Adding a battery to existing solar panels: what to know in 2026

Key takeaways

• Yes, you can add a battery to existing solar panels: In most cases, battery storage can be retrofitted to an existing solar PV system, though some setups may require an inverter upgrade.
• Battery storage helps you use more of your own solar energy: Instead of exporting electricity during the day and buying it back later, you can store it and use it in the evening when electricity prices are often higher.
• The best results come from a connected system: With Aira, your existing solar panels, the Aira Power Store and the Aira Power Hub work together as part of the Aira Home Energy System, optimised by Aira Intelligence.

Already have solar panels? Then you’re already generating your own electricity.

But without a battery, a lot of that energy leaves your home before you get the chance to use it. It goes to the grid during the day, then you buy electricity back later when prices are often higher.

That’s where home battery storage for solar panels changes things.

A home battery lets you keep more of the electricity your solar panels produce, use it later in the day, and rely less on the grid. And if you’re on a smart tariff, it can also store cheaper off-peak electricity from the grid for when you need it most – like in the evening when electricity prices peak.

If you’re thinking about adding a battery to existing solar panels in the UK, here’s what to know.

Can you add a battery to an existing solar system?

In most cases, yes.

If you already have solar panels, battery storage can usually be added later. This is often called a solar battery retrofit – adding storage to an existing solar PV system so you can store more of the energy your panels generate.

But the right setup depends on how your current system was installed and what equipment you already have. The most important component is the inverter.

Some homes already have a hybrid inverter that can work with a battery. Others need a new inverter or additional equipment to make battery storage possible.

With Aira, the route is simple: the Aira Power Store is installed as part of the Aira Home Energy System, alongside an Aira Heat Pump. If you already have solar panels, they can still work with the system – but we install the Aira Power Hub (our intelligent hybrid inverter) so everything works together properly and can be optimised by Aira Intelligence.

So yes, you can add battery storage to existing solar panels in the UK. But the best results come from making sure the battery, inverter and wider system are designed to work together.

Why add a battery now?

Because the value of storing your own electricity has never been clearer.

If your panels produce more electricity than your home needs during the day, that surplus is usually exported to the grid. Under the Smart Export Guarantee, suppliers pay you for exported electricity – but rates vary by tariff and supplier.

At the same time, the electricity you buy back from the grid is often worth much more to you than the electricity you sell.

A battery helps flip that around.

Instead of exporting your solar electricity during the day and importing electricity from the grid in the evening, you store that energy and use it later.

That means:

• more of your own solar electricity stays in your home
• less grid electricity is needed in the evening
• smart tariffs become even more useful
• your energy bills can fall further

There’s also the upfront cost to consider. Qualifying solar and battery installations currently benefit from 0% VAT, which reduces the cost of installing battery storage for solar panels in the UK.

How battery storage is added to existing solar panels

There are two main ways battery storage can be retrofitted to an existing solar PV system.

AC-coupled battery systems

This is often the simplest retrofit solar battery setup.

The battery works alongside your existing solar inverter and connects to your home’s electrical system separately. It can store energy generated by your solar panels or electricity imported from the grid.

AC-coupled systems are often used when the existing solar inverter is kept in place.

DC-coupled battery systems

This approach is more integrated. It usually involves installing a hybrid inverter that manages both the solar panels and the battery together.

This can improve efficiency and allows the system to work more intelligently.

With Aira, we install the Power Hub, which acts as the central inverter for the system. It converts electricity, manages how energy flows between your solar panels, battery, heat pump and the grid, and enables everything to be optimised by Aira Intelligence.

The result is a system designed to work together from day one – rather than separate technologies working independently.

What needs to be checked first before adding a home battery?

Before adding a battery to an existing solar setup, there are a few things worth looking at.

1. Your current inverter

This is the big one.

Your existing inverter determines how easily battery storage can be added. Some systems can be adapted. Others need an upgrade.

With Aira, we install the Aira Power Hub so the battery, your existing solar panels and your Aira Heat Pump can work as one connected system.

2. Your solar generation

Battery storage works best when your solar panels regularly produce more electricity than your home uses during the day.

If you’re exporting a meaningful amount of electricity already, a battery can help you keep more of it for later.

3. Your energy use

Homes with higher evening electricity use often benefit most from battery storage, because that’s when stored solar energy becomes valuable.

If you’re out during the day and home in the evening, a battery usually makes even more sense.

4. Your available space

Home batteries are compact, but they still need the right installation space.

That could be a garage, utility room or another suitable indoor location. We’ll check this as part of the assessment.

5. Your wider system

If you’re planning to add a heat pump later – or want one system that can grow with your home – it’s worth thinking beyond the battery alone.

