Solar battery storage is optional, although when buying a solar energy system, most will opt for a battery to store and use their power once the sun goes down. 

A solar battery can be a relatively inexpensive addition to any solar energy system, especially as you won’t pay 20% VAT which is a UK government policy. 

Plus, you’ll save money in the long run by using renewable energy to power your home whether the sun is out or not. 

Most systems will produce more energy than you can use during daylight hours, so if you spend a great deal of time at home during the day, you can utilise that power. 
 
But, if you need to leave the house for huge chunks of the day, then the power from your panels will either go to the grid for pennies or not get used. 

Hence storing that energy to keep the lights on when you are at home is a no brainer for most people. 
 
Our goal in this piece is to provide you with all the information you will ever need on battery storage, addressing all the questions we get asked in our years of experience.   

If you want to know something specific, just click on the ‘table of contents’ above.

What is a Solar Battery? 

Solar batteries enable you to use the energy you produce at any time, reducing your reliance on external energy sources.

Without a battery that energy has to be used immediately or is sold back to the grid.

This also has environmental advantages as you will be using that clean energy to power your home and not power from fossil fuels.  

They will usually come with battery management software to ensure they charge and discharge in the best way. 

This lengthens the life of a battery and ensures it is safe. 

If the battery doesn’t have its own management system, then the inverter which will be supplying its charge, will. 

Most batteries used for residential solar installs are currently Lithium-Ion.

Lithium-Ion batteries

Lithium-ion batteries have become the most cost-effective solution for home energy storage due to the explosion in electric vehicles. The tech needed to develop a good electric car battery has benefited the domestic energy market too.

Why are Lithium-ion batteries so good for solar?

Low maintenance – with a good battery management system even a cheap Lithium-Ion battery will last for over 6000 charging cycles.

Low Price – while the batteries we put in our remote controls seems to be going up, EV production has brought the price of Lithium-Ion batteries down by over 97% in the last 30 years!

Higher battery energy density – this means they can hold way more energy than a lead acid battery – those are the ones in your remote.

High Depth of Discharge or Efficiency – this is how much of the stored energy you can use before the battery stops working properly. Which means less recharging.

Longer Lifespan – most companies will guarantee them for at least 10 years.

Do you need solar battery storage?

You don’t need battery storage for your solar panels to work, but the savings from having a battery is a no brainer for most people.

If you want to you your self-generated solar energy in the evening, you are going to need battery storage.

Having solar panels without any battery storage is still a great idea, but you will be wasting a fair bit of energy.

Say you aren’t in your home much during the day and, at the height of summer, your panels are producing oodles of energy every hour.

Without batteries, the best you can do is sell that back to the grid via an SEG (Smart Export Guarantee) you have with your energy supplier.

The problem is that the demand for electricity is comparatively low during daytime, so the price you get per kWh can be as low as 1p.

So, for the 8 hours you’ve been at work a 4k system may earn you less than 32p.

If you had batteries, that electricity could be stored and used later in the day when demand is higher and, therefore, the price higher.

Using the batteries at those times would save you the 27p per kWh we are currently paying.

What Size Solar Battery Do You Need?

The size of the battery you use will be totally dependent on your home and the amount of electricity you use, but to give you an idea we will use averages.

Batteries come in a myriad of sizes, from 1 kWh to 13.5 kWh – and they’ll be available in bigger and smaller sizes before long as technology improves.

Type of Property	Size of Battery
One bedroom flat of bungalow	2 kWh
Two-bedroom terrace house	4 kWh
Three-bedroom semi-detached house	8 kWh
Four-bedroom detached house	9.5 kWh

Now, some companies recommend that you have twice as much storage as you have solar power generation, but this seems a waste as that means using 100% of the power you generate to fill batteries up, and you just wouldn’t do that.

For 2 kWh of battery storage, we would suggest a 3-kW peak system of panels, that way you can balance the electricity you use and still power the home during the day.

We’d use that kind of formula on all storage:

4 kWh battery = 3 kW system (8 panels)

5 kWh battery = 4 kW system (10 Panels)

6 kWh battery = 5 kW system (13 – 14 panels)

8 kWh battery = 6 kW system (15 – 16 panels)

Of course, you could also use your SEG to fill the batteries at night too, so you could easily add even more storage to your system.

How much does solar battery storage cost? 

Factors like brand name, the availability of materials and the quality of the build will affect the cost and with price dropping all the time it’s more likely to be between £400 – £500. 

This table is a very rough guide but, later on, we’ll take a look at a few different models more closely.

Searching for an average price on the internet the number comes up as £900 per kWh of storage capacity, but we think this is very high as none of the batteries we mention are anywhere near that.  

