The Ultimate Solar Battery Storage Guide - 2025

It is generally accepted that Solar Energy Systems are more beneficial if they have battery storage included.

There is no VAT to pay on solar batteries at the time of install, so that makes them a real value-for-money addition to any system.

Plus, installing a battery gives you chance to use the electricity your panels produce even after the sun goes down.

Solar energy system, obviously, produce all their electricity during the day which is great if you are in most of the day.

Most people are out of the house for large chunks of the day so that energy isn’t being used so it will export to the grid – which will earn you money.

But if you have battery storage that will save you more money than you can earn by exporting alone.

So, in this blog, we’d like to give you the low-down on what’s available and how you can best manage your energy.

Solar Batteries – what are they?

Well, we all know what a battery is, and solar batteries are just large energy storage units that can be charged and discharged when needed.

This helps with managing your energy use and allows you to use an excess energy your system produces during the day.

The most energy you can use from your panels, the less you need to use from your energy supplies – which saves you money.

What’s more they usually come with clever software that allows you to control when you use them and when you export.

This software can also maintain the battery’s health, so it performs well throughout its lifetime.

Battery management can also be handled by an inverter, another essential component in a Solar Energy System.

Lithium-Ion batteries are the kind that are used for most residential solar installs currently.

Lithium-Ion batteries

We won’t go into the science here, but the tech behind Lithium-Ion batteries has come on in leaps and bounds over the last decade, mostly due to the rise in EV sales.

This also makes the demand higher, which lowers production costs.

Why Lithium-ion batteries?

That are indestructible - Well, not really, but they are very low maintenance. Most solar batteries come with at least 6000 cycles. This means they can be charged and discharged over 6000 times.

Cost effective – no one would describe solar batteries as ‘cheap’ but Lithium-ion batteries are the most cost effective right now. The smallest battery worth having will cost around £1500 – £2000, so that’s £150 - £200 a year, and you’ll be saving more than that.

High energy retention – Lithium-Ion batteries will hold more charge than a typical lead acid battery (the kind of battery you find in household remote controls).

High Depth of Discharge – a lot of batteries can be damaged if they discharge all of their power. But some lithium-ion batteries can discharge to the full 100%.

Longer Lifespan – this is down to the cycles and, as mentioned before, that means they generally last 10 years.

Should you get solar battery storage?

While a solar energy system doesn’t need any storage to function correctly, most companies would recommend it – and not just because it means more cash for them.

Solar panels are still a great idea whether you have storage or not, but why waste energy?

Battery storage gives you the opportunity to use any electricity your panels generate while you are away from home.

You may be at work during the day or, even if you work at home, it could be a bright summers day, and your panel could be pumping out loads of power.

You can certainly sell that power back to the grid via an SEG (Smart Export Guarantee) but you’re never going to get paid more than the energy supplier charges you.

Some pay as little as 1 penny per kWh.

Meaning, if you sell the energy while you are at work, say for 8 hours, you’d earn less than 32p.

Using a battery to store that energy would save you over a pound an hour at today’s prices.

What size solar battery do you need?

How long is a piece of string … or a string inverter for that matter!

Batteries can range from 1 kWh up to 13.5 kWh and you would choose based on the size of your system.

You don’t want to install a 3kWh battery on a huge 25 panel system as you’d be losing energy to the supplier.

A larger battery on a smaller system can work though, as you can charge them with cheap energy from your energy company.

How much does solar battery storage cost?

This can be a very difficult question to answer and that can come across as evasive, but it really does have a lot to do with brand names, the availability of products and the build quality.

The price of storage drops all the time and, giving google a quick look, prices are around £900 per kWh of storage capacity.

We think that’s a little on the high side unless you figure in replacing the batteries after 10 years.

It’s more than  with while though, with the average UK home saving around £665 from adding battery storage to a system.

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

This one’s easy:

• Energy Use

• Cost

• Space

Energy Use

How and when you use your energy is probably the most important factor to consider when you’re thinking about adding battery storage to your solar.

