EASun SMG II Minimum PV voltage

[CPet]

Hi all

I've just finished connecting a EASUN SMG II, 3.6KW inverter ( https://easunpower.com/products/eas...vdc-input-batteryless-support-with-wifi-pllug ) to 2 pcs 380 Wp JA-SOLAR panels (34,77V 10,93A).
I don't have any battery connected yet. The Offgrid inverter supports batteryless mode and also bypass via mains.
However I cannot get the inverter to show any "watts" produced by the PV panels. It only powers up when I have it connected to the mains (bypass mode).
I measured the voltage coming from the Panels and it was around 78V.
Now going over the manual I found something I might have misread, it says:
PV Array MPPT Voltage Range 120Vdc~450Vdc under "Charge specifications" (see attached picture from the manual).
At first I thought that would only be relevant to charging batteries, but now I am not so sure, would it minimum PV voltage needed to startup? - Hence I would probably need to add another 2 panels to get it to operate?

 

[Cklio]

Hi Cpet,

I think this might be a huge misinterpretation of this common technology. "Batteryless" inverters are always a bit of a buzz word but realistically you cannot operate devices with volatile power sources that may or may not be enough to provide you with the electricity required to run a device. Like if you turn your TV on, and suddenly there's an overcast so no more tv? it's impossible to expect any kind of result with a system that functions this way, hence the need for batteries being so critical in any system (Or a constant AC source).
I seriously doubt you're able to power this inverter with the PV alone. If the PV panels are fed to integrated MPPT's that are inside the inverter, then I'd speculate that it's highly likely that the MPPT input terminals have no relation to the input that feeds the inverter to turn it on. (as that would probably need to be a non-volatile source of electricity. Like a constant DC voltage source, or a consistent AC source like shore or generator. "Batteryless" likely pertains to using the inverter to power AC loads with the use of PV while ALSO using the AC source that feeds the inverter to pick up any slack left behind by the panels. Usually to cut electricity costs of a load you run regularly during the day.

 

[meetyg]

Yes, you would need at least 120v for the MPPT to consider the panels. But in reality you need to be around 250v or higher in order to get some real power under load, for you inverter model.

 

[CPet]

Thanks for the replies.
@Cklio I understand what you are saying, however this is where I think the bypass method should work well, if not sufficient PV power it would use the GRID power. Anyway I do plan to add a couple batteries. Just hoped I'd be able to see some production already.
@meetyg Ok, that's what I suspected :/ realisticly I will only be able to add 3 more panels, so that would come to around 40 x 5 = 200 Volts :/

 

[Cklio]

Yes, you would need at least 120v for the MPPT to consider the panels. But in reality you need to be around 250v or higher in order to get some real power under load, for you inverter model.

Yes, true. The Mininmum MPP Voltages exist to make less work for the MPPT to do converting. So the minimal limit means the MPPT is not able to convert a voltage that is that far down, all the way up to 230VAC that your loads require. It's better to have higher voltage that either exceeds the output voltage or at least comes close to it. Otherwise your MPPT will not be able to produce the needed voltage on the output.

 

[CPet]

Just to confirm, I've added another 3 panels, so I now have a total of 2 x 380 watt+ 3x 400 watt panels, giving roughly 1900 Watt/peak (34,39V*10,93A*5) in theory. The SMG II requires around 120V before it powers up / starts producing.
Unfortunately weather hasn't been the best the last 2 days it has been running, its been peaking about 150watt/hour for now.
But check out the attached screenshot from the Dessmonitor (/ SmartEss app), I assume it is buggy.?
It should not be able to backfeed to the grid. Anyone else had readings like this? or checked that these units do not backfeed?

 

[CPet]

And this I get now, after the sun has gone down (it is completely dark now). At other times without PV power it has been showing same going in and out :/

 

[Mattb4]

It would help if you gave a diagram of how you have wired this inverter to your home.

 

[CPet]

It would help if you gave a diagram of how you have wired this inverter to your home.

Ok, I have attached a picture of how I made the setup.

 

[Mattb4]

Does not give much detail. Based on it it would appear that you run your entire home from the AC output of the inverter. If this is the case you should not have any power going back to the grid. However running this battery free could create strange issues when it comes to your monitor program. In order to run without battery the inverter is taking power from the grid and either feeding the DC common bus with it or it is paralleling with AC grid. The latter would than certainly give readings for backfeed.

 

[EliteSolar]

I have this inverter.

I can answer all your questions. I have been running this inverter batteryless without grid and with grid.

First let me tell you I am very happy so far with it .

Yes when you have Grid mixed with AC grid , it shows false readings of feeding the grid. But a bidirectional smart energy meter shows otherwise . 0.00000kwhr. So the inverter is never backfeeding. Although the monitor program says it does.

I agree with what other people say about voltage.

