Tesla Powerwall 3 is the simplest all-in-one choice with a 10-year, 80% warranty, but it is the dearest unit and needs a Tesla certified installer. Fox ESS suits homes that want to start small and add modules, with 10 or 12-year warranties depending on the range. Sunsynk's 48V modules are widely fitted in retrofit systems and carry a 10-year warranty. GivEnergy is not a buy in 2026 because its maker is in administration.
Comparison · Published by SEO Dons Ltd · Updated 27 September 2026
Most “best battery” lists are written by someone who sells one of them. This site does not install or sell batteries, so this comparison is about fit, not a winner. It sticks to what each manufacturer publishes and what UK suppliers charge, and it leaves out claims that cannot be checked.
Compare on these four numbers, not the brand
- Usable capacity in kWh. The energy you can actually use, not the “total” or “nominal” figure. It is what the price should be divided by.
- Price per usable kWh, installed. The official median for a 6 to 11 kWh battery fitted in 2025/26 was £890 per kWh, and £630 per kWh above 11 kWh (DESNZ). Standard packages from big suppliers come in below that.
- Warranty terms. Years, the share of capacity promised at the end, any cap on energy throughput, and the conditions: internet connection, approved installer, registration.
- Backup. Whether anything stays on in a power cut, and what hardware the quote includes to make that happen.
The three batteries side by side
| Tesla Powerwall 3 | Fox ESS | Sunsynk | |
|---|---|---|---|
| Usable capacity | 13.5 kWh per unit | Modular; for example EVO 10 at 10.24 kWh, EP5 at 5.18 kWh | 48V modules from 3.07 to 16.07 kWh |
| Chemistry | Lithium-ion | Lithium iron phosphate (LFP) | Lithium iron phosphate (LFP) |
| Inverter | Built-in solar inverter, 3 MPPTs, up to 20 kW of solar | Hybrid inverters and all-in-one units | Pairs with a hybrid inverter |
| Warranty | 10 years, 80% of energy retained; certified installer required | 10 years (EP, CQ) or 12 years (EQ, EVO) at 70%, with throughput caps | 10-year product warranty; 6,000+ cycles at 80% depth of discharge |
| Published price | £5,000 to £5,975 before VAT and installation (Tesla); from £7,999 installed (Octopus) | From £3,947 (5 kWh) and £5,336 (10 kWh) installed, battery only, Fox or Enphase (Octopus) | From £3,995 via EDF, capacity not stated (Which?, May 2026) |
| Suits | New solar plus battery, whole-home backup, one large unit | Starting small and adding modules later | Retrofit systems built around a hybrid inverter |
Sources are listed at the foot of the page. Prices are the suppliers’ own “from” figures; a survey can add to them.
Tesla Powerwall 3: the all-in-one
The Powerwall 3 combines a 13.5 kWh battery with a solar inverter that takes three strings of panels, which makes it a tidy choice for a new solar and battery system. Its output can be set between 3.68 and 11.04 kW at 230 V, and up to four Powerwalls and three Expansion units can be linked for 94.5 kWh.
Two conditions matter more than the spec sheet. The warranty only applies to a Powerwall bought from Tesla or a Tesla certified installer, and the full ten years depends on the unit staying connected to the internet; without it, Tesla commits to at least four years. And backup is not automatic: in the configuration that uses a Remote Meter instead of the Backup Gateway 2, nothing stays on in a power cut. Tesla’s own prices show the difference, £5,000 without the gateway and £5,975 with it, before VAT, delivery and installation. The full Powerwall 3 guide has the UK installed prices.
Fox ESS: modular and expandable
Fox ESS sells stackable lithium iron phosphate batteries and all-in-one units, which suits a home that wants a modest battery now and more capacity later. Its UK warranty policy (version 4.5) gives 10 years on the EP and CQ ranges and 12 years on the EQ and EVO ranges, each promising 70% of nominal energy until the period ends or a throughput cap is reached, whichever comes first. The EVO 10, for example, is capped at 47.88 MWh.
Fox ESS is also one of the cheaper routes in suppliers’ published prices: Octopus’s battery-only range, which offers a Fox ESS EVO or an Enphase battery at each size, starts from £3,947 for about 5 kWh and £5,336 for about 10 kWh at April 2026 prices. Fox ESS models and warranty.
