"Line side" tap on sub panel for PV installation possible?

ggunn
ggunn Solar Expert Posts: 1,973 ✭✭✭
in Grid Tie and Grid Interactive Systems #1
We have a customer who wants to install a substantial amount of PV on a ranch. The ranch is on a single meter with a 400A main feeding several subpanels and the PV inverter would be located at one of the subs...

I apologize for the edit here, but I misunderstood the question.

What we have is a 400A disconnect feeding multiple smaller disconnects which in turn feed subpanels. The rancher wants to install possibly as much as 35kW of PV out by one of the subpanels, which is probably 200A. Four SB8000's require a total of 160A OCP. The question is if we can combine the output of the inverters in an aggregation panel and tap into the 200A rated supply line feeding the 200A subpanel.

Sorry for any confusion.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: "Line side" tap on sub panel for PV installation possible?

    this won't work for 35kw of pv for the most the 400a service can handle on the bus is 20% more for 80a. 80a x 240v = 19.2kw. if you put a smaller breaker for the main panel to account for the extra power he wishes to feed the grid, it may fly.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #3
    Re: "Line side" tap on sub panel for PV installation possible?
    niel wrote: »
    this won't work for 35kw of pv for the most the 400a service can handle on the bus is 20% more for 80a. 80a x 240v = 19.2kw. if you put a smaller breaker for the main panel to account for the extra power he wishes to feed the grid, it may fly.
    I realize that, but that's precisely the point of my question as there are no busses involved. There is no 400A service panel, just a 400A fused disconnect feeding smaller disconnects which in turn feed panels. This tap would be between one of the smaller (200A) disconnects and the panel that it feeds. It would be a line side tap to the panel with nothing upstream of it (i.e., in the direction of the grid) except two fused AC disconnects.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
    Re: "Line side" tap on sub panel for PV installation possible?

    ok, sorry for my misunderstanding and as far as i can see you should be able to go with up to the rating of the wire as the wire would carry the utility power and the output of the pvs. the wire would be acting like a bus technically.

    maybe some of our linesmen in here can comment.
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  • ggunn
    ggunn Solar Expert Posts: 1,973 ✭✭✭
    #5
    Re: "Line side" tap on sub panel for PV installation possible?
    niel wrote: »
    ok, sorry for my misunderstanding and as far as i can see you should be able to go with up to the rating of the wire as the wire would carry the utility power and the output of the pvs. the wire would be acting like a bus technically.

    maybe some of our linesmen in here can comment.
    That's what I was thinking. It seems to me that the only difference between this situation and a "normal" line side tap is that it is downstream of two disconnects in series rather than just the one.
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