Deye Hybrid Inverter Review - Off-grid [Sunsynk, Sol-Ark]

[Svarky]

Deye hybrid inverters have become increasingly popular over the last few years, so I decided to purchase one of the SUN-8K hybrid inverters to see how they perform for off-grid use. For reasons explained below, I’m generally not a fan of all-in-one inverters for off-grid systems. However, if the specifications are accurate, this could be one of the first affordable all-in-one inverters suitable for smaller-scale off-grid installations. Update: The Deye inverter has recently been included as one of the best off-grid inverters for small capacity systems.

Deye Vs Sunsynk Vs Sol-Ark Vs Noark

Several companies worldwide have rebranded and modified Deye inverters to suit local markets. However, they are all manufactured by Ningbo Deye Inverter Technology Co. SunSynk inverters are very popular in the UK and South Africa and are identical in hardware but use different operating software. In North America, Sol-Ark is the primary distributor and has modified Deye hybrid inverters to suit the US’s split-phase (120/240V) power requirements.
Update: In Australia, the popular electrical components supplier Noark Electric just released a Noark-branded version of this inverter as well.

SUN-8K Inverter Power Rating

Deye inverters are transformerless, unlike dedicated off-grid inverters, so they do not have the peak (surge) power of similar-sized off-grid inverters like Victron or Schneider, which use large, heavy-duty transformers. The specifications are confusing as the datasheet does not list the continuous power rating but multiple variations of the peak (Max) power rating.
The max battery discharge power is listed at 190A, or approx 9.5kW at 50V, but the off-grid peak power is listed at “2 times the rated power for 10 seconds”. This peak rating would only be possible with battery and PV power combined. The “rated AC output power” is 8kW, and the “Max AC output” is also 8kW, which doesn’t make sense. I’m assuming the continuous power rating is closer to 7kW, and the max peak power is around 10kW, but I’m yet to test this in real-world conditions.

High Solar MPPT current ratings

In regards to solar, the MPPT voltage range is a bit narrow (200V to 425V), but the input current rating is very good at 26A per MPPT, meaning parallel strings is possible on both MPPTs. Ics max current is also very high at 39A per MPPT, which is great. The max DC input power is listed at (10400W) 10.4kW, but based on the high input current rating, it should have no issues with oversized PV arrays higher than 10kW.

Build Quality

The build quality appears surprisingly good for a relatively low-cost inverter. The dual AC inputs are very useful for UPS backup power in a hybrid system. The on/off and DC isolator switches are solid, and the large cable glands make it easy to install. Battery terminals are solid, but a little more clearance would help.

The inverter will be installed and operational in about a week, so I’ll post an update about the setup and operation.

Edit: There is another thread discussing the Sol-Ark and Deye hybrid inverters here. Although, there is not much information about the operation and performance. Sol-Ark 12K hybrid / off-grid inverter - Deye SUN - #8 by Svarky

[Svarky]

Update: The inverter was installed and commissioned about a week ago and is running great so far. Installed with 6.2kW of solar on two strings, and 3 x Pylontech US3000C (3.55kWh) batteries.
Startup and programming were relatively straightforward. However, the Lithium settings are a little confusing, and the manual has very little information about how the system should be configured for various lithium battery types (see more details below).

The household loads are generally very low, so we haven’t had a chance to test the inverter under higher loads to see what the continuous and maximum power output is. (The house is still under construction, and some electric appliances are still yet to be installed.)

[Svarky]

Lithium Battery settings: One of the more confusing settings is the “Lithium Mode” setting which I cannot seem to change? It is set to 00, but there appear to be 18 settings from the display. (Or that’s what I assume the 00/18 is referring to?)
Also, as mentioned previously, the battery data is very limited. The battery temperature reading was -100C as soon as it was connected, which is clearly wrong.

EDIT: This issue has been fixed by using the correct CANbus cable with pins 1,2,3 disconnected, as shown in the post below.

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[Svarky]

Deye tech support just informed me that the problem with the battery data not being reported may be due to the CANbus connection between the battery and inverter. There are certain pins that need to be disconnected (pins 1,2,3).

[Superfly]

are you able to give a final recommendation or summation of your experience? I have an off-grid business in the Pacific region and sadly, we’ve learned the hard way regarding your sentiment on ‘all in one’ offgrid inverters. However, the Deye option is a bit more expensive than our current brand - about 1.8X and comes with a 5yr warranty and a decent IP rating. So we’re really keen to give them a crack…

[Svarky]

@Superfly, It’s too early to tell until we have conducted high-load testing. However, overall the construction and built quality are very good, and the solar performance has been excellent. This inverter is far better than the other low-cost, all-in-one hybrid inverters I have seen, like the Voltronic Infini series (also used by Growatt).

The only real issue so far has been using the Solarman App and the user manual is a little vague and a bit confusing.

We plan on doing some more thorough testing next week.

[Bursu]

Regarding the batteries. Between your Deye manuals and literature you have a document regarding Lithium Mode settings. It’s a list with most LiFePo4 battery brands and what lithium mode to use with each brand and battery model. Also with your LiFePo4 battery you again have a list regarding the settings of those small red and white dip switches. On the battery documentation you have a list of inverters and how to set those dip switches for communicating properly with each brand of inverters.
You need to have both documents in order for the inverter to comunicate with, and charge properly the batteries, similar with my examples.

