The Sunsynk Elite battery is a 5.12 kWh lithium iron phosphate module with IP65 protection that stacks up to six high, for 5.12 to 30.72 kWh, paired with a Sunsynk Elite hybrid inverter. E.ON Next sells it from £3,995 (4.6 kWh usable) and EDF from £3,995 including an inverter, or £2,495 for the battery alone, both with a 10-year warranty and 0% VAT on EDF's page until 31 March 2027. That is about £868 per usable kWh including the inverter, against an official median of £1,300 for batteries under 6 kWh. Sunsynk UK Ltd is an active company incorporated in 2013 and trading under that name since September 2021.
What Sunsynk sells
Sunsynk describes itself as a designer of solar storage systems “trusted by installers in over 40 countries” and sells hybrid inverters from 1 kW to 80 kW, low-voltage and high-voltage lithium iron phosphate batteries, all-in-one units and commercial systems. In UK homes you will meet two things: the Sunsynk inverter, which many installers use with other makes of battery, and the Sunsynk Elite, the all-in-one battery and inverter system that E.ON and EDF sell. This page is about the battery.
The Elite battery is a single 5.12 kWh module that stacks. According to one UK retailer’s listing:
| Sunsynk Elite battery module | |
|---|---|
| Nominal capacity | 5.12 kWh |
| Chemistry | Lithium iron phosphate (cell maker not stated) |
| Voltage | Low voltage, 40 to 60 V |
| Stacking | Up to 6 modules per stack, 1 stack per inverter: 5.12 to 30.72 kWh |
| Protection | IP65, -20°C to +55°C operating |
| Weight and size | 55 kg, 720 × 300 × 255 mm |
| Inverter | Sunsynk Elite hybrid, single-phase 3.6, 5 or 7 kW, plus an Elite PDU and base unit per stack |
| Warranty | 10 years |
| Cycle life, maximum power | Not stated |
The listing does not give cycle life or the battery’s maximum power in kW, and it mixes in marketing text for a different, commercial cabinet, so treat it as a starting point and ask for the datasheet of the exact model number you are quoted.
What E.ON and EDF charge
Two energy suppliers publish prices for the Sunsynk, and they match:
| Supplier | Sunsynk price | What it includes | Warranty | Read |
|---|---|---|---|---|
| E.ON Next | from £3,995 | Sunsynk Elite, 5.12 kWh (4.6 kWh usable) | 10 years manufacturer | 18 October 2026 |
| EDF | from £3,995 | Battery with an inverter | 10 years | 20 October 2026 |
| EDF | £2,495 | Battery alone, as listed in its table | 10 years | 20 October 2026 |
On the lower usable figure that is about £868 per usable kWh with an inverter and about £542 for EDF’s battery alone, against the official DESNZ median of £1,300 per kWh for batteries under 6 kWh. Both prices are below the median, but a 5 kWh battery is the most expensive size per kWh whoever sells it: the Tesla Powerwall 3 at E.ON’s £7,795 works out at about £577 per usable kWh. EDF says its Sunsynk and Tesla prices carry 0% VAT until 31 March 2027, and E.ON’s page does not mention VAT, so ask for the quote to show no VAT on an installed battery. The E.ON Next battery guide has the finance terms and the expired September discount.
Some other prices will mislead you. UK sellers list older-series Sunsynk 5.12 kWh units at about £999 to £1,095 before VAT, but those are different products, one of them sold only as part of a bundle. The Elite is a retail-channel product and its price on one installer’s trade site is behind a login.
The warranty is where Sunsynk needs a closer look
A 10-year warranty is the headline for the Elite, and E.ON and EDF both repeat it. The detail is less tidy:
- Different products, different warranties. For the CATL-cell 5.12 kWh Sunsynk products, UK sellers describe a 5-year product warranty with a 10-year performance warranty, and one seller lists 10 years for one version and 5 years for another. The 10 years on the Elite is the exact model you are quoted, not “a Sunsynk battery”.
- Sunsynk’s terms are in a PDF. Sunsynk links its manufacturer and extended warranty terms from its site as PDFs, and registration is by form. Ask the installer to give you the terms and to register the battery.
- The company behind it. Companies House shows Sunsynk UK Ltd (08778087) as active, incorporated on 15 November 2013 as Global Tech China Limited and renamed on 16 September 2021, with a registered office in Wrexham and accounts made up to 31 March 2025 (next due by 31 December 2026). Sunsynk’s website gives a Widnes address and says it is part of Sunsynk Group Limited. That is a distributor with a decade of filings, not a start-up, but it is a UK arm of a group whose structure is not described on the site. The GivEnergy administration is the reason to ask the question at all.
