Sol-Ark 12K + Enphase IQ8 microinverters

[timselectric]

I could have sworn that in Bens Sol-Ark video he said they Frequency shit to 62Hz to shut them off.
He has both systems running at his house and he is a Sol-Ark installer.

That's what I thought, too.
Maybe, there's been issues. And Sol-Ark is changing the instructions?

 

[timselectric]

I researched them in depth, over a year ago. And AC coupling was a big part of my plans. I know that everything I read, said that it was possible. I was going to build a micro grid. And they were all going to feed into it, or take from it as needed.

 

[robby]

I don't really know at this point what is correct and I hate making statements on stuff that I am not familiar with.
I watched Bens Video again and it is Solaredge Inverter Grid Tied that he is talking about, so I am probably wrong.
The Sol-Ark probably just kills the power at the Gen Breaker input like you said.

 

[azgrogg]

I could have sworn that in Bens Sol-Ark video he said they Frequency shit to 62Hz to shut them off.
He has both systems running at his house and he is a Sol-Ark installer.

He did say that but he is using a SolarEdge system not an Enphase.

 

[timselectric]

At this point, I don't know either.
I was surprised by their statement.
Maybe it only pertains to micro inverters.

 

[Ampster]

could I put 2 batteries in series for 96volt at 100 amps and get the 9.6 kw constant discharge?

Yes you can get 9600 Watts of constant discharge but what are you going to discharge it to that takes 96 volts? Why don't you put them in series and get 48 volts at 200 Amps into two 48 volt inverters, or one 6000 Watt inverter if that is all you need?

 

[Quattrohead]

I now have a Sol-ark and Solaredge units so I will test this all out in the next few weeks.
Oh boy do I have a story about getting a used system.....

 

[Ampster]

He did say that but he is using a SolarEdge system not an Enphase.

Maybe it only pertains to micro inverters.

It does not matter what brand the GT, grid dependant inverter is, it has to follow the response dictated in the UL1741SA standard.
Just to be clear the SolArk is 1741SA compliant which means it can respond to frequency from the grid as the standard intended. As far as I know, the standard does not apply to the algorithm that the grid forming inverter uses to AC couple with a GT inverter. Two different issue. That is the question, whether the SolArk has the subtleness to slowly increment frequency to modulate an AC coupled GT inverter. It is clear in some scenarios it does have to rely on using the relay in the interface to disconnect the GT inverters if it can not reduce the output quickly enough.

 

[timselectric]

It does not matter what brand the GT, grid dependant inverter is, it has to follow the response dictated in the UL1741SA standard.
Just to be clear the SolArk is 1741SA compliant which means it can respond to frequency from the grid as the standard intended. As far as I know, the standard does not apply to the algorithm that the grid forming inverter uses to AC couple with a GT inverter. Two different issue. That is the question, whether the SolArk has the subtleness to slowly increment frequency to modulate an AC coupled GT inverter. It is clear in some scenarios it does have to rely on using the relay in the interface to disconnect the GT inverters if it can not reduce the output quickly enough.

Right
It seems like it is a compatibility problem.

 

[timselectric]

I'm pretty sure that Engineer77 connected Enphase to Sol-Ark, at least once. I don't remember how he connected it.

 

[Ampster]

It seems like it is a compatibility problem.

I think the problem has gotten confused along the way. The intent of standards is to avoid compatabilty problems, As far as I understand it, UL 1741 was developed to give grid operators the abillity to shut down grid tie inverters if there was too much power coming at the grid. Then they realized they did not want them all shutting down at the same time because that would be a big shock to the grid, so they came out with the additial SA designation to make the GT inverters modulate down based on frequency Watts.
Then some smart people figured out they could use this functionality to add battery backed inverters to existing GT systems and sell backup to existing GT system owners. They called that AC coupling, Tesla sold a lot of Powerwalls and others entered into the market, The question that started this discussion was about how the SolArk can do that, and as far as the SolArk is concerned it may have a problem in how it can effectively AC couple with any UL1741SA inverter. I still do not know the answer because the details are not clear exactly how SolArk does it. All I know is they have to use a relay if all else fails.

 

[Ampster]

I'm pretty sure that Engineer77 connected Enphase to Sol-Ark, at least once. I don't remember how he connected it.

He does not usually go into the details as far as modulation is concerned. If I remember one of his videos was the first time that I heard that the SolArk had to AC couple through the bidirectional Generator port.

 

[Hedges]

So, could I put 2 batteries in series for 96volt at 100 amps and get the 9.6 kw constant discharge?

