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Poor experience with Sol-Ark 15k

BVI-Matt

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Feb 24, 2024
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British Virgin Islands
Despite the reputation that Sol-Ark has on this forum, I feel the need to report a none to happy experience of our Sol-Ark installation.

In September 2023, we installed 3 x 15Kw, hybrid inverters, in parallel, as a 3 phase system.

We have seen varying issues, including ramping issues, to which Sol-Ark have applied a firmware increase the speed of the MPPT operation, which appears to have helped reduce the ramping.

However, we have also experienced an ongoing problem with the MPPT input voltage fluctuating, going between open circuit voltage, and less than 100V. This problem has been present since nearly day 1.

This problem only exhibits itself, when the units are in Parallel, with batteries in the system. If the system is put into grid tie mode, and the units taken out of parallel operation, with no batteries in the system, then the issue does not exhibit itself. It also does not exhibit itself, when not in parallel, and the batteries only connected to a single inverter.

It does not appear to be continuously present, and may or may not appear on restart, but does eventually, normally within 2 hours, reappear.

Sol-Ark technical support have spent considerable time with us trying to troubleshoot the problem.

We have proved that it is not related to the TIGO RSD’s, having taken them out of the MPPT 3 string, and still seeing the problem.

It also does not matter which string is connected to MPPT3 input, it is only that input that is affected. It is not, therefore string related.

Sol-Ark, having ruled out external factors, sent us a replacement inverter under warranty which they bench tested before sending out. The new inverter exhibited identical behaviour to the old one.

Sol-Ark have now advised us that they have no resolution to the problem, which they say is unique to our installation.

Our only resolution appears to be to purchase an additional inverter, and remove the 2 off MPPT3 inputs from our existing installation, and run them through the new inverter as a stand alone grid tie unit.

Quite apart from the additional cost incurred to purchase and install the additional inverter, this also removes the ability to use this PV power to gain the advantage of the hybrid functionality of the existing installation, and therefore increases the time to recover the Capital expenditure.

Despite having pointed out to Sol-Ark that the entire system was purchased and installed, based on the functionality they claim, together with their reputation, and the inverters not operating correctly, Sol-Ark are refusing to allow us to keep the good inverter we removed, to use as the 4th grid tie only inverter for the 2 off MPPT strings we need to remove from the existing 3 inverter installation.

I am not happy that they appear to be washing their hands of any responsibility for a product that does not work as claimed. We have invested nearly $200k in a system that does not work as specified, and are now expected to invest more money to put in place a work-around to cover their problem.

I am open to any feedback from forum members as to anyone who has, or are, experiencing the same issue, and any suggestions as to what might be causing this, apart from a firmware issue within the inverters themselves.

Attached is an example MPPT3 voltage graph from Solar Assistant monitoring.
 

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Take them to federal court and sue them for violation of the Magnuson Moss warranty act. The product does not operate as advertised and they're refusing to help you under warranty.
 
Sol-Ark have now advised us that they have no resolution to the problem, which they say is unique to our installation.
In the interest of trying to debug this, it feels like there is an unintended coupling of something between inverters that is a subtle fault that has escaped detection.

The big clue here is that isolating the battery changes the behavior. I would check any sort of connection between the battery leads and the PV leads.

Without an accurate wiring diagram, it is hard to give specifics, but my feeling is that with weird issues like this, the best plan is to carefully check everything from the beginning to the end. Some inadvertent ground or connection can cause weird things.

I agree you should get what you paid for, but I also agree with Sol-Ark that there is something odd about your setup that may be inducing this issue.

It might be helpful for you to be more specific on the setup and observed conditions, plus the tests you have done. For example, it wasn't clear to me if this afflicts only MPPT3 or others, and if you rotate strings between MPPTs, does the problem move with the string or the MPPT port? Exacting details are required to expose the issue.

Mike C.
 
In the interest of trying to debug this, it feels like there is an unintended coupling of something between inverters that is a subtle fault that has escaped detection.

The big clue here is that isolating the battery changes the behavior. I would check any sort of connection between the battery leads and the PV leads.

