PV Interconnection/Tap

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bwaryjasz

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Location
Pittsfield MA
Site Details: 150A Single Phase Service
Customer needs around a 30kW PV system to cover 100% annual.
Proposed Solar AC Interconnection = 132.5 A (After 1.25 correction)

My question is that I will be doing a load side meter tap to interconnect this system into the Electrical system of the building. What are some of the issues that I should be looking at as far as the service? I will be replacing the existing feeders from the meter and putting them in a New 200A disconnect with 150 A fuses for the Main Service Disconnect. Come out of that disconnect into a gutter to house my Tap/Interconnection of the PV. Then come out of the gutter and re-feed existing 150A Main Breaker in Main panel. Obviously doing the same on the PV side with disconnects and fuses to protect this portion as well. Is there something in the Code that I may be missing?

-Bryan
 
bwaryjasz said:
Site Details: 150A Single Phase Service
Customer needs around a 30kW PV system to cover 100% annual.
Proposed Solar AC Interconnection = 132.5 A (After 1.25 correction)

My question is that I will be doing a load side meter tap to interconnect this system into the Electrical system of the building. What are some of the issues that I should be looking at as far as the service? I will be replacing the existing feeders from the meter and putting them in a New 200A disconnect with 150 A fuses for the Main Service Disconnect. Come out of that disconnect into a gutter to house my Tap/Interconnection of the PV. Then come out of the gutter and re-feed existing 150A Main Breaker in Main panel. Obviously doing the same on the PV side with disconnects and fuses to protect this portion as well. Is there something in the Code that I may be missing?

-Bryan
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I would say that a primary concern of mine would be whether or not the AHJ considers the PV AC disco closest to the interconnection to be a service entrance.
 
ggunn said:
I would say that a primary concern of mine would be whether or not the AHJ considers the PV AC disco closest to the interconnection to be a service entrance.
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As in the PV being a "Separately Derived Service"?. I will have two separate disconnects. one for the service before the Tap. and one before the Tap for PV.
 
bwaryjasz said:
As in the PV being a "Separately Derived Service"?. I will have two separate disconnects. one for the service before the Tap. and one before the Tap for PV.
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Not separately derived, but a separate service with a N-G bond in the disco and its own ground rod (bonded to the service ground) and no EGC connecting the PV with the service. In Texas, CPS (San Antonio) is the only AHJ I know of that wants it that way. The rest have us keep N and G separate in the disco and run the EGC from the PV all the way back to the existing GEC the same as if it were a load side connection. I'd advise you to get this straight with your AHJ before construction.
 
ggunn said:
I would say that a primary concern of mine would be whether or not the AHJ considers the PV AC disco closest to the interconnection to be a service entrance.
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If he taps into the [new] feeder after the [new] service disconnect, it cannot be considered a service entrance. It will be a load-side connection and must comply with 705.12(D)(2), under 2014 NEC IIRC.
 
Smart $ said:
If he taps into the [new] feeder after the [new] service disconnect, it cannot be considered a service entrance. It will be a load-side connection and must comply with 705.12(D)(2), under 2014 NEC IIRC.
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This is what I thought. I just didn't know if there was going to be an issue with the Panel being a 150 A panel and me having up to 132.5 A of PV potential on this panel.
 
bwaryjasz said:
This is what I thought. I just didn't know if there was going to be an issue with the Panel being a 150 A panel and me having up to 132.5 A of PV potential on this panel.
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Why?

If the PV output maxes out and the local load is less than that, the surplus is pushed out onto the grid.

Under nominal conditions, no point on the feeder will ever conduct more than 150A.
 
Smart $ said:
Why?

If the PV output maxes out and the local load is less than that, the surplus is pushed out onto the grid.

Under nominal conditions, no point on the feeder will ever conduct more than 150A.
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I am under the impression you can only load that main to 80% of the main breaker rating? is that correct? which would be 120A. I am in NEC 2014
 
bwaryjasz said:
Site Details: 150A Single Phase Service
Customer needs around a 30kW PV system to cover 100% annual.
Proposed Solar AC Interconnection = 132.5 A (After 1.25 correction)

My question is that I will be doing a load side meter tap to interconnect this system into the Electrical system of the building. What are some of the issues that I should be looking at as far as the service? I will be replacing the existing feeders from the meter and putting them in a New 200A disconnect with 150 A fuses for the Main Service Disconnect. Come out of that disconnect into a gutter to house my Tap/Interconnection of the PV. Then come out of the gutter and re-feed existing 150A Main Breaker in Main panel. Obviously doing the same on the PV side with disconnects and fuses to protect this portion as well. Is there something in the Code that I may be missing?

-Bryan
Click to expand...

Your installation sounds fine to me under the 2014 code as far as it's described. Electrofelon's advice about reconfiguring the neutrals and grounds in the original main panel is probably the most pertinent potential pitfall, especially if that panel was not intended for optional use as a subpanel.

Another way to do it might be to just have a tap between the meter and existing panel. In that case you'll have a supply side connection and get into the issues ggunn was taking about. Whether hashing out those issues out with your AHJ would be worth saving the cost of the 200A disco is something you'll have to judge for yourself. :cool:
 
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