Possible to use Sol Ark Gen terminals with a 3 Phase Generator ? Sol Ark techs said NO !

[Hedges]

Subject to Carlos' response, my thoughts are:


The ATS has to be Break-Before Make (otherwise the Gen is connected to Grid and you have even worse problems). I'm guessing that the "break" time is at least 4ms (1/250th of a second). At which point, the Sol-Ark would have disconnected from the Grid Input.

Don't count on that.
I hear my Sunny Boy disconnect immediately, but Sunny Island battery inverter remains connected for maybe half a second.

You can count on the maximum allowed time according to UL-1741

If SolArk doesn't disconnect before "make" of generator, it gets slammed out of phase.

DPDT relay would be fast, but I don't think that's what is used in a transfer switch. Rather, 2x DPST relays, with time delay between them.

A UPS or grid-interactive inverter can be faster, because it is keeping count with the grid the entire time, can pick up the load in-phase having only missed a fraction of a beat.


You could of course use a transformer to derive 120/240V split-phase from a 3-phase generator.
But I assume you've got your inverter configured to 3-phase matching 3-phase grid.

So is the statement "Sol-Ark supports split or 3 phase, but when configured for 3-phase the Gen input can't be used for input, only for controllable loads"?

"Chargeverter" or other battery charger it is.

 

[Cmiller]

Except that, in general, that is how they work. It shift its own production to synchronize with the grid (or generator), and then connect. I suppose a bad inverter can do a hard switchover. But one that is grid enabled has to be able to synch to the grid.

I was specifically referring to the Sol-Ark "catching" the transfer... that would depend on how slow the transfer is. I would assume the Sol-Ark would catch it, but it's not a guarantee.

Yes there is, or the settings wouldn't work. You don't tell by frequency, voltage, wave form, directly. There are dirty grids and ckean generators. Although grids tend to have very stable frequency, but a good generator can too.

No, that's not true. The operation of the Sol-Ark auto start is like this:

no grid available/operating on battery > grid start trigger met by low battery volts/SOC > close gen relay > charge volts and amps met (or TOU target met) > open gen start relay.

There is no "check if AC source on grid input is grid or gen".... in fact even when using gen terminals (120/240v configuration) and auto start relay, the gen keeps running until parameters are met! Even if grid comes back on, and the Sol-Ark transfers back to grid, but gen is still putting 120/240VAC to gen terminals! This happened for one of our customers!

Not hard to wire the SA's gen start line through the ATS gen start line. When the ATS switches back to grid, it opens the circuit.

Yep. I call that a workaround! The first time I did that type of configuration was 10+ years ago, and it sure wasn't because an inverter's "gen" port didn't work right....

Why do we need to create "fixes" that are workarounds?

If you want to charge batteries with the generator, it has to be able to supply more than load. Impossible to charge if there is no excess.

What better inverters can do: 5kw generator. Load goes above 5kw, and inverter supplements (6000xp can't). Load drops below 5kw, and inverter uses excess to charge batteries. What that allows you to do is run a 5kw generator for 6 hours to provide for your 30kwh daily use.

If the inverter can't supplement, then when load goes above 5kw, then inverter has to disconnect generator and run off battery. Now you don't know how long you have to run to recharge because you don't know how long you have been on generator. The only way you know for sure is to get a bigger (10 kw?)

Let me give you a real world scenario. (Not an actual job, but a typical scenario for us.)

Inverter is sized to loads, peak loads are ~10kW. Sol-Ark 15K fits the bill.

Battery storage: 40kW

Auto start gen: Kohler 14RESA (12kW on nat. gas)

In grid down scenario plus low battery the gen starts and loads are average ~4kW. What do you suggest would be a good way to avoid overloading the gen? Set battery charge to max of 2kW to stay under 12kW gen rating? (10kW peak loads + 2kW charge = 12kW)

Or how about this... how about Sol-Ark changes their hardware to support gen shave. Now we could set gen shave to 10kW to stay under the gen's rating, 95% of the time the gen runs it's pushing (10kW - average 4kW load) ~6kW to the batteries. Thsi setup works absolutely perfectly with Schneider, Outback, Magnum, Victron, Midnite Rosie inverters and probably many others.

Why does everyone dance around manufacturers that drop perfect features that have been available for many years now? I'll comment on these for of posts any time I can in order to try to get Sol-Ark's attention!