Without an accurate wiring diagram, it is hard to give specifics, but my feeling is that with weird issues like this, the best plan is to carefully check everything from the beginning to the end. Some inadvertent ground or connection can cause weird things.

I agree you should get what you paid for, but I also agree with Sol-Ark that there is something odd about your setup that may be inducing this issue.

It might be helpful for you to be more specific on the setup and observed conditions, plus the tests you have done. For example, it wasn't clear to me if this afflicts only MPPT3 or others, and if you rotate strings between MPPTs, does the problem move with the string or the MPPT port? Exacting details are required to expose the issue.

Mike C.
Mike,

Many thanks for your feedback.

Whilst I agree that the big clue appears to be given by isolating the batteries, unfortunately that cannot be done alone.

This is a 3 phase, 3 inverter solution, and to isolate the batteries, you also have to take the units out of parallel operation. Therefore, running with no batteries, also means no communication between the inverters, so the fault is not necessarily connected to the batteries or their shared interconnection.

I wanted to split the battery bank into 3 banks, each one dedicated to its own inverter, but Sol-Ark tells us that for a 3 inverter, 3 phase system this does not work. The installation manual does also say this.

The fault only affects MPPT3, and only on 1 inverter at a time.

Swapping the PV strings around leaves the fault with MPPT3 ( I.e. does not follow string )

Due to our set-up, we are only using 8 of the 9 available MPPT’s. When the fault first occurred, on the inverter set as ‘Master Phase A’, we moved the PV string in MPPT3 across to the spare MPPT 3 on inverter set as ‘Master Phase B’. The fault then appeared on MPPT3 on Master Phase B inverter.

We also tried using just MPPT’s 1 and 3 on Inverter ‘Master Phase A’, and get no fault on MPPT3. The fault only appears when all 3 MPPT’s are in use on an inverter, is not a specific string related issue, occurs at any PV Power level, and only affects MPPT3 on the first phase unit that has 3 string!

We have been through the wiring of these units, several times ( maybe 4 or 5 times ) over the last six months, and can find no issues at all.

My gut feeling is that this is a firmware issue, caused by communication between inverters when in Parallel, but I have no way to prove this.

Matt.
 
Instead of doing 3x 15k units, would one of the commercial models work instead? They have a 208v 3phase model and a 480v 3 phase model. Maybe solark will let you substitute them for minimal cost?
 
Instead of doing 3x 15k units, would one of the commercial models work instead? They have a 208v 3phase model and a 480v 3 phase model. Maybe solark will let you substitute them for minimal cost?
That would force the adoption of higher voltage batteries as well though. I do like single unit operation, but that's a complete re-work at that point.

Matt,
If there is a way to simplify the troubleshooting you may be able to prove an issue. If you had extra panels around, perhaps strings of just a few panels each (above the minimum 125V) to each of the 3 MPPTs on the controller that is acting up? If the problem persists, it's pretty easy to say that something is going on. If the problem dissapears, it is related to higher voltage, or some other wiring/TIGO issue that exists in your "real" setup.
 
Wow, you just blew my mind! I pulled up data from a job where we have (3) 15Ks on 3 phase, and I'm seeing the exact symptoms you described! I never even noticed it before! We have all 3 mppts on all 3 inverters filled, but inverter 1 is the one that has these symptoms! I will add screenshots from the Solar Assistant on that job!

I have also added a screenshot from the Sol-Ark Powerview data.

One interesting thing though, is that the monthly PV productions shows very similar between the 3 inverters. They all have the exact same amount of solar connected to them. Inverter 3 gets a very small amount of shading in early morning, that 1 & 2 don't, so 3 has slightly lower production, but 1 & 2 are pretty well identical. I find this hard to believe with how terrible the voltage and power curves are on that mppt3!

How does your historical production data look? Can you pinpoint a lower total production?

