Do UK solar panels generate enough to bother storing? Will your battery be stolen?
Many homes that use solar panels also make use of solar battery storage.
Put simply, solar batteries allow you to store the excess energy your panels generate and don't use during the day.
In fact, without a battery around 50% of the energy your panels generate goes unused.
Batteries effectively revolutionise solar, allowing you to use the energy your panels generate, whatever the time of day.
They also allow you to store energy from the grid when it's at its cheapest off-peak times and sell your energy when the prices are high.
But what exactly can you expect from a solar battery? How do they work? And are they always worth the investment?
Let’s explore...
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Solar Battery Storage Key Points:
A solar battery allows you to consume more of the energy generated from your solar panels.
It allows you to store excess energy for use in the evenings - as opposed to drawing it from the grid.
It ultimately reduces your reliance on the National Grid.
It also has the potential to reduce your carbon footprint by reducing your reliance on electricity from the National Grid, which is not always renewable, unlike your panels that produce 100% clean electricity.
It allows you to store energy from the grid when it's at its cheapest.
It provides you with a reliable power backup in the event of a blackout.
It allows you to avoid giving more of your hard-earned money to energy companies.
Battery vs No Battery Comparison Table
The table below shows a brief comparison between having solar with no battery storage vs having solar with battery storage.
Solar With No Battery | Solar With Battery | |
Can you use solar energy during the day? | Yes | Yes |
Can you use solar energy in the evening? | No | Yes |
Can you store energy from the grid when it's the cheapest? | No | Yes |
Provides reliable power backup in the event of a blackout? | No | Yes |
What's the Problem with Having No Battery Storage?
The peak electricity generation with solar will coincide with the peak sunlight hours e.g. typically between 11 am and 2 pm in the UK.
However, the major problem is that most households are not at home during these times meaning that they are unable to utilise much of the energy (unless they have a solar battery that is).
For reference, the average 3-bed home with a solar system that consists of 10 panels will generate around 7.9kWh of electricity daily.
Yet, according to the Home Office, as of 2023, only around 19% of people work from home 5 days a week.
So, if these households each use a computer for around 7 hours and their dishwasher, they would consume around 7kWh of electricity, that's 88% of the total energy generated via solar.
However, if you are like the other 81% of the population and do not work from home, it means you won't be home to consume most of that free solar energy you've generated. Instead, you will be forced to draw more expensive electricity from the National Grid.
Equally, although your household may not be using the energy as it’s being generated, if you’re selling your energy back to the grid through the day for a standard rate of 5p per kWh, you’ll then be buying electricity back from your provider at a standard rate of 36p per kWh later in the evening when you pop in that round of washing, turn the oven on for your casserole, watch the Corrie omnibus while you wait with lamps on in every room for “mood lighting”.
Explore a Battery Storage Case Study: Check out an insightful Q&A session featured in one of our detailed case studies on battery storage. Hear directly from a Heatable customer in the UK and gain valuable perspectives on their experience here.
The image above features a Tesla Powerwall 3 installation performed by our team of Tesla-certified installers at Heatable.
What is a Solar Battery?
When sunlight makes contact with the surface of a solar panel, direct current (DC) of electricity is generated.
This current can then head straight to an inverter (needed to convert DC to AC for domestic use) or alternatively, it can be directed to a solar battery for storage.
On average, solar batteries have a usable capacity of somewhere between 4kWh and 9kWh.
Usable capacity refers to the amount of energy that can be stored and used from a battery without damaging it or reducing its lifespan.
It is essentially a measure of how much energy can be discharged from the battery without causing any major battery wear and tear.
For example, if a solar battery has a total capacity of 10 kWh and a usable capacity of 8 kWh, it means that 8 kWh of energy can be safely used without damaging the battery or reducing its lifespan. The remaining 2 kWh are held in reserve to ensure the longevity of the battery.
Usable capacity is an important factor to consider when choosing a battery for a solar system since it determines how much energy can be stored and used during periods of low solar production or high energy demand.
A higher usable capacity means that more energy can be stored and used, providing greater energy independence and potential cost savings over time.