In parallel, not in series. 48V at 200A, 9.6kW

Then some smart people figured out they could use this functionality to add battery backed inverters to existing GT systems and sell backup to existing GT system owners. They called that AC coupling, Tesla sold a lot of Powerwalls and others entered into the market,

Some smart people figured that out at least 20 years ago.
Later, someone at the utilities got smart and took advantage of it.
Now a number of battery inverters support it.

Schneider xw pro 6848 not powering up with eg4 lithium battery

The XW was design at a time when individual system components were common, where there were no BMS controllers, battery's were fuse/breaker protected and didn't have "start-up" requirements. The XW has been out for close to 16 years now, which few manufactures can make that claim, only one...

diysolarforum.com

 

[Ampster]

Some smart people figured that out at least 20 years ago.

I was actually referring to the functionality of UL 1741 which has only been around a few years. If I recall SMA has been AC coupling their GT inverters with their battery inverters with proprietary communications for some time. Perhaps that is who you are referring to? I have no doubt there are some smart people at SMA.

 

[Hedges]

The frequency-watts function of UL-1741-SA is what would have grid tie inverters modulating their output as frequency shifts.
I don't know if the grid ever does that. Would have to be the entire western grid all at once.

Volts-watts seems like it would work better locally, full power if grid sags but ease off as voltage climbs.

There may have been something clunky and proprietary with the early Sunny Island/Sunny Boy coupling.
The later series I have smoothly adjusts power in response to frequency. That is essentially same feature as UL-1741-SA and predates it by a decade.

Even if it was not the US standard UL-1741 for anti-islanding (dates back at least 20 years), link to SMA's history in that post appears to say they developed the first PV inverter (which I take to mean grid-tie.) So I think they created the market, and came up with something utilities could accept.

 

[Johndo]

The micro inverters modulate their own power. Whenever the frequency shifts. But, Sol-Ark is now saying that they can't control the micro inverters. Which means that they evidently can't shift the frequency. They are now saying that they can only disconnect them from the system.
(According to post #81)

You may be right about just disconnecting, but that was not my understanding after an extensive discussion with SolArc tech support. My understanding was they rapidly modulated the frequency untill they turned off. (rapid is a relative term)

 

[fromport]

The frequency-watts function of UL-1741-SA is what would have grid tie inverters modulating their output as frequency shifts.
I don't know if the grid ever does that. Would have to be the entire western grid all at once.

There are High Voltage DC connected grids in the USA ;-)

List of HVDC projects - Wikipedia

wikiless.org

Funny to see how at the enduser level we try implementing AC coupling while our direct sources are DC (PV/battery)
and at the high power side it is more effective to convert AC <-> DC and transport DC

HVDC transmission losses are quoted at 3.5% per 1,000 km, about 50% less than AC (6.7%) lines at the same voltage. This is because direct current transfers only active power and thus causes lower losses than alternating current, which transfers both active and reactive power.

source: https://wikiless.org/wiki/High-voltage_direct_current?lang=en#Comparison_with_AC

 

[timselectric]

There are High Voltage DC connected grids in the USA ;-)

List of HVDC projects - Wikipedia

wikiless.org

Funny to see how at the enduser level we try implementing AC coupling while our direct sources are DC (PV/battery)
and at the high power side it is more effective to convert AC <-> DC and transport DC

source: https://wikiless.org/wiki/High-voltage_direct_current?lang=en#Comparison_with_AC

Interesting reading. But very expensive to implement.

The only time that people should need AC coupling.
Is when they are trying to add a battery backup to an existing grid-tied system. A lot of people bought into grid-tied systems, not realizing that they would have no power when the grid went down. If starting fresh with knowledge of how things work. DC should always be the choice, in my opinion.
Only inverting once, when the power is being used.
Instead of the back and forth losses.

 

[fromport]

Interesting reading. But very expensive to implement.

The only time that people should need AC coupling.
Is when they are trying to add a battery backup to an existing grid-tied system. A lot of people bought into grid-tied systems, not realizing that they would have no power when the grid went down. If starting fresh with knowledge of how things work. DC should always be the choice, in my opinion.
Only inverting once, when the power is being used.
Instead of the back and forth losses.

If you would start over from scratch, what equipment would you use? All AC, all DC or a mix?
I am currently temped to think along the lines of a hybrid (dual in parallel for redundancy) with 48V DC batteries for the main part and then use minor AC coupled to supplement both grid tied netmetering and support load in case of grid troubles.
I think it might depend on what kind of loads you have, eg well pump, old & large central AC units would be a challenge for HF hybrid inverters.
So many variables.....

 

[timselectric]

Strictly off grid 48v system.
With grid as a backup, only.