That’s where an integrated system becomes more valuable than a one-off add-on.

Can a home battery charge from the grid?

Yes – and this can unlock even greater savings.

Most modern home batteries can store electricity from the grid as well as from solar panels. This means you can charge the battery during cheaper off-peak tariff periods, then use that stored electricity later when grid prices are higher.

For example, some smart tariffs offer very low overnight electricity rates. Your battery can charge during those hours and power your home the next day or evening.

With the Aira Home Energy System, the Power Hub and Aira Intelligence help manage when electricity is used, stored or imported – so your home can take better advantage of these tariff windows.

The result is a home that doesn’t just generate energy, it uses it more intelligently too.

Why battery chemistry matters

Not all home batteries are built the same way.

Two of the most common battery chemistries are NMC and LFP. For home energy storage, LFP (Lithium Iron Phosphate) is often the stronger choice. It offers:

• a longer lifespan
• strong safety performance
• slower degradation over time
• stable performance in everyday home use

That’s why Aira uses LFP battery technology in the Aira Power Store.

If you’re installing battery storage for the long term, chemistry matters. This isn’t just about adding storage for now. It’s about choosing a system that’s built to last.

Why modular battery storage matters

One of the biggest questions homeowners ask is: how much battery storage do I need?

And the honest answer is: it depends.

Your ideal battery size depends on how much solar electricity you generate, how much electricity you use, and when you use it. That’s why modular storage matters.

The Aira Power Store starts at 6.7 kWh and can be expanded up to 20 kWh over time.

That means you can:

• start with what suits your home today
• add more storage later if your needs grow
• future-proof your system without replacing everything

So if you later add an EV, increase your electricity use, or want to store more cheap off-peak energy, your system can grow with you.

How much does it cost to add battery storage?

The cost depends on your current setup, how much storage you want, and whether your inverter needs upgrading.

Because every existing solar system is different, the only reliable way to price adding battery storage to solar panels in the UK is with a compatibility assessment.

That’s especially true if your current inverter needs replacing or your system layout needs updating.

We’ll find this out and calculate your bespoke quote during your free home energy assessment.

How long does installation take? And what happens when battery storage is installed?

Adding battery storage to an existing solar system is usually quick and straightforward.

With Aira, the process typically looks like this:

1. Free home energy assessment 

We start with a free home energy assessment to review your current solar system, electricity use and available installation space.

2. System design

Our team designs the right battery setup for your home and checks compatibility with your existing solar panels.

3. Installation

Our technicians install the Aira Power Store and Power Hub, connect everything safely to your home’s electrical system, and test the setup.

4. App setup and handover

Finally, we connect your system to the Aira app, show you how to monitor your energy use, and make sure everything is running as expected.

In many cases, installation takes just one to two days.

Is it worth adding a battery to existing solar panels?

For many homes, yes.

If your solar panels are already generating electricity during the day, battery storage helps you get more value from what you already have.

It means more self-consumption. Lower dependence on the grid. And more control over when and how your home uses electricity.

It can be especially worthwhile if:

• you’re exporting a lot of solar electricity today
• your home uses more electricity in the evening
• you’re on a smart tariff
• you want one connected system that can support a heat pump too

The Aira difference

A lot of battery retrofits are treated like add-ons. At Aira, we take a different approach.

We install battery storage as part of the Aira Home Energy System. That means your Aira Heat Pump, existing solar panels, Power Store battery and Power Hub inverter are designed to work together – and optimised by Aira Intelligence.

So instead of separate technologies doing separate jobs, your home energy system works as one.

That’s how you unlock better performance, better control and better savings.

Can the Aira Power Store work with existing solar panels?

Yes – in most cases it can.

If you already have solar panels installed, they can still be part of your home energy system. The key is making sure everything works together properly.

With Aira, we install the Aira Power Hub, our intelligent hybrid inverter. This allows your existing solar panels, the Aira Power Store battery, and your Aira Heat Pump to operate as one connected system.

That means:

• your solar panels can still generate electricity as normal
• surplus solar energy can be stored in the Power Store instead of exported immediately
• the whole system can be optimised by Aira Intelligence

During your free home energy assessment, we’ll check your current solar setup and confirm exactly how battery storage can be integrated.

Want to know if your solar system is compatible?

If you already have solar panels and want to add battery storage, the first step is checking what your current system can support.

During your free home energy assessment, we’ll assess your setup, explain what would be needed, and show you how the Aira Power Store could work with your existing solar and an Aira Heat Pump.

To arrange yours, or to speak to one of our experts, answer a few quick questions about your home.