PV System Interconnection

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Sirs


I would like to know according to your experience as engineers, how you would interconnect these 5 inverters of the 225A with this customer's system that only has one control unit of 2000A for the main switch and another for the transfer switch and several panels of smaller capacity downstream.


As I said, next Monday I will thave a meeting with people with more experience in this type of projects, but most of the projects in the country are residential and commercial, and not so big (I mean distributed generation).


Regards,
 
INGMRS said:
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Before to ask in this forum i have talked with people from eaton, because the switchboard of my client is from them, they made a proposal, they propose to install a new switchboard to collect all the inverters and a new structure attached to the switchboard of my client to interconnect the PV System to the electrical system of the client. Something like this:

View attachment 21679
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This diagram is showing a supply side connection and is a totally legitimate way to go especially if the switchboard manufacturer is creating the connection for you. It's probably what I'd go for if they aren't charging way too much.

You don't need them to provide the individual inverter breakers, just the 1200A one.
 
jaggedben said:
This diagram is showing a supply side connection and is a totally legitimate way to go especially if the switchboard manufacturer is creating the connection for you. It's probably what I'd go for if they aren't charging way too much.

You don't need them to provide the individual inverter breakers, just the 1200A one.
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Hi,


So, do you consider that is not necesary a switchboard to collect the feeders of each inverter? i mean to connect directly the feeders of the inverters to bars in the 1200A Switchboard?, yes, i think is an option to discuss with eaton people, because we have a breaker in each inverter protecting the feeder.


Thanls and Regards,
 
INGMRS said:
Hi,


So, do you consider that is not necesary a switchboard to collect the feeders of each inverter? i mean to connect directly the feeders of the inverters to bars in the 1200A Switchboard?, yes, i think is an option to discuss with eaton people, because we have a breaker in each inverter protecting the feeder.


Thanls and Regards,
Click to expand...

If you are asking if you can combine the inverter outputs before interconnecting them, the answer is yes; I do it all the time.
 
INGMRS said:
Hi,


So, do you consider that is not necesary a switchboard to collect the feeders of each inverter? i mean to connect directly the feeders of the inverters to bars in the 1200A Switchboard?, yes, i think is an option to discuss with eaton people, because we have a breaker in each inverter protecting the feeder.


Thanls and Regards,
Click to expand...

What I meant is, if it saves you money, you could choose your own equipment to be connected to the the 1200A breaker. It's an advantage to have Eaton reconfigure their existing equipment to add the 1200A main breaker for the solar, because it may not be allowed you make your own modifications to their equipment. However the second, separate switchboard for collecting the inverter outputs could be done by anyone.
 
It looks like Eaton is suggesting adding tabs to the existing busbar and then there would be conductor run between that and the new section with the 1200A OCPD. Always nice to have a manufacturer approved supply side interconnection. Eaton can make up an inverter AC combiner but I would compare the cost to other PV AC combiners. There are several manufacturers in the PV industry that make them.
 
INGMRS said:
Hi,


So, do you consider that is not necesary a switchboard to collect the feeders of each inverter? i mean to connect directly the feeders of the inverters to bars in the 1200A Switchboard?, yes, i think is an option to discuss with eaton people, because we have a breaker in each inverter protecting the feeder.


Thanls and Regards,
Click to expand...

The breaker at each inverter protects the inverter against catastrophic damage from grid power if there is an internal short circuit. The wires from the bus bar to the inverter would only be protected at the source (for this fault situation the grid would have to be considered the source, not the inverter) and would therefore be a tap unless the wire is rated for 1200A or the connection is a supply side grid connection. If a short occurs in the run of wire itself, a 1200 main is not going to be any protection at all.
 
electrofelon said:
Is there something specific about an "AC combiner" as opposed to an appropriate panelboard or switchboard? Ive never heard of such a thing.
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There's nothing special about them, hardware-wise; most that I deal with are simply MLO panelboards. What is special about them is under which part of 705.12(D) or (B) (B for 2017, D for 2014) you qualify the panel busbars.
 
electrofelon said:
Is there something specific about an "AC combiner" as opposed to an appropriate panelboard or switchboard? Ive never heard of such a thing.
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It's really just cost. I've used standard AC panelboards as combiners and I've used purpose-built PV AC combiners. I'm sure the PV BOS manufacturers would like it if people thought they were special now that the DC combiner market is getting much smaller due to RSS.
 
pv_n00b said:
It's really just cost. I've used standard AC panelboards as combiners and I've used purpose-built PV AC combiners. I'm sure the PV BOS manufacturers would like it if people thought they were special now that the DC combiner market is getting much smaller due to RSS.
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So there are products specifically marketed as "PV AC combiner panels"? Or when you say "purpose built AC combiner" do you mean just ordering a factory panelboard that may, for example, be set up to comply with the 120% rule? Sorry to nitpick, just curious.
 
electrofelon said:
So there are products specifically marketed as "PV AC combiner panels"? Or when you say "purpose built AC combiner" do you mean just ordering a factory panelboard that may, for example, be set up to comply with the 120% rule? Sorry to nitpick, just curious.
Click to expand...

I try not to call out brands but I'm talking about products from PV BOS manufacturers like Shoals, Bentek, AmTec, etc. They all make AC and DC combiners specifically for the solar industry. Whereas Eaton and Schneider make a wide range of electrical equipment, some of which can be used in solar projects to combine things.
 
pv_n00b said:
I try not to call out brands but I'm talking about products from PV BOS manufacturers like Shoals, Bentek, AmTec, etc. They all make AC and DC combiners specifically for the solar industry. Whereas Eaton and Schneider make a wide range of electrical equipment, some of which can be used in solar projects to combine things.
Click to expand...

Ok thanks, never knew there were pv specific ac combiners.
 
ggunn said:
There are, but I never use them if I don't have to because they are significantly more expensive.
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I've not really understood what they really have to offer over general electrical equipment. On the DC side it was hard to find equipment so they had something to offer but on the AC side I'm not so sure.
 
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