Solar Batteries: Who Makes the Best Solar Battery?

Compare solar power batteries

This article was updated on 26th October 2018

Did you know that in just one hour the sun radiates more energy than the whole world uses in a year? That’s free energy that the vast majority of us are missing out on, but solar battery storage systems are changing the game.

Solar panels transform the sun’s energy into power for our homes, but solar batteries enable us to store it for those times when the sun isn’t around. This technology means we can store more of the free energy produced by our panels and buy less from energy suppliers, saving money and increasing our independence from the National Grid.

Why Get a Solar Battery?

  • Energy bill savings: By storing energy during times of lower demand you can reduce the amount you need to buy from your energy supplier when energy usage is higher, saving you money on your energy bills.
  • Backup Power Supply: Even homes which do not rely on solar energy can benefit from the added security of a solar battery. When a power cut strikes a store of this ‘off the grid’ energy could be invaluable to your household.
  • Feed-in Tariff Closing(FiT): Back in 2010, the UK government introduced the Feed-in Tariff scheme to encourage homeowners to generate their own electricity with solar panels. Owners of eligible PV systems would be paid for every kWh of energy they generated (Generation Tariff) and then paid again for energy not used and exported to the National Grid (Export Tariff).
  • Your energy supplier will pay you 5.24p for every kWh you export. If/when you need to buy energy from a supplier because your PV panels aren’t generating enough energy, they will charge you a significantly higher price the buy the same amount of energy back (on average around 14p – 16p). A battery storage system means you can keep hold of your surplus energy (that cost you nothing to generate) for use at another time (when your panels aren’t generating) so you can avoid paying their higher prices.


    The FiT scheme is closing to new applications on March 31st 2019. However, solar PV systems registered and successfully accepted onto the scheme before this date will be eligible to receive FiT payments for the next 20 years.

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The Best Solar Batteries & Prices

Solar battery prices can range from £500 to £8,000 excluding the cost of having it fitted. We estimate installation charges to be at least £500 worth of an electrician’s time. You may also have to add the cost of an inverter if retro fitting solar batteries to your existing solar panels which could be around £1,000. It’s worth noting that there are quite a few ‘hybrid’ systems which combine an inverter and battery storage.

The table below details all you need to know to make a fair comparison but as price is a major factor in any major purchase we’ve extracted the prices out for quick reference.

  • Tesla Powerwall 2.0: £5,970
  • LG Chem Resu: £2,628+
  • Sonnen Batterie Eco: £4,500+
  • Powervault 3: Not available without a direct quote request
  • Enphase: £1,700+
  • Samsung SDI: £3,500+
  • Moixa Smart Battery: £2,950+
  • xStorage by Nissan: £3,000+
  • BYD B-BOX: Unknown
  • OVO: Unknown – currently being trialled by OVO customers
  • Solax: £1,920+
  • Varta Pulse: £3,579+

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Supplier Capacity Technology Cycles Warrantied Warranty Weight Operating Temperature Dimensions (mm) Mounting Cost
Tesla Powerwall 2.0 Tesla Powerwall 2.0 13.5 kWh Lithium-ion n/a 10 years 125kg -20°C to 50°C 1118 x 737 x 140 Floor / wall / interior / exterior £5,970
LG Chem Resu 6.5 solar battery storage LG Chem Resu 3.3 – 9.8kWh Lithium-ion 6,000 10 years 31 – 99.8kg -10°C to 45°C 452 x 403 x 120 to 744 x 907 x 206 Floor / wall / interior / exterior £2,628+
sonnenBatterie Eco Sonnen Batterie Eco 2 – 16 kWh Lithium-ion 10,000 10 years 71 – 273kg 5°C to 40°C 702 x 641 x 221 to 1839 x 641 x 221 Indoor £4,500+
Powervault ECO Battery Powervault 3 4.1 – 20.5 kWh Lithium-polymer >6,000 10 years 129 – 329 kg 0°C to 35°C 120 x 98 x 25 to 205 x 98 x 25 Indoor Unknown
Enphase Solar Battery review Enphase 1.2 kWh Lithium-ion 7,300 10 years 25 Kg -20°C to 45°C 390 x 352 x 220 Wall mounted indoor £1,700+
Samsung SDI Solar Power Storage Samsung SDI 3.24 kWh Lithium-ion 6,000 5 years 95kg -10°C to 40°C 1000 x 267 x 680 Floor standing £3,500+
moixa storage battery Moixa Smart Battery 2-3 kWh Lithium Ion Phosphate – LiFePO4 10,000 10 years *Lifetime with GridShare 3 – 49kg -5°C to 40°C 505 x 345 x 245 Wall Mounted £2,950 – £3,450
Nissan xstorage xStorage by Nissan 3.6 – 6 kWh Lithium-ion n/a From 5 years for 4.2kWh system, 10 years for 6kWh system 135kg 0°C to 30°C 1230 x 890 x 220 Wall Mounted £3,000
byd bbox BYD B-BOX 2.5 – 409 kWh Lithium Iron-Phosphate n/a n/a 88 – 202kg -20°C to 55°C 1000 × 600 × 600 Floor standing n/a
ovo battery OVO Home Energy Storage 4.2 – 10 kWh Lithium-ion n/a n/a 96 -122kg n/a 650 x 300 x 1080 Floor standing n/a (currently in trial with OVO customers)
solax battery Solax Battery 3.3 – 6.5kWh Lithium-ion 3,000 10 Years 26 – 44kg n/a 330 x 450 x 110 n/a £1,920+
varta pulse battery Varta Pulse 600 x 690 x 190 Lithium-Ion 10,000 10 Years 45 – 65kg -5°C to 30°C 330 x 450 x 110 n/a £3,579+
*Prices are estimates only and do not include installation costs which can range from £500 to over £2,000.