Sunsynk: 48V modules for hybrid systems
Sunsynk’s battery range is built around 48V lithium iron phosphate modules, from the 3.07 kWh L Series to 16.07 kWh units, which are usually paired with a Sunsynk or compatible hybrid inverter. Sunsynk describes the range as IP65-rated, rated for 6,000 or more cycles at 80% depth of discharge, and backed by a 10-year product warranty. Much of the brand’s UK presence is through installers and trade retailers, so installed prices vary more than for a single-supplier package; Which? reported EDF offering Sunsynk batteries from £3,995. If you want one pick for your own situation rather than a three-brand comparison, the best solar battery guide chooses by home and budget. The Sunsynk battery guide covers the Elite module, the warranty differences between product lines and who stands behind it.
As with any modular system, the question to ask is what the quote’s modules add up to in usable kWh, and whether the inverter can charge and discharge fast enough to use them in the hours that matter.
GivEnergy: not a buy in 2026
GivEnergy Ltd entered administration on 9 April 2026 and stopped trading, and the administrator has said it will honour no further hardware warranties. Batteries already fitted keep working and the app is run by a separate company, but a battery is a ten-year purchase and its warranty is only as good as the company behind it. Owners should read what happened to GivEnergy for the practical steps.
The GivEnergy All in One page sets out the specifications, the warranty conditions and what the administration changes for owners and buyers.
Other batteries worth knowing
- Enphase IQ Battery 5P: AC-coupled modules of about 5 kWh with a 15-year or 6,000-cycle warranty at 60% capacity, useful on systems that already use Enphase microinverters. Enphase details.
- Alpha ESS SMILE G3: listed by Heatable at about £2,550 supply for 10.1 kWh plus about £1,400 installation, among the lowest supply prices it tracks.
- Budget modular brands such as Pylontech sell battery modules that installers build into systems; the installed price depends on the inverter and labour around them.
Which one fits your home?
- New solar and battery, want whole-home backup: Tesla Powerwall 3 with the Backup Gateway 2, from a Tesla certified installer.
- Want to start at 5 kWh and grow: Fox ESS or another modular system.
- Already have a hybrid inverter: a battery made for it, such as Sunsynk modules on a Sunsynk inverter.
- Existing Enphase microinverter system: Enphase IQ Battery.
Whichever you lean towards, get more than one written quote for the same usable capacity and put each through the quote checker. If you only have one price, compare it with more battery storage quotes (we reply by email) before you sign.
Whichever you choose, test the price against the official medians in the solar battery cost guide, and if you have solar and can join Octopus Flux, check the Octopus Flux rates for your region before you settle on a size.
If you want power in a cut, price home battery backup separately: Tesla’s Gateway adds £975 at list prices, and other brands wire an emergency output or a changeover arrangement that the installer must price.
Questions people ask
Which home battery is best in the UK?
It depends on the home. Tesla Powerwall 3 suits a new solar and battery system where you want one unit with a built-in solar inverter and optional whole-home backup. Fox ESS suits a modular system you can expand. Sunsynk suits homes pairing a hybrid inverter with 48V battery modules. Compare them on price per usable kWh and warranty terms rather than brand.
Is Tesla Powerwall 3 worth the extra cost?
It can be if you need the whole-home backup and a large single unit. Octopus lists a Powerwall 3 battery-only installation from £7,999, against from £5,336 for about 10 kWh, where Octopus fits one Fox ESS EVO 10 or two Enphase batteries. Per usable kWh the gap is smaller than the headline suggests: about £593 against about £550.
What happened to GivEnergy?
GivEnergy Ltd entered administration on 9 April 2026 and stopped trading. The administrator has said no further hardware warranties will be honoured. Existing batteries keep working, but it is not a sensible new purchase. The full update.
How long do home battery warranties last?
Usually 10 years, sometimes 12 or 15. Tesla promises 80% of capacity after 10 years; Fox ESS promises 70% for 10 or 12 years depending on the range, up to a throughput cap; Enphase promises at least 60% for 15 years or 6,000 cycles. Read the conditions, such as keeping the battery online.