In the average UK home, the usual power peaks are around breakfast time, say 7am until 8.30 am … and then again between 5pm and 7pm.

So, you jump out of bed at 6.30 am, put the kettle on, start the shower and ask your smart speaker to play 80s bangers.

That’s a lot of energy being used at one time and, in the summertime, you could be getting a good yield from your panels – in winter, not so much.

But no matter what time of the year, your panels are probably kicking out the most power when you are out of the house and at work.

If you’d rather sign up to an excellent SEG and sell that excess power back to the grid, that’s still a great idea, but you will save more by using the energy yourself.

Always ask yourself: Am I getting the best ROI by adding battery storage?

It’s telling that most solar energy systems sold in the UK have additional battery storage.

Cost

So, can we answer that last question for you?

We can certainly try.

9 times out of 10 you will get a great ROI by adding battery storage to your system as there are very few circumstances that mean you earn more from selling energy than you save from storage energy and using it at peak time, .

Solar batteries come in many sizes, models and costs.

So, we wouldn’t recommend connecting a 13 kWh Tesla Powerwall 3  to a system that has a peak output if 1.5 kW, but if you have a roof covered in PV a Powerwall would save you 1000s.

Space

Space isn’t quite the consideration it used to be as a lot of solar batteries have an IP rating over 65 so they can be located outside – some are even flood-proof!

While batteries are getting smaller, they are pretty hefty units, so if they are inside you do need the space for them – but it needs to be well ventilated and easily accessible.

Specifications to look for in solar batteries?

Let’s take a look at the most important things you need to look out for when researching solar batteries.

Depth of discharge – this is a fancy way of saying how much of the battery’s storage you can actually use.

For instance, having a 4 kWh battery with a 90% depth of discharge means you can only use 3.6kWh before you start to damage the battery itself – don’t worry about that though, as the software won’t let you exceed 90%

Operating Temperature – you may be familiar with stories about EVs not starting in Siberia and other super-cold places, so we all know batteries can be affected by the weather.

Batteries that have dropped to an extremely cold temperature will struggle to charge but will still provide power.

If the same battery gets too hot it will overheat and be subject to thermal runaway – which we do not want!

If you find that all a bit scary, don’t worry too much, the temperatures in the UK are unlikely to get anywhere near these extremes so your battery will perform extremely well all year round.

Lifespan – if a battery just sat on a shelve and never used, it won’t ‘go off’, so the lifespan isn’t a physical measurement.

It is, in fact, the amount of time the battery can charge and discharge.

Solar battery cycles are, generally, between 6000 and 10,000.

So, if you base calculations on a battery charging and discharging twice a day – that’s at least 10 years if life. Some will last 15 years and will offer a warranty to match.

The software controlling your system will also manage you battery, so you don't have to worry too much about keeping and eye on your cycles.

Keeping all storage in a cool, dry place means your battery’s life-span will not be affected too much by temperature.

Can I install more than one solar battery?

You can – so long as all parts of the system are compatible.

The more modern solar storage systems have stacking, or daisy-chaining, abilities so you can easily add more storage as you get used to the system.

Even the mighty 13 kW Powerwall can be daisy chained to 4 more power walls AND each of them can have 3 additional battery-only units.

That’s gives you 208 kWh of storage – which is enough to completely power an average UK home for nearly 4 weeks.

How much can you save with solar battery storage?

Again, and I know this is getting repetitive, it really depends on your home, energy use and the weather –

Experts say you can save an extra 30% so we can give you a few pointers on how to save.

Saving by storing energy

Storing energy to use when demand is high is a great way to save money on your energy bills.

The current, on-peak price of electricity is around 27p per kWh, the current price of filling up tour battery from your solar panels is 0p per kWh.

You may look like you only save a couple of pounds a day, but that soon adds up to a fair chunk of your bill.

Having batteries also makes people more mindful of their energy use and creating good habits that will also reduce your bills.

Saving with an SEG (Smart Export Guarantee)

Save money, earn money AND power your house – sounds too good to be true, yeah?

