Solar edge 11.4 on high leg shutting down

electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Occupation
Electrician
I've got some HD wave 11.4's on a 120/240 3 phase system. The inverters are spread across All phases so some are on the high leg. The service is a closed Delta. We are getting an over voltage fault on on some, but not all of the inverters connected to the BC phases. The site is rather far away and I have not been there yet but I thought I would just throw a couple preliminary questions primarily since I'm not familiar with solar edge products (I just did the AC side connection on this system for someone).

1. My understanding is these inverters are okay with high leg systems and being connected to it. But Is there any particularly set up or setting that needs to happen for the inverters to be happy, that maybe was not set right?

2. Is anyone familiar, if it comes down to it, with increasing the high voltage set point on these? I have done it on SMA inverters, but like I said I'm not at all familiar with solar edge. Do you need any special permission from solar edge to access that setting?
 
Is the over voltage line-to-line, or line-to-neutral? Sounds like these are single phase inverters installed on a 3-phase service. I just checked the manual, and this type of install is supported by the manufacturer. Here is the is relevant page from the manual. I would check that you have selected the correct grid for all of the inverters. Is this a corner-grounded Delta grid. If so, see the note below about how L1 and L2 are not interchangeable. And of course verify that that you don't have excessive voltage drop from the inverters to the transformer that would cause the voltage to rise above the inverter's limits

Screen Shot 2025-03-23 at 9.11.35 PM.png
 
Thanks. It is a center tap grounded not corner. I don't know the specifics of where the voltage was measured, I haven't been down there yet and have just limited information. There isn't all that much conductor between the inverters and the interconnection point, so I doubt that is a problem. I'll certainly have more info when I go down there in person.
 
Update:

Had a phone meeting with the solar contractor and the utility field rep. Kind of went the may i expected, with the utility guy skeptical there was anything wrong on his end :rolleyes: . One interesting thing I found out was the utility bank is an open delta. Back in the design phase, the solar contractor told me it was open delta but the utility was going to close it. Clearly they had a change of plan and just decided to run with it as is. I also misunderstood and the inverter that is tripping out is the only one connected to those phases, I though there were others. So there are 4 inverters, (2) on AC, (1) on AB, and (1) on BC. I am surprised the utility sanctioned connecting an inverter to the open jaw. I dont know if that is the one that is tripping, but i'd bet a milkshake that it is. Utility guy put in an order to put a voltage monitor on the system.
 
Update: the Poco had the monitor on for a week with the PV system off. Nothing note worthy there, I saw the report, but I don't think there was anything above 250 volts. They're doing another week with the PV system on, I am not sure if that is happening now or soon.

But I went to the site today since I happened to be nearby, and took some measurements. I may have to eat some Crow on blaming it on the power company. It's strange, the inverters just don't seem to like the BC phase and will not accept it. I tried with several inverters several times, then switched them to other phases. None of them would work on BC but would work everywhere else. Voltage on BC was about 245. Voltage on AB was actually higher at about 250. I kept a good eye on the BC voltage when trying to get the inverters to come on, and it never went above 245. So what is it about BC that these inverters are not liking? BC does appear to be the open phases best I can tell, but kind of hard to tell conclusively looking up at the pole and without being certain if the color coding is consistent.
 
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electrofelon said:
Update: the Poco had the monitor on for a week with the PV system off. Nothing note worthy there, I saw the report, but I don't think there was anything above 250 volts. They're doing another week with the PV system on, I am not sure if that is happening now or soon.

But I went to the site today since I happened to be nearby, and took some measurements. I may have to eat some Crow on blaming it on the power company. It's strange, the inverters just don't seem to like the BC phase and will not accept it. I tried with several inverters several times, then switched them to other phases. None of them would work on BC but would work everywhere else. Voltage on BC was about 245. Voltage on AB was actually higher at about 250. I kept a good eye on the BC voltage when trying to get the inverters to come on, and it never went above 245. So what is it about BC that these inverters are not liking? BC does appear to be the open phases best I can tell, but kind of hard to tell conclusively looking up at the pole and without being certain if the color coding is consistent.
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Maybe some instability that is not detected by a multimeter, but that the inverter sees. Open delta is the devil. The customer show request the third transformer.
 
Here in Austin the POCO will not allow a PV connection to the B (high leg) phase of any 120V-208V-120V to N service.
 
Is there maybe some kind of load on those phases that might be triggering it? I am unfamiliar with inverter faults but maybe the load comes on and the voltage changes enough to trigger it?

Customer should 100% pay the poco for the 3rd transformer. It could be that simple. The reduced "KVA" in the system could be playing tricks on the BC inverter.
 
electrofelon said:
I've got some HD wave 11.4's on a 120/240 3 phase system. The inverters are spread across All phases so some are on the high leg. The service is a closed Delta. We are getting an over voltage fault on on some, but not all of the inverters connected to the BC phases. The site is rather far away and I have not been there yet but I thought I would just throw a couple preliminary questions primarily since I'm not familiar with solar edge products (I just did the AC side connection on this system for someone).

