Solar panel battery storage

Solar panels don’t always generate the most electricity when you want to use it. You can send excess electricity back to the National Grid, and use mains electricity in the evenings and at night. Or, you can install a home storage battery. 

These store up your electricity to use later, making your energy system more independent from the National Grid. 

Usually battery storage is used alongside solar panels. But it can also be used with an energy tariff that offers cheaper electricity at off-peak times.

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What is solar panel battery storage?

Battery storage allows you to keep electricity stored and ready do you can use it when you need it.

You can charge them using excess electricity generated from solar panels, or other home generation. Or you can charge them using your mains electricity supply.

Energy storage can be useful if you generate renewable electricity and want to use more of it, or outside of daylight hours. 

It may also be worth considering if you have a time-of-use energy tariff that means you could charge a battery cheaply at off-peak times.

Read on to find out about different energy-storage products, how much they cost, and the pros and cons of batteries. 

Or jump straight to our table of the battery storage products and prices.

Solar panel battery storage: pros and cons

Pros

• Helps you use more of the electricity you generate.
• Cuts your electricity bill if you buy less from your energy supplier.
• Some energy tariffs pay you for allowing your battery to be used to store excess grid electricity.
• Could enable you to take advantage of cheap-rate electricity, for example from a smart time-of-use tariff.
• Requires little maintenance: 'Fit and forget', said one owner.
• You no longer have to pay VAT to add batteries to an existing solar PV system (until February 2024 it was 20%). Batteries installed at the same time as solar panels have always been subject to 0% VAT.

Cons

• Currently pricey, so payback time may be long.
• If you have an old feed-in tariff (FIT) contract, a DC system could reduce your payments.
• Likely to need replacing during the lifetime of a solar PV system.
• If retro-fitted to existing solar PV, you may need a new inverter.

We asked solar-panel experts and owners for their top tips. Find out how to make the most of your solar panels.

Is solar battery storage right for my home?

If you have solar PV panels, or are planning to install them, then using home batteries to store electricity you’ve generated will help you to maximise the amount of renewable energy you use. 

Storing your solar energy will reduce how much electricity you use from the grid, and cut your energy bills. If your home is off-grid, it can help to reduce your use of fossil fuel back-up generators.

Without solar panels, you could use a battery to make the most of a time-of-use tariff by storing up electricity while it’s cheap (overnight, for example) to use during peak times.

But if you’re at home during the day and already use a large proportion of the electricity you generate through solar panels, or divert surplus electricity to heat your water (for example), then a battery may not be right for you.

That's because buying and installing the battery will usually cost upwards of £2,000, so you’ll need to make sure it's a worthwhile investment and you'll get your money back on your energy bills. But with grid electricity currently very expensive, and projected to stay that way until the end of the decade, the payback times might be quicker than you think.

Bear in mind that the best way to bring down your energy bills is to  make sure your home is as energy efficient as possible. 

What size solar storage battery do I need?

The average home uses between 8kWh and 10kWh of electricity per day. The capacity of new lithium-ion batteries ranges from around 1kWh to 16kWh.

If you’re using it alongside solar panels, ideally you want a battery that will cover your evening and night-time electricity use, ready to be charged again when the sun comes up. Check how much your solar panels can generate - there's no point buying a battery that's bigger than they can fill.

With a battery that is well chosen for your home's energy use and your solar panels' output, you should find that you can have enough electricity stored for the evening for most of the year. You might find that you still need grid electricity on the longest winter nights.

We recommend you speak to an expert battery installer for a tailored quote to discuss the right size for your home.

Can I save money with a solar battery?

Battery storage tends to cost from less than £2,000 to £6,000 depending on battery capacity, type, brand and lifespan. 

Keep reading to see products with typical prices.

Installing a home-energy storage system is a long-term investment to make the most of your solar-generated energy and help cut your energy bills.

Whether a battery will save you money depends on

• the cost of installation
• the type of system installed (DC or AC, chemistry of the battery, connections)
• how it’s used (including the effectiveness of the control algorithm)
• the price of electricity (and how it changes during the lifetime of your system)
• the battery’s lifetime.

Several battery systems come with a 10-year warranty. They require little maintenance, so the main cost is the initial installation. However, solar PV panels can last 25 years or more, so you should factor in the cost of replacing the battery at least once into your total costs.

Batteries are expensive to buy, but prices are dropping all the time, as are solar panel prices. With electricity prices at record highs, the payback times are improving.

Some battery storage companies offer financial benefits – for example, payments or reduced tariffs for providing services to the grid (eg. letting spare electricity from the grid be stored in your battery).

We haven’t yet tested home-energy storage systems to be able to calculate how much they could cost or save you. However you should take into account whether you are on a tariff which has different electricity costs depending on the time of day (time-of-use, or TOU tariff) and, if you generate your own electricity, how much of this you use already.

The Feed-in Tariff (FIT) is now closed for new applications, but many solar panel owners signed up when it was open. If you get it, part of it is based on the amount of electricity you generate and export to the grid. If you don’t have a smart meter the amount of electricity you export is estimated at 50% of what you generate.

