The best solar batteries: at a glance

The Fox ESS Energy Cube (EC) range is peerless when it comes to providing reliable, all-round excellence for a reasonable price.

We’ve shone our spotlight on the EQ2900 because it’s particularly great value for money, with a high level of performance in all the most important areas. This makes it ideal for UK households looking to cut their energy bills with a solar & battery system.

It operates with a strong round-trip efficiency of 95% – which refers to how much electricity is lost per cycle – and offers a wide range of capacity options.

The system in the table above is made of the primary battery and one stackable unit, but you can build a system with a total of seven units, which is known as the EQ2900-L7.

At this size, the system can provide 20.16kWh of storage, which is more than enough for the vast majority of UK households.

And no matter how big your battery system gets, its high charge/discharge rate will increase alongside it, as long as you have a large enough inverter.

So if you size your inverter correctly, you’ll always be able to fill or unload your battery in an hour flat.

Your battery will also stay nice and compact: together, a primary and secondary module take up just 0.22m², and every extra module adds a mere 12cm to the system’s height.

A battery’s charge/discharge rate - measured in kilowatts (kW) - refers to the rate at which electricity can pass in or out of it, a bit like a hose’s water pressure.

The Fox ESS EP12 offers a market-leading charge/discharge rate of 11.52kW.

This allows you to power more appliances with your battery at any one time, because it can provide more continuous energy than other models.

For example, you may want to run a 5kW heat pump, 2kW oven, 2kW washing machine, and 2.5kW tumble dryer all at once – and with the EP12, you can power all of them with your battery.

This is also beneficial if you’re signed up to a time-of-use import tariff, which comes with peak and off-peak times for buying grid electricity. You can charge your battery with cheap electricity overnight, then use or sell it for the rest of the day.

With a high discharge rate, you can profit by rapidly selling your battery's contents each evening at the peak rate, which will also get it ready to charge back up to full during the off-peak period.

And the EP12’s equally high charging rate enables you to make the most of having a large solar panel system, as you’ll store more of the electricity your panels generate, with less going to the grid.

Its round-trip efficiency of 95% and size of 0.45m² makes this a lean, mean machine. Every battery will lose some energy during its charging/discharging cycles, but the EP12 keeps this to a minimum.

The battery, which can be installed outside or inside – and on the ground or mounted on a wall – only comes with a couple of minor downsides. Its 90% depth of discharge (DoD) is slightly below average, as is its scalability, which stops at four modules.

This machine, with its plain, white, minimalist design, looks like an homage to a storage heater – and has the jargon-filled name to match – but it holds incredible potential.

You can build a network that includes 16 of these 15 kilowatt-hour (kWh) batteries. When you take its 90% DoD into account, this results in a usable capacity limit of 216kWh.

That’s enough to run the average UK household for 23 days, so it should be sufficient for the great majority of homes. This will allow you to cut your running costs for any electric vehicles, heat pumps, or hot tubs you have (or may buy in future).

If you require a larger system than most, or want to future-proof your home, this SolaX model is the best around – and at 0.49m², it packs its powerful punch into a petite package.

EcoFlow will give you a 15-year warranty with this battery, which guarantees that it’ll be functioning at no less than 70% of its initial capacity at the end of this term.

This warranty will only last until your battery has carried out 15,000 cycles, but if you charge and discharge once per day – as most households should – the 15-year mark will come first.

You can therefore maximise your savings without worrying about invalidating your warranty.

The PowerOcean has a DoD of 96% that allows you to use almost the entire battery, you can discharge fully in around 90 minutes, and it's expandable.

You can only add a couple of additional modules, but a total useable capacity of 14.5kWh is still more than most homes need.

A battery’s round-trip efficiency measures how effectively a machine can hold on to electricity as it passes through the charge-store-discharge cycle – and the Enblock E15 excels in this area, with a 96% rating.

This helps you to make the most of your solar & battery system by limiting your losses – and it reflects LG’s increasingly impressive work in this area.

