Solar Panel Battery
Are you wondering if you should include a home battery with your solar PV panel installation? In this comprehensive guide, the experts at NimbleFins dive into the fundamentals of solar panel batteries, explaining why solar panel systems should include a battery, how a solar battery storage system works, how long solar batteries last and how to determine what size battery you need. Our experts have also researched and ranked the best solar panel batteries, considering storage capacity, depth of discharge, battery cycles, warranty and price. We'll also address the financial aspects, including how much solar panel batteries cost, how much money you can save with a battery and whether or not solar batteries are worth it. By the end of this article, you'll have a clear understanding of how solar batteries can help you get the most out of your solar panel system.
- Why solar panel systems should include a battery
- Solar Battery Cost
- Best Solar Battery
- How does a solar battery storage system work?
- How much can I save with a solar battery?
- Are solar batteries worth it?
The simple reason why solar panel systems should include a solar battery
Peak solar PV generation typically occurs in the middle of the day, from roughly 11 am to 4 pm. But peak household electricity demand occurs at different times of the day, typically around 8am - 10am and again from 5pm - 8pm—when the sun is not shining strongly (if at all!).
Due to this large mismatch (i.e. solar produces the most energy in the middle of the day when it's typically not as needed by a home), a battery can be super useful. A home battery can store up excess unused energy during the sunny hours of the day, when solar panels are kicking out lots of free energy that can't be used up right away by the home. Then, later in the day, this 'free energy' can be drawn from the battery so your home solar panel system can still power your home during peak demand in the evening (even when the sun is down).
Additionally, a battery can be charged overnight on cheap electricity from the grid using a special Time of Use tariff—this cheap grid electricity can help power the home during the morning peak demand hours (e.g. 8am - 10am) before the sun kicks in. But how much do batteries cost?
Solar Battery Cost
A typical home battery installed within a solar panel system costs roughly £500 per kWh, or £2,500 for a 5kWh battery. But batteries prices can vary depending on the quality of the battery, the technology, the installer, and more. And larger installation companies periodically offer discounts (e.g. we recently saw 15% off from one national solar installer, Egg), which can help bring prices down.
We compared solar panel proposals from three national solar panel installers, and teased out costs for a number of popular solar batteries. We found prices range from around £400 per kWh up to £730 per kWh of storage, with the average falling at £519 per kWh:
| Average Solar Home Battery Costs | Price per kWh |
|---|---|
| Low End | £396 |
| High End | £730 |
| Average | £519 |
Here are specific prices we were quoted in 2024 for a range of solar batteries. As you can see, the larger batteries cost more, due to their larger storage capacity. These prices include installation, and were quoted as part of a solar panel system installation.
| Solar Battery Costs | Power | Installer Quoted Price | Per kWh Cost |
|---|---|---|---|
| GivEnergy LiFePO4 Gen 2 | 5.2kWh | £2,150 | £413 |
| PureStorage II | 5kWh | £2,150 | £430 |
| Pylon US5000 | 4.8kWh | £1,900 | £396 |
| SolarEdge Home Battery^ | 9.7kWh | £6,940 | £715 |
| Solax Triple Power^ | 5.8kWh | £4,232 | £730 |
| SunSynk | 5.32kWh | £2,250 | £423 |
| Tesla Powerwall^ | 13.5kWh | £7,062 | £523 |
| Average | £519 |
^Note about discounts: the SolarEdge, Solax and Tesla battery prices reflect a 15% discount, as offered to us by the installer at time of quote.
Note about installers disclosing battery prices: when you get a solar quote from an installer, they probably won't break down the cost of the battery in the formal quote you receive. But, you can ask what the battery cost is when you speak with them and get your solar panel quote—most of them will arrange a Zoom call as the first point of contact. We think it's good to find out how much they're charging separately for the battery and panels. But keep in mind that if you then Google the cost of the battery, you'll probably see lower prices online—that's because those online prices are typically for the supply of the battery only, without installation. The higher price being charged by the installer includes the installation costs as well.