For instance, the Greenlinx 3.2 kWh is around £1500 while the Tesla Power Wall 2 13.5 kWh is around £9500 – both coming in under the average per kWh.  

If you were to include the cost of replacement batteries over the lifetime of your system, some would come in at £900 – but it’s not a ‘normal’ price. 

An average home will save £665 from a system that has battery storage, so it’s defo worth the cash.

Learn more about battery storage costs.

What should you take into consideration when choosing a solar battery? 

Although we would always recommend battery storage for a solar fast energy system, there are still a few things to consider before making that investment – like your energy usage, cost and space.

Energy usage

The biggest factor in deciding on whether you need a solar battery or not, is how and when you use your power.  

Most homes have peaks in their electricity use in the early morning and again at teatime.  
 
Take, for instance, mornings when people are having breakfast, getting ready for the day using hair dryers etc, and generally plugging stuff in.  

That’s a big spike in energy use and, depending on how early you rise or what time of year it is, you may not be getting the best yield from your panels.  

However, when you are at work or out of the house during the day, your panels are working at their peak with no one home to use the energy.  

Now, that doesn’t mean you have to get batteries, you could easily sign up for the best SEG you can get your hands on and earn from your panels.  

Doing that would certainly reduce what you spend on energy and that is always a good thing.  

However, if you had battery storage you could save all that extra energy for when you need it in the evenings, night and early morning.  

The thing you must look at is: Am I getting a return on my investment if I get batteries?  

That’s a question only you can answer, but we would add that the vast majority of our customers express a preference for storage.  

Cost

Which brings us neatly to the next consideration, cost.  

When choosing a solar battery, you may want to consider if it’s worth the outlay.  

9 times out of 10 it is, especially in the UK where the winter days are so short.  

However, solar batteries come in a multitude of sizes, models and costs.  

There’s no point blowing 10 grand on a 13.5 kWh Tesla Powerwall 2, if you only have 4 panels on your roof with a peak output of 1.6kW.  

Solar batteries start from as little as £1000 and can be as expensive as the aforementioned Tesla Powerwall 2. 

Space

We’ve seen space mentioned as a factor in getting batteries, but we don’t feel it’s that much of an issue these days.  

Batteries are chunky items, even the small ones will take up about a cubic metre, but most homes have room in the loft, garage and or spare bedroom.  

If you don’t have room in the house, most companies will offer a free standing, waterproof cabinet that can be placed outside.  

Understanding specifications for solar batteries 

When you are researching batteries, you’ll be coming across manuals and tech specs that are just plain confusing. 

So, let’s see if we can demystify a few of the phrases you’ll see.  

Depth of discharge – this merely refers to how much of the power the battery can store you can actually use. Some batteries can be irreversibly damaged if they lose 100% of their charge, your battery management system will control this.  

As an example, if your battery has a 4kWh storage capacity, but a 90% depth of discharge, it means you have 3.6kWh available to use.

Operating Temperature – all batteries have a perfect operating temperature but the good thing about Lithium-Ion batteries is that they operate very well in both high and low temperatures. 

Now, that doesn’t mean you can sit your battery on the hob or throw it in a freezer, they do have a ‘perfect’ operating temperature and deviating from it will affect the battery’s performance.  

If the battery drops to an extremely cold temperature, it will struggle to charge but will still provide power – if it gets too hot it could overheat and be subject to thermal runaway.  

All that said, the UK’s weather is a fair temperature, so your battery will perform well for most of its life.

Lifespan – a battery’s lifespan isn’t measured in years or months, but in charge/discharge cycles.  

The battery management system connected to your system will strive to charge and discharge your battery at an ideal rate to prolong the life of the unit.

As mentioned above, extreme temperatures can reduce the number of cycles the battery can do so it’s best to keep all storage in a cool, dry place.  

Solar batteries generally have lifecycles of between 6000 and 10,000 – which usually equates to between 10 and 15 years in an average, domestic solar system.  

Could I have more than one solar battery? 

You certainly can have more than one solar battery, in fact, you can have as many as your heart desires – but your system will dictate the actual number.  

Some manufacturers will make batteries that can be daisy chained or connected, in multiples, to the inverter. 

But inverters will have a limit on how many batteries they can charge and, if you don’t have the means to charge to batteries there is no point having them.  
 
If you are looking for a lot of battery storage you will have to make a decision on whether you buy 1 or 2 batteries with a huge amount of storage, or lots of little batteries.  

For us it’s the ‘many little ones’ option that way, if anything goes wrong with one battery, you can replace that and not have to shell out huge amounts for a big battery.  

How much can you save with solar battery storage? 

Well, we have kind of answered that in the previous section, and the experts would say around an extra 30% … but let’s look in more detail as each system will be different. 
 