1. My understanding is these inverters are okay with high leg systems and being connected to it. But Is there any particularly set up or setting that needs to happen for the inverters to be happy, that maybe was not set right?

2. Is anyone familiar, if it comes down to it, with increasing the high voltage set point on these? I have done it on SMA inverters, but like I said I'm not at all familiar with solar edge. Do you need any special permission from solar edge to access that setting?
Click to expand...
Is there any possibility that the BC transformer is being overloaded by the PV system? Since B phase loading by the customer on a high leg service is usually less than the others and may be zero, all the inverter output on the B phase could all be going back to the utility; are the service conductors large enough that there will not be enough voltage rise to kick an inverter or two offline?

We had a situation on a split phase service where on a bright sunny but cool (not cold) day, usually on a weekend, a couple of a bank of inverters would trip off due to overvoltage and it wasn't the same inverters every time. We figured out that when the business was closed and the HVAC wasn't running, most or all of the PV output was being sent back to the utility; the service conductors were so small that the voltage rise would trip off an inverter or two, which would let the voltage come back down to where the rest would keep running. It was a bit of a head scratcher at first.
 
ggunn said:
Is there any possibility that the BC transformer is being overloaded by the PV system? Since B phase loading by the customer on a high leg service is usually less than the others and may be zero, all the inverter output on the B phase could all be going back to the utility; are the service conductors large enough that there will not be enough voltage rise to kick an inverter or two offline?

We had a situation on a split phase service where on a bright sunny but cool (not cold) day, usually on a weekend, a couple of a bank of inverters would trip off due to overvoltage and it wasn't the same inverters every time. We figured out that when the business was closed and the HVAC wasn't running, most or all of the PV output was being sent back to the utility; the service conductors were so small that the voltage rise would trip off an inverter or two, which would let the voltage come back down to where the rest would keep running. It was a bit of a head scratcher at first.
Click to expand...
No, I was monitoring voltage the whole time and it never got above 246. Also this was around 5:30 so the inverters were only putting out about 8 amps, not a substantial amount.
 
solarken said:
Maybe some instability that is not detected by a multimeter, but that the inverter sees.
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I thought about that, but I don't believe voltage variation, as long as it is within the window, is any concern. I don't believe there is any voltage stability parts of UL 1741. In fact the new supplement b, to my understanding, has further aspects to ensure inverter ride through voltage and frequency events.
 
The only other thing I can think of that has not been discussed is a higher resistance connection to the BC phase. If the voltage at the service is okay but the voltage at the inverter is high due to the resistance of the circuit between the two that will cause an OV alarm.
 
pv_n00b said:
The only other thing I can think of that has not been discussed is a higher resistance connection to the BC phase. If the voltage at the service is okay but the voltage at the inverter is high due to the resistance of the circuit between the two that will cause an OV alarm.
Click to expand...
Since the BC phase is the open phase, can that by itself mean that the source impedance is high enough for the above to occur?

Would it be useful to check the BC source impedance at the inverter by saying measuring no-load voltage, adding a load, and measuring the resulting voltage and the load current? And maybe compare that with the AB and AC source impedances?

Cheers, Wayne
 
ggunn said:
From the OP: "The service is a closed Delta."
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Thanks, I had forgotten that part.

But I guess checking source impedances could determine if that is the source of the problem? Revealing either a high resistance connection as pv_noob suggested, or a problem or failure on the BC transformer?

Cheers, Wayne
 
wwhitney said:
Thanks, I had forgotten that part.

But I guess checking source impedances could determine if that is the source of the problem? Revealing either a high resistance connection as pv_noob suggested, or a problem or failure on the BC transformer?

Cheers, Wayne
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I would also look at the size of the service conductor feeding the B phase.
 
pv_n00b said:
The only other thing I can think of that has not been discussed is a higher resistance connection to the BC phase. If the voltage at the service is okay but the voltage at the inverter is high due to the resistance of the circuit between the two that will cause an OV alarm.
Click to expand...
I don't think so. I was playing around in the combiner panel which is right next to the inverters. I was looking at voltage the whole time, specifically when the inverters were first energized and qualifying the grid. I never saw any high voltage, or any change whatsoever from approx 246.
 
electrofelon said:
I don't think so. I was playing around in the combiner panel which is right next to the inverters. I was looking at voltage the whole time, specifically when the inverters were first energized and qualifying the grid. I never saw any high voltage, or any change whatsoever from approx 246.
Click to expand...
How quickly do the inverters trip out? If they don't trip until they try to put out some current, and then quickly trip on overvoltage, that would point to a source impedance issue. That might happen fast enough your meter wouldn't catch it?

You could try turning on the inverter in low light conditions (or otherwise limit how much current it can put out), that would let you see if it will hold without tripping, and checking what the voltage rise is compared to the current it is putting out.

Cheers, Wayne
 
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