120V generator on Grid input of Sol-Ark 15K

[samus250]

Hi all,

I just got solar installed with a Sol-Ark 15K inverter and HomeGrid stack'd batteries. Before all this, I just used a little 3kW, 120V Honda inverter generator. During an outage, I'd simply connect it outside and switched via a transfer switch that's outside the house. Of course, no 240V appliance would work at all with this.

My solar installers connected the Sol-Ark's grid input to the output of the outside transfer switch. So if I connect my little 120V Honda generator, the Sol-Ark 15K will always see it at the Grid input. I have a transfer switch right next to the Sol-Ark for the house/load, so I could connect the house directly to the generator and free the Sol-Ark of all load. However, the Sol-Ark will always see the 120V generator at the grid input and I have no transfer switch to disconnect it completely. I haven't tried connecting my generator since I got solar installed, and don't know exactly what will happen if I do.

My question is: will anything explode or get damaged if I connect my 120V generator in this scenario?

Ideally, I wouldn't have to touch nor change any settings at all in the Sol-Ark, and the Sol-Ark simply wouldn't connect to Grid given that it's a 120V source. In case of extended multi-day outages (they happen quite a bit where I'm at), I could use the 120V generator during the daytime to free the Sol-Ark of all load and use all available sunlight to keep the HomeGrid charged as much as possible (thus helping insure uninterrupted 240V during the night even in very cloudy days). Is my idea correct, or would I have to change settings / install another transfer switch for my idea to be possible? Note: I greatly prefer not having to buy a 240V generator.

Thanks!!!

 

[timselectric]

There should be a disconnect/breaker installed ahead of the Sol-Ark, that you can turn off. If not, the Sol-Ark has breakers built-in.
Another option is to use an EG4 Chargeverter to charge the batteries from the generator.

 

[samus250]

There should be a disconnect/breaker installed ahead of the Sol-Ark, that you can turn off. If not, the Sol-Ark has breakers built-in.
Another option is to use an EG4 Chargeverter to charge the batteries from the generator.

I've experienced the built-in breakers in the Sol-Ark; it has disconnected before because of over-voltage on the grid (it was measuring more than 132V per leg for many continuous minutes). I can ask my installers to install a switch ahead of the Sol-Ark, but I'm wondering if it's necessary, or if the Sol-Ark would simply ignore the 120V source (or maybe if there's some manual setting in the Sol-Ark to force it to disconnect from the grid input while I use the 120V gen). Definitely don't want to damage the Sol-Ark, nor overload the 120V generator, nor have the Sol-Ark try to inject solar into it.

I asked this question to two of the technicians that installed my system, and they gave me conflicting answers, so I'm not going to assume that they know what they're talking about. One of them said that the Sol-Ark won't connect at all, and the other told me to turn off the grid sell setting and the grid charge setting so that it doesn't damage the generator.

EG4 Chargeverter looks good, but I'm thinking that the sun should be good enough even in cloudy days, provided that I power the house via 120V during the day.

 

[timselectric]

I believe that it would see the 120v as a grid down situation. And just disconnect itself.
But can't be completely sure of this.

The installer should have put some sort of protection ahead of the Sol-Ark. Was this system inspected?

 

[samus250]

I believe that it would see the 120v as a grid down situation. And just disconnect itself.
But can't be completely sure of this.

The installer should have put some sort of protection ahead of the Sol-Ark. Was this system inspected?

Well, I don't know much about power in general, so I'm not 100% sure about all this, but it seems to me that ahead the Sol-Ark, we only have:
1. Grid input via power meter
2. 100 amp main breaker
3. A transfer switch with a Ditek surge protector (which I can use to disconnect the Sol-Ark from the grid if I put it in the middle OFF position). I can also select the 120V generator using this transfer switch.

And that's it. There's a PV rapid shutdown switch next to the transfer switch as well, and the Sol-Ark is also wired to the rapid shutdown via its wireway. The installation wasn't inspected by Sol-Ark. It was inspected by a licensed electrical PE (that worked for the installer company), who sketched diagrams of everything, and then submitted all details to the power authority, so I'm guessing it's all good (but again, I'm not at all an expert on this).

 

[timselectric]

2. 100 amp main breaker

This is what I was referring to.
But, it appears that the first transfer switch is between it and the Sol-Ark. So while it's code compliant, it's not a very handy configuration.

I still think that the chargeverter is the best option. Because it can be tuned to get the most efficiency from your generator. And all of your loads (120v and 240v) can continue to be used.

 

[timselectric]

If I'm understanding the configuration correctly.
You can operate both transfer switches. And this will isolate the Sol-Ark and allow you to run the house on the generator?

Edit: I think that I'm mistaken.

 

[samus250]

If I'm understanding the configuration correctly.
You can operate both transfer switches. And this will isolate the Sol-Ark and allow you to run the house on the generator?

Edit: I think that I'm mistaken.

Here's my best try at ASCII art:

      ______                  _______
Grid--|SW-1|-out------grid_in-| Sol |
     -|    |      |           | Ark |
Gen---|____|      |           |_____|
                  |             |load_out
                  |             |         ______
                  |             |---------|SW-2|-out---> House
                  |                      -|    |
                  |-------------grid/gen--|____|

I can disconnect the house from the Sol-Ark because in SW-2, I can choose the input that comes directly from the SW-1 transfer switch (in this graphic, it will be the DOWN position). So I can run the house solely on generator. But I can't completely isolate the Sol-Ark, since if I connect my 120V generator at SW-1 (the DOWN position of SW-1), it will be directly connected to the "grid_in" port of the Sol-Ark.