@Carlos_Sol-Ark are you listening? I love the Sol-Ark inverters.... for the most part... but you guys lack some critical features. If you want to be the best, then be the best. And please listen to the people that work with hundreds of inverters! We already have hundreds of Sol-Arks installed! But if someone else comes with the missing features that you guys don't have, you will lose us just like that! I know we are only one fish in the ocean, but those little details (though I feel this is a big one) are the difference between the men and the boys!

 

[Cmiller]

Don't count on that.
I hear my Sunny Boy disconnect immediately, but Sunny Island battery inverter remains connected for maybe half a second.

You can count on the maximum allowed time according to UL-1741

If SolArk doesn't disconnect before "make" of generator, it gets slammed out of phase.

That's my concern, though I'm thinking Sol-Ark is probably quick enough to catch the power glitch in transfer between grid and gen.

DPDT relay would be fast, but I don't think that's what is used in a transfer switch. Rather, 2x DPST relays, with time delay between them.

I don't think that is how the Sol-Ark is set up. I believe it simply has a dpst contactor for each leg, and simply syncs and connects up. So transfer from grid to inverter amounts to relay opening and Sol-Ark "flipping" from charge to discharge on the AC to HV DC bus end of things.

So is the statement "Sol-Ark supports split or 3 phase, but when configured for 3-phase the Gen input can't be used for input, only for controllable loads"?

Yes that is correct!

 

[Cmiller]

I'm going to dig up some more information on my end so can get a decent response for all the points you brought up, but I will say I have seen many installations work in that configuration with no issues, but its certainly woth looking into for you especially if it brings some peace of mind on your installs. I have to ask though, how fast is the transfer back to utility power on the transfer switch you are using? This single question will determine if this will be an issue or not. The Grid sample rates on the Sol-Ark are pretty quick.

Here is a screenshot of a Kohler transfer switch spec sheet. Looks like 100ms. I am fairly certain the Sol-Ark would catch that. Though it's still something to keep in consideration.

Im pretty sure this is true of all configurations. If an AC charging cycle starts (GEN charge and GRID charge), it will run until the batteries reach full or the programmed cap ( in TOU). I will also double check on this for you too.

Schneider XWs will shut down gen that is feeding into gen input, when grid comes back on.

When gen terminal works properly, its an easy code fix. Grid on == gen relay disable... but if you are using ATS to use grid terminals for gen, while grid is down, that option kind of goes out the door.

Ideally gen start and stop would not be linked to TOU. And also there should be a specific stop setting available. Many times you want to have TOU set for let's say a discharge to 30%. But then when grid is down and the gen starts at say 15%, it's not remotely practical (ever!) To only charge from 15-30%..... on a cloudy day the gen would start 10 times in the same day.... and you can't tell a customer that he needs to change settings when grid goes off! The Sol-Ark is supposed to make it so that they don't even find out when grid goes off. How will they know that they need to go change settings? What if they are on vacation?

It really depends on how big the loads are and how fast you need the batteries to charge. Most people dont need a 24kW gen to cover loads and charge batteries at the same time in my experience. I typically saw 7-15kW generators being used in residential installs with great results. I also saw my fair share of 20-48kW gens too. If they have big loads and want to do a large load back up with double or triple redundancies you typically have to commit to sizing everything for the expected load (battery charging being considered a load for the generator).

I wouldn't do it to set up a 8kW gen on auto start on a 15K Sol-Ark! 15K inverter tells me loads are going to be higher than what a 7kW gen is continous rated at. (Probably only 5.5kW)

How about this scenario:

Average load of 4kW, with peak of 10kW. Kohler 14RESA (rated 12kW) standby gen. Your suggestion? With proper gen shave function, on gen terminals, you would set gen shave to 10kW, then most of the time batteries can charge at 6kW with load at 4kW, and when loads spike, battery charge drops until loads drop again. Pretty simple and works perfectly on the good old "low frequency" brands for the last 15 years...

And also, how would an ATS be workable for this scenario? You can't set grid shave to 10kW for normal operation, which again means the customer would need to adjust settings when grid goes down.

Please don't take my comments personal! I'm simply giving constructive criticism! And straight from the issues we are regularly dealing with!

 

[DIYrich]

No, that's not true. The operation of the Sol-Ark auto start is like this:

no grid available/operating on battery > grid start trigger met by low battery volts/SOC > close gen relay > charge volts and amps met (or TOU target met) > open gen start relay.

There is no "check if AC source on grid input is grid or gen".... in fact even when using gen terminals (120/240v configuration) and auto start relay, the gen keeps running until parameters are met! Even if grid comes back on, and the Sol-Ark transfers back to grid, but gen is still putting 120/240VAC to gen terminals! This happened for one of our customers!