Cost of Solar Panels and Battery
The cost of solar panels and a battery will vary primarily by installer, manufacturer and size of the system (i.e. solar generation and battery storage capacity). Below is a list of real-life quotes we received from three national installers for a range of system sizes; you can look through this to give you an idea of how much a solar panel system with a battery might cost today. As you can see, prices started from £9,000 for 2.25kW solar power and a 5kWh battery and went up to £11,866 for a system with 3.9kW solar power and a larger 10kWh battery.
| Quoted costs of solar panels + battery | Number of panels | Total solar power | Battery capacity | Quoted price |
|---|---|---|---|---|
| System 1 | 5 | 2.25kW | 5kWh | £9,000 |
| System 2 | 9 | 3.9kW | 5.8kWh | £9,307 |
| System 3 | 9 | 3.9kW | 10kWh | £11,866 |
| System 4 | 10 | 3.95kW | 4.8kWh | £8,735 |
| System 5 | 10 | 4.1kW | 5.2kWh | £9,628 |
| System 6 | 10 | 4.3kW | 5kWh | £10,124 |
Curious about the real cost of solar panels and a battery? Read our in-depth article on the cost of solar panels that provides factors that influence pricing and the financial implications of going solar. The experts at NimbleFins have considered variables from installer variations to manufacturer differences and system size considerations.
Best Solar Battery
When deciding which solar battery is best for you, take a look at these metrics to start off:
- Storage Capacity: The most common battery size we've seen is around 5kWh of storage capability. This is a sensible size for most UK homes, as median daily electricity usage is around 8kWh (2,900kWh per year median household electricity consumption divided by 365 days per year equals 8kWh of daily electricity use)
- Depth of Discharge: Typically between 80-90% (the higher, the better)
- Battery Cycles: Typically 6,000 to 10,000
- Warranty: Mostly, this will be listed in years, but some manufacturers refer to cycles
- Price: Costs rise with storage capacity (in kWh); also keep in mind the average cost is roughly £520 per kWh (~£2,500 for a 5kWh battery)
Below, we've compared depth of discharge and warranties of some popular UK home batteries that are used by a few of the larger, national solar panel installation companies. If you'd like us to expand this table with other battery manufacturers, please let us know in the comments section at the bottom of this article.
In the table below, we include more information on the best batteries to help you compare them, including storage capacity and where they're made.
| Best Batteries | Battery storage | Warranty | Cycles | Depth of Discharge | Country of Origin | Note |
|---|---|---|---|---|---|---|
| GivEnergy LiFePO4 Giv-Bat | 5.2kWh | 52MWh / 12 years | unlimited cycles over 12 years | 80% | Headquartered in Stoke on Trent in the UK and manufactured in China (using their own factories) | premium |
| PureStorage II | 5kWh | 10,000 cycles (equiv to 27 years of 1 full cycle/day) | 10,000 | 90% | Designed and Developed in the UK (‘All-in-One’ PureStorage II is also built in the UK) | ultra |
| Pylon US5000 | 4.8kWh | 10 years | 6,000 | 95% | China | value |
| SolarEdge Home Battery 400V | 9.7 kWh | 10 years | n/a | up to 94.5% | Various (7 manufacturing facilities e.g. China, South Korea, Israel, etc.) | premium; known for shaded systems |
| SolaX Triple Power | 5.8 kWh | 10 years | 6,000 | 90% | China | premium |
| SunSynk | 5.32kWh | 10 years | 6,000 | 80% | China | value |
| Tesla Powerwall | 13.5kWh | 10 years | unlimited cycles over 10 years | 90% | ultra |
If you're learning about equipment, you may also want to read our related article on the Best Solar Panels.
How does a solar battery storage system work?
A solar battery can enable you to use up to 100% of the solar power you generate from your solar panels (or close to it...).
The battery storage system works by storing the excess solar power generation that is not used real-time by a home. Instead of letting that unused energy go to waste (or sold back to the grid at super low SEG rates), it can be stored in a home battery for use later in the day, so you aren't buying (as much) energy from the grid when the sun is down.
Where is the solar battery installed in my home?
It depends! Ideally, a battery is installed as close as possible to the incoming supply (meter) and your distribution panel (fuseboard) at ground level. Some batteries (e.g. Tesla Powerwall and Puredrive) are fully weatherproof, so they can be installed on an outside wall of your home. Otherwise, the battery can be placed in a garage, or even in loft space in the attic. A sheltered, not too hot or cold, location is best. Your solar panel installer will discuss the options available for the best solar and battery installation for your unique home.