EDIT: The main breaker + surge protector sits before the Grid input of SW-1.

 

[timselectric]

Here's my best try at ASCII art:

      ______                  _______
Grid--|SW-1|-out------grid_in-| Sol |
     -|    |      |           | Ark |
Gen---|____|      |           |_____|
                  |             |load_out
                  |             |         ______
                  |             |---------|SW-2|-out---> House
                  |                      -|    |
                  |-------------grid/gen--|____|

I can disconnect the house from the Sol-Ark because in SW-2, I can choose the input that comes directly from the SW-1 transfer switch (in this graphic, it will be the DOWN position). So I can run the house solely on generator. But I can't completely isolate the Sol-Ark, since if I connect my 120V generator at SW-1 (the DOWN position of SW-1), it will be directly connected to the "grid_in" port of the Sol-Ark.

EDIT: The main breaker + surge protector sits before the Grid input of SW-1.

You can turn off the grid input breaker, that is built into the Sol-Ark.

 

[samus250]

When I open the cover, I don't see any breaker for the grid input in my 15K model. I only have 2 battery breakers and a load breaker.

 

[timselectric]

When I open the cover, I don't see any breaker for the grid input in my 15K model. I only have 2 battery breakers and a load breaker.

That's strange.
I would have expected the 15k to have it.

 

[timselectric]

I still think that the Sol-Ark will see the generator 120v as a grid down situation.
Without seeing 240v, it should self disconnect.

 

[samus250]

Thanks! Yeah I think so too, but maybe someone has had a similar set up before and can let us know.

There's a section near the end of my Sol-Ark's manual called "Troubleshooting Phasing Issues" and says that

If the Sol-Ark screen shows Grid Phase Wrong, there is a phasing issue with your wiring, and it may cause overload faults (F18, F26, F34) even with the Load breaker off and WILL CAUSE DAMAGE if left unchecked.

That makes me a bit nervous. But I'm also not sure if it would categorize the non-split, 0V scenario between the two legs as a "phasing issue".

Later on, it says:

Single Sol-Ark: To locate the improperly wired phases, measure L1 to L1 (Top Screws) between the Grid and Load breaker; you should see 0V AC. Repeat for L2 to L2 between the Grid and Load breaker. Attempt to correct the wiring until you are only reading 0V AC between L1 to L1 & L2 to L2.

Again, I'm not an electrician, technician, nor do I consider myself familiar with electricity... but given that everything is wired correctly, I suppose that with the 120V generator connected and powered on, I'll read 0V AC between L1 to L1 & L2 to L2.

 

[timselectric]

Again, I'm not an electrician, technician, nor do I consider myself familiar with electricity... but given that everything is wired correctly, I suppose that with the 120V generator connected and powered on, I'll read 0V AC between L1 to L1 & L2 to L2.

Correct

 

[Danke]

 

[DIYrich]

I would expect Sol-ark to reject 120v (one leg down) on both grid and gen input. It is expecting 240v split phase.

There is a limited amount of amp difference between L1 and L2 that the Sol-ark can support off-grid (unbalanced load). Only powering one of the legs creates an immediate imbalance.

 

[samus250]

I would expect Sol-ark to reject 120v (one leg down) on both grid and gen input. It is expecting 240v split phase.

There is a limited amount of amp difference between L1 and L2 that the Sol-ark can support off-grid (unbalanced load). Only powering one of the legs creates an immediate imbalance.

Ah thanks, I didn't know that, and just saw in the manual that in a case like that, it'll produce error F26 - BusUnbalance_Fault. I think it shouldn't apply to me, because before attempting to connect the 120V generator, I would first disconnect all AC load from the Sol-Ark, so no AC would be flowing through. Definitely good to know that this limit exists though.

Also, I suppose there's a difference between one leg down and the 120V generator. If I understand correctly, the generator will power both legs at 120V, it's just that they're both in the same phase, so between the legs you'll get 0V instead of 240V.

 

[timselectric]

Also, I suppose there's a difference between one leg down and the 120V generator. If I understand correctly, the generator will power both legs at 120V, it's just that they're both in the same phase, so between the legs you'll get 0V instead of 240V.

The Sol-Ark will either see it as zero volts or a short between L1 and L2.
Either way, it should disconnect itself.

 

[samus250]

Got the answer!

I had written an e-mail to Sol-Ark earlier, and got this response:

With the 15K, the only generator voltages it can accept it 220V. 240V, and 208V. We are not able to use a 120V generator connected to the inverter.

When I asked "Can you clarify what will happen if I attempt to connect the 120V generator as shown in the diagram", the response was a bit better:

The inverter would not connect to it. The inverter would be looking to make sure what the gen is outputting is per parameters. Assuming your grid is split phase, we would want to have a 240V 60Hz generator. The inverter would not fault out. The grid relay would not engage.

So I decided to go ahead and try it out during the night. As expected, the Sol-Ark simply didn't connect to it, and produced no alarms nor faults, and it seems like it was just being powered by the battery. It reported the 120V in both legs, but 0.0 Hz:


So in very cloudy days, I could power the house with the 120V generator with my current setup, and use all available solar to charge the batteries for the night. I think it should be enough. If it turns out to not be good enough, then I'll definitely get either the Chargeverter, or a 240V generator (which should work fine with my current setup + the "Generator in GRID input" setting).

 

[DIYrich]

You could use an autotransformer to convert the 120v to 240v split phase. However, the min Generator Sol-ark recommends is 4kW. I'd go the chargeverter route.