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Kodak King "dropping" DC input from PV panels


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We had an installation done beginning of August 2020. This installation consisted out of:

  • 6x Canadian Solar 365W panels
  • 2x Pylontech US2000 2.4kW batteries
  • 1x Kodak King inverter

Three days in I discovered on the inverter's display it would indicate that MPPT is present (icon visible), but it won't utilise it, power is only drawn from batteries (see attachment). After a lot of back forth with installer and distributors, which included different settngs, rewiring the panels to lower voltage, no luck. I purchased the latest ICC and started to analyse the data to try and understand the problem a little better (see attachment).

What I discovered was batteries are charged via PV input during the course of a sunny morning, with little loads, reaching 99%-100% SOC. When the battery reaches this SOC, the PV input starts to "oscillate" from max to zero for several minutes, whereafter the PV input simply "drops out" (see screenshot attached). The effect is that for the remainder of the day, output is drawn from only the batteries. The only way to get the inverter to utilise the PV input again is to physically shut down and power up both the batteries and interter. I have to do this on a (near) daily basis.

Inverter was booked back in for testing recently and it was confirmed that it had a faulty PV input controller. A replacement unit was installed three days ago and yesterday I noticed exactly the same issue occurring.

Obviously there could be many factors that can cause this. The installer is now suggesting that I upgrade from the Kodak to a slightly more expensive Growatt unit, but is that the solution? Although I've searched this forum up and down for answers, I can't seem to pinpoint the exact problem. I am not an expert in this field and would appreciate any assistance.

Kodak.jpeg

ICC.jpeg

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16 hours ago, Stefan Buys said:

Inverter was booked back in for testing recently and it was confirmed that it had a faulty PV input controller. A replacement unit was installed three days ago and yesterday I noticed exactly the same issue occurring.

It's possible that the solar charge controller was damaged by excessive PV voltage. My guess is that you have wired your panels 3S. See FAQ 8.

16 hours ago, Stefan Buys said:

The installer is now suggesting that I upgrade from the Kodak to a slightly more expensive Growatt unit, but is that the solution? 

My understanding is that the Growatts are work-alikes, i.e. their 145 V max PV models will have pretty much the same problem. It's a pain; if your panels are wired 3S, get them rewired for 2S.

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Looking at your graphs it appears that you are already wired 2S.

Given that a hardware issue is unlikely (2 different inverters), the strongest remaining possibility is in your settings. (I have had similar behaviour on my King when I had screwed up a setting)

Please list all your settings, and the inverter firmware version.

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That to me would appear like incorrect settings on the battery settings.  It would look like the inverter is trying to charge the pylontechs, but because they have reached 100% state of charge the BMS is refusing the charge current.  Please show a screenshot of your settings and battery graphs at the time when the PV drops occurs

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21 hours ago, Calvin said:

Looking at your graphs it appears that you are already wired 2S.

Duh. Well spotted. People so rarely give PV voltage information, that I didn't even look for it.

20 hours ago, Bloubul7 said:

It would look like the inverter is trying to charge the pylontechs, but because they have reached 100% state of charge the BMS is refusing the charge current.

Agreed.

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