SEG, Smart Export Guarantees, is the scheme that replaced the Feed In Tariff and it enables energy providers to take advantage of your carbon free electricity.

The energy companies are obliged by law to buy your energy, but they also want it – and they want to use your storage too.

The ‘national’ grid is producing energy 25/7 – no matter what the demand, as it’s too expensive to turn power stations on and off.

So, if they can store that energy in your batteries, it means they can access) when demand is high.

These means you can fill your batteries over night t a reduced rate, then either sell the energy back to the supplier or use it yourself so you’re not paying on-peak prices.

SEG tariffs for solar batteries

The popularity of SEGs, and their effectiveness for the energy companies, means the market has been flooded with tariffs for just about every scenario.

You can have SEGs for EV charging, ones for solar panels only, lots for peak exports … you get the gist.

There are, of course, SEGs specifically for those people with solar storage.

You can fill your batteries, export from your batteries and use your batteries to regulate your energy usage – all while saving money on your overall energy bills.

Learn more about SEG (Smart Export Guarantee) rates.

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

Yes and no – companies are obliged to offer an export rate for the excess energy your panels produce, but they don’t have to take energy you have stored in your batteries.

So, you’ll need to shop around to find the right energy provider for you.

Most are coming round to battery storage these days, so you won’t have to look far, just make sure your getting a good deal.

Google is your friend here.

How long does a solar battery last?

A battery’s life is measured in ‘cycles’ – one cycle is the total discharge and charging of a battery.

Most, if not all., solar battery storage utilises Lithium Ion batteries, which can be charge and discharge 1000s of times.

How many times it can do that is down to the down to the manufacturer and the design.

Lithium-Ion batteries generally last around 5 to 15 years if they are well managed – with the average being 6000 cycles – meaning it will charge and discharge 6000 times before it dies.

That’s pretty much twice a day for over 10 years.

Solar batteries come with a 5-, 10- or 15-year warranty – so insure you read all the paperwork your installer offers you.

Tesla Powerwall 3s have ‘unlimited’ cycles – so you know they are going last you a fairly long time.

Will battery storage work with my existing panels?

Again, yes and no, it will depend on the kind of inverter you have in your system and also what type of system you have.

Mostly it’s a ‘yes’ but let’s have a look at what inverters do.

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

The simplest of the inverters as they ‘merely’ convert the DC energy produced by your panels into AC energy you can use in your home.

They can’t feed batteries and as that requires extra conversion, but they will also export your excess power to the grid.

Hybrid Inverters

This is the kind of inverter you will need if you want to manage exports, imports and battery storage.

The word ‘hybrid;’ comes from the fact they contain a few different converts.

There is the usual DC to AC converter to ensure you can export to the grid AND power your homes.

But they also contain a DC-to-DC converter … a what now?

A DC-to-DC Converter! This is need as the DC energy from your panels isn’t the same as the DC power that charges your battery.

The DC power from the panels is too high a voltage so a power inverter ‘drops’ the voltage before that power is fed directly into the battery.

The advantage of this is that the power loss between panels and battery are minimal.

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

Yes, but again this depends of the make, model and manufacturer of your system.

The improving tech in battery storage means we are seeing more and more ‘stackable’ systems coming onto the market.

From simple systems like the Sigenergy one that allows you to build up your storage in 5 or 8 kWh units until you have 48 kWh on one inverter… the Tesla Powerwall 3 can be added to until you have a whopping 54 kWh!

So, while you can stack systems, not all systems will stack … bear this in mind when you are buying your initial system.

Do I have enough space for battery storage?

Yes, yes you do – because modern batteries are usually IP65, or above, rated – which means they can be stored outside!

If you don’t want your batteries outside then there is no problem having them indoors.

Lofts are no longer recommended for battery storage, but under-stairs cupboards and other out-of-the-way places are perfect so long as they are well ventilated.

Batteries get warm, usually not worryingly warm, so they need to be kept in well ventilated areas.

If the batteries are outside, you can also source cabinets to keep them safe and clean.

