The biggest differences are in how each battery connects and what its warranty promises. Tesla Powerwall 3 is a single 13.5 kWh unit with a solar inverter built in and 80% of capacity promised after 10 years. Fox ESS EVO batteries combine the battery with a hybrid inverter and carry 12 years at 70%, up to a throughput cap. Enphase IQ Battery 5P units are 5 kWh AC-coupled modules with 15 years or 6,000 cycles at 60%. Per kWh, the published installed prices are close.
Side by side
| Tesla Powerwall 3 | Fox ESS EVO 10 | Enphase IQ Battery 5P | |
|---|---|---|---|
| Usable capacity | 13.5 kWh | 10.24 kWh nominal at 95% depth of discharge (about 9.7 kWh); EVO 5: 5.12 kWh | 5.0 kWh per unit |
| Power output | Set from 3.68 kW to 11.04 kW | Versions from 5 kW to 10 kW | 3.2 kVA per unit |
| How it connects | Built-in solar inverter (3 inputs, up to 20 kW of panels); can also join existing solar | Built-in hybrid inverter and charger | AC-coupled: six built-in microinverters, works beside any solar inverter |
| Battery warranty | 10 years, 80% of energy retained | 12 years, 70% retained, or 47.88 MWh throughput | 15 years or 6,000 cycles, 60% retained |
| Warranty conditions | Bought from Tesla or a certified installer; internet connection for the full term | Claims made by the installer; the inverter has a separate policy | Registered within 45 days; continuously online; transfer form and fee on a house sale |
| Backup | With Backup Gateway 2 (£975 extra at list price) | EPS output, switchover under 4 ms | Full Backup mode with the system hardware |
| Size and weight | 1,105 × 609 × 193 mm, 130 kg | 584 × 1,009 × 197 mm, 113 kg | 980 × 550 × 188 mm, 82 kg installed |
| Weather rating | IP55 | IP66 | IP55 |
| Published price | £5,000 to £5,975 list, before VAT and installation; installed from £7,999 (Octopus) | Installed from £5,336 for about 10 kWh (Octopus, a Fox EVO or two Enphase units) | Installed from £3,947 for 5 kWh (Octopus, or a Fox EVO) |
Price per usable kWh
Published installed prices put the three close together once capacity is taken into account: about £593 per usable kWh for a Powerwall 3 at £7,999, about £550 for a Fox EVO 10 in Octopus's £5,336 package, and about £790 for a single Enphase unit at £3,947. The official medians for MCS-certified batteries fitted in 2025/26 were £1,300 per kWh under 6 kWh, £890 for 6 to 11 kWh and £630 for 11 kWh or more, so all three sit below the median for their size. An independent installer's price for the same battery will usually be higher than a large supplier's package; the quote checker shows whether a quote is within the normal range.
Choosing between them
- New solar and a battery together: a battery with the solar inverter built in, such as Powerwall 3, or a hybrid all-in-one such as a Fox EVO, avoids a separate solar inverter and converts stored solar more efficiently.
- Adding a battery to solar you already have: an AC-coupled battery such as the Enphase IQ Battery 5P leaves the existing system untouched. Tesla says Powerwall 3 can also be added to existing solar. See adding a battery to existing solar.
- A small home: one 5 kWh unit may capture most of the saving; see the sizing guide.
- Backup matters: all three can provide it with the right equipment, but check exactly what is included; see home battery backup.
- Warranty priorities: the longest term (Enphase) has the lowest capacity floor; the highest floor (Tesla) has the shortest term. Read the conditions, and check who handles a claim: how long batteries last compares them in detail.
Other brands you may be quoted
Installers quote many other batteries, including Sunsynk, Sigenergy, SolaX, myenergi, Duracell and GivEnergy. The same checks apply to all of them: usable capacity, power, the warranty's years, percentage and throughput cap, who handles a claim, and whether the manufacturer has a UK presence that will outlast the warranty. The GivEnergy administration is the reason that last check matters, and the best home battery comparison includes Sunsynk.
Brand pages
Tesla Powerwall 3
The UK list price and installed prices, what the Gateway and Expansion units add, and the warranty conditions that catch people out.
Price, specs and warranty →Fox ESS
EVO all-in-one and EP modules compared, installed prices, and the warranty's throughput caps and claim route explained.
Price, specs and warranty →Enphase IQ Battery
The AC-coupled 5 kWh unit: installed prices, what 3.2 kVA means, and the 15-year warranty's registration and connectivity conditions.
Price, specs and warranty →GivEnergy
What GivEnergy sold, what the administration means for the 12-year warranty, the app subscription and the options for owners and buyers.
Price, specs and warranty →A brand decision is easier with real prices in front of you. Ask for two or three battery storage quotes, ideally for different brands at the same usable capacity, and compare them with the line-by-line checklist.
Questions about brands
Which home battery has the longest warranty?
Of the three compared here, Enphase: 15 years or 6,000 cycles for the IQ Battery 5P, but with a floor of 60% of capacity. Fox ESS gives its EVO batteries 12 years at 70%, up to a throughput cap, and Tesla gives Powerwall 3 10 years at 80%. Compare the percentage and the conditions, not just the years.
What is the difference between usable and nominal capacity?
Nominal capacity is what the cells hold; usable capacity is what the battery lets you draw after keeping a reserve. Fox ESS lists the EVO 10 at 10.24 kWh with a 95% depth of discharge, so about 9.7 kWh is usable, while Tesla and Enphase quote usable figures. Always compare prices per usable kWh.
Which batteries do the big energy suppliers install?
Octopus offers a Fox ESS EVO, the Enphase IQ Battery 5P or a Tesla Powerwall 3 for battery-only installations. EDF lists a Powerwall 3 from £7,995. Which? reported in May 2026 that So Energy sells Duracell, Fox and Tesla batteries from £2,999, and that EDF and E.ON Next sell Sunsynk batteries from £3,995.
Should I still buy a GivEnergy battery?
It is hard to recommend. GivEnergy Ltd has been in administration since April 2026 and its administrator has said no further hardware warranties will be honoured, so a new unit comes without a working manufacturer warranty unless the seller provides its own cover.