Also, there are more ways than one to make those savings. 

Saving on Electric with Solar batteries

The most obvious way to save money with solar storage is by filling up the batteries using your solar panels and then using the energy after the sun goes down. 

Most domestic systems will easily fill 6kWh batteries up during the day and still power the house – based on the ‘out all day, in at night’ model.  

Let’s say your electricity is 27p per kWh in the evening, your batteries are going to save you £2.40 a day. 

Doesn’t sound like much per day, but that certainly builds up into a substantial pot of cash over a year.

Saving electricity with Solar Batteries and SEG (Smart Export Guarantee) 

This is where you can save money, make money AND power the home.  

SEGs come in many shapes and sizes but a few companies now offer tariffs that will allow you to charge your batteries at a cheap rate and sell the energy back at peak times. 

Sounds a bit too good to be true, doesn’t it?  

The truth of the matter is the grid produces power 24 hours a day, 7 days a week.  

You can’t just turn a coal or oil-fired PowerStation off and on and will, so they are kept running during the night and the grid companies pay the energy suppliers to take it off their hands. 

That means they can give you a very cheap rate at nighttime – this used to be called Economy 7 and various other things.  

Traditionally used to charge up storage heaters, you can now use these tariffs to charge your batteries – usually for around 9p per kWh.  

Fill your 6kWh of battery storage up for 54p and then save yourself 27p per kWh using that power at peak times.  

You can also sell that energy back to the grid for as much as 29.97p per kWh (Octopus Flex). 

We’re not going to do the maths for you here, as rates vary from area to area, but you can clearly see it’s a great way to save money.  

Choosing the best SEG tariff for Solar Batteries 

There are 2 ways of looking at this, and multiple tariffs to choose from when you are looking for a suitable SEG.  

There are SEGs that give a great export rate but don’t include energy stored in batteries, so you must work out if your panels will help you make the cash. 

There are other SEGs that include stored energy but may not give good rates on either imported or exported energy.  

We’ve made a table here that shows you some of the variations.

	Octopus	Scottish Power	OVO	E.ON	Utility Warehouse
Name	Agile	SmartGen+	OVO SEG	Next Export	Standard
Rate	0 to 35p per kWh	15p	4p	3p	2p
Payment	Monthly	Half year	3 Months	Yearly	Unknown
Includes Battery Storage	Yes	Yes	Yes	No	No
MCS/Similar Certified	Yes	Yes	Yes	Yes	Yes

Learn more about SEG (Smart Export Guarantee) rates.

Can I sell the energy stored in my solar batteries to the grid?  

UK energy companies are obliged to offer you a feed in rate for your excess electricity – but not every company will accept power from battery storage

So, it really depends on which energy company you get your SEG with.

We listed some on our Choosing the best SEG tariff for Solar Batteries (link) header further up this blog.

How long does a solar battery last?

As a benchmark figure, Lithium-Ion batteries should last between 5 and 15 years, but a badly managed battery will have trouble making it to the 5 year mark.

Solar Batteries have different lifespans depending on what make they are, how much charge they store and, of course, how they are used.

The average solar battery, almost always Lithium Ion, will have 6000 lifecycles – meaning it will charge and discharge 6000 times before it dies.

Charging and discharging once a day would be 3,650 times over 10 years.

But your solar battery will charge a few times a day, once or not at all depending on use, weather and management system so 6000 cycles is about average for 10 years.

Most solar batteries will come with a 10-year guarantee and any repeatable installer will factor in the replacement of batteries, and inverters, into their quote.

Tesla claims their Powerwall 2 has a 20-year lifespan, even 25, but it’s a huge unit and very expensive.

Our recommended solar batteries

Choosing a battery for your system is usually down to the installer and their suppliers, so you’ll get the battery that works best with the inverter and is the most cost effective.

But there is no harm in being informed and comparing your potential battery with what’s out on the open market.

Alpha Smile 5 ESS 10.1 

The Alpha Smile5 Ess 10.1 stores a whopping 9.1 kWh, but you will be shelling out between £5,500 and £7,500 for one.

These last around 10 years, which is usual, and work with a huge array of different inverters and management systems.

The only strange thing about this battery is that it comes with a 10-year guarantee, but only if the system stays connected to the internet.

If the connection to the ‘net goes down for more than 20 minutes, Alpha can reduce your warranty to 3 years!

Specification	Value
Dimensions	Height 160mm x Width 610.5mm x Depth 236mm
Weight	100kg
Depth of discharge	90%
Warranty	10/3 years
Storage capacity	10.5 kWh
Usable capacity	96.1 kWh
Max power output	4.0 kW
Installation	Standing

Puredrive PureStorage II 

The Puredrive PureStorage battery comes in at around £2,500, and will store 5 kWh, so it’s very much in the average price and storage bracket.