Specifics for our job:
-(3) Sol-Ark 15K
-(3) mppt1 =(10) 450W solar panels (5S2P), these (30) panels are on roof #1
-(3) mppt2 =(12) 450W solar panels (6S2P), these (36) panels are on roof #2
-(3) mppt3 =(12) 450W solar panels (6S2P), these (36) panels are on roof #2
-PV total = 45.9kW
-(30) Rubix Stack RS51100 batteries, 5.12kWh each (153.6kWh total)
 

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With the understanding that Sol-Ark should just fix this or make it whole - Would getting an MPPT charge controller from someone reputable and just dump it into the battery work to fix this problem so you can move forward? They can be had for relatively low cost and for the most part solve the problem. Maybe ask Sol-Ark is they would be willing to pay for it so they can wash their hands too.

You didn't say what type of battery you have so it may or may not be possible.
 
With the understanding that Sol-Ark should just fix this or make it whole - Would getting an MPPT charge controller from someone reputable and just dump it into the battery work to fix this problem so you can move forward? They can be had for relatively low cost and for the most part solve the problem. Maybe ask Sol-Ark is they would be willing to pay for it so they can wash their hands too.

You didn't say what type of battery you have so it may or may not be possible.
Sol-Ark is one of the top tier outfits from what I have seen. They should either fix it properly, or advertise as only being able to use 7 of 9 MPPT's or whatever the limit is before the odd behavior. Half-hearted efforts are for low tier equipment in my opinion. I'm not saying you are wrong automatikdonn, but this level of investment requires solid backing.
 
Sol-Ark is one of the top tier outfits from what I have seen. They should either fix it properly, or advertise as only being able to use 7 of 9 MPPT's or whatever the limit is before the odd behavior. Half-hearted efforts are for low tier equipment in my opinion. I'm not saying you are wrong automatikdonn, but this level of investment requires solid backing.
I don't disagree and the system owner is fully correct for wanting it to work right.

With the imperfect world we live in, it was just a suggestion to get the max out of his system without having to put in much more. 200k is a crazy amount of money to spend on a system and I would personally be extremely upset about the situation. I am surely not discounting that.
 
Sol-Ark is one of the top tier outfits from what I have seen. They should either fix it properly, or advertise as only being able to use 7 of 9 MPPT's or whatever the limit is before the odd behavior. Half-hearted efforts are for low tier equipment in my opinion. I'm not saying you are wrong automatikdonn, but this level of investment requires solid backing.
IMO they’re Tier 2 definitely not tier 1
 
IMO they’re Tier 2 definitely not tier 1
As compared to any other AIO unit available right now, I haven't found one that didn't have things about that made me decide not to try it. If you want to know specifics that I prefer Sol-Ark over others for, just ask. I'll be glad to dive in for you.

As far as menus and settings go, they don't hold a candle to the likes of Midnite (Rosie), Schneider, Outback, Victron.... the list goes on. But in the AIO world, I have yet to find another one that holds a candle to Sol-Ark... Eg4 18k maybe, but when I considered trying it out, there were just too many specifics that I didn't like about it to even try it out. And I feel like I keep hearing about too many bugs.
 
Would getting an MPPT charge controller from someone reputable and just dump it into the battery work to fix this problem so you can move forward?
This ^^^

If you were an installer and have multiple clients with that need, then you need the problem solved. Or just factor in the cost of mppts into your quote.

As an end user, the cost of moving one or two strings to a stand alone charge controller is cheaper than investing more time into getting the right solution.

You do loose the potential export of power when the batteries are full.
 
I just saw that according to todays numbers (I haven't checked history for this.) the DC current side of things go up and down with this PV production issue....

1718220953205.png

I also looked at the "layout" portion of historical data in PowerView and I saw a ~12% lower PV Production on the A Phase inverter on a 2024 yearly basis. That would be from 1/1/24 through 6/5/24 when the migration to US based servers occurred.

2024 production layout - Copy.png

Going off the average production of the other 2 inverters that yields a net loss of ~815kWh of power! Which, in my opinion, is a fairly substantial amount of power.
 
Sorry all, but don’t regularly look at the site.

For me, it is great to hear that we are not alone in experiencing this problem, and lends support to my belief that this is not a problem with our installation, but is a problem within the Sol-Ark firmware.

