Deye makes the OEM platform behind Sunsynk’s hybrid inverters, so the hardware is closely related. But I would not treat the two as one purchase. Identical silicon does not mean identical risk: the badge still decides your UK warranty, firmware support and certification route, and it decides who answers the phone when something misbehaves.
Are Deye and Sunsynk really the same inverter?
They can be very close, but “same factory” is not a complete buying decision. Deye is the manufacturer behind OEM and private-label inverter platforms, including Sunsynk. That explains the resemblance between some units. It does not prove that every Deye and Sunsynk model has the same firmware, approval status, warranty or support route.
I would compare the full model number, not the badge alone. In this case, that means the Sunsynk 5kW ECCO Sunk-5K-SG04LP1 against the Deye SUN-5K-SG03LP1-EU. They are closely related single-phase, 5kW hybrid inverters for 48V low-voltage batteries. The Deye relationship is useful context, but it is not a promise that the two boxes arrive configured and supported in the same way. Deye describes its OEM and partner route.
What is different between the Sunsynk 5kW ECCO and Deye SUN-5K-SG03LP1-EU?
The useful comparison is not Deye versus Sunsynk as whole brands. It is this exact pair of 5kW units and the route by which you buy them. The two models share headline characteristics, but the available evidence does not establish that the exact SG03 and SG04 units use the same electrical platform. Check UK sales, certification, firmware and after-sales details unit by unit.
| Buying point | Sunsynk 5kW ECCO Sunk-5K-SG04LP1 | Deye SUN-5K-SG03LP1-EU |
|---|---|---|
| Type and rated output | Single-phase 5kW hybrid inverter. | Single-phase 5kW hybrid inverter. |
| Battery system | 48V low-voltage battery support, 40V to 60V. | 48V low-voltage battery support, 40V to 60V. |
| Published electrical detail | 5kW rated output, 5.5kW maximum AC output and 120A battery limit. | Do not assume matching figures without checking the exact Deye datasheet. |
| UK hardware price and sales route | £855 excluding VAT was shown in UK retail stock on 13 July 2026. | UK price and UK sales channel were not verified in the research. |
| Grid documentation | Confirm the exact unit’s current G98/G99 listing before connection. | The official manual lists G99, but confirm the exact supplied suffix and current listing. |
| Support and warranty | UK retail stock was shown at the time of writing. Confirm the supplying retailer’s current warranty process, firmware support and fault-support contact before buying. | Confirm who provides firmware help, warranty handling and fault support before paying. |
The Sunsynk figures above come from its 5kW ECCO datasheet and the UK retailer listing that showed the £855 excluding-VAT price. The Deye manual covers the SUN-3.6-6K-SG03LP1-EU range and lists G99.
Why do firmware and the G98/G99 listing matter more than the badge?
A grid connection is based on the equipment being connected, not on a broad claim that two brands use the same factory. The DNO process needs the correct equipment evidence. A manual that covers a product family is useful, but it is not a substitute for checking the exact suffix, certificate and firmware supplied to you.
This is where a bargain can become expensive, and it is the real difference between the two badges. Identical hardware does not mean identical support: the question that matters is who answers the UK phone when the firmware misbehaves. Before ordering, ask the seller for the exact model suffix, the current G98 or G99 listing that covers it, and the firmware version it will ship with, then keep those answers with your installation paperwork. My wider guide to choosing an inverter explains why the inverter is a system decision rather than just a power rating.
Do the same check for Sunsynk. A UK-supported brand makes the conversation easier, but it does not remove the need to match the actual inverter to your connection paperwork. The model number on the listing, the unit and the certificate should all agree.
What do I get by paying for Sunsynk?
With Sunsynk, the important extra is not a magical difference in the inverter hardware. It is the established UK support and warranty route around it. For someone building or maintaining a DIY system, having a recognisable UK channel and a large community can make a fault, firmware question or compatibility query less uncertain.
The 5kW ECCO was listed at £855 excluding VAT in UK retail stock on 13 July 2026. That is a hardware price, not an installed-system price. VAT, delivery, labour, DNO work, backup equipment and an installer’s willingness to fit customer-supplied hardware are separate costs. My experience with the smaller Sunsynk 3.6kW ECCO is why I would treat the support route as part of the component, not an afterthought.
When is the Deye the sensible choice?
A Deye can be the sensible choice if it is genuinely cheaper and the seller can document exactly what you are buying. The potential saving only counts after you know the UK sales route, current firmware, G98/G99 evidence, warranty claimant and support contact. At that point, you are comparing a real offer rather than an assumed clone.
I would want those answers in writing before paying. “Deye made it” is not enough if a firmware issue appears later and the retailer, distributor and manufacturer each point elsewhere. Check the model against the UK inverter directory, then ask who will handle a fault in the UK and what evidence they need from you.
Which would I choose?
I would choose the Sunsynk 5kW ECCO when I value a clear UK warranty and support channel, a known retail route and the practical help of the DIY community. The £855 excluding-VAT reference gives a starting point, but I would still check the delivered and installed total rather than comparing sticker prices.
I would choose the Deye only when the exact SUN-5K-SG03LP1-EU is meaningfully cheaper and the seller confirms its firmware, current UK certification and responsibility for support and warranty. The hardware may be closely related, but the buying risk is not automatically the same. If you are also comparing other hybrid brands, see my Solis versus Sunsynk hybrid inverter comparison.
