Sol-Ark 15k will only invert 13k of DC PV to AC

[Clint-L]

I have a 15k with three arrays of DC PV connected to each of the three MPPT controllers. Each array can max output of 6,400 watts. So that is 19,200. The 15k specs state that it allows 19,500 of PV connected and will invert 15k max.

Here’s the problem- once the panels hit 13,200 that is the maximum and it clips / throttles all day with a perfect flat line. It absolutely will not invert 15k at this point.

Sol-Ark support has been working with us. They have updated software, reapplied update, and performed a full factory reset with no luck. Originally, the inverter would hit about 12k to 13k of PV power and literally disconnect from the grid. During the grid disconnect, we would see completely inaccurate reading of the VoC of the arrays. Voltages that were absolutely untrue. We were also checking with metering equipment and have never seen such a VoC spike. Nonetheless, It seems the software update corrected all of that. Sol-Ark support advised that they had seen some software issues with voltage misreading on the MPPT inputs we were seeing in the software as well as the inverter ramping up the output voltage to the grid too high, causing disconnect. I’ve seen both of these issues. Again, these were corrected not only with a software update, but a full reset of the unit.

As of the final software update and reset on 10-18-2022 we no longer see the grid disconnect. However, we are still seeing the clipping at 13k.

I really believe in the company and we are an installer and we have put in over 20 of the 12k units. However, I could not in good faith sell a 15k until this is addressed on our test unit.

Additionally, we are waiting to connect 19k of AC coupling through the AC coupling input, if Sol-Ark can address the PV DC inverting clipping / throttling issue.

I worry that Sol-Ark never tested this unit fully with the maximum PV specifications that they have published. Is anyone else out there seeing this, if you happen to have enough PV to see it max at 13k?



@Devin
@solark_cooper
@Will Prowse - do you have enough panels to do this same test?

 

[Ampster]

Additionally, we are waiting to connect 19k of AC coupling through the AC coupling input, if Sol-Ark can address the PV DC inverting clipping / throttling issue.

Let us know how the AC coupling works when the grid is down. Unless you have a big battery that would seem to be a lot of AC coupling capacity for the SolArk to manage smoothly.

 

[Clint-L]

I agree with you 100%! We have a 35 KWh bank for this system. We can place it under loads for testing. Our goal is to ensure what we are selling will actually perform as it states. We have a potential customer asking to do 200 KWh of storage using a 15k with 19,,200 AC and 19,200 DC. All QCELL 400 watt panels (96 of them!). We are excited to do it, but I’m skeptical until I can really see it proven. That’s a big job to have go south on us. It would be detrimental to our small company.

 

[Ampster]

We have a 35 KWh bank for this system. We can place it under loads for testing. Our goal is to ensure what we are selling will actually perform as it states. We have a potential customer asking to do 200 KWh of storage using a 15k with 19,,200 AC and 19,200 DC. All QCELL 400 watt panels (96 of them!). We are excited to do it, but I’m skeptical until I can really see it proven. That’s a big job to have go south on us. It would be detrimental to our small company.

AC coupling is only tricky when the system has to run when the grid is down. Then the Grid forming inverter has to control the grid dependent inverter with frequency Watt iterations. SolArk must have a recommended maximum AC coupled capacity? It varies by manufacturer and I would presume it has to do with how good their algorithm is. I know that SolArk used a unique arrangement to have the AC coupled solar go through the Generator port. I heard that was so that they could open the gen port relay to disconnect the AC coupled solar.

 

[robby]

I wonder what the current is that your putting into each MPPT.
My 12K Clips the minute it goes past 20A which is the maximum rating for the 12K.
The 15K is going to clip at anything past 26 Amps.

 

[niktak11]

What are the specs on each of the 3 arrays?

 

[Clint-L]

AC coupling is only tricky when the system has to run when the grid is down. Then the Grid forming inverter has to control the grid dependent inverter with frequency Watt iterations. SolArk must have a recommended maximum AC coupled capacity? It varies by manufacturer and I would presume it has to do with how good their algorithm is. I know that SolArk used a unique arrangement to have the AC coupled solar go through the Generator port. I heard that was so that they could open the gen port relay to disconnect the AC coupled solar.

The maximum specs are 19,200 watts in to the AC Couple port/lugs. It controls the input by putting grid type sync voltage to it based on the voltage of your battery bank. The more AC coupled PV you have, the larger bank you potentially need.

Would it potentially shut off and on the micros when the batteries are full if you do not have enough loads - yes.

Our customers is not concerned that the AC Coupled PV would only input in to the batteries “when needed” if the grid is down. When the grid is up however, the Sol-Arc “should” pass all of the AC coupled 19,200 watts from the micros to the grid. Let’s hope they have actually tested this as well. I will keep everyone updated, but I imagine it will be a few weeks before we are able to do that.

 

[Clint-L]

I wonder what the current is that your putting into each MPPT.
My 12K Clips the minute it goes past 20A which is the maximum rating for the 12K.
The 15K is going to clip at anything past 26 Amps.

If we remove one of the arrays, the other two are able to max out at about 21 amps, which is well below the 26 amps that are sled limiting.

What’s interesting is with the three 6.4kw arrays (one on each MPPT) all connected is just equally throttles them. Sol-ark has agreed that everything is within their published specifications.

I feel like the 12k units are very solid and meet their specs. I’m sure hoping this is simply a software issue that is plaguing the 15k on the PV production.

Fingers crossed they can correct it.

 

[Clint-L]

What are the specs on each of the 3 arrays?

