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EASun ISolar SM II 5kw - MPP tracker issue?


Payback2
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Dear all,

I own a system of three EASun ISolar SMII 5kw inverter (identical to MPP Solar PIP-5048MG and others) running in 3 Phase mode. Each of them is connected to 9 solar panels, 1 string to the west and 2 strings to the south. What I discover is, that espcially during cloudy dark winter days, one is producing much less power than the other two. All are running on the same software and to avoid issues with the solar panels, I swapped the both strings to the south but the behaviour remains the same. As you can see, the proplematic inverter is sticking to the 120V while the others ramp up to the optimal voltage around ~315V.

On the picture below you can see:

Top: after the swap, below before. Left power, right voltage. WR1 is connected to west string, WR2 and WR3 to the south strings. WR3 is the faulty one.

pasted-from-clipboard-1.thumb.png.361580a132e3ada432f2590dcd7e685c.png

 

And here you have the behaviour for full two days, but without a swap of the strings.

pasted-from-clipboard-2.thumb.png.69fd99977a3ece63a9d089275d551136.png

I contacted already EASun and they are quite responive, but we still haven't found a solution yet. So I rely on your knowledge... :)

Thank you!

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44 minutes ago, Payback2 said:

What I discover is, that espcially during cloudy dark winter days, one is producing much less power than the other two.

I have the same problem, only with 2 older inverters in parallel and single phase. In my case, it's because one of the inverters reads the battery voltage quite poorly. I tried calibrating it one time, but the problem seemed to linger. I found that was because the method I used for calibration doesn't store the result in EEPROM.

See this post for details.

I must get around to fixing mine... 😳

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Thank you for the fast reply @Coulomb!

But I'm not so sure if this applies to me as well. I added a chart for the Batterie Voltage to be inline with the power and volatage readings. For me there is not so much difference between the three inverters (see below). FYI: I use 5x US2000 Batteries from Pylontech.

grafik.thumb.png.9a0ec4f38aef1570c04ee90207e705de.png

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15 hours ago, Payback2 said:

I added a chart for the Batterie Voltage to be inline with the power and volatage readings. For me there is not so much difference between the three inverters

Huh, yes. Your "Bat Spannung" seem to be moderately well matched 🙂

If you had a model with a separate Solar Charge Controller processor, I'd guess that the SCC's battery measurement was off. (They do seem to talk to each other though, and occasionally correct the SCC calibration). But since you have basically an Axpert MKS II, the DSP does the solar charging itself, using its own reading of the battery voltage.

I'm out of ideas.

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9 hours ago, Coulomb said:

I'm out of ideas.

Never expected that this could happen... :)

May I assume, that in this case the faulty inverter has some kind of hardware issue and needs to be replaced?

Best Regards

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12 hours ago, Payback2 said:

May I assume, that in this case the faulty inverter has some kind of hardware issue and needs to be replaced?

First, I'd check that if you isolate the PV on the other two inverters, the one that doesn't charge much still doesn't charge much. If not, it's faulty.

But I suspect it will charge normally when the others don't. If so, it's something to do with the others raising the battery voltage when charging. So that small difference in battery voltage calibration might still be the issue.

I find it strange that the PV voltage starts low, and shoots up at a certain time in the morning. But that could just be how the high voltage SCC models work. I don't own one, and haven't found that part of the firmware to figure out if it should be like that.

Do other owners of high voltage SCC models see that behaviour?

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Thank you again. This was one of the first things the support from EASun proposed: disconnect the two other inverter and run it in single mode. So I did it: The performance was quite low. To check if it was due to bad weather conditions, I switched it off and started the second one in single mode. You can see that the performance was much better:

grafik.thumb.png.6141dc73f072ca76a252ea24cd678004.png

So I will ask them definitly for a replacement. Let's see, so far I have no reason to complain about their service!

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