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

The electric items in your house don’t care where the power comers from so long as it’s AC and at the right voltage.

So, of course you can power your home from your batteries, but they will drain very quickly if you don’t manage your energy consumption correctly.

So, make sure your batteries are full before the sun goes down, whether from the panels or the grid, and then make sure you don’t fire up the tumble-dryer, cooker and water heater all at once!

Can you have batteries with no solar panels?

While we feel that this was always an option, battery only installations have been gaining in popularity overt the last few years.

This is down, mostly, to the energy companies providing SEGs that allow you to charge batteries from the grid and even sell power back to the grid from your batteries.

So, you can charge your batteries during the night, or at off-peak times, for pennies – and you can use that power when the prices go up!

Of course, power from panels is free, so you should defo get some of them too.

Do I need professional help to install batteries?

The way batteries fit together these days means it looks really easy just to stack them up and get as much storage as you wish.

But if it was that easy you could just pick up a system in B&Q while you were getting a drill for the new shelving.

Batteries need fairly low DC voltage to charge safely – the power from your panels is DC, but at a much higher voltage, and the power from the grid is AC.

Basically, this means you need the correct inverter, or transformer, in the correct place, making the correct calculations and managing the battery in the correct manner.

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

Management is as important as fitting the battery correctly – if a battery isn’t charged and discharged correctly it’s not going to last for 10 years.

So, unless you are a qualified electrician it probably best to leave all this to the professionals.

Utility Battery Storage

For various reason beyond the UK’s control, and a few we absolutely have control of, the renewable energy offer is being taken much more seriously these days.

This means Utility Storage is become something of a political hot potato.

Bigger storage means more heat and. Of course, more space needed.

From Lithium to normal Lead Acid, battery technologies are getting pretty long in the tooth to be used for the next few decades to store our country’s energy.

You know what is great, safe and (relatively) cheap?  Pumped hydro-electric storage!

Basically, energy being generated when it’s not needed is used to pump huge amounts of water into a holding reservoir at the top of a hill or incline.

When that energy is needed the water is released into turbines that create more energy to be fed into the grid.

Genius! But you probably couldn’t get it in your loft.

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

With permission you can install a solar battery storage system anywhere!

Plus, as a landlord, you be increasing the rent-ability of your homes if the electricity bill were super low.

So long as you make sure whatever you have fitted is MCS accredited and well maintained

If you’re not the landlord, you’re just a tenant, you need to make sure you have the landlord’s permission before you do anything to thee home, and solar batteries are no different.

If you own the home, what are you waiting for? You can get as much solar storage as you want!

Even a Tesla Powerwall 3 wouldn’t look out of place in a flat, they are neat, clean and very aesthetically pleasing.

Technology is improving by the month, so look out for new styles, innovative mounting systems and even balcony ready panels that you can fit yourself.

What maintenance is required for a solar battery storage system?

Very little to be honest, your inverter, or similar, will be doing all the management for you.

Battery do degrade over the years as the bits their made of wear out and stop being able to hold charge.

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

In fact, short of dropping it, or setting it alight, a solar battery will be fine for a decade or more.

We do recommend a few things though.

Best ways to prolong the life of your battery

Don’t over or undercharge

Not so much of a problem these days as battery management apps are so good at their jobs, they’ll keep your battery on track.

The batteries and the apps have come on so far over the last few years that some batteries are able to discharge 100% of their energy without causing any damage at all.

A correctly managed solar battery can easily last more than 6000 charging cycles.

Give them a visual once over

Always check for damage or anything that may be a problem at least once a month.

Check the connections, cables, casing and anything else you can without getting the screwdrivers out.

DO NOT open your batteries – they may look like little, innocent cubes but putting anything inside them could result in a hospital visit or worse.

Don’t let your batteries get too hot or too cold

Solar batteries are designed to work at their optimum level between 10 and 30 degrees Celsius.

That said, they are pretty much OK down to about minus 20 and up to plus 40 these days – but those temperatures will affect their performance.

