not generate enough solar power to fill the battery every day. The battery’s brain can be programmed to automatically charge only during cheap hours.
While Economy 7 tariffs still exist (e.g. offering a c. 15p/kWh night rate but a high c. 32p/kWh day rate), the real power comes from Smart Tariffs.
These require a smart meter and are designed for batteries. A prime example is Intelligent Octopus Go (for EV owners), which offers a rate of just 7p/kWh for 6 hours every night.
The payoff: Your battery fills itself up at 7p. The next day, you use that 7p energy to power your home instead of buying from the grid at normal grid rate of about of 27p/kWh. This simple, automated action saves you about 20p for every single kWh you use from the battery.
This table helps illustrate how different tariffs can save you money:
| Tariff Type | Peak Import Rate | Off-Peak Import Rate | Peak Export Rate | Your Battery’s Job |
|---|---|---|---|---|
| Standard Variable (Price Cap) | c. 27p/kWh | n/a | c. 15p/kWh (fixed) | Solar saving: Store free solar to avoid buying at 27p. |
| Economy 7 (Example) | c. 32p/kWh | c. 15p/kWh | c. 15p/kWh (fixed) | Simple arbitrage: Charge at 15p to avoid buying at 32p. |
| Octopus Go (Intelligent) | c. 27p/kWh | 7p/kWh | c. 15p/kWh (fixed) | Smart arbitrage: Charge at 7p to avoid buying at 27p. |
| Octopus Flux (Solar + Battery) | c. 37p/kWh | c. 16p/kWh | c. 37p/kWh | Active trading: Store free solar. Sell ALL power at the 37p peak. Re-charge at 16p. |
How Much Electricity can a Battery Store?
Battery storage varies enormously in size. The capacity (how much energy it can hold) is measured in kilowatt-hours (kWh).
In 2026, most home battery storage installed is in the range of 5 kWh to 20 kWh.
- A 5 kWh battery is an excellent starting point for an average three-bedroom home, typically enough to cover the high-demand evening period.
- Larger, high-consumption homes might look at systems in the 10 kWh to 20 kWh range.
A key trend in 2026 is modularity. Many modern systems like Sigenergy SigenStor are ‘stackable’. You can install a 5 kWh battery today and have an installer add another 5 kWh module later if your needs change. The size you need depends on your solar system, your energy use, and your budget.
Power Output
This is different from capacity. ‘Power’ (measured in kW) is how quickly the battery can discharge its energy. A continuous power output of 5 kW is typical for a good modern system. ‘Capacity’ (in kWh) is how much it stores.
This matters. Consider a typical kettle rated at 2.5 kW.
- If your battery has a power output of only 1 kW, it cannot boil the kettle on its own. It will deliver 1 kW, and grid electricity will be automatically drawn to make up the 1.5 kW shortfall.
- If your battery has an output rating of 5 kW, on the other hand, it will easily power the 2.5 kW kettle and still have 2.5 kW of power to spare for your lights, TV, and fridge, all at the same time.
Making a perfectly green cup of tea.
Back-up Power in a Power-cut
Some modern batteries, like the Tesla Powerwall 3, can provide back-up power in the event of a power-cut. This is a major advantage over a noisy diesel generator. Often, the battery is wired into just your ‘essential circuits’ (e.g. fridge/freezer, lights, and Wi-Fi router) to make the stored power last longer. But there are also more advanced batteries that can power your whole home.
To make this work, the system needs an Automatic Transfer Switch (ATS) , which is often built right into the battery’s ‘gateway’ or ‘brain’. When the grid fails, the ATS instantly (in milliseconds) disconnects your home from the grid. This creates a safe ‘island mode’ and is so fast your Wi-Fi router may not even flicker.
This ‘islanding’ is also critical because it allows your solar PV system to carry on working. Normally, in a power-cut, your solar inverter has to switch off for safety. But when safely islanded, your solar inverter will continue to function, safely supplying solar electricity to your home and – crucially – re-charging your battery during the power-cut.
2. Ten Reasons to install Battery Storage
If you’ve read the section above, you will already have a feeling for what battery storage is and how it can help you.
Now read these 10 benefits of battery storage and see what you think:
- Capture your surplus solar power instead of losing it to the grid – store it for when you actually need it.
- Use solar energy day and night by discharging stored electricity after sunset or on cloudy days.
- Buy low, use high: store cheap off-peak electricity (for example from Octopus Go) and use it when prices rise.
- Charge your EV with 100% renewable energy when you combine battery storage with solar panels.
- Reduce your reliance on the grid – with enough capacity, you can cover most of your home’s needs independently.
- Stay powered during an outage: certain systems (like Tesla Powerwall 3) can supply backup power in a cut.
- Earn extra income – smart-grid-ready batteries can export power during Demand Flexibility Service (DFS) events.
- Cut your carbon footprint by using your own clean, locally generated electricity instead of importing from fossil sources.
- Support a smarter, decentralised energy network – every battery reduces strain on the national grid.
- Join the modern energy revolution: with solar panels, an EV, a smart charger and battery storage, you have the ‘magic four’ for a truly future-ready home.
Are any of these points attractive to you? If you’re tempted, read on…
3. Explore Battery Storage Products
There are now many home battery storage systems available in the UK, with new models arriving every few months.
The technology has matured rapidly in recent years. Leading manufacturers are earning strong reputations for reliability, efficiency, and smart energy management. Production quality has improved, warranties are longer, and UK-based support teams are becoming the norm. Today’s batteries are quieter, safer, and far smarter than the first-generation products launched just a few years ago.
Battery prices typically scale with capacity – for example, an 8 kWh battery will obviously cost more than a 4 kWh unit, particularly when comparing models from the same brand. However, advances in manufacturing and modular design mean prices per kWh are steadily falling.
Below is a selection of some of the main battery manufacturers with products now available in the UK market. Click the links to visit their official websites and learn more about each system’s capacity, warranty, and smart-integration features.
4. Find a Battery Storage Installer
If your appetite has been whetted, and you’re keen to get some proposals for battery storage, it’s time to speak to some local installation companies.
Remember: always get three quotes. Assuming prices are similar, dig a little deeper on Checkatrade / Trustpilot, etc., and ask for references. Sometimes it’s better to pay a little more if you feel comfortable with a particular company.
Ask the installers to justify the make, model and storage capacity of the battery they recommend. There is no point in having more capacity than you need.
Having said that, if you might want to store more electricity in the future, e.g. if you plan to buy an electric car, you could invest in more storage than you require at the moment.
Click on your county name to find local installers (Scottish and Welsh counties coming soon!)
