Solar and battery storage

Solar panel battery storage

Battery storage for solar panels helps make the most of the electricity you generate. Find out how much solar storage batteries cost, what size you need and whether you should get one for your home.

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.

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. 

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.

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.

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.

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.