Considering that the average UK household uses about 8kWh of electricity a day, most solar batteries can be stored somewhere in the region of half a day to a full day’s use of electricity.
Once you decide to use the solar battery’s energy, it will head to the inverter (still as DC) where it will be converted into AC current, making it suitable for domestic use or for selling back to the National Grid.
How Much Are Solar Batteries?
The cost of a solar battery depends on the brand, size, warranty, and type of battery materials used.
Typically, a new solar battery will cost somewhere in the region of £2,000 to £6,000.
For the most part, the more storage capacity a solar battery offers and the higher its quality, the more expensive it will be.
A solar battery is an additional cost to your solar installation but it means you can consume more of the energy your solar panels generate since it allows you to store solar energy for use in the evenings.
Although a solar battery is an additional cost, it is undoubtedly worth it in the long term.
Additionally, battery storage is a great way to reduce your carbon footprint and be greener, since this energy is generated from your panels as opposed to coming from the National Grid.
So if being greener is a major priority for you, a solar battery is undoubtedly worth it.
Still, learning about solar? Check out our guides on how many solar panels you need and how solar car charging works.
How Long Do Solar Batteries Last?
The average solar battery is not likely to be a one-time purchase.
That’s because the average solar battery lasts for around 10-15 years, which is close to half the life expectancy of the average solar panel array.
As a result, if you’ve had a solar system installed recently (or plan to in the future), you’d probably need to buy a solar battery twice during your solar system’s total lifespan.
Of course, like any new type of technology, prices will likely drop by then but for now, we can only assume the future costs based on today's prices.
PS You can check the average costs of solar panels here.
Types of Solar Batteries in the UK
Another consideration worth looking at is the two primary types of solar batteries, namely, lead-acid and lithium-ion solar batteries.
Lead-Acid Solar Batteries (Old School)
Lead-acid batteries are the more old-school of the two.
These guys have been around storing energy for centuries but you might know them more commonly as being the power source for golf buggies and car jump-starters.
Tried, tested and trusted, these guys are the safe and reliable option for solar energy storage which often comes in at the lower end of the pricing scale.
Having said that, they are now largely viewed as outdated and aren’t necessarily the most efficient option for optimising your storage potential compared to more modern solutions.
The average 4kWh lead-acid solar battery costs about £2,000. It would offer about 1,800 lifecycles.
These cycles are essentially the number of times a solar battery is used.
If it’s used daily then 1,800 lifecycles = a life expectancy of 1,800 days or just shy of five years, but if you used it every second day, you’d be more likely to get ten years out of it.
Beyond that, lead-acid batteries rated at 4kWh have a depth of discharge or DoD of about 50%, which is significantly less than that of their lithium-ion counterparts.
Overall, the cost per kWh per cycle of these batteries stands at around £0.56, again if you’re going with a 4kWh product.
Lithium-Ion Solar Batteries (New & Improved)
Lithium-ion batteries are the gold standard when it comes to battery storage.
Lithium-ion batteries are more compact, lightweight alternatives with higher performance ratings, faster charging speeds and a higher storage capacity per square centimetre.
Yes, that means they’re more expensive but they often come with much longer warranty periods compared to lead-acid batteries meaning, although the initial outlay is higher, you’re definitely getting more bang for your buck.
Now looking at lithium-ion solar batteries, the average 4kWh product would cost about £4,000, twice as much as an average 4kWh lead-acid solar battery.
However, a 4kWh lithium-ion solar battery would offer around 4,000 lifecycles (a lifespan of around 10-11 years) and a DoD of 90%.
Moreover, the cost per kWh per cycle of an average 4kWh lithium-ion solar battery would be approximately £0.28.
Disadvantages of Solar Batteries
Like anything, there are some disadvantages to solar battery storage, here are the major two:
Solar Batteries Increase Initial Solar Outlay
Having to buy a solar battery is an added expense to the overall cost of your solar array.
Even though a solar battery has a number of advantages and allows you to consume more of the energy your panels generate, some may claim that the added expense of a battery is not financially sensible.
However that all really depends on the break-even point and calculations you employ.