Keep in mind that all batteries produce a gentle hum during operation, because they contain a pump and a fan. But a battery shouldn't be any noisier than a refrigerator.
What size solar battery do I need?
A 5kWh home battery is good for around 2,000 kWh/year of electricity to use in your home. The typical (median) home uses around 2,900 kWh of electricity per year, so in most cases a 5kWh battery would be sufficient.
But it really depends on the amount of electricity the home consumes and the size of the solar panel system.
Keep in mind that a larger home battery enables charging from solar panels AND from the grid during the night using a cheap nighttime Time of Use tariff or EV tariff.
The optional home battery for solar does add thousands of pounds to the all-in cost, but enables storage of solar power for use later in the day. This can really be worth the money if you aren't home and using all of the solar-powered electricity as and when it's produced. Why? If you don't use or store unused solar energy in a home battery, that energy is either just lost or it's sent back to the grid earning you poor rates.
That is, you can 'sell' solar power back to the grid, but you can only earn very little, if anything—SEG rates mean you can sell energy back to the grid for only 3-4p/kWh, which is far less than the cost you pay to buy energy from the grid if you need to at some point in the day. Generally speaking, every evening you'd rather be able to draw on stored solar energy from your home battery than draw expensive electricity from the grid.
How long do solar batteries last?
Most solar batteries have a 10-year warranty, but the expert installers we've spoken to tell us they expect solar panel batteries to last 15-16 years.
How long a solar panel battery lasts depends largely on the number of cycles a battery is capable of in its life cycle. For example, a SunSynk 5.32kWh (as used by Effective Home) is capable of 6000 Cycles @ 80% Depth of Discharge (DOD). If the battery is charged up once per day, 6,000 cycles equates to 16.4 years (i.e. 6,000 divided by 365 days per year = 16.4 years).
The PureDrive PureStorage II Hybrid is good for 10,000 cycles, which translates into a whopping 27 years.
How much can I save with a solar battery?
Is a home battery actually cost efficient? How much money can one save you? To get a rough idea of this, we've calculated the 'Potential Annual Electricity Savings' in the table below, which is the estimated annual cost of buying the amount of electricity that can be stored in the battery each day.
In other words, if you could fill up the battery for free using solar power each day, and then you used this power in your home throughout the rest of the day, how much money would you avoid paying for National Grid electricity? As you can see in the table below, a 5.2 kWh battery could save roughly £372 in grid electricity, a 9.7 kWh battery could potentially save £820 and a large 13.5 kWh battery could save over £1,000 a year in electricity costs. Of course, this assumes you can use a full battery's worth of electricity each day (note, a typical home uses around 8kWh/day of electricity, so e.g. a 13.5kWh Tesla Powerwall would be excessive for a typical household's needs).
| Home Battery Annual Savings | Capacity | Depth of Discharge | Potential Annual Electricity Savings |
|---|---|---|---|
| GivEnergy LiFePO4 Gen 2 | 5.2kWh | 80% | £372 |
| PureStorage II | 5kWh | 90% | £402 |
| Pylon US5000 | 4.8kWh | 95% | £408 |
| SolarEdge Home Battery^ | 9.7kWh | 94.5% | £820 |
| Solax Triple Power^ | 5.8kWh | 90% | £467 |
| SunSynk | 5.32kWh | 80% | £381 |
| Tesla Powerwall^ | 13.5kWh | 90% | £1,087 |
In the calculations above, we assumed you lose a % of solar-generated energy based on the depth of discharge estimates for each battery, because home batteries are not 100% efficient (and if you want to keep some power in the battery at all times and never drain it totally to ensure power during black or brown outs, the savings figures would be even less.). We also assumed a cost of electricity of 24.5p/kWh.
Ok, so the table above shows you can potentially save hundreds of pounds a year using a home battery with solar. That still doesn't tell us if home batteries are worth the expense—because let's face it, they're expensive.
Are solar batteries worth it?
