Put the Sunsynk 5kW ECCO and the Deye SUN-5K next to each other with their user manuals open, and the settings screens are nearly identical, because Sunsynk sells a Deye platform under its own badge. I went through both manuals control by control. The battery current limits, the grid-protection tables and even the engineer passwords match. Only about five controls genuinely differ, and most of what looks different is the same feature filed under a different menu.
Which controls does the Deye have that the Sunsynk manual doesn’t?
Five controls stand out as genuinely different rather than just relabelled: named work modes, a day-of-week time-of-use schedule, a grid-code self-test, separate import and export power limits, and an arc-fault switch. Each appears in the Deye 5kW manual with no clear equivalent in the Sunsynk 5kW ECCO manual.
| Control | What it does | Deye 5kW | Sunsynk 5kW ECCO |
|---|---|---|---|
| Work mode selection | Sets how the inverter prioritises solar, battery, grid and export | Named modes: Selling First, Zero Export To Load, Zero Export To CT | Tick-boxes: Zero Export, Solar Export, Limit to Load Only |
| Time-of-use by weekday | Runs a different charge and discharge schedule on chosen days | Mon to Sun day selector on the schedule | No day-of-week selector in the manual; one schedule runs every day |
| Grid-code self-test | Guided compliance test with a pass or fail report | CEI-021 self-test with per-point results | Plain “System selfcheck” diagnostic, no report |
| Grid power limits | Caps how much power crosses the meter | Separate Import and Export limiters | One combined “Inverter Power Limiter” |
| Arc-fault control | Switches the DC arc-fault detector on or off | On/off toggle plus a manual clear button | No user switch; only reports the F63 fault code (US market only) |
Most of these matter less than the list suggests. The work-mode names describe the same behaviour the Sunsynk tick-boxes produce, so that one is cosmetic. The CEI-021 self-test is an Italian grid-code tool that a UK or South African install never touches. The arc-fault switch only does anything on US-market units. That leaves two that can affect a real home: the day-of-week time-of-use schedule, which is genuinely useful if your electricity tariff changes by day, and the split import and export limits, which help when your network operator caps export and you also want to cap what you pull from the grid.
Are the Sunsynk and Deye settings actually the same?
Yes, overwhelmingly. The proof is in the values that match to the decimal place. I compared the grid-protection and battery pages field by field, and these were identical on both the Sunsynk 5kW ECCO and the Deye 5kW.
| Setting | Both inverters |
|---|---|
| Battery charge and discharge limit | 0 to 120A |
| Overvoltage trips (HV1 to HV3) | 265.0V, 0.10s |
| Undervoltage trips (LV1 to LV3) | 185.0V, 0.10s |
| Over and under frequency trips | 51.50Hz and 48.00Hz |
| Frequency-watt droop | 40% per Hz |
| Time-of-use slots | 6 |
| CT ratio default | 2000 |
| AGM absorption and float | 57.6V and 53.6V |
| Micro-inverter AC-couple on and off | 95% and 100% state of charge |
| Engineer passwords | 9999 factory reset, 7777 grid unlock, 1234 self-check |
When two inverters that are sold as different products share the same trip voltages to one decimal place and the same factory passwords, you are looking at one firmware platform with a different skin on top. That is the whole reason the Deye and Sunsynk comparison is really a question about the badge, not the box.
Does the size change any of this?
No. The 3.6kW, 5kW and 8kW versions run the same menus, and the five differences above apply to all of them. What changes with size is the hardware headroom: how much battery current the inverter will push, its rated output, and how much solar you can wire to it. Those figures match between Sunsynk and Deye at each size, because both are the same SG05 platform.
| Model size | Battery charge and discharge limit | Rated AC output | Max solar (PV) input | MPPTs |
|---|---|---|---|---|
| 3.6kW | 90A | 3,600W | 4,680W | 2 |
| 5kW | 120A | 5,000W | 6,500W | 2 |
| 8kW | 190A | 8,000W | 10,400W | 2 |
These are the current Sunsynk and Deye SG05LP1 datasheet figures, and the charge and discharge limits share the same value at each size. So comparing an 8kW Sunsynk against an 8kW Deye tells you the same story as the 5kW: the same control set, the ceilings in the table above, and a menu laid out slightly differently. Choose the size for your loads, then choose the badge for the warranty and support, not for a feature one has and the other lacks.
Why the menus still feel different
If the settings are so similar, why do installers say the two feel different to set up? Because the same controls are filed in different places. Deye gathers most of the advanced settings onto a single Advanced Function page. Sunsynk spreads the same settings across several tabs.
The controls themselves are present on both, with matching values: the CT ratio, the island-mode signal, the BMS error-stop, the generator and grid peak-shaving all appear on each inverter. So moving from one to the other means relearning where a setting lives, not whether it exists. That is a real annoyance for an installer working across both brands, but it is not a capability gap.
Controls that exist on both but read differently
Two settings are worth a closer look because the manuals present them differently, even though the underlying feature is shared.
The first is the low-battery cut-off. The Deye manual documents two default sets depending on battery type: 10%, 20% and 40% for a communicating lithium battery, and 20%, 35% and 50% for lead-acid or a non-communicating pack. The Sunsynk manual shows a single screen at 20%, 20% and 40%. Both inverters almost certainly adjust these by battery type in firmware; the difference is how clearly each manual spells it out.
The second is G100, the UK export-limitation scheme. Sunsynk’s manual calls it out directly and tells you to set the inverter to G99/G100 for compliance. Deye lists the same G98/G99 family inside a 16-standard grid-code picker but does not single out G100 in its notes. The grid code is available on both; Sunsynk just gives a UK reader clearer instructions.
So does the badge change what the inverter can do?
Not in any way that should decide a purchase. On the 5kW models, the Sunsynk badge and the Deye badge give you almost the same control set. The badge changes the menu wording, a handful of controls at the edges, and the part that actually costs or saves you money later: who ships your firmware and who answers a support call. That is the case I make in the main Deye versus Sunsynk buying guide.
The practical takeaway is simple. If you already own one of these inverters, do not assume the other would give you a feature yours is missing. On these two manuals, it would not. Choose on price, warranty and support, then set the box up knowing the menu will look slightly different depending on which badge you bought.
Which models and manuals this compares
This comparison uses the Sunsynk 5kW ECCO, model SYNK-5K-SG04LP1, from its user manual version 26 dated 23 May 2024, against the matching Deye generation, the SUN-5K-SG04LP1-EU-SM2. I read every difference above from the on-screen menu screenshots in both manuals rather than a spec sheet.
One wrinkle is worth knowing before you shop. Deye’s model naming is not linear: its newest 5kW manual is the SUN-5K-SG02LP1-EU-AM2 from May 2026, even though the number looks older than SG03 or SG04. Most UK retailers still list the SG03 or SG04 units. I checked the differences above against that newest manual too, and they held, so this is a stable difference between the brands rather than a gap between a 2024 and a 2026 firmware.