Ask for three things in writing: the warranty years for your model number, the capacity it guarantees at the end, and who pays a claim if the installer stops trading. The how long solar batteries last guide lists what to compare.
What a Sunsynk battery saves
This site’s model, for a London home using 3,000 kWh a year, with Sunsynk Elite modules taken at the lower 4.6 kWh usable each:
| Set-up | Modelled saving a year |
|---|---|
| 1 module (4.6 kWh), 4 kWp solar, flat tariff | £162 |
| 1 module, no solar, Agile Octopus | £188 |
| 2 modules (9.2 kWh), 4 kWp solar, Octopus Flux | £376 |
| 3 modules (13.8 kWh), 4 kWp solar, Octopus Flux | £580 |
| 3 modules, no solar, Octopus Go with an electric car | £503 |
The small battery saves little: £162 a year on £3,995 is a payback of about 25 years, which is why one 5 kWh module is the weakest buy at any price. The money is in two or three modules on a time-of-use tariff, where payback is much closer to the 13 to 14 years of the larger systems, but the Flux rows assume the battery is accepted by the tariff (see the FAQ above). The 10kWh battery and 13kWh battery pages compare the sizes across brands, and the cost guide shows what each size cost in 2025/26.
How it compares
Next to the other batteries a supplier will quote: the Tesla Powerwall 3 is 13.5 kWh as one unit with a built-in inverter and whole-home backup; a Fox ESS EVO is an all-in-one 5 or 10 kWh; the Enphase IQ Battery 5P carries a 15-year warranty; and the Duracell Dura5 is a 5.12 kWh module with 4.6 kWh usable and a 10-year warranty from a licensee. The best home battery comparison puts Tesla, Fox and Sunsynk side by side.
Before you buy one
Put the Sunsynk quote next to at least two others for the same usable capacity, divide each by usable kWh, and check the VAT line. Ask which inverter is included, whether your existing solar inverter is compatible if you are adding a battery, who notifies your network operator, and the MCS certificate number. If you would like a reply by email, send a battery storage quotes request. This site does not install batteries and is not affiliated with Sunsynk, E.ON or EDF.
Questions people ask
Are Sunsynk batteries any good?
On specification the Elite is conventional: lithium iron phosphate cells, IP65, a 10-year warranty on the product listing, and stackable to 30.72 kWh. Two UK energy suppliers, E.ON Next and EDF, sell it, which is a form of vetting. This site has found no independent long-term test of it. The sensible checks are the usable capacity, which of Sunsynk's warranties applies to the exact product, and who answers a claim.
How much is a Sunsynk battery?
E.ON Next lists the Sunsynk Elite from £3,995 and EDF from £3,995 including an inverter, or £2,495 for the battery without one, on pages read on 20 October 2026. A UK retailer hides the Elite price behind a trade login. Other 5.12 kWh Sunsynk products appear at about £999 to £1,095 before VAT, but those are different, older-series units, and one is sold only in a bundle.
How long is the warranty on a Sunsynk battery?
The Elite 5.12 kWh module is listed with a 10-year warranty by a UK retailer, and both E.ON and EDF state 10 years. The warranty is not the same across Sunsynk's range: for CATL-cell 5.12 kWh products UK sellers describe a 5-year product warranty with a 10-year performance warranty, and one lists the 10-year figure for one version and 5 years for another. Check the exact model number against Sunsynk's warranty terms before you sign.
What is the usable capacity of the Sunsynk Elite?
It depends on who you ask. A UK retailer lists 5.12 kWh usable with 100% depth of discharge, while E.ON Next quotes 5.12 kWh capacity and 4.6 kWh usable. The difference is 0.52 kWh, about 10%, so work out the price per kWh on the lower figure and ask your installer to state usable capacity in writing.
Who owns Sunsynk and who honours the warranty in the UK?
Sunsynk's UK website names Sunsynk UK Ltd, company number 08778087, as part of Sunsynk Group Limited, and Companies House shows it as an active private company incorporated on 15 November 2013 under the name Global Tech China Limited until 16 September 2021. A warranty claim goes through the installer or Sunsynk UK. Ask the installer whether claims run through them or directly, and what happens if the installer stops trading.
Can I put a Sunsynk battery on Octopus Flux?
This site could not confirm it. Octopus lists the battery brands it accepts for Intelligent Octopus Flux (it names Enphase, Fox ESS, GivEnergy, Huawei, Sigenergy and SolarEdge, not Sunsynk), and standard Flux asks for an MCS certificate, a smart meter and an export meter number. Ask your supplier in writing whether your exact battery and inverter are accepted before relying on Flux to pay the battery back.