[Svarky]

@Bursu, thanks for the Lithium mode settings (approved battery) document. This should be included with the inverter as there is no information provided about the various Lithium modes.

The Pylontech battery is listed under lithium mode ‘00’ Canbus, and also lithium mode ‘12’ RS485. This is strange, but I’m guessing it will work on either mode. Although, when I tried to change the mode from ‘00’ to ‘12’ setting, it would not change. It was stuck on ‘00’ which is very frustrating.

[Bursu]

The inverter can communicate with the battery’s BMS in two ways. Primarily, through the BMS/CAN combo port, which is recommended, I had to use a splitter to combine two cables into the BMS port (Orange Pi 3 LTS and Battery) or, alternatively, through the RS485 port.
The whole document that came with my inverter DEYE - SUN-12K-SG04LP3. It has 19 Lithium Modes in it’s battery menu.

[Svarky]

Problem charging from a backup generator. I have followed the setup procedure and changed the settings to charge from a generator, but it does not work. The Generator symbol does not show on the display, and it will not charge from the generator when connected. (It is a manual start generator, not auto-start)

Edit: Problem solved - See post below

[Bursu]

Hi, I do not have a generator but as I understand, if you have batteries, as in my case, the inverter will seek for generator signal, and display the generator icon, only when the battery is near a certain percentage that it set for the battery to disconnect the power and no Grid is available, OR in order to start charging the batteries using the generator. If you are not using batteries, that Icon will appear when the grid fails and when there is not enough energy being generated by the panels, at night for example.
Basically the icon appears when the Inverter tries to use the generator, in emergency situations. At least this is how it behaves when using have batteries too.
Maybe if you also check GEN signal option, on the display, generator icon might show up.
I am new to this too, i hope it helps a little.

Best wishes, Marius

[Svarky]

Backup Generator charging issue fixed

The system is now charging from the generator input. The problem appears to be due to the unstable generator frequency, which is a very common issue with older generators. Also, as suggested by @Bursu, the Gen signal checkbox setting should be ticked (Even though the generator is not an auto-start model). The generator icon only appeared once it was connected.

[Svarky]

The Deye off-grid system has been operating well for several months, and we got to see how it performs under high loads. The house recently had an air-conditioner (split system) installed and an electric oven, so we tried running the A/C along with the oven and some other loads (electric kettle), which gave a total load of just over 6.2kW.

High Load Test

The inverter had no problem running this high load continuously for 15 minutes, and it peaked at around 7kW for a few seconds. The external cooling fans didn’t even turn on. However, it was quite cold at about 12 degC, so the inverter was not under any thermal stress. It will be interesting to see how it performs under high loads in summer.

[Jlemos_Silva]

@Svarky Svarky Excelent review. . Did you evaluate the perfomance of the inverter at nigth, with no grid connected (an outage, for instance). How long does your battery bank withstand the peak load and how efficient the inverter is?

Another doubt concerns the power delivered to loads from PV + Battery. As we have a maximum inverter DC input power, is that possible to manager the power delivered from battery bank, in order to avoid reach the maximum Inverter DC input power?

Best Regards.

Julião

[Svarky]

@Jlemos_Silva, yes, this is an off-grid installation, so it has been used without any grid connection. It has been running high loads such as air-conditioners (Split-systems) and water pumps without any problems up to 8kW peak loads. The inverter appears to be very efficient and performs very well, but it has not yet been tested in high summer temperatures (it’s still cold here in Southern Australia).

I’m confused with your second question. The inverter AC power output is rated at 8kW, this is the same regardless of the amount of solar generation or battery capacity. Note, Pylontech US5000 batteries can deliver up to 5kW continuously for 15 minutes, and there are three batteries installed.

[mgu]

Hello and thank you for the very useful report.

Other than max load I wonder how the MPPT voltage range (200 - 425V) turned out in practical operation?

I noted other models have even higher start values for “full load” ranges, eg240 or even 300V
Wouldn’t this mean it will operate in best efficiency mode only on best sun light conditions?

[Svarky]

@mgu, the inverter’s limited string voltage is not a huge issue since the high MPPT input current (26A) allows parallel strings. Unless you really want long strings to reduce voltage drop over a long distance or some other reason.

The amount of sunlight (solar irradiance) doesn’t actually have a large effect on the string voltage. It does, however, dramatically affect the current output, which of course affects the power output.
The panel temperature does have quite a big impact on the string voltage though, as you can see when using this string voltage calculator tool.

The biggest issue with the limited string voltage range is the number of panels you can have In a string. It’s the upper voltage limit that is the biggest issue, most regular string inverters have a string voltage limit of 500 to 550V, meaning they can have strings of up to 14 panels. The Deye 425 limited means strings are limited to 8 or 9 panels.

[mgu]

Thank you very much for this insightful response (especially after the edit)

[Jlemos_Silva]

@Svarky

Pylontech US5000

@Svarky Thanks a lot for your answer. Forget the second question. I just mixed things up.

How long does the battery bank withstand the combination of Air-conditioner + water pump in continuous utilization?

[Svarky]

@Jlemos_Silva, it all depends on the pump size and the type of air-conditioning system.

Each US5000 battery has 5kWh capacity, so 3 batteries have a total of 15kWh, with 80% usable capacity (12kWh).
If the combined loads are 1kW continuous, then the battery can supply power for roughly 10 to 12 hours taking into account some inverter losses.