Personally, and this goes for the Alpha Smile and Tesla Powerwalls, we’d prefer to have an array of separate batteries, that are smaller and cheaper, to get this kind of storage as it means you can replace some items without having to shell out a huge amount of cash.

These batteries are compatible with most inverters, have an Integrated DC isolator, a whopping 10,000 cycles and are weather and waterproof so they can live outside!

Specification	Value
Dimensions	Height 345mm x Width 505mm x Depth 245mm
Weight	69kg
Depth of discharge	90%
Warranty	10 years
Storage capacity	5 kWh
Usable capacity	4.5 kWh
Max power output	5.0 kW
Installation	Standing or mounted

Moixa Smart Battery

The most attractive thing about the Moixa Smart battery is its warranty.  

The average warranty on a solar battery is 10 years, some are more some are less, but if sign up to Moxia’s Gridshare they’ll extend that to a lifetime guarantee. 
 
It does mean paying Moxia 50% of the money you get from exporting to the grid, so you’d have to weigh that up with having a battery for life.  

In terms of storage, it’s a perfectly acceptable 4.8 kWh and costs £4,450 which we feel is a bit pricey. 

Specification	Value
Dimensions	Height 345mm x Width 505mm x Depth 245mm
Weight	156.9g
Depth of discharge	85%
Warranty	10/3 years
Storage capacity	4.8 kWh
Usable capacity	4.04 kWh
Max power output	850 W
Installation	Mounted

Greenlinx 3.2 

Greenlinx are known for their reliable, workhorse kind of batteries and we can’t argue with that.

They are value for money, well designed and do exactly what they are supposed to.

They do have a fantastic battery management system so they can discharge to a full 100%.

Greenlix batteries work brilliantly with the LuxPower Hybrid Inverter, they hold 3.2 kWh of power and cost around £2,250.

Specification	Value
Dimensions	Height 484mm x Width 302mm x Depth 165mm
Weight	34.9 kg
Depth of discharge	100%
Warranty	10 years
Storage capacity	3.2 kWh
Usable capacity	3.2 kWh
Max power output	2.4 kWh
Installation	Mounted

Huawei Luna 2000 

Like the Greenlinx offer, Luna 2000s uses a modular system that means you can add to, or subtract from, the storage capacity whenever you see fit.

Each unit is 5kWh each, they cost about £2,700 and you can have 3 stacked together to give you 15 kWh of storage.

Then you can link 2 stacks together to get 30 kWh!
The Huawei Luna 2000 is a very clever little set up and even comes with its own software to communicate with inverters and apps.

Specification	Value
Dimensions	Height 960mm x Width 670mm x Depth 150mm
Weight	63.8 kg
Depth of discharge	100%
Warranty	10 years
Storage capacity	5 kWh
Usable capacity	5 kWh
Max power output	3.5 kWh
Installation	Stacked

Learn more about the best rated solar batteries.

Will Battery storage work with my existing panels?

You can absolutely retrofit batteries to existing panels, however, there are a few other parts of the system you need to think about.

Panels are generally a simple plug and play kind of deal and will work with most systems – so long as the inverter can handle them.

This brings us to the inverter, which is what will dictate whether you can use batteries.

There are two main types of inverters on the domestic market – string and hybrid.

String Inverters

A sting inverter converts the DC electricity produced by the panels into AC electricity you can use in your home.

They can be used to ‘funnel’ power into your home or into the grid.

Hybrid Inverters

As the name suggests these do more than one job and that is because, as well as a string inverter, they also contain a power inverter.

This is needed to charge your batteries as, although they are also DC, the power received from the panels is at too high a voltage.

The power inverter takes the DC electricity before it is converted to AC, drops the power a little, and feeds it directly to the battery.

This means there is very little loss of power between the panels and the storage.

Learn more about types of inverters.

Can I expand my solar battery storage system in the future?

Yes, usually you can add to your storage after your initial installation, but this will also depend on the make and model of the battery, the kind of inverter you have and space.

Many batteries come as ‘stackable’ systems, so you can add more units depending on what you are using in the home.

Stackable systems are a great idea for those people just joining the solar revolution as you can have a small outlay to start with, then build your system as you work out the best way to use your energy.

Then you have to look at prices.

A Greenlinx battery 3.2kWh comes in at around £1900 – £2500.

If you have a compatible inverter, Greenlinx always has 8 of these to ‘stack’ on one string.

So, you can easily swap batteries in and out if they have a problem, without losing too much storage.

A less practical option, for us, is the Tesla Power Wall 2.

You can link 2 of these together – however, they do store about 13.5 kWh of power and cost upwards of £10,000.