I have 340V DC VOC from the panels , and they are suffering under load when its REALLY cloudy. Basically , the MPPT will go down to 120V under load, since this is the minimum operating voltage , to try to extract maximum power ( ampers ) but this is a "bad" zone. More voltage = better. I am not sure how exactly the MPPT works to favor the direct DC to AC but what I know is that it works really good when its sunny , not so good when its VERY cloudy. When its normal cloudy its fine with my 340V VOC.

I mean it works really good.

Also dont listen to people that say it doesnt work batteryless or it's not supposed to work like that.

I have tested it batteryless without AC and if your loads are fine under the cloudiest time, the inverter will work fine and as intended.

So example : Put 300w loads , with 3.1kw of solar panels flat on the ground , they switch on in the morning , run for the whole day fine and switch off when it gets dark. IT WORKS FANTASTIC AND AS INTENDED . I know though you will be wasting a lot of power this way but there are special applications where this makes sense. Worst case scenario is the inverter will cycle on/off.

Obviously if you are powering a home , you would need batteries to even the cloudy times and not lose energy but trying to have always the load at the minimum power production of the day ( like 300w from 3.1kw flat panels in November ) . The whole point is that you can mix with AC and avoid batteries.

I don't use batteries and it works FINE and as intended.

It's great.

The only problem is the N/G bond when you lose the AC in , which is solved with the dry contacts' external grounding box.

As people said , I would recommend at least 340V VOC like me , even more if you live in a very cloudy place . I would try to hit the 450V ideally. As I said when its really cloudy , the MPPT is kind of struggling.

Let me know if you have any questions .

Cheers.

 

[CPet]

Thanks @Mattb4 and @EliteSolar for the replies.
Actually I am only using this system on a small shed, hence the limited amount of panels (there is no more space on the roof now), with the intention to serve as a backup power system for my pellet & solar heating systems and its many pumps (4). In the summer however I would like to use it for powering a ~1000W air conditioner too.
I also have a grid tied solar system (6000 watt) on the main house roof, but it will stop working if the grid is down.
I will get back with questions when they arise, thanks again.

 

[onobeka]

I have the bigger model, Easun igrid iv 5600W. Currently I am running it with only 6 panels, 395W each, so roughly 2.4kWp. I have currently no battery and I've been running it without grid-tie and with. Mind you this inverter can feed into the grid, but that option is disabled in my case.
My panels are oriented SW (230) with a low slope for winter time in my location: 20deg. At this time of year, probably 45deg and S would be best for my location (Central Europe). I also have some shading in the afternoon.
The inverter is a power hog, it needs ~70Wh for itself to produce anything on the output, and about 40Wh in standby (output breaker down).

Some observations:

Only PV connected
1) When the day breaks, even if very foggy, I already read 245V on the inverter, around 0C;
2) I can already power two laptops without big loads, Dell Precision, the inverter reports it's feeding ~90Wh on the output and a total of 150Wh;
3) I was able to run under sunshine a heat gun of total 2000W, yet the inverter entered protection at about 1200W as the PV voltage dropped bigly. I turned up the temperature gradually to observe the behavior. At 1000W it barely ran, but it ran.
4) I can run about 400Wh consumers constantly for the very short November days when the fog is gone and until I get significant shading on some of the panels.

PV and AC-in connected:
1) The inverter seems to prefer to run itself from the grid - this is very aggravating, as 70Wh is a lot;
2) It can cope with very large loads, water pump, infrared heating, welding, grinding ... it balances itself nicely when it has not enough sun or not enough PVs;
3) To me it seems if it detects it has a load it can deliver from the PVs it does that briefly but then it balances it with AC-in. I would expecting it to try to harvest as much as it can from the sun.
4) Related to 3) it does not seem to want to get out of this mode, I would have expected that the AC-in function is ALSO thought of to be used without a battery for instance when a cloud covers the sun and there is load close to what the PVs can produce.

The PV/AC-in connected I've been experimenting only for three days now. The PV only mode for about two weeks.
For today, very foggy until 2h ago, my system produced to the very small consumers 0.6kWh, yet it used 0.3kWh from the AC-in. I've added two meters on AC-in and AC-out.
Under these circumstances I do not leave the unit running before 9AM and later than 5PM. Without a battery, the best idea right now for me would be to try to run constant small consumers that I do not need in the evening/night up to those 400Wh. It's an insane cost for the system to only power that.

My current settings are:
01 - SBU (Solar, Battery, Utility) for Output source priority;
05 - LBU (Solar energy provides power to the loads as first priority) for Solar supply priority
10 - 050 (Solar only) for Charger priority.

For some reason, the inverter still reports a low battery issue. I found no way to set a "no battery" mode. The setting is default, AGM.

Next week I am getting (hopefully) a LiFePO4 Pylontech us5000 battery.

This post is with the intention to help but also to ask for an opinion if something is wrong in my settings.

