A solar battery allows you to store electricity for use when the sun goes down. Here's our guide to the costs and benefits
Solar batteries store the electricity your solar panels produce, allowing you to use it to power your home after dark. By doing so, they make solar panels a much better investment. However, with solar battery costs averaging thousands of pounds, you’ll want to make sure that the benefits of installing a solar battery far outweigh the cost of doing so.
In our opinion, solar batteries are well worth their upfront cost. For the average household, a £4,000 solar battery would pay for itself in two or three years by dramatically slashing energy bills, and then provide free solar electricity for another seven or eight years to the point it needs replacing.
The average price of a solar storage battery in the UK is around £4,500 including installation, but prices range from around £2,000 to £11,000 or more. In this article, we run through the costs of solar batteries and help you choose the right unit for your home.
You’ll get the best deal if you buy your solar battery at the same time as your solar panels. To get a tailored quote for a PV system and battery, fill in our short form below and we’ll put our trusted suppliers in touch.
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What is a solar battery?
A solar battery, or battery energy storage system (BESS), is a device that lets you store energy from your solar PV system and then use it when you need to.
If you don’t have a solar battery, but your electricity use is highest after dark, much of that electricity will come from the National Grid, rather than your panels – and your energy provider will charge you for it. Meanwhile, most of your solar-generated energy will go to waste (well, it would actually be donated to the grid). So, a solar battery enables you to use far more of the free electricity your panels generate.
Most of today’s domestic solar batteries are lithium-ion units. The speed of their development has accelerated in recent years, thanks to the popularity of electric vehicles (EVs). Cars need small, reliable batteries to keep them on the road, and the energy sector realised there was a potentially huge market here. Modern DC-coupled lithium-ion solar batteries can be used to charge EVs as well as power home appliances.
How much do solar batteries cost?
The average price of a solar battery in the UK is currently £4,500 including installation, according to renewable energy guru The Eco Experts. However, you can pay as little as £2,000 or more than £11,000, depending on factors such as usable capacity and brand name. Note that it will usually cost less to have a battery installed at the same time as a solar PV system, rather than later on.
Solar batteries typically come with a 10-year warranty, and a battery’s useful life is about half that of a solar PV system. This means you’ll probably need to buy two batteries during your system’s lifespan.
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Do bigger solar batteries cost more?
As mentioned above, the main factor that dictates the price of a solar battery is its “usable capacity”. This refers to the amount of stored energy you can actually use, minus the small amount (usually 5-10%) used by the battery while charging and discharging.
For example, the market-leading Enphase Encharge 10T solar battery has a high usable capacity of 10.5kW and typically costs £8,000, while the Moixa Smart Battery has a usable capacity of 4.08kW and typically costs £3,500. For comparison, the average UK household of three to four occupants uses about 8kW of electricity per day.
You’re unlikely to need a battery with a capacity exceeding 10kWh unless you also run an EV or two, or if your power frequently goes down for days. Also bear in mind that very large-capacity batteries tend to be physically sizeable, too, so you’ll need to find the space.
It’s important to buy the right size battery for your household and your solar PV system, as well as for your budget. As we explain in our article on finding the right size solar battery, your battery not only needs to be big enough to cover your energy needs, but small enough to be fully charged by your solar panels. A battery that’s too big for your panels to fill won’t work properly.
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What else makes some solar batteries more expensive?
Size isn’t everything when it comes to solar battery price. There are plenty of other factors at play – chiefly brand name, build quality and availability of materials. Here are a few more factors that you can compare when pricing up your ideal solar battery:
- Depth of discharge (DoD): Effectively the same as usable capacity, but as a percentage. If a battery has a 100% DoD, then 100% of its total capacity is usable. The Enphase Encharge 10T and the Tesla Powerwall 2 (which costs around £8,500 and offers 13.5kW usable capacity) both boast 100% DoDs, and are among the most expensive solar batteries you can buy. Most of the best solar batteries advertise a DoD of over 90%.
- Power output: This refers to the amount of stored electricity a battery can discharge at once. If you need to power multiple high-drain devices at once when you get home from work – the kettle, fan heater and tumble dryer, for example – then you’ll need a battery that can handle a high power output, and it will likely cost you more. Note that high-output batteries tend to wear out faster than low-output batteries.
- Durability: Solar battery warranties aren’t quite as generous as they are for solar PV panel systems, but you can still expect a 10-year limited warranty as standard. Also look for a high “cycle guarantee”, which indicates how many times it can completely discharge and recharge before losing performance. A cycle guarantee is a good indicator of the quality of the product, and of the manufacturer’s confidence in it.
- Smart charging: Premium solar batteries automatically calculate their charging patterns based on factors including the amount of energy your solar panels produce, your electricity usage habits and even the weather forecast. These smart functions and other metrics can be managed via the battery’s mobile app.
- Power cut support: Many of today’s batteries instantly kick in to provide emergency electricity whenever the national grid cuts out. They do this without feeding any current back into the grid, to spare the safety of any poor engineers working to restore power.
- Modular capacity: Modular battery systems let you start with a smaller capacity and then add more as needed. Smaller capacities are generally more affordable, but the modular option will add a bit to the unit price. For example, the modular Huawei Luna 2000-10 typically costs £5,500 and offers 9kW usable capacity per unit.
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How much does a solar battery cost to install?
A solar battery on its own costs around £500 to add to an existing solar PV system. Note that some solar batteries, such as the Huawei Luna 2000-10, can only be installed with solar panels from the same brand.
You can save on installation costs by having a battery fitted at the same time as your solar panels, solar inverter and other elements of a solar PV system.
How much do solar batteries cost to maintain?
You shouldn’t have to pay anything to keep your solar battery working well for up to about 15 years. It isn’t necessary to service a solar battery unless something goes wrong. Any performance faults within 10 years or so will likely be covered by your free warranty.
Your solar battery will work at its best, and for as long as possible, if you use it properly. A battery’s lifespan is largely down to how often it is fully charged and discharged. If your battery is regularly under-charged or over-charged, the components inside can oxidise or become damaged by heat. Over-charging will create the same problems.
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Can I get a grant for solar battery storage in the UK?
Solar battery grants are currently only available if you live in Scotland. The Scottish government offers 10-year interest-free loans of up to £15,000 for energy-saving improvements, including solar battery storage. Find out more from Home Energy Scotland.
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Is a solar battery worth buying in the UK?
Absolutely, yes. It’s very common for people to use most of their home appliances after dark, especially in autumn and winter, and during these times you can’t draw electricity directly from your solar panels. As such, you need some way to store it. A solar battery is arguably an essential part of a solar PV system in the UK.
During the evening is also when you’ll pay the highest rates for national grid electricity. The current UK price cap is the highest it’s ever been, at 27p per kW (as of the Spring 2023 Budget). If you can store electricity from your panels in a battery, and draw from it in the evening, you can avoid paying peak rates entirely.
Of course, £4,500 is a lot of money to spend upfront; but a battery will soon pay for itself. If your electricity bill is about £2,000 per year and you can cut it to £0 by adding a battery to your solar panels, then the cost of the battery and installation will be paid off in just a couple of years – and then provide free electricity for years. It will also reduce the number of years your solar panels will take to pay for themselves.
To find out more about the size of the battery and solar PV system your home needs to set yourself free from electricity bills, fill in our quick form above, and we’ll ask our hand-picked local providers to get in touch.