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How do solar batteries work?

Solar panels are fitted onto a roof or exterior wall where they can be exposed to the most sunlight. Each panel includes solar cells which convert the sun’s energy into DC electricity which is then converted to AC electricity by an inverter. This can then be used to power your home.

Whatever you don’t use is sent back to the National Grid to be redistributed around the country. Your energy supplier will pay you for every kWh of energy you send back (which is deducted from your energy bills) but you will pay a significantly higher price per kWh when you buy it back at a later date.

So you can only use solar energy as and when it is available i.e. when the sun is shining. This means that complete independence from the National Grid isn’t a realistic option, although you can reduce the amount of power you are buying from them.

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By introducing a solar battery into the process you can keep hold of the surplus energy you’ve produced for use at a later date and further reduce your reliance on the National Grid.

Fitting a solar battery to your home

Solar energy systems that can store their own electricity have three main components:

  • Solar panels that absorb and convert the sun’s energy to DC electricity.
  • A battery (or batteries) to store the electricity that is not used straight away for use later on.
  • An inverter that converts DC electricity to AC ready for use in your lights, appliances etc.

As solar technology continues to progress many modern systems also incorporate smart technology such as apps and Wifi so you can easily monitor the battery’s charge level and general efficiency.

Types of Solar Batteries

AC or DC?
The solar battery you choose needs to be the right size or voltage for your needs. This is very important as the wrong size could pose a very real safety risk. We highly recommend consulting with multiple professional installers about your needs before reaching a final decision.

In addition to choosing the right voltage, you will need to consider if AC or DC is the best type of panel for your system. The main difference is in the way the battery connects – or doesn’t connect – to your solar panels.

AC: An AC (alternating current) battery is not connected directly to your solar panels but is connected via the electricity meter. This means it is easier to retrofit to existing panels, so if you have solar panels already in place this may be the best solution for you. You will need an additional inverter to convert DC electricity to AC for use in your home and then back to DC to be stored in the battery.

DC: DC (direct current) batteries tend to be installed at the same time as solar panels as they connect directly to the panels. You do not need an additional inverter as it is connected before the electricity meter.

Lithium Ion Vs Lead Acid

All of the solar batteries featured in this article are Lithium-ion based, this is the more progressive technology and the same battery technology you’ll find in your lap-tops, mobile phones and electric vehicles. There is still a strong and well established market for lead-acid batteries (the kind you’d find in your car) and they are still popular with many solar power users who live off grid. Lead acid batteries are tried and tested technology that dates back over 100 years and they are cheaper in terms of upfront cost. However Lithium-ion batteries have a lower life-time cost and operate at a much higher efficiency level.

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Things to consider

Ongoing Maintenance
A solar battery is not a simple ‘install and leave’ unit. It needs regular monitoring and maintenance to keep it working both efficiently and safely. This includes keeping it charged at an optimum level, carrying out regular power ‘boosts’ and gassing as well as ensuring it is stored at a correct temperature and protected from the weather.

Replacement Parts
Solar batteries do not last as long as solar panels. Currently, a high quality solar battery will last for around 10-15 years, but this is dependant on how much you use it and ensuring it is maintained correctly. A battery can cost up to £2,000 (not including installation) so it is a significant expense to consider.

It’s not a complete energy solution (yet)
The ultimate ambition for many is to make complete energy self-sufficiency a reality, without any reliance on the National Grid at all. While technology is certainly moving in the right direction and has made great strides in recent years, a solar battery system is still not a viable option to completely disconnect from the mains supply. Batteries have their faults, shelf-lives and limitations, so until things have progressed it’s necessary to have the option of a backup supply from the National Grid.

Solar Battery FAQs

Do you need solar panels to have a solar battery?

No. If you live in an area affected by regular power cuts then a home battery could be just the system you need to keep the lights on. On average you’ll probably get around 24 hours of backup power but this can be increased by simply installing more batteries. If you’re on an Economy 7 rate a home battery can also save you money by charging when electricity is at it’s cheapest for you to use when it’s not so cheap. Finally, you can even make money by storing energy for the National Grid who can discharge it from you in times of need.

Can you add a solar battery to existing solar panels?

Yes and no. Some batteries will only work when installing a new system or one that was specifically designed for it (Tesla Powerwall 2) and some systems will retrofit to any system.

Are solar batteries safe?

They are as safe as as any other electrical item in your home. Generally installing a solar battery is not a DIY job and for the most part the public can’t buy solar batteries direct from the manufacturer but rather via an approved installer.

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Jargon Guide

      • Capacity: This is the ‘usable’ amount of energy in kWh (units) that the battery will store. It’s never a good idea to run a battery down to empty as it will cause damage, so when you are comparing capacities remember to check if the figure given is ‘total’ or ‘usable’.
      • Cycle: The number of cycles refers to the amount of times a battery can be charged and discharged. It will give you an indication of how much ‘life’ a battery has but doesn’t relate to the number of years it’s been operating.
      • Technology / chemistry: Batteries are generally Lead Acid or Lithium Ion. While acid is cheaper it is not as efficient and doesn’t last as long as Lithium Ion.
      • Power output: This is, quite simply, how much power the battery can deliver at one time. The more appliances / lights etc. that you plan to power with the battery the higher this will need to be.

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