How much does a solar battery cost?

How much does a solar battery cost by size?

A home battery cost £1,300 per kWh at the median if it held under 6 kWh, £890 at 6 to 11 kWh and £630 at 11 to 30 kWh, installed, in 2025-26 [1]. The Department for Energy Security and Net Zero (DESNZ) publishes these figures from the Microgeneration Certification Scheme (MCS) database. They are based on 42,903 of the 44,033 MCS-certified batteries fitted to existing homes across the UK in 2025-26, after DESNZ removed invalid cost and capacity records, and include installation and VAT where it applied [1].

The median is the middle price, so half of the batteries cost more per kWh and half cost less. DESNZ does not split batteries added to existing solar panels from those fitted with new panels, and its costs leave out the panels themselves [1].

What does a 5 kWh, 10 kWh or 15 kWh battery cost?

At the 2025-26 median rates, a 5 kWh battery works out at about £6,500, a 10 kWh battery about £8,900 and a 15 kWh battery about £9,500, by our calculation [1]. DESNZ records prices per kWh of nominal capacity for each size band, not for each size, so these are illustrations, not prices anyone was quoted for those exact batteries.

The Energy Saving Trust's figure for a 5 kWh battery is lower: around £4,600, and its battery page gives £1,500 to £10,000 depending on the type and size of battery, without a date or basis for either figure [2]. Its storing energy page says battery storage systems typically cost around £5,000 to £8,000, also without a basis [3]. Because the Trust does not say how its estimate was made, we cannot say whether it or our calculation is closer to what a particular 5 kWh battery costs today; a written quote settles it for your home.

Is a 10kW battery the same as a 10 kWh battery?

Not necessarily: kWh is how much a battery stores, and kW is how fast it charges or discharges. If a listing uses "10kW" to describe storage capacity, its units are unclear or wrong, so check the datasheet for both figures, and do the same before comparing a 5kW solar battery price with the figures here. Tesla's Powerwall 3, for example, stores 13.5 kWh usable and charges at up to 5 kW [7]. DESNZ prices batteries by kWh of nominal capacity [1].

Nominal capacity is the battery's rated total; usable capacity is what you can draw on, and it can be lower. On Sigenergy's datasheet, usable capacity is about 3 per cent below total capacity (our calculation from 8.76 and 9.04 kWh) [9]; the other two examples below publish only usable capacity. More sizes are compared in what size solar battery do I need.

What makes a battery quote cost more?

Price per kWh differs by size: in 2025-26 the median cost per kWh for batteries of 11 to 30 kWh was about half that for batteries under 6 kWh [1]. At our illustrative figures above, a bigger battery still costs more in total. Other things a quote may include:

• The inverter. Some batteries connect through a separate compatible inverter, such as Fox ESS's EP12 Plus, whose datasheet lists the Fox ESS inverter series it works with [10]; others carry their own, such as Enphase's AC-coupled IQ Battery 5P [11].
• Backup in a power cut. Some batteries need an extra gateway or controller to run the house in a power cut, such as Tesla's Powerwall 3 and Enphase's IQ Battery 5P [7][11]. Tesla's UK order page lists Powerwall 3 at £5,000 without its gateway and £5,975 with it, excluding VAT, delivery, installation and other costs and fees; the version without the gateway also needs a Tesla Remote Meter, not included in that price [8]. Backup wiring also needs isolation from the grid and may need extra testing [5].
• Network approval. If the battery and any panels together can put out more than 16 amps per phase (the MCS standard's example is a 3 kW solar system and a 3 kW battery on one single-phase supply), the installer follows the G99 process, full or fast-track, instead of G98, and handles the notification to the network operator [5]. See solar panel installation.
• Buying the battery without installation. A battery installed in a home is zero-rated for VAT until 31 March 2027, including one added to existing panels or with no panels at all; bought without installation, it is charged at the standard rate, currently 20 per cent [4]. From 1 April 2027 the installed rate is due to be 5 per cent [4].

MCS guidance says a quote should show a cost breakdown, the price before VAT and the VAT, and a contract should state the battery's power rating and storage capacity [6]. Our suggestion: compare quotes with each other on cost per kWh of usable capacity where the datasheet gives it. To compare a quote with the DESNZ figures on this page, divide by nominal capacity instead, because that is the basis DESNZ uses.

Is a battery cheaper with new solar panels?

The Energy Saving Trust says you should be able to save money by fitting a battery at the same time as panels, because the installer is already on site [2]. The DESNZ figures cannot show the difference: their costs leave out the panels and they do not separate the two cases [1]. Package prices are on solar panels with or without a battery, and adding one later is on adding a battery to existing solar.

Are battery prices falling?

Not in every size band. Between 2024-25 and 2025-26 the median cost per kWh rose for the smallest and largest batteries and fell slightly in the middle band, as the table above shows [1]. These are cash prices, not adjusted for inflation, and DESNZ gives no reason for the changes. The number of batteries in the sample rose from 23,896 to 42,903 [1].

Whether a battery pays back is a separate question: the Energy Saving Trust notes the savings "won't always be enough on their own to justify the cost" [2]. Is a solar battery worth it weighs it up, and what size battery do I need helps pick a size.