ideal setup for 3 Phase 208V 43.2KW SolarEdge Inverter 175-200 OCPD

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Building has 3@ Delta 4 wire 240V. POCO can change to 208V Y 3$ for lots of $. Thinking about using Federal Transformer instead. Possibly 45KVa (125A calculated) T24SH2Y-45. Max output of PV inverter is 125A. Thoughts on using a 45KVA inverter?


Probably use MDP and feed 225A panel and then 45KVA transformer to inverter.
 
hevnbnd said:
Building has 3@ Delta 4 wire 240V. POCO can change to 208V Y 3$ for lots of $. Thinking about using Federal Transformer instead. Possibly 45KVa (125A calculated) T24SH2Y-45. Max output of PV inverter is 125A. Thoughts on using a 45KVA inverter?


Probably use MDP and feed 225A panel and then 45KVA transformer to inverter.
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3P4W 240V may mean high leg. If so and if it's open delta it might not be a good idea to connect to the B phase.
 
hevnbnd said:
Yes it has a high leg. 235v phase to phase
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You need to be sure that you won't overload the transformer feeding the high leg. Many times it is much smaller than what feeds the others.

Many AHJ's will not allow you to connect three phase to a service like that but are OK with you connecting to the A and C phases just as you would a 120V - 0V - 120V single phase service. I'd advise talking to them before you get too far into the design process.

Free advice, worth every penny. :D
 
ggunn said:
I haven't tried any sort of end run around their policies; they just say no and we obey. Except for CPS (San Antonio) they all allow IPC connections to the service conductors in the MDP, so that's pretty easy. Most of them, anyway; one of them allows no supply side interconnections, period.
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pv_n00b said:
The local muni utility in my town says no PV supply-side interconnections, and that's the end of the discussion with them. Never been a supply-side interconnection here and they have PV systems from residential up to I think 700kW commercial. All load-side.
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I am sure I am preaching to the choir about the ridiculousness of these "no line side tap" rules. My point is that, depending on a few specifics, there may not be any difference between a "supply side connection" and a 230.40 exception 2 or 3 install with a load side connection. I doubt they disallow 230.40 exception 2 or 3 so I don't see how you couldn't do a "supply side" connection this way. (is that a triple negative? Did I get that right?).
 
electrofelon said:
I am sure I am preaching to the choir about the ridiculousness of these "no line side tap" rules. My point is that, depending on a few specifics, there may not be any difference between a "supply side connection" and a 230.40 exception 2 or 3 install with a load side connection. I doubt they disallow 230.40 exception 2 or 3 so I don't see how you couldn't do a "supply side" connection this way. (is that a triple negative? Did I get that right?).
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Where I have encountered this I don't believe that calling it something else would make any difference.
 
electrofelon said:
I am sure I am preaching to the choir about the ridiculousness of these "no line side tap" rules. My point is that, depending on a few specifics, there may not be any difference between a "supply side connection" and a 230.40 exception 2 or 3 install with a load side connection. I doubt they disallow 230.40 exception 2 or 3 so I don't see how you couldn't do a "supply side" connection this way. (is that a triple negative? Did I get that right?).
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You are trying to use logic on the NEC, silly PV person. :lol:

Keep in mind that when a utility says no supply side interconnections they are not required to refer to the NEC. They live in an NEC free world. So all those words in 230.40 don't mean squat to them.
 
My supply house got the following message from Federal Pacific after asking them about using the T24SH2Y-45 Isolation Transformer FT0616.

From factory.

"That unit is suitable to reverse feed. However their mention of the Grid makes me think this is Solar application.

We will not recommend stock units for Solar. If it solar I can custom quote you a unit for this."

So my question would be what is different from a Solar Transformer vs a stock unit... Also anyone have an reason why not to use a 45KVa Transformer for a max output 125A from my Solar array?
 
ggunn said:
Where I have encountered this I don't believe that calling it something else would make any difference.
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pv_n00b said:
You are trying to use logic on the NEC, silly PV person. :lol:

Keep in mind that when a utility says no supply side interconnections they are not required to refer to the NEC. They live in an NEC free world. So all those words in 230.40 don't mean squat to them.
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So say I have the super common setup of two service panels side by side (230.40 ex 2). I'm sure you can do a load side connecton to a breaker in one. So at what point does the POCO consider it a supply side? If there are no non solar loads in one of the panels?
 
electrofelon said:
So say I have the super common setup of two service panels side by side (230.40 ex 2). I'm sure you can do a load side connecton to a breaker in one. So at what point does the POCO consider it a supply side? If there are no non solar loads in one of the panels?
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It's not a matter of what the POCO considers to be supply side; any connection to the unprotected conductors between the utility meter and the first OCPD is supply side. Any other connection is load side, and whether or not there are loads in a panel is irrelevant to the question.
 
ggunn said:
It's not a matter of what the POCO considers to be supply side; any connection to the unprotected conductors between the utility meter and the first OCPD is supply side. Any other connection is load side, and whether or not there are loads in a panel is irrelevant to the question.
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I imagine this is mainly an issue where the POCO and the AHJ are one in the same, or amount to as much. Where the POCO is separate from the AHJ, and the utility owns nothing on the load side of the service point other than their actual meter (or CT equipment), what say does the utility have in where you connect on the load side of the metering equipment?
 
hevnbnd said:
My supply house got the following message from Federal Pacific after asking them about using the T24SH2Y-45 Isolation Transformer FT0616.