Requires More Space
The size of the solar battery's dimensions usually depends on the storage capacity, but they are typically the size of a household appliance.
That means that you will need some space to house the battery and connections.
Many people decide to install and dedicate a space on their garage wall to their solar battery storage as this is a comfortable place and helps to protect the battery from external elements like moisture and rain.
Can You Sell Energy with a Solar Battery?
Some homeowners use solar batteries as part of an effort to sell energy back to the grid.
A solar battery could be used purely for this purpose to store excess solar energy before selling it to an energy provider.
However, you should be aware that not all energy providers who purchase solar electricity will accept it if it’s been stored in a battery.
Out of the most predominant SEG licensees and other energy providers offering to purchase solar energy from households at least six will accept solar electricity which is stored in a solar battery.
However, you should also be aware that it typically makes more financial sense to use your energy rather than sell it where possible.
The reason for this is that electricity currently costs 34p per kWh, and the best UK-wide SEG rate is 12p per kWh.
Quality of the Solar Battery
A range of factors can shape how much money any given solar battery could save a household. Aside from their usable capacity, solar batteries will vary in overall quality.
Some will also wear down faster than others and solar batteries come with varying warranties.
For that reason, if you want to buy a solar battery, again it’s best to spend time shopping around before finding the right option for you.
Storing Electricity at the Right Times
One way of making the best of a solar battery is to keep energy stored so you can use it when electricity prices go up.
This of course would assume that your solar panel array won’t cover your full electricity needs and that you are still somewhat reliant on the national grid.
Here’s an example of how a household could have used stored electricity in a financially intelligent manner:
Let’s imagine a typical three-bedroom home which meets half of its electric needs through solar energy, with the other half reliant on the grid (we are not considering heating as we’ll assume this household uses natural gas heating).
Based on the above scenario, if in late September 2022, this property were to store electricity in a solar battery (when the cost of electricity was 28p per kWh), the stored energy would suddenly increase in value come October 1st.
That’s because electricity costs rose to 34p per kWh with the arrival of the new month. So, using that electricity in October would prove more financially helpful than it would have been in September.
Of course, with the abovementioned scenario, we knew that another energy price increase was coming.
Also, since solar batteries can generally only store electricity for several days, they would have only worked within a short window.
Nonetheless, you could still take a similar approach when it comes to peak electricity times.
These are times of the day when energy providers tend to charge more. With the right strategy, you could store energy in your solar battery one day and then use that energy to cover your electricity needs (or much of those needs) during peak electricity times the following day.
We have also reviewed the best solar panels and covered how long solar panels last in the UK.
Future Cost of Solar Batteries
As mentioned, the cost of solar batteries is set to come down in the near- to mid-future.
But when exactly, and by how much?
Given that the prices of metals have been on the rise lately (as seems to be the cost of everything), solar batteries are unlikely to see their prices fall until 2024 according to London-based analyst IHS Markit.
But when prices do begin to fall, there are reasons to hope that the years that follow will see a significant decline in cost.
After all, technological progress helped reduce the cost of solar panels by 82% from 2010 to 2020.
If that’s anything to go by, solar batteries may be significantly cheaper by the end of this decade.
Check our guide on debunking solar panel myths.
Are Solar Batteries Worth It? Conclusion
All in all, solar batteries offer a range of benefits, but whether or not it’s worth the cost would depend on your budget, preferences, and financial goals.
On the one hand, solar batteries offer a range of benefits such as reducing electricity bills and reducing your reliance on the National Grid.
They also allow you to reduce your carbon footprint, since electricity generated by solar is 100% green, it's always better to use it rather than electricity from the Grid which is generated by mixed sources.
Ultimately, whether a solar battery is worth it is a choice for you to make, but you don't need to make it alone, start your journey here.
Next Steps For Your Battery Journey:
When planning to install battery storage for your home, there are several important factors to consider. Make sure to refer to the following guides to help you make informed decisions:
To dive deeper into these topics, head over to our advice section, check out our YouTube channel for informative videos, or read a customer case study to see how others have benefited from their battery installation.
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