Yes, but your first parameter is "no grid available". When grid is available, the entire logic string is now false.

Let me give you a real world scenario. (Not an actual job, but a typical scenario for us.)

In grid down scenario plus low battery the gen starts and loads are average ~4kW. What do you suggest would be a good way to avoid overloading the gen? Set battery charge to max of 2kW to stay under 12kW gen rating? (10kW peak loads + 2kW charge = 12kW)

From the current 15k manual. Gen Limit to 12,000 (or 10,000 to max out at 80% of generator rating).

Or how about this... how about Sol-Ark changes their hardware to support gen shave. Now we could set gen shave to 10kW to stay under the gen's rating, 95% of the time the gen runs it's pushing (10kW - average 4kW load) ~6kW to the batteries. Thsi setup works absolutely perfectly with Schneider, Outback, Magnum, Victron, Midnite Rosie inverters and probably many others.

I think the problem with Gen limit/Shaving is when it is on the Gen Port. The Gen Port is not as "tricked out" as the Grid Port. It would also require a Transfer Switch.

 

[Oldphile]

Once upon a time Sol-Ark did support Gen Peak Shaving and used external CTs to do so.

 

[Cmiller]

Yes, but your first parameter is "no grid available". When grid is available, the entire logic string is now false.

Correct. That's my whole point. Fix the gen port issues. Use gen port for the gen. Add logic to shut down the gen when grid comes back on, on the grid port.

From the current 15k manual. Gen Limit to 12,000 (or 10,000 to max out at 80% of generator rating).

Maybe you didn't catch the whole conversation around gen limit not working. It's literally "no longer supported" since the last firmware update. And that is pretty Sol-Ark tech support, not just me making something up....

I think the problem with Gen limit/Shaving is when it is on the Gen Port. The Gen Port is not as "tricked out" as the Grid Port. It would also require a Transfer Switch.

Apparently you didn't read what I wrote about why using s transfer switch on the grid side, to pick gen or grid, doesn't work well..... I've only been involved on a few hundred Sol-Ark setups now, by the way.

 

[Cmiller]

Once upon a time Sol-Ark did support Gen Peak Shaving and used external CTs to do so.

View attachment 213248

That is correct! And I think this option would be 10x better than what we have now! That "old" way at least allowed gen shave to happen, if grid shave wasn't needed. The "new" way today, pretty well all gen functionality of the gen port is out the door.

 

[Oldphile]

That is correct! And I think this option would be 10x better than what we have now! That "old" way at least allowed gen shave to happen, if grid shave wasn't needed. The "new" way today, pretty well all gen functionality of the gen port is out the door.

It's not Gen Peak Shaving, but according to the manual:

Gen Limit Power: Sets the Sol-Ark limit to keep the power drawn from the “GEN” terminal below the
threshold. The inverter will reduce the charge power rate to the batteries if this value is reached.

 

[Cmiller]

It's not Gen Peak Shaving, but according to the manual:

Gen Limit Power: Sets the Sol-Ark limit to keep the power drawn from the “GEN” terminal below the
threshold. The inverter will reduce the charge power rate to the batteries if this value is reached.

You are right. I phrased that wrong. But gen limit goes a long way! And works a lot better than no limit option!

 

[Oldphile]

You are right. I phrased that wrong. But gen limit goes a long way! And works a lot better than no limit option!

I was frustrated that Gen Peak Shaving is no longer supported, but then realized what I was planning to do probably isn't practical, that is charge batteries on 3 separate Sol-Arks at the same time. Instead I'll just use TOU to stagger charging of each battery bank. Gen Peak Shaving would be a bonus, but not critical. I have a single 17KW Generac that will be wired to the Gen Input on the 3 Sol-Arks. The existing generator feeds are on 40 A breakers limiting each to 32 A.

 

[DIYrich]

I have a single 17KW Generac that will be wired to the Gen Input on the 3 Sol-Arks. The existing generator feeds are on 40 A breakers limiting each to 32 A.

One chargeverter for each bank, and charge all 3 at the same time. I have a socket that is hooked up to the generator wire, and a 240v on/off switch from the generator wire into the sol-ark. I can turn off the generator power to the sol-ark, and plug in the CV to charge the battery directly.