Do I have enough space for battery storage?

Yes, yes you do!

Of course, this all depends on the battery, again.

Tesla Powerwalls take up a fair bit of room, they are 1.15 metres high, 0.73m metres wide and 0.15 metres deep – so, if you were looking to pop one in the loft or under the stairs you might struggle.

Whereas the Greenlinx battery is 0.48 metres, 0.3 wide and 0.17 metres, so they are much easier to fit if you’re running out of room.

Most batteries will fit easily in small spaces so long as they are well ventilated and not too hot.

Plus, you can easily purchase storage cabinets that will keep your batteries, inverters and associated wiring, safe and dry outside.

A lot of batteries now come with weather and waterproof testing, which means many of them can just live in the wild, but we wouldn’t recommend that as they’d get covered in all sorts of stuff … ick!

Can I use solar battery storage to power my entire home?

While we could answer this with a simple yes if you have enough storage, you can easily use batteries to feed energy into your home.

However, you need to be able to charge the batteries and most domestic installations just won’t have enough room for that many panels.

You can sign up for an SEG that will allow you to charge your batteries at night, using a cheap tariff, but it would take 8 hours to power enough batteries to run an average family home.

Plus, most cheap, nighttime tariffs are only 4 hours.

Can you have batteries with no solar panels?

Battery only systems are becoming more and more popular as people start to manage their energy better.

This is helped in no small part by the energy companies offering a selection of great, cheap SEGs.

Instead of filling your batteries with the power from solar panels, they are charged during the night at very cheap rates – then you just use that power during peak hours.

It’s still better to have panels though, as that makes life even cheaper!

Should I DIY solar battery storage, or do I need professional help?

It’s not a great idea to start messing about with electricity unless you know what you are doing, so the simple answer is to get the professionals in.

Solar panels produce DC, or Direct Current, electricity, which was the first kind of electricity discovered by Edison.

Tesla decided DC was a bit hard work, so he came up with AC electricity which is what we use in our homes.

AC electricity zips back and forth at 50 times a second and will always find the quickest way to earth – which makes it, bizarrely, much less dangerous than DC.

If you grab onto a live DC wire it will contract your muscles and you will not be able to let go of that wire, with an AC current you’d get thrown away from the current.

So, as Solar panels produce DC electricity, and batteries are charged using DC electricity, it’s best not to get involved.

On top of the danger, there’s the technical side.

Batteries need to be managed, meaning charged and discharged correctly, if they are going last for 10 years.

The inverter, app and even standalone software are all capable of managing the battery, so long as they are suitable and installed correctly.

Solar battery storage for commercial solar energy installs/utility

Here’s a hot potato now – Utility Solar Storage!

Now, before we get into what is suitable for this let’s look at why it’s important and why it’s so difficult to install.

Utility Battery Storage

There is more heat for a start, and the systems need to be more robust.

In the UK the storage is still, mostly, Lithium-Ion batteries much like ones in domestic systems only bigger!

Flow batteries are the new technology that is currently being rolled out all over the planet.

These are essentially big batteries full of fuel cells.

They work the same way as normal Lithium-Ion batteries, chemical energy comes from two chemical components, dissolved in liquids, and separated by a membrane.

The potential difference, and flow of positive charge, is what gives us the electricity.

Public objection to utility battery storage

Storing a huge amount of power requires different kinds of tech than using a domestic system.

The UK is, unfortunately, full of NIMBYs – which stands for Not In My Backyard and means people who like the idea of green tech, but not at the cost of what they can see out of their window.

Until very recently, a wind turbine’s construction could be stopped if just a single person in the area objected – consequently, there have been just 16 new turbines built in England between 2016 and 2020.

It seems battery storage is, through misinformation and scaremongering.. going the same way.

Proposals for new, integrated battery storage facilities are being kyboshed from Hawkchurch to Allerton Bywater and there seems to be a lot of fluff as to why.

Batteries fires seem to be the main one, but even the scientists who object to battery storage can only find 5 of these from the last 20 years

The truth is batteries are safer, more well managed and easier to look after than they have ever been.

Can I install a solar battery storage system in a residential apartment?

As a landlord it would certainly be an advantage to have a solar system in your properties, and even more so if you include battery storage.

There is no legal reason why you can’t have battery storage, but it will have to ensure they are MCS accredited and well maintained

If you are simply renting, you would have to get permission from the owners if you rent your flat or apartment and, of course, having solar panels on an apartment block isn’t usual.

But, if the home is yours, you can make as many home improvements as you like, including energy storage.

Solar batteries are safe, clean and aesthetically pleasing, but they can be quite large so if your flat is on the small side then you’d need to think about space.

