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Supply Side Connection for Residential SolarPV

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    Supply Side Connection for Residential SolarPV

    When installing a SolarPV system in a home, many times the point of connection to the main service panel (MSP) is made by tapping onto the service feeders using 'bugs' ("Supply side connection" - see attached photo). (With the other method of connection, by back feeding via an OCPD (breaker) in the MSP.)

    Are there any code restrictions that prohibit a "supply side connection" in the existing Main Service Panel? If so, where in NEC2011 (or older) does it state such a connection shall not be in the existing MSP?

    Attached photo shows this connection in the MSP, but a local electrician stated recently that this connection can never be located in the MSP, and must be installed between the Utility meter and the MSP.

    Thanks for your input, Rob
    Attached Files

    #2
    No violation to tap the service conductors in a service disconnect enclosure. However, when you tap the service conductors, the tap conductors become/are service conductors. They require a service disconnecting means (w/OCPD) that meets the two-to-six disconnect grouping rule. Looking at it from the PV side of it, the output of utility-interactive inverters are only permitted to be connected to the load side of [a] service disconnecting means [705.12(D)].
    I will have achieved my life's goal if I die with a smile on my face.

    Comment


      #3
      PS: I just noticed the above was your first post...

      Welcome
      I will have achieved my life's goal if I die with a smile on my face.

      Comment


        #4
        Code permits it,

        I have done it many times,

        never recently.

        Many AHj's won't allow it any more. Not due to specific location in MSP, but no supply side taps for PV. period.
        Up to them.

        Comment


          #5
          Originally posted by Zee View Post
          ...Many AHj's won't allow it any more. Not due to specific location in MSP, but no supply side taps for PV. period.
          Up to them.
          It is only up to them if they have officially amended the rule in the NEC that permits a supply side connection.
          Don, Illinois
          (All code citations are 2017 unless otherwise noted)

          Comment


            #6
            Originally posted by don_resqcapt19 View Post
            It is only up to them if they have officially amended the rule in the NEC that permits a supply side connection.
            Where is that rule BTW?


            Anyway, if you tap and run taps to [another] service disconnect, connect the PV system to the load side of that service disconnect, the PV system is not connected to the supply side!!!
            I will have achieved my life's goal if I die with a smile on my face.

            Comment


              #7
              705.12(A)
              Don, Illinois
              (All code citations are 2017 unless otherwise noted)

              Comment


                #8
                See also 230.82(6)

                Comment


                  #9
                  Originally posted by Smart $ View Post
                  Where is that rule BTW?
                  Section 705.12(A) allows for supply side connections. The capacity of the power production source is only limited by the rating of the service. Since load side connections are limited by the bus or conductor rating per 705.12(D), a supply side connection is useful if the proposed interconnected PV capacity is large relative to size of the main load panel.

                  If an AHJ doesn't want you adding big insulation-piercing connectors inside of a load panel, you may be able to use something like this, depending on the meter supplier:

                  http://www.milbankmfg.com/products/c.../PDF/K4977.pdf

                  Comment


                    #10
                    [Prior to NEC 2011, the allowance for supply side connected PV systems is found in 690.64(A).]

                    Comment


                      #11
                      there may be concern with backfeeding power to utility lines in the event of an outage. how do you prevent that with the way this photo is shown ? is there a disco between the service panel and the meter, or does the ho pull the meter when power goes out.?
                      Last edited by PEDRO ESCOVILLA; 09-27-12, 03:03 PM. Reason: spelling

                      Comment


                        #12
                        Originally posted by PEDRO ESCOVILLA View Post
                        there may be concern with backfeeding power to utility lines in the event of an outage. how do you prevent that with the way this photo is shown ? is there a disco between the service panel and the meter, or does the ho pull the meter when power goes out.?
                        Our utility would require a disconnect at the meter for the PV system, even when the connection is made on the load side of the service disconnect. The solar inverters will automatically shut down their output when they sense loss of utility power to prevent a back feed to the utility. This is required by the UL listing standard.
                        Don, Illinois
                        (All code citations are 2017 unless otherwise noted)

                        Comment


                          #13
                          Originally posted by don_resqcapt19 View Post
                          The solar inverters will automatically shut down their output when they sense loss of utility power to prevent a back feed to the utility. This is required by the UL listing standard.
                          Correct, but it's not just because of the listing. If an inverter did not shut down when the grid went away it would be trying to feed pretty much a dead short, since many/most of the loads on the grid would still be connected. You aren't going to power up the city from your 4kW inverter.

                          Comment


                            #14
                            Originally posted by don_resqcapt19 View Post
                            It is only up to them if they have officially amended the rule in the NEC that permits a supply side connection.
                            Good to know. I may have to rely on that in the future!

                            Comment


                              #15
                              Originally posted by don_resqcapt19 View Post
                              It is only up to them if they have officially amended the rule in the NEC that permits a supply side connection.
                              It's not an amendment to the NEC, it's an addendum, and many AHJ's do exactly that.

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