 

[Oldphile]

I need an automatic setup. This is a 2 unit condo with a separate common building (garage). The well pump is on the common building. My neighbor is not technical and has no idea how any of this works. It has to work without manual intervention when I'm travelling. Also, I don't want to leave my condo during a storm to setup a battery charger at the other locations. Within an hour or 2 of losing power I also lose internet, so I won't know the status of the batteries at the other 2 locations.

Using TOU, I can ensure that each Sol-Ark will have access to the generator every 8 hours. Each Sol-Ark will have a 20 KWH battery bank.

 

[Hedges]

I don't think that is how the Sol-Ark is set up. I believe it simply has a dpst contactor for each leg, and simply syncs and connects up. So transfer from grid to inverter amounts to relay opening and Sol-Ark "flipping" from charge to discharge on the AC to HV DC bus end of things.

Right, most inverters don't have a transfer switch, just a relay to let grid feed in or not. Only one input, so they can sync to it before closing relay.

External transfer switch, SMA says allow 5 seconds to ensure disconnect before feeding in out of phase source.

Here is a screenshot of a Kohler transfer switch spec sheet. Looks like 100ms. I am fairly certain the Sol-Ark would catch that. Though it's still something to keep in consideration.

Which means this fast 100 ms transfer could blow up an inverter operating in parallel.

 

[Carlos_Sol-Ark]

@Carlos_Sol-Ark are you listening?

Yeah Haha I'm here, I just get off at 6 pm Central time. Also monitoring the forums is more like a third priority to my other duties so I may be a bit slow to respond sometimes, but I will get back to you. I certainly hear the point you are making.

There is no "check if AC source on grid input is grid or gen"

The Sol-Ark checks every AC connection it makes on the GRID terminals to determine GEN or GRID status.

View attachment 213200

The grid monitoring and reaction are magnitudes faster than this. I can't give you the exact response time, but I was told anyone is welcome to use an oscilloscope on their units. Once the Sol-Ark disconnects it will initiate a default 300S delay before reconnecting to any new AC source, you can lower it if you like but I wouldn't recommend anything lower than 60S. This should answer the question of a possible mis-phase connection.

Or how about this... how about Sol-Ark changes their hardware to support gen shave. Now we could set gen shave to 10kW to stay under the gen's rating, 95% of the time the gen runs it's pushing (10kW - average 4kW load) ~6kW to the batteries. Thsi setup works absolutely perfectly with Schneider, Outback, Magnum, Victron, Midnite Rosie inverters and probably many others.

I have recently been assigned to a group of app engineers who can do testing specifically for our residential systems so I think I can get some testing done to solve the battery charging problem you brought up here. In the past, the options available would be either the customer would have to adjust or monitor their loads during generator to battery charging, or they would charge the batteries slowly and use Time of Use to set an AC charging cap and have the generator stop charging the battery at a certain point. This would allow the generator to run for a shorter time, but keep the batteries going until solar power returns. Most people do the latter if they are strictly off the grid.

If they are on the grid most of the time and they want to use the batteries while grid-tied to offset loads, but they also want to have the generator kick on during a long-term outage to charge the batteries back up when they get low, but their generator isn't big enough to cover loads and fast battery charging, and they are not able to manage loads or are not on sight, they can still use Time of Use to make sure the generator doesn't stay on too long. However, there will be compromise as to how high the generator charging cap while off-grid would be and how low the batteries can get when off-setting the loads when grid-tied.

Note: I am not the head honcho, but I am here to listen to use-case issues exactly like this. This is gold to me, and I am on forums like this to find out what we can do to make the Sol-Ark easy to use in as many applications as possible. Well that and answer questions

Summary so far:

• Generator Terminals Can not do 3-phase connections, but the Grid terminals can due to hardware differences between Gen and Grid terminals on the Sol-Ark.
• Sol-Ark will be able to break the connection from the 3-phase transfer switch from the generator to the grid fast enough to prevent a connection to a mismatched phase. ---- STILL USE BREAK BEFORE MAKE ATS.

Use case problems I will try to find solutions/answers for:

• Sol-Ark Generator relay staying closed after grid connection status is re-made.
• GEN Peak Shaving equivalent????? I need to confirm why we stopped supporting it in the first place. It certainly wasn't due to a hardware change.

 

[XO4001]

The Sol-Ark checks every AC connection it makes on the GRID terminals to determine GEN or GRID status.

Just curious how the Sol Ark knows who is on the grid input gen or grid?

 

[Cmiller]

@Carlos_Sol-Ark you are very helpful, and I greatly appreciate that! I might try to DM you tomorrow sometime with some specific things we are running into to see if you have any ideas on solutions for me.