As technology improves, we are seeing some great innovations in mounting and using solar panels.

That includes balcony ready panels that you can fit yourself or even small, free-standing panel systems you can easily move around.

What maintenance is required for a solar battery storage system?

The good thing about Lithium-Ion batteries is they need very little maintenance or looking after, but it’s always good to give them the occasional check.

The battery will degrade over time, as the chemicals inside get older and naturally lose their ability to hold charge.

Your system will also come with a battery management system that ensures that the battery discharges and charges correctly.

This is essential to protecting the life of the battery as not charging, and discharging, correctly can damage the chemicals that store the energy.

Best ways to prolong the life of your battery 

Don’t over or undercharge 

This will be taken care of by the battery management software, so just make sure you check the monitoring app regularly.  

A lot of batteries don’t allow a full discharge for this very reason, but that does reduce the amount of useable storage you have.  

A correctly managed battery will last for around 6000 charging cycles. 

Monthly visual checks

This is just to make sure all the cables, connections and casing are all in good working order.

The connections should be free from corrosion or oxide – that’ll be a green coating on the copper.

Don’t try to clean those without turning the power off.

Keep your battery at the right temperature

Solar batteries work best between certain temperatures – usually between 10 and 30 degrees Celsius.

They can function at temperatures as low as –20 degrees Celsius but operating at these temperatures means everything is working harder, so the battery will not last as long as it should.

You won’t be able to move your battery around the house much, so bear in mind you’ll need to install it in a place with a consistent temperature.

Garages and understairs cupboards seem to be the best places, but as The UK isn’t really cursed with extreme weather the loft will work just as well.

Like any electrical appliance, batteries can be damaged by a surge in power.

However, the batteries in a solar energy system will be managed by an app and charged via a hybrid inverter which will regulate the input.

Power surges are very rare in the UK but, as before, keep an eye on the monitoring app/software.

Do not overload your battery

Overloading a battery means you are drawing too much power from it too quickly.

Once again, the battery management system should stop this happening in an average domestic solar system, but we recommend managing your use anyway.

If you put the tumble dryer, the cooker and a hair dryer on at the same time, this will add a huge ‘load’ to your battery, and it’ll drain very quickly.

Replace your battery when necessary

Solar batteries usually come with a 10-year warranty, so you can expect them to last at least as long as that.

As your panels will be good to go for at least 25 years, any reputable company will factor in replacement batteries when doing your quote.

Store your battery properly

We have kind of covered this with the temperature section, but this is a good time to mention other places to store batteries.

It must be dry; electricity and water do not mix well!

As well as the danger, the battery, connections and cable will all suffer if the area the battery is stored in is damp.

If you need to store your batteries, or inverter, outside then it must be in a waterproof cabinet.

Check the rest of the solar system

If you have kept the battery clean, dry and at the perfect temperature, then any problems with charging will usually come from somewhere else in the system.

First thing to check is the cables for damage or disconnections.

Check all terminals next to make sure there are no short-circuits, ‘air gaps’ or corrosion.

If everything is connected and working well, make sure there are no faults on the inverter.

Once you’ve eliminated all those things, have your panels cleaned!

Grants for solar battery storage

There are no grants, as such, available in England and Wales but the government backed ECO4 scheme does cover solar batteries.

ECO4 scheme?

The ECO scheme is a long running program that aims to improve the energy efficiency of people’s homes – it’s an acronym for Energy Company Obligation

The current, and final, phase is number 4 and, while some of the criteria have been narrowed, it is still available to most people claiming benefits of one type or another – including Child Tax Credits.

It’s not, strictly speaking, a grant as the energy companies pay the money and the government compensates them.

There is also a sister scheme called LA Flex that allows local authorities to offer loans and grants to people who don’t claim benefits but do live in fuel poverty.

Many companies use spammy adverts that say ‘free solar’ or ‘free battery storage’ but don’t be fooled, energy companies are not the ones who will determine your eligibility.

Eco 4 funding is either means tested and benefit dependent.

It must also improve your home’s energy efficiency.

Who will install a system under ECO4? 

An energy company with over 150,000 customers is obliged to offer ECO4. 

The big names to check out are:  

• British Gas 
• E 
• E.ON 
• Ecotricity 
• EDF 
• ESB Energy 
• Octopus Energy 
• Outfox The Market 
• OVO Energy 
• Scottish Power 
• Shell Energy 
• SO Energy 
• The Co-Operative Energy 
• The Utility Warehouse 
• Utilita Energy

ECO 4 eligible benefits 

• Child Tax Credits
• Child Benefits – income dependent
• Income based Jobseekers Allowance
• Income related Employment & Support Allowance
• Income Support
• Pension Credit Guarantee Credit
• Universal Credit
• Warm Home Discount Scheme Rebate
• Working Tax Credit
• And here is what was previously available but is no longer on the list:
• Armed Forces Independence Payment (AFIP)
• Attendance Allowance
• Carer’s Allowance
• Constant Attendance Allowance
• Disability Living Allowance (DLA)*
• Industrial Injuries Disablement Benefit (IIDB)*
• Personal Independence Payment (PIP)
• Severe Disablement Allowance*
• War Pensions Mobility Supplement (WPMS)

Is ECO4 means tested?  