If you have a smart meter, your export payments will be based on actual export data. However, if you also have a home battery installed, your export payments will be estimated at 50% of what you generate. This is because your export meter cannot determine whether electricity exported from your battery was originally generated by your panels or taken from the grid.

If you are looking to install solar panels and a solar battery, new Smart Export Guarantee (SEG) tariffs mean that energy firms will pay you for any excess renewable electricity you have generated and export to the grid. All suppliers with more than 150,000 customers have to offer them.

Compare rates to find the best for you – but check that you’re eligible if you have storage installed.

Financing energy storage

While battery prices are coming down, it’s still a significant investment.

The best option is to pay for your battery upfront using your own savings. If you don’t have the cash to do this, you could consider a loan. However, remember you’ll have to pay interest on money you borrow, so make sure that gains made from battery storage would outweigh this.

If you live in Scotland, you might be able to get a grant or interest-free loan. Up to £6,000 is available towards energy storage (as a combination of grant and loan). 

But you can only get it if you buy a 'package of measures'. This means you have to buy a heat pump or high retention storage heaters at the same time. 

You'll have five years to repay the loan. See Energy Saving Trust’s Home Energy Scotland Grant information to find out more.

Tesla, Samsung, EDF, Eon and Ovo home energy storage packages

Some big tech brands, including Samsung and Tesla, sell home-energy storage systems. Energy companies including EDF Energy, Eon and Ovo are also currently selling solar panel and storage packages. 

EDF Energy sells solar batteries and says customers can get a discount in return for helping EDF balance the grid. It says it’s trying to create a ‘network of small-scale batteries to help balance the peaks and troughs of energy production and customer demand'.

Eon Next is selling batteries alongside solar panels so that customers can store excess electricity generated, or charge their electric vehicle. It also pays its customers for excess electricity they export to the grid.

Ovo Energy is selling a home energy-storage device that charges from the grid when electricity is cheaper and less carbon-intensive, and discharges it to run appliances when electricity is pricier and more carbon-intensive later.

Battery storage products and prices

The batteries below range from the size of a small computer to the size of a washing machine. Greater capacity means a bigger and heavier battery. 

Small systems can be wall-mounted, while larger ones sit on the floor. Some companies offer 'stackable' batteries that can be used together.

Use the table to compare prices, capacities and key features.

Energy storage systems with price excluding installation

Bear in mind that usable capacity is usually less than stated capacity. This is because batteries tend to lose some energy in charging and discharging, and most aren’t designed to be fully discharged on a regular basis.  

The products in the table above are designed to work with the grid. If you’re off-grid, speak with an installer directly to get an appropriate system for your situation.

Before you install a home-energy storage system

• Consider whether you’re generating enough electricity that you don't use to make it worth adding energy storage to an existing solar panel system.
• If you’re looking to protect yourself against power cuts with a home battery, not all systems are suitable - ask your installer whether your battery will work in a power outage, and for how long.
• Get quotes from several installers on the cost of installation and estimated savings. Ask them to explain their calculations to you and question anything you’re not sure about.
• Check that your installer is signed up to the Renewable Energy Consumer Code (RECC), which now covers storage. This means they’re signed up to a high standard of conduct, including providing good information about your installation. You also have access to RECC’s complaints process if something goes wrong.
• Check that your installer is certified by the Microgeneration Certification Scheme (MCS). This means they meet industry standards. MCS can also help with complaints.

Do I have to have solar panels to install a battery?

No. You can also charge a home battery using electricity you buy from the grid. 

If you have a time-of-use electricity tariff you could save money by charging your battery when electricity is cheaper, and using the power from it at peak times, to avoid buying from the grid.

But most people do not have time-of-use tariffs yet. These are likely to become more widely available as smart meters are rolled-out, as they make it easy for energy companies to see exactly when you've used energy. Economy 7 and Economy 10 are types of traditional time-of-use tariffs, usually linked to storage heating systems.

Find out more about smart time-of-use tariffs.

Battery storage installation systems

There are two types of battery installation: DC and AC systems.

DC battery systems

A DC system is connected directly to the generation source (eg. solar panels), before the electricity generation meter. You won’t need another inverter, which is more efficient.

However, charging and discharging is less efficient, so could affect your feed-in tariff, if you have one. DC systems aren't usually recommended if you’re retrofitting a battery to an existing PV system. 

DC systems can’t be charged from the grid, according to the Energy Saving Trust.

AC battery systems

These are connected after the electricity generation meter. So you’ll need an AC/DC power unit to convert the electricity you generate into AC you can use in your home (and back again to store it in your battery).

AC systems are more expensive than DC systems, according to the Energy Saving Trust. But an AC system won’t affect feed-in tariff payments, as the generation meter can register the total system output.

Battery installation tips

If you’re installing a storage system, you should notify your local Distribution Network Operator – check with the Energy Networks Association if you’re not sure who it is. You may also need to inform your local council.

Beware of pressure selling by installers. Check our solar panels buying advice for things to look out for, including rapidly reducing quotes and lack of detailed information. A good installer should be able to clearly show you how they’ve worked out what size and type of system you will need for your home, and how they’ve calculated any potential payback times.