Your installer will advise you on the best place to put your battery storage – and if they’re outside that’ll be in shade somewhere.

Overloading your battery

We mentioned earlier about not putting all your electric appliances on at once if you are powering everything from batteries – as that could overload a battery.

It’s difficult to overload a battery that’s being monitored by modern apps though, even surges in the power grid can be managed to a certain extent.

Replace your battery when necessary

Solar panels can last for decades so you will need to replace your batteries during the lifetime of your system.

You can use your batteries well past their 10-year warranty but you’ll experience worse and worse performance.

They won’t charge as much, or as fast, and they will discharge much more quickly.

Any reputable installer will include replacement batteries in your forward projection.

Storing You Battery Correctly

Electricity and water are not a good mix.

So, keeping batteries as dry as you can is always good – though they are manufactured to IP67 these days which means there are very water resistant.

Keeping them cool is a good idea too, batteries can overheat although that is a very rare occurrence especially with solar batteries as they are regulated by the inverter app – and sometimes their own app.

Check your system, don’t replace your battery

If you are having problems charging or discharging your batteries, don’t jump straight to replacing your battery.

Check all the cables for wear or damage … make sure the app you have is the latest version … check all terminals for short-circuits, ‘air gaps’ or corrosion.

Now, look at the stats for your inverter, make sure it’s doing its job and isn’t directing power anywhere it shouldn’t be.

If all these things are ship-shape and above board … get your panels cleaned!

After all that, if you are still having problems, it’s probably your battery.

Grants for solar battery storage

Home Energy Scotland Grant and Loan

These are only available until 2026 – so be quick!

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.

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

Unfortunately, the Home Energy Scotland Grant doesn’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

Your batteries are cover under energy storage systems though!

The loans are a little more flexible as they come under different criteria.

You can apply for an interest free, £15,000 for energy-efficient improvements to your home… this would include PV, batteries, even hot-water solar,

Or you could borrow £17,500 for two renewable systems or connections to an approved renewable district heating system.

And a further £6,000 batteries or other energy storage.

These are more flexible because you have to pay them back over 12 years but under certain circumstances, you may not have to pay the full amount back.

VAT Free

OK, it’s not a grant, but it is a discount of sorts.

Until until 2027 you won’t pay VAT on any new solar installation, or the equipment used, including batteries.

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

What problems might you encounter with solar battery storage?

None, really, but the media likes to get a bit excited about ‘thermal runaway’.

Thermal Runaway - if some tabloids are to be believed, Lithium-Ion batteries are exploding all over the planet. Which is, of course, a massive exaggeration that borders on fabrication. Thermal runaway is real, and it can be very dangerous, but with a likelihood of 0.0001% it’s not something we need to worry about too much. It happens when a battery gets too warm and that sets of a chemical reaction that leads to the battery igniting. But keeping batteries cool and dry will ensure they are safe from exploding.

Damage to your battery – not what you are thinking. While external damage could affect a battery’s performance, you’d really have to make a mess of the casing. Damage would be caused by incorrect charging and discharging. This kind of problem has been more or less eliminated by excellent battery management software.

Extremes in Weather – Not generally a problem in the UK, but extremes in weather can affect the health of any battery. Again, less of a problem as battery technology advances. But, if you were in a place where you experienced lows of -20 and highs of plus 40, your battery would suffer a bit.

Bad battery management – Even with a great battery management app, you can still over-ride the software to force charge or discharge your battery. Not something you want to be doing very often as it will damage your battery. Sometime this can happen if you have 2 pieces of software, say one for the inverter and one for the battery, and they contradict or over-ride each other.

What is Parasitic Draw – no, that’s not the latest rock band to storm Eurovision, it’s a sure-fire way of damaging a battery over a number of years. It’s basically a slow discharge created by the electrical appliances in your home never actually turning off – just being sat in Stand By. This is why we talk about good energy management in your home.

Day to day system problems – Always check the management software and system stats before you start to mess about with the battery. Charging problems can be caused by everything from a faulty panel or badly fitted CT Clamp to a loose cable or corroded fitting.