It can be if you receive Child Benefit and limits are:

• A single adult with 1 child: £19,900
• A single adult with 2 children: £24,800
• A single adult with 3 children: £29,600
• A single adult with 4 or more children: £34,500
• Couple with 1 child: £27,500
• Couple with 2 children: £32,300
• Couple with 3 children: £37,200
• Couple with 4 or more children: £42,000

(based on Ofgem’s Administration Consultation released on 13 June 2022)

Learn more about ECO4 funding.

Home Energy Scotland Grant and Loan

There is some extra help available for Scottish solar heroes in the guise of the Home Energy Scotland Grant and Loan.

Under this government scheme homeowners can access grants of up to £9000, and interest-free loans of up to £38,500, to improve the energy efficiency of their house.

You can get up to 75% of the combined cost of your home improvements – up to £7,500 if you’re in a town or city or £9,000 if you’re in a rural area.

Don’t get too excited, as the Home Energy Scotland Grant and Loan don’t cover:

• Replacement heat pumps
• Wind or hydro turbines
• Warm air units
• Solar water heating systems
• Double or secondary glazing
• Insulated doors
• Heat network connections

However, you can get grants for PV systems, energy storage systems, biomass boilers/stoves, and high-heat-retention storage heaters.

The loan, however, is much more generous.

One loan scheme offers, interest free, £15,000 for energy-efficient improvements to your home… in another, you can borrow £17,500 for two renewable systems or connections to an approved renewable district heating system, plus a further £6,000 can be added for batteries or other energy storage.

The loans are paid back over 12 years, and under certain circumstances, you may not have to pay the full amount back.

Barclay’s Greener Home Reward

Barley’s Greener Home Reward program has been extended until 2024.

This means you can apply for extra cash on your mortgage specifically for buying energy efficient improvements for your home.

You must register for the scheme before the end of next January and claim it before July 2024, and you are only eligible if:

• You already have a Barclay’s domestic mortgage
• You are not in arrears
• You have the work done by a TrustMark-registered business or tradesperson
• You pay your mortgage by Direct Debit
• You haven’t previously claimed
• If you tick all those boxes, you can borrow £1000 towards your Solar Installation or Battery from Barcley’s.

VAT Free

Not exactly what one would call a grant but, until 2027 you won’t pay VAT on any new solar installation, or the equipment used.

That includes batteries – so long as they are part of a solar installation.

Batteries bought sperate from an installation will carry the full 20% VAT, so make sure you think about that initial install very carefully.

Learn more about VAT free solar panels.

Problems with solar battery storage?

The biggest ‘scare’ that seems to be making it into the media is ‘thermal runaway’.

We can hear the gasp from here, but it’s not a common problem.

The actual risk of thermal runaway in domestic batteries is 0.0001% and that’s only if there is an external problem.

Batteries are incredibly safe but keeping them cool and dry will make sure they aren’t in much danger of getting too hot.

So, as we know thermal runaway isn’t really going to affect you, what should you look out for?

If the battery is draining, or isn’t charging to its full potential, your problems may include:

There is damage to your battery – this will be internal, so there will be no external tell-tale signs, and the problem is caused by incorrect charging and discharging. Ensure your battery management is functioning correctly and not overcharging your battery or discharging to 0%. Some batteries can discharge to 0% but we don’t recommend it.

The weather has gone mad – extreme temperatures will affect the health of the battery. Not usually a problem here in the UK but, after 2023’s unusually hot September, it may be something we have to look at in the future. To mitigate this, just ensure your battery is someone it can be kept at around 30 degrees most of the time.

Problems with battery management – This goes along with the first point, if your battery management is draining and charging the battery too fast, or too deep, it is going to cause you problems in the long run. This is an unusual problem to have and may be caused by badly written software, or even 2 different systems (app or inverter) trying to control the battery at the same time.

Parasitic Draw – great name for a heavy metal band, but not something you want on your battery. This is a process in which the battery is discharged because many appliances in your home never really switch off – like a TV being on stand-by or a laptop charging while you sleep. This can be prevented with good energy management in your home.