Array 1 -
2 strings of 10 QCELL G5 320w Q peak BLK in parallel = 6400 watts

Array 2 -
2 series strings of 8 QCELL G10+ 400w Q peak ML BLK in parallel = 6400 watts

Array 3 -
2 series strings of 8 QCELL G10+ 400w Q peak ML BLK in parallel = 6400 watts

All of the published VoC etc are perfectly within spec of what is recommend and they show to be acceptable on the Sol-arc panel sizing tool.

I’m sure hoping Sol-ark can correct this with software changes.

 

[Ampster]

When the grid is up however, the Sol-Arc “should” pass all of the AC coupled 19,200 watts from the micros to the grid. Let’s hope they have actually tested this as well. I

I don't know any reason, when the grid is up, that it would not pass through a lot more than 19kWs. I don't know what the breaker is on the generator port which would be the constraint.

 

[niktak11]

I don't know any reason, when the grid is up, that it would not pass through a lot more than 19kWs. I don't know what the breaker is on the generator port which would be the constraint.

The gen port doesn't have a breaker but it says max of 100A. 80% of 100A is 19.2kW.

 

[Clint-L]

The gen port doesn't have a breaker but it says max of 100A. 80% of 100A is 19.2kW.

Yes. Correct. 19,200 watts is the maximum allowed on gen port when configured as AC coupled. The client that is wanting to do the 19,200 of ACC plus 15k of DC PV is mainly wanting the added ACC for when on grid to get him near net-zero on his monthly usage from the grid. He understands that if the grid is down, the ACC micros will be cycled on and off depending on the battery voltage. I sure hope Sol-Ark gets the DC PV issue of load shedding at 13k corrected. I know it’s only 2k, but over 5 hours of that clipping that’s a potential loss of 20Kwh

 

[RCinFLA]

AC coupling is only tricky when the system has to run when the grid is down.

True, but you never know when grid might go down. Then all of a sudden you have 19 kW that has to go somewhere.

I highly recommend you put AC coupling in through Gen input. This gives the ability of SolArk to do an immediate disconnect from GT inverters if it gets into trouble with excessive PV production.

You cannot rely on freq shifting GT inverter power reduction for a sudden overproduction situation. It takes too long to react for safe operation on a HF inverter. There are a couple of ways this sudden over production situation can happen.

Alternative would be an addition load dump like a hot water heater.

SolArk has direct control over its internal PV charge controller so it can immediately shut it down if need be.

 

[Clint-L]

True, but you never know when grid might go down. Then all of a sudden you have 19 kW that has to go somewhere.

I highly recommend you put AC coupling in through Gen input. This gives the ability of SolArk to do an immediate disconnect from GT inverters if it gets into trouble with excessive PV production.

You cannot rely on freq shifting GT inverter power reduction for a sudden overproduction situation. It takes too long to react for safe operation on a HF inverter. There are a couple of ways this sudden over production situation can happen.

Alternative would be an addition load dump like a hot water heater.

SolArk has direct control over its internal PV charge controller so it can immediately shut it down if need

 

[Clint-L]

Yes, you are correct. We would never put Micros on the “load side” of a solark. We either use ACC, disabling the gen port and enabling ACC to connect them or we put them upstream on the grid tie side of the solark. When we use the term ACC in the installation world, it is a given, but I’m glad you brought this up, because otherwise folks may have been misled. Good discussions for sure!

 

[Clint-L]

Update on this - 10-26-22
I’ve been continuing to work with Solark support.

I’d say we have absolutely confirmed there is a limitation here with the 15k. If we raise the output load limit to 15k, once the PV gets to about 13,500 watts, it resets PV and drops to zero watts. It then ramps back up.

It seems like they are trying to duplicate this on their side, but I have concern that they don’t have the max spec of arrrays connected per their documentation which is three arrays, each 6.4kw. One on each MPPT for a total of 19.2kw. With that setup, the inverter should cap out at 15kw of production and MPPT would “self limit” at 26 amps.

At this point Solark support seems to believe it is a software issue.

I’ve also found other bugs. TOU is not working as it should. I’ve set it up on multiple 12k Solarks and have even setup in my exact situation with my old 12k before installing this 15k unit.

I’ll give another update when appropriate.

 

[robby]

Any chance of seeing the MPPT graphs that we discussed about in the other thread.

 

[Clint-L]

Any chance of seeing the MPPT graphs that we discussed about in the other thread.

Here’s graphs showing it capping at 13k. Once in morning and once in evening you can see where it drops out and the voltage spikes. I do expect voltage to spike with the MPPT would halt the amperage being received. The 600v spikes were back on the older software. I could post it, but not sure it’s very relevant since they seemed to have addressed it with this latest update.

Array 1 is two strings of 10 QCELL G5 320w in parallel.
Array 2 is two strings of 8 QCELL G10 400w in parallel
Array 2 is two strings of 8 QCELL G10 400w in parallel

 

[SolarRich]

Wow! Those charts like just like the ones I have in another thread here on the forum. Except in my case (12k) the spikes happen at any power level.

 

[robby]

I actually dropped by my Solar Installer near me yesterday and during our conversation I asked him about this problem and he said he has installed four of the 15K but only two of them had the maximum amount of PV. He said he is seeing the full 15K and a bit when it's 11am and the batteries are all charging. So yes they do work at the advertised 15KW with 19KW of PV.

The funny thing is that looking at your Ipv graph it does not look like clipping. It almost seems like the PV array is just not going any higher than 14+ Amps. By any chance have you tried removing one string and trying it on another inverter to see if it does the 6KW that is expected?

When my 12K clips it's a hard clip that does not vary.


Have you just discussed with Sol-Ark that this is probably a lemon Inverter and needs to be exchanged or repaired?
I know it's painful taking out something that is working 80% of the way and then having nothing and waiting on a replacement but it's better then frustrating yourself over a problem that may be due to a damaged circuit.