Given the amount of time and cost that we have sunk into trying to resolve this issue, together with Sol-Arks response that they could do nothing more, we have brought down a Fronius 6Kw, grid tie inverter, and routed the 2 strings that were connected to MPPT3 inputs across to this inverter.

With only 2 strings connected to MPPT’s 1 and 2 on each of the 3 Sol-Arks, they are working as expected.

The strings moved across to the Fronius worked fine with the Fronius immediately.

We are back to full PV, with hybrid operation on 120 panels ( 44,400 W of panel PV ), with the remaining 20 panels ( 7400W ) supported through the Fronius as grid tie only.

Not the solution we had planned, but the only sensible solution we had to cover Sol-Arks failings. Unfotunately, we now loose a significant amount of solar production during grid outages, which are not uncommon, but normally short lived, here in the British Virgin Islands, but the power recovered during grid availability, and correct MPPT operation, on balance is far greater.

Matt.
 
I just saw that according to todays numbers (I haven't checked history for this.) the DC current side of things go up and down with this PV production issue....

View attachment 221679

I also looked at the "layout" portion of historical data in PowerView and I saw a ~12% lower PV Production on the A Phase inverter on a 2024 yearly basis. That would be from 1/1/24 through 6/5/24 when the migration to US based servers occurred.

View attachment 221681

Going off the average production of the other 2 inverters that yields a net loss of ~815kWh of power! Which, in my opinion, is a fairly substantial amount of power.
When we took our set up out of parallel, and removed batteries, our daily av production went from 218 kWh to 240 kWh’s, so we saw a 10% increase in output across the system, not insignificant.

We also noted the battery current flow that you have noted. They are definitely connected, but why is the firmware telling the inverters to transfer DC power?

Matt
 
The strings moved across to the Fronius worked fine with the Fronius immediately.

We are back to full PV, with hybrid operation on 120 panels ( 44,400 W of panel PV ), with the remaining 20 panels ( 7400W ) supported through the Fronius as grid tie only.

Unfotunately, we now loose a significant amount of solar production during grid outages, which are not uncommon, but normally short lived, here in the British Virgin Islands, but the power recovered during grid availability, and correct MPPT operation, on balance is far greater.
How about setting the Fronius to only charge the battery and take it off grid?
 
What disturbs me about this situation is that Sol-Ark seems to lack the knowledge and ability to find out what's going on.
 
This should be a good lesson for everyone to simplify their installs as much as possible.

Using 3x solark 15k's was a questionable design choice from the start. Solark and other vendors make a 30k and 60k for 3phase power installations. Yes that means different batteries but I would have leaned that way because its less expensive just for the inverters plus I'm sure solark has more 3 phase customers using the 30k/60k vs 3x 15k's. I prefer to be in a larger user base from a support perspective.

That's not letting solark off the hook for resolving this. But just the reality of getting support in the modern day.
 
This should be a good lesson for everyone to simplify their installs as much as possible.

Using 3x solark 15k's was a questionable design choice from the start. Solark and other vendors make a 30k and 60k for 3phase power installations. Yes that means different batteries but I would have leaned that way because its less expensive just for the inverters plus I'm sure solark has more 3 phase customers using the 30k/60k vs 3x 15k's. I prefer to be in a larger user base from a support perspective.

That's not letting solark off the hook for resolving this. But just the reality of getting support in the modern day.
In response to your comments, the 60kW, 3 phase units are 480V, not 208V, so not really a lot of use for a situation where 480V does not exist.

We did consider going for 2 off the 30kW, 208V units, but at time of ordering the equipment, these had only just been announced, and were not even available. Also, they would still be operating in parallel, and were untested in the field, so who knows what problems they may have had.

The 15kW units, whilst new on the market, were an upgrade to the 12kW units, which had a proven track record, and available in a reasonable timescale. When you have an instal on a remote Caribbean Island, with little support available locally, reliability and proven technology is hugely important. That is why in purchasing the equipment, we paid particular attention to the manufacturers reputation and chose the Sol-Ark units as the solution.
 

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