Manufacturers are increasingly releasing batteries with 95% round-trip efficiency, but no other model currently achieves more than this.

This sleek, silver battery is larger than most, but it makes the most of vertical space, which can be useful if you’ve got limited floor space. Its 49kg weight is also well below average.

It does however take 2.5 hours to fully discharge, and isn’t scalable.

The SMILE-G3-BAT-4.8S can transform to better suit your requirements, and is the most flexible battery on the market.

You can get up to six battery modules installed, for a maximum usable capacity of 27.4kWh, and pair it with a scalable inverter that rises to 8kW for most homes.

As an added bonus, AlphaESS states that this 4.8kWh battery will still maintain at least 80% of its original performance after a massive 10,000 cycles.

This relatively lightweight machine also takes just an hour to charge or discharge, which is much quicker than the 1.7 hours we've identified as the industry average.

If you like being able to easily adjust your home as your needs change, you’ll love the Dura5, which can be scaled up to 32 modules.

This means you can expand your storage as your household's electricity consumption grows.

The Dura5 also has a huge total usable capacity of 147.5kWh. It may be a distant second to SolaX’s monster system – and may involve piling what look like silver, bank robbery-style briefcases against your wall – but it’s comfortably larger than any other domestic model.

It’s better to just start off with a bigger battery though, as you’ll pay much more in labour costs if you scale up later on. You’ll also be able to use more of your solar-generated electricity straight away, which will help you cut your electricity bills even more significantly.

Being able to buy more storage when you need it does give you the space to change your mind, but it’s much more cost-effective to get a large system in the first place, if you can.

The Powerwall 3 is a top-tier machine – as you might expect from Tesla – even though it falls short in a couple of areas.

Its most impressive quality is its Ingress Protection rating. This rating standard, developed by the International Electrotechnical Commission, shows how well a machine guards against dust and water – and no battery scores higher.

‘IP67’ means the Powerwall 3 is completely dust-tight and protected against the effects of temporary immersion in water – which means it can endure a metre of water for 30 minutes.

So if your battery is installed on the garage floor with your other appliances, and one of them floods the area, the battery may be safe if you get to it quickly enough.

The most common rating for solar batteries is IP65, which means they’re dust-tight and protected against water jets. This is usually sufficient, but IP67 just means your product is that much safer.

The Powerwall 3 also comes with 100% DoD and a warranty that guarantees your battery will perform at 80% of its starting capacity after 10 years, with no cycle limit.

However, its 89% round-trip efficiency is poor, and it’s larger and heavier than the average battery.

The Hinen B5000 is excellent at dealing with extreme temperatures.

It can cope with the thermostat plunging to -20°C or rising as high as 55°C – and though UK households may not be concerned about these extremes, this still speaks to the machine’s resilience.

Fox ESS's EVO 10 battery performs equally well on this front, but we’ve chosen to spotlight the B5000 because Fox ESS already appears twice on this list.

This sets them apart from many batteries – including a few on this list – that stop charging when the temperature falls below 0°C, which it does every year in the UK.

So if you live in a region where it can get particularly hot or cold, it’s worth considering the B5000.

It also comes with a 90% DoD and 5.12kW charge/discharge rate, which are both above industry averages.

And it's relatively scalable, with an overall useable capacity of 46.1kWh – which is better than the market average and more than enough for most UK households.

This stylish battery is a gleaming silver, with a minimal logo design and nicely encompassed power button.

It looks futuristic, which lines up perfectly with its technologically advanced attributes, including six in-built microinverters.

Because of course, the IQ Battery 5P isn’t just for show.

It’s one of the most scalable batteries around, with customers able to reach 14 modules for an overall capacity of 66.5kWh, when you take the machine’s 95% DoD into account.

And it comes with an excellent warranty, too. Enphase covers this battery for 15 years or 6,000 cycles – which, if you perform one cycle per day, will last you more than 16 years.

The manufacturer only guarantees that your battery will work at 60% of its original capacity at this time, but after 15 years, that’s reasonable.