System problems – this is the first thing you need to check if your battery isn’t charging as the problem may be external. Maybe you have a faulty panel, a broken or badly fitted CT Clamp, or even just a loose cable somewhere.

What other batteries can be used to store your energy?

There are other types of batteries you can use for storing energy, that we will take a look at here, but you are likely to find that Lithium-Ion will be the primary choice for any registered solar installer.

Lead acid batteries

Lead acid batteries were the norm when the solar industry was in its infancy.

They are certainly still very popular in the DIY, off-grid sector.

Now, the words ‘lead’ and ‘acid’ probably aren’t going to set your heart on fire, but these are the kind of batteries you use in your car or as leisure batteries for caravans.

They have a ‘deep’ charge and discharge cycle so they can be fully discharged without affecting the health of the battery.

They don’t last as long as their Lithium-Ion cousins, but they are significantly cheaper.

Pros	Cons
Very Cheap.	Can get very hot so needs ventilation.
Easily Recycled.	Will leak acid if damaged
DIT Maintenance	Regular maintenance.

Nickel cadmium batteries 

Invented in the 1800s and updated in the 1980s Nickel cadmium (Ni-Cd) batteries are not used for Energy storage in the domestic market as Cadmium is dangerous to humans.

In fact, most countries in Europe have restricted or banned it.

This doesn’t mean you won’t find Ni-Cd batteries in use in the correct environments as they are super hardwearing and little to no maintenance.

They are often used in utility storage, that’s the grid to you and me, and aircraft.

Basically, Ni-Cd batteries are an industrial asset or used in commercial settings where they can be maintained and operated safely.

Pros	Cons
Durable	Poisonous
Work in extreme temperatures	Could be banned
Don’t need to maintain	Hard to recycle

Flow batteries

Flow batteries may be new tech, but they are starting to appear in more utility storage situations due to the fact they are very affordable.

They work in a comparable way to a ‘normal’ battery but on a much larger scale.

They contain a water-based electrolyte between two chambers which allows charged particles to flow as the battery charges and discharges.

Flow batteries are significantly bigger than other batteries, as well as being pretty pricey, so they won’t be available domestically for a good while.

Pros	Cons
Very Cheap.	Can get very hot so needs ventilation.
Easily Recycled.	Will leak acid if damaged
DIT Maintenance	Regular maintenance.

Graphene Batteries 

This is a little glimpse into the future as graphene is the new, wonder-material that’s taking the electronics world by storm.

Graphene is constructed by creating a sheet from carbon atoms that is 2 atoms thick.

In a battery, these are sheets, one positive and one negative, and they are suspended in distilled water.

The graphene sheets create a power differential like any other semiconductor and that generates the current.

Graphene is 100 times stronger than steel, increases storage capacity and reduces heating in batteries – so it really is a fantastic development.

Unfortunately, the roll out of graphene batteries for domestic use is quite far in the future due to affordability – a square metre of 2-layer graphene is around £8,000!

Pros	Cons
Resilient	Expensive
Low Maintenance
Huge storage
Low temperature

Battery only systems (with AC inverter), why do it, is it expensive, you don’t need solar

Where to store your batteries – operational temperatures and how hot/cold they can get before shutting down. Outside cabinets for storage. Batteries are generally waterproof etc.

EPS/UPS – for commercial and domestic – why you’d want it, why Emergency power supplies are needed in the industry.

What’s the future of solar battery storage?

There are some, mind-blowing technologies in development in the field of energy storage. 

Compressed Air Energy Storage  

This one, frankly, blows our minds a bit.

Surplus power is used to compress air in huge chambers and, when it’s needed, that air is released into huge air turbines to create electricity. These systems are super-green but also super-massive.

Mechanical Gravity Energy Storage? 

Another simple, age old and well tested solution for storing energy.

Energy is used to lift concrete blocks, or other heavy weights, into the air within a tower.

When the energy is needed, the blocks are lowered creating electricity through the power of gravity.

Sand batteries! Yep, we can store energy in sand – heat mostly. This is already being using in Finland to heat homes and swimming pools.

Basically, the sand is heated to 600 degrees Celsius during the day using solar panels and wind turbines, then the heat is released via water filled pipes and used for practical purposes.

Genius!

Teams in labs all over the world are examining the practicalities of using heated sand to boil water and make steam to drive a traditional turbine too.

Solid-State Batteries 

These are other innovations that are starting to be seriously explored. Replacing the liquid and chemicals found in traditional batteries with a dry, solid circuit is the way these batteries work.

Unfortunately, we are looking at 2030 before they start to hit the market.

Recycling  

We need to ensure we are recycling all batteries not just solar ones.

But solar batteries are now being produced with recycling in mind and, the more popular energy storage becomes, the more recycling businesses will pop up around it – like any sector.