 

[EliteSolar]

I have the bigger model, Easun igrid iv 5600W. Currently I am running it with only 6 panels, 395W each, so roughly 2.4kWp. I have currently no battery and I've been running it without grid-tie and with. Mind you this inverter can feed into the grid, but that option is disabled in my case.
My panels are oriented SW (230) with a low slope for winter time in my location: 20deg. At this time of year, probably 45deg and S would be best for my location (Central Europe). I also have some shading in the afternoon.
The inverter is a power hog, it needs ~70Wh for itself to produce anything on the output, and about 40Wh in standby (output breaker down).

Some observations:

Only PV connected
1) When the day breaks, even if very foggy, I already read 245V on the inverter, around 0C;
2) I can already power two laptops without big loads, Dell Precision, the inverter reports it's feeding ~90Wh on the output and a total of 150Wh;
3) I was able to run under sunshine a heat gun of total 2000W, yet the inverter entered protection at about 1200W as the PV voltage dropped bigly. I turned up the temperature gradually to observe the behavior. At 1000W it barely ran, but it ran.
4) I can run about 400Wh consumers constantly for the very short November days when the fog is gone and until I get significant shading on some of the panels.

SAME

PV and AC-in connected:
1) The inverter seems to prefer to run itself from the grid - this is very aggravating, as 70Wh is a lot;
2) It can cope with very large loads, water pump, infrared heating, welding, grinding ... it balances itself nicely when it has not enough sun or not enough PVs;
3) To me it seems if it detects it has a load it can deliver from the PVs it does that briefly but then it balances it with AC-in. I would expecting it to try to harvest as much as it can from the sun.
4) Related to 3) it does not seem to want to get out of this mode, I would have expected that the AC-in function is ALSO thought of to be used without a battery for instance when a cloud covers the sun and there is load close to what the PVs can produce.

The PV/AC-in connected I've been experimenting only for three days now. The PV only mode for about two weeks.
For today, very foggy until 2h ago, my system produced to the very small consumers 0.6kWh, yet it used 0.3kWh from the AC-in. I've added two meters on AC-in and AC-out.
Under these circumstances I do not leave the unit running before 9AM and later than 5PM. Without a battery, the best idea right now for me would be to try to run constant small consumers that I do not need in the evening/night up to those 400Wh. It's an insane cost for the system to only power that.

My current settings are:
01 - SBU (Solar, Battery, Utility) for Output source priority;
05 - LBU (Solar energy provides power to the loads as first priority) for Solar supply priority
10 - 050 (Solar only) for Charger priority.

For some reason, the inverter still reports a low battery issue. I found no way to set a "no battery" mode. The setting is default, AGM.

Next week I am getting (hopefully) a LiFePO4 Pylontech us5000 battery.

This post is with the intention to help but also to ask for an opinion if something is wrong in my settings.

Not same , if I understand correctly your behaviour , mine is different . The grid will work like battery in my case , it will draw max PV always and add from grid whatever is needed. But my model is SMG II without an option to export and ct sensor , so its a different design.

Mine also flashes no battery connected but works fine.

 

[Mattb4]

Hey EliteSolar.

Good to hear you are all up and running now. It would probably help others out if you would do a review of your setup/inverter model in the off grid inverter forum. If I recall you were having some issues at first with how you were going to wire it all up.

 

[CPet]

The inverter is a power hog, it needs ~70Wh for itself to produce anything on the output, and about 40Wh in standby (output breaker down).

Thanks for sharing your experinces.
The above line seems quite a nuisance, since this time of year we maybe have (cloudy) day for 8 hours and darkness for 16 hours.
If the inverter is really using 40 Wh in standby just to pass through the power from the grid (bypass), I should design a circuit to bypass the inverter using a schedule of sunrise/sundown for a given country's time/date, maybe I could combine this with the PE -> N bonding relay.

 

[EliteSolar]

I dont think when its bypass mode it uses 40watt . This is when the inverter is ON. When in bypass mode t he inverter is off . Its probably around 5-10watt when in bypass mode. Mine shows now 2watt difference between grid and load power , but its probsbly not accurate.

edit : now it shows the same .. it could be 2-3watts ? that would be amazing

 

[onobeka]

Just measured with a clamp meter. Output switch off, output breaker off, battery less, 0.173A on the AC-in at 231V =39.6W.

 

[onobeka]

I dont think when its bypass mode it uses 40watt . This is when the inverter is ON. When in bypass mode t he inverter is off . Its probably around 5-10watt when in bypass mode. Mine shows now 2watt difference between grid and load power , but its probsbly not accurate.

Posts have crossed. I’m not sure what actually it means to be in bypass mode. I just measured the consumption of the unit without any output.

 

[EliteSolar]

Take note that SV II is entirely different design than the SMG II , the SV II has CT sensor and export grid and it has different circuity to mix grid

EDIT ; bypass mode is when there is no battery or PV , and it powers only through the grid. Then our inverter (SMG II) goes into bypass mode. The inverter goes off and the AC grid goes directly to the output , no inverter needed .

EDIT 2 : Also its 5.6kw not 3.6kw , totally different power consumptions.