Everything you need to know about battery storage
Battery storage for renewable energy allows you to save the electricity generated by your solar panels, so it’s ready for you whenever you need it.
This means you can make even better use of the clean, free energy your system produces.
A battery energy storage system allows you to store the electricity generated by your solar panels, so it’s available whenever you need it.
By using a battery, you can make the most of your free, renewable electricity instead of exporting it back to the grid - helping you maximise your savings and your energy independence.
What is battery storage?
A battery stores energy until you need it, which can be especially useful in homes with solar panels.
With battery storage, you’re not limited to using electricity only when your renewable system is generating power during daylight times. You can rely on it whenever it suits you.
Solar panels generate most of their electricity during the day. Any appliances you run at that time, such as your washing machine or your kettle, will use this free power. But if your panels produce more electricity than you’re using, the surplus energy normally will go back to the grid.
In a home with battery storage, any electricity you don’t use straight away is stored instead of going to the grid. The battery charges when there’s excess power, and you can then use that stored energy to run your appliances when your solar panels aren’t generating.
This gives you more control, more flexibility, and more value from the clean energy your system produces.
How does battery storage for energy work?
Battery storage makes it easy to use your renewable electricity exactly when you need it. Here’s how the process works:
- Your solar panels generate electricity.
- An automatic power controller (also known as a diverter) sends any excess electricity to the battery for energy storage.
This ensures that spare energy isn’t wasted or immediately exported to the grid. - The excess electricity charges the battery.
The battery stores this unused power, keeping it ready for you to use later. - An inverter prepares the stored electricity for use in your home.
It converts the energy from DC (direct current) to AC (alternating current), making it safe and compatible with your household appliances.
With this system, you can make the most of the clean, free energy your solar panels produce, day or night, sunshine or no sunshine. Winner!
Choosing a battery storage system
When choosing a battery storage system, there are a couple of important things to think about:
- What type of battery to install
Different batteries offer different benefits, such as longer lifespan, faster charging, or better performance in varying temperatures. Understanding these options will help you select the one that works best for your home and usage (lifestyle). - Which type of system to install
AC- and DC-coupled systems work in slightly different ways, and each has its advantages depending on whether you’re installing a new renewable system or adding a battery to an existing one.
Types of batteries for energy storage
When it comes to storing renewable energy from solar panels, historically two proven battery technologies have dominated the scene: lead-acid and lithium-ion. Both are reliable solutions, with the main differences being in cost, performance, and lifespan.
Lead-acid batteries are a well-established and trusted form of energy storage that has been used for decades. While they store less energy than newer technologies and typically provide around 700–1,000 charging cycles, they remain a popular and dependable option. especially in off-grid configurations.
Their biggest advantage is affordability. The lower upfront cost can make them an attractive entry point for some households.
Because they contain lead, responsible recycling and disposal are important, but well-established recycling systems already exist to manage this safely.
Lithium-ion batteries represent the modern standard for home energy storage. Developed in the late 1980s, they are lighter, more compact, and far more energy-dense than lead-acid batteries.
While the initial investment may be higher, their long lifespan and strong performance provide excellent long-term value. With around 4,000 charging cycles, a lithium-ion battery can typically last 10 years or more, making it a dependable, low-maintenance choice.
They also contain fewer toxic materials than lead-acid batteries, and like all batteries, can be safely recycled at the end of their life.
Type of systems: DC systems and AC systems
Your battery connects to your solar panels using either AC (alternating current) or DC (direct current) coupling. Both approaches work very well: the key difference is simply how electricity flows between your renewable system, battery, and home.
Renewable systems generate electricity as DC power. Homes, however, use AC power. Batteries store energy as DC, so electricity sometimes needs to be converted between the two. The real distinction between AC- and DC-coupled systems is how often this conversion happens.
A DC-coupled battery connects directly to your solar panels, creating a simple and efficient energy pathway.
Electricity flows straight from your renewables into the battery as DC power. When you want to use that stored energy in your home or export it to the grid, it passes through an inverter that converts it to AC.
Because there are fewer conversion steps, DC-coupled systems are often highly efficient and make excellent use of the energy your system generates.
An AC-coupled battery connects on the AC side of your home’s electrical system.
Here’s how the process works:
Your renewable system generates DC electricity.
An inverter converts it to AC so your home can use it.
Any unused electricity is converted back into DC and stored in your battery.
While this involves an extra conversion step, AC-coupled systems are extremely flexible and are often ideal for adding battery storage to an existing solar setup.
Battery energy storage system cost
A typical domestic battery energy storage system (4kWh–10kWh) in the UK usually costs between £2,500 and £10,000, fully installed, with average setups often costing around £4,000–£6,000.
It’s always best to get a quote from at least three installers, as installation costs can vary.
Would you like to learn more about solar pv?
Check out our solar pv page and our living with solar panels page to find out more.
How do I find out more?
Want to know if solar panels will work for your home? PEC can help.
Our Future Fit services provide independent, expert advice on the suitability of solar panels for your property and how they can fit into a wider home upgrade.
If you are just starting out on your retrofit journey, a free Home Visit is the easiest way to explore what’s possible for your home.
If you are ready to make your home feel even better choose a Future Home Survey for a detailed retrofit plan tailored to your home.
Visit our Retrofit Services page or complete the contact form below to get started.