From factory.

"That unit is suitable to reverse feed. However their mention of the Grid makes me think this is Solar application.

We will not recommend stock units for Solar. If it solar I can custom quote you a unit for this."

So my question would be what is different from a Solar Transformer vs a stock unit... Also anyone have an reason why not to use a 45KVa Transformer for a max output 125A from my Solar array?
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Sorry if your thread is getting hijacked...

I'm not an expert in transformers but I hope the manufacturer is not trying to fleece you. I don't buy that you need a custom quote, at least not at this power level. But maybe those with more experience specifying transformers (ggunn, pv_noob?) will chime in on that.

Also I think you may need to multiply your inverter output by 125% to spec your transformer rating, but that may be a debatable point.
 
jaggedben said:
I imagine this is mainly an issue where the POCO and the AHJ are one in the same, or amount to as much. Where the POCO is separate from the AHJ, and the utility owns nothing on the load side of the service point other than their actual meter (or CT equipment), what say does the utility have in where you connect on the load side of the metering equipment?
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I don't think that has anything to do with whether it's a load or a line side connection; I'm pretty sure it's whether the conductors are OCPD protected or not. The jurisdiction that we encountered recently where they don't allow supply side interconnections isn't one where the utility is municipally owned.
 
electrofelon said:
So say I have the super common setup of two service panels side by side (230.40 ex 2). I'm sure you can do a load side connection to a breaker in one. So at what point does the POCO consider it a supply side? If there are no non solar loads in one of the panels?
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If it's connected to the service entrance conductors with no interposing service disconnect/OCPD then it's supply side. I would assume both panels in your example have main CBs and not be directly connected to the service.
 
hevnbnd said:
My supply house got the following message from Federal Pacific after asking them about using the T24SH2Y-45 Isolation Transformer FT0616.

From factory.

"That unit is suitable to reverse feed. However their mention of the Grid makes me think this is Solar application.

We will not recommend stock units for Solar. If it solar I can custom quote you a unit for this."

So my question would be what is different from a Solar Transformer vs a stock unit... Also anyone have an reason why not to use a 45KVa Transformer for a max output 125A from my Solar array?
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Because they think it's solar and solar makes bags of money on the huge markups so they want some of that? Just speculating here.

If they say the unit is fine for bi-directional current flow there is nothing special about a "solar transformer" in the LV range of dry-type transformers that requires customization. Maybe they want to specify a particularly high-efficiency copper wound transformer. I'm all for the high-efficiency units but I can still get those off the shelf at that size.
 
ggunn said:
I don't think that has anything to do with whether it's a load or a line side connection; I'm pretty sure it's whether the conductors are OCPD protected or not. The jurisdiction that we encountered recently where they don't allow supply side interconnections isn't one where the utility is municipally owned.
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That wasn't my point. My point is that if, say, you want to install a tap box between the meter and the service disconnect, in my experience an AHJ who doesn't speak for the utility wouldn't care diddly about that and the utility would have little clout to stop them approving it. But if they AHJ and the utility are the same (or have a close relationship where they work out of the same office building and occasionally swap personnel), then the AHJ will enforce the utility's wishes even if those requirements have no resemblance to the NEC.

Put another way, it's where you have municipal utilities that you run into this the most, no?
 
jaggedben said:
That wasn't my point. My point is that if, say, you want to install a tap box between the meter and the service disconnect, in my experience an AHJ who doesn't speak for the utility wouldn't care diddly about that and the utility would have little clout to stop them approving it. But if they AHJ and the utility are the same (or have a close relationship where they work out of the same office building and occasionally swap personnel), then the AHJ will enforce the utility's wishes even if those requirements have no resemblance to the NEC.

Put another way, it's where you have municipal utilities that you run into this the most, no?
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In the city where I live the municipal utility has an interconnection standard that says no supply side interconnections. The city building department doesn't have a prohibition. If someone puts in a supply-side interconnection it's the utility inspection they would fail not the building department inspection. So it's not the building department imposing a utility requirement. The utility owns the service up to the main disconnect and can dictate how it is used. While I don't know if it has ever come up my guess is that the utility would be reviewing a tap box installation on their side of the service disconnect, the city building department might or might not be involved.
 
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pv_n00b said:
In the city where I live the municipal utility has an interconnection standard that says no supply side interconnections. The city building department doesn't have a prohibition. If someone puts in a supply-side interconnection it's the utility inspection they would fail not the building department inspection. So it's not the building department imposing a utility requirement. The utility owns the service up to the main disconnect and can dictate how it is used. While I don't know if it has ever come up my guess is that the utility would be reviewing a tap box installation on their side of the service disconnect, the city building department might or might not be involved.
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Right. And if there isn't a municipal utility then there isn't a utility inspection. Or at any rate, around here that's the case for single phase under 30kW. Just curious how similar it is elsewhere.
 
pv_n00b said:
If it's connected to the service entrance conductors with no interposing service disconnect/OCPD then it's supply side. I would assume both panels in your example have main CBs and not be directly connected to the service.
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But the line is blurry for what is a supply side connection vs a 230.40 exception 2 or 3 install. Can i only have one ocpd for a supply side connection? Does a supply side connection become not a supply side connection once I put in an inverter output combiner panel and feeder?
 
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