Are there other batteries apart from Lithium Ion?

There are other batteries available for storing your solar energy, but they aren’t widely marketed or supplied as yet. This is down to affordability, safety and technological sticking points, But let’s take a look anyway.

Lead acid batteries

This was the first solar storage option – and you can still find them in DIY set ups … so long at the owner has plenty of room!

While ‘lead’ and ‘acid’ are words that don’t inspire confidence, Lead Acid batteries are what you’ll find in a traditional car or to power a caravan.

Nickel cadmium batteries

Don’t use these! Most European countries have banned or restricted the use of Ni-Cd batteries as they aren’t the safest way to store energy.

Cadmium is pretty dangerous stuff.

Invented in the 1800s and updated in the 1980s, Ni-CD need little to no maintenance and last forever.

But, the fact they are dangerous and a little unstable means they are usually only found to be used as either an industrial asset or in commercial settings where they are regulated very closely.

Flow batteries

Flow batteries are starting to filter into the utility storage environment and they are incredibly cost-effective.

They work in the same way most traditional batteries do, a water-based electrolyte between two chambers allows particles to move between negative and positive to create a charge and discharge.

Flow batteries are generally massive though which make them expensive to set up and also removes them from the domestic market.

Although set up is expensive, they work so efficiently the initial outlay is worth it on an industrial scale.

Graphene Batteries

This is the future, as Peter Kay might say.

Graphene is a recently discovered wonder-material that’s taking the electronics world by storm.

It’s 100 times stronger than steel and, in terms of energy storage, it increases storage capacity and reduces heat.

Graphene is created by making sheets of carbon only 2 atoms thick.

These sheets can be used in batteries by making one positive and one negative … then suspending them in distilled water.

This creates the power differential needed to create a current like any other semiconductor.

Currently a square meter of 2-layer Graphene is around £8,000 so don’t expect a big take up for solar batteries just yet.

What does the future hold for soar battery storage?

OK, let’s get the crystal ball out and see if we can predict future innovation in solar storage.

Compressed Air Energy Storage

Energy from the air? Yep, but I guess we all know about air source heat pumps, yeah Well, this is nothing like them, lol.

Basically, excess energy is used to move huge compressors that squeeze the air in specially designed chambers until it can be compressed no more.

When energy is needed, that air is released into air turbines, creating energy.

Absolutely, 100% green energy storage solution … but also super massive and space hungry.

Mechanical Gravity Energy Storage?

Again, another way to ‘store’ energy using ‘potential’.

If you have a rock suspended in the air, that rock is full of potential energy which can be released if the rock is dropped. The potential energy in the rock is converted into kinetic, sound and heat energy as gravity pulls it towards the earth.

That is how Mechanical Gravity Energy Storage works. The excess energy pulls a series of weights into the air, where they are suspended until the energy in them is needed.

When it is, the weights are dropped, and the resulting energy is used to power turbines.

Sand Batteries

Yep, we can store energy in sand – well, we can store energy in everything really, but sand is very good at retaining heat energy.

One would expect this tech to be very popular in hot countries where there is a lot of sand – but it’s becoming popular in Finland to heat homes and swimming pools.

Sand is heated to 600 degrees Celsius during the day using solar panels and wind turbines.

As we know, energy is always looking to be converted so, when needed the heat is released into water filled pipes and used to power turbines and other devices.

Solid-State Batteries

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

But much like solid state hard-drives, these replace moving parts (liquid/electrolytes) with a solid material that does the same job.

It’s all very technical, and we’ll get up to speed on Solid State Batteries when they start to become commercially available.

Recycling  Batteries

This was probably one of the biggest barriers to solar being as green as it can possibly be.

But ‘Where there’s muck, there’s brass’ as we say in Yorkshire, and recycling solar equipment is starting to become big business.

All solar equipment is now produced with recycling in mind.

This isn’t a ‘green’ decision, it’s completely commercial – the more we recycle, the cheaper the manufacturing costs over solar products will be.