Here's a really back-of-the-envelope calculation to decide if a home battery is worth the cost, using purchase price quotes received from three large, national installers. The NimbleFins team used these prices and the potential savings figures in the previous table to estimate Years to Pay Back the cost of the battery. This can give an idea of whether or not the battery is worth the cost to you.
Here are our calculations, showing that typical battery pack back occurs in between 4 and 8 years. This assumes you can fully use and discharge the battery every day (limited by each battery's respective Depth of Discharge %, of course).
| Battery Pay Back | Capacity | Installer Quoted Price | Depth of Discharge | Potential Annual Electricity Savings | Est. Years to Pay Back |
|---|---|---|---|---|---|
| Pylon US5000 | 4.8kWh | £1,900 | 95% | £464 | 4.1 |
| PureStorage II | 5kWh | £2,150 | 90% | £458 | 4.7 |
| GivEnergy LiFePO4 Gen 2 | 5.2kWh | £2,150 | 80% | £424 | 5.1 |
| SunSynk | 5.32kWh | £2,250 | 80% | £433 | 5.2 |
| Tesla Powerwall^ | 13.5kWh | £7,062 | 90% | £1,237 | 5.7 |
| SolarEdge Home Battery^ | 9.7kWh | £6,940 | 94.5% | £933 | 7.4 |
| Solax Triple Power^ | 5.8kWh | £4,232 | 90% | £532 | 8.0 |
Keep in mind that the median household electricity consumption is 8kWh/day, so many homes wouldn't be able to get full use out of the larger 10kWh batteries. If you can't use the battery in full each day, you effectively increase the pay back time.
Will a home battery last this long? Home batteries have become more reliable, but let's see how long the manufacturers are willing to guarantee their products. Most home batteries are guaranteed for 10 years (e.g. Tesla Powerwall, SolarEdge, SunSynk); GivEnergy guarantees their battery for 12 years. So a battery should last long enough to pay back its initial cost in these scenarios. But if you don't make full use of the battery on a daily basis, it may be more difficult to get your money's worth before the end of the warranty term.
Can I add a solar panel battery later?
Yes, you can add a solar panel battery to a solar panel system at a later date, or you can even add another battery later if you start with just one and decide you could benefit from adding a second one (most popular batteries are modular, meaning you can stack multiple batteries together to increase your energy storage capacity).
But, there will be extra costs involved overall if you choose to split the PV panel installation and the battery installation. In that case, you'll need to hire installers and electricians twice. And you'll need to pay to have the system reconfigured and reprogrammed.
If you're considering buying a solar system now but adding the battery at a later date (perhaps to reduce the upfront costs of buying the solar PV panel system), be sure to tell your installer that you may add a battery later. Why? So they can install a (slightly more expensive) battery-ready hybrid inverter with your initial solar panel setup. That'll save you the cost of buying a brand new one when you add the battery later. A hybrid inverter costs roughly £200 - £300 more than a regular inverter, FYI.
Note on VAT of solar batteries: It used to be that there was a tax advantage to including the battery in the initial install (when they'd be subject to 0% VAT), and a tax disadvantage to installing them later, separately from the panels (when they were charged 5% VAT). However, the law has changed and the 0% VAT treatment is now the same, regardless of if you install independently or with solar panels.
From 1 February 2024, electrical storage batteries installed in residential accommodation count as zero-rate (i.e. 0% VAT) installations until 31 March 2027, including:
- the retrofitting of a battery for storing electricity generated by one or more of the microgeneration systems including solar panels, wind turbines and water turbines
- batteries installed as part of the installation of a microgeneration system
- the installation of a standalone battery for storing electricity from the grid (the mains electricity)
- the installation of a battery for storing electricity from one or more of the microgeneration systems and from the grid
For further information about the VAT treatment of solar panels and batteries, check out the Gov Solar Battery VAT site.
Methodology
Battery prices can be a bit of a mystery, as installers typically give you one quote for all of the equipment—they tend not to itemise the costs of the individual components. But they'll tell you if you ask specifically. So we asked some of the big national installers for solar panel system quotes and teased out the prices of the batteries. Prices will vary from company to company; these figures represent the sample quotes we were provided in 2024.