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Three-Line Diagram with Enphase Microinverters

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  • Three-Line Diagram with Enphase Microinverters


    I'm building my own grid-tied PV system in Massachusetts. One of the requirements to qualify for the rebate is a three-line diagram. Can anyone share an example of a single string 3-line diagram using enphase microinverters? I would greatly appreciate the help.


  • #2
    Good luck. Do you have a PE stamp registered in MA to certify the drawings?
    MSEE, PE


    • #3
      No I don't. Is it required for these drawings?


      • #4
        Depends on your local jurisdiction requirements. I have done work in Boston and all drawings and plans have to be approved by a state certified Professional Engineer, and all work done by union electrical contractors.

        Call your local Building Code Enforcement agency and find out what they will require. Some jurisdictions will allow you to do some or all of the work if it can pass inspections, while others will not allow you to do anything. I suspect since you do not live in a Right-To-Work state the unions will have a death grip on all construction and professional trades and activities.

        But typically most Code Enforcement agencies will require a Professional Structural Engineer to sign off on the roof, and a Professional Electrical Engineer to sign off on the drawings and building plans. You will just have to call and find out.
        MSEE, PE


        • #5
          MA requires PE stamps for structural. Most AHJs require PE stamps for electrical also.
          MD requires PE structural. Sometimes PE electrical.
          NJ requires both.
          Most Engineering firms will want to draw the system schematics themselves, sometimes they will cut you a better deal if you draw it yourself, but in your case it probably isn't worth it.
          The Union labor may be required in order to get the state grants. In NJ it was cheaper to not accept the state grant because of this.


          • #6
            Maybe they will take the Enphase diagram:

            The enphase diagram does not show a separate AC disconnect switch which may be required.
            For a single string, I'd say just blank out all but one of the three strings.

            The Enphase diagram was all I needed for the permit here in Montana.

            Two detailed descriptions of DIY enphase system -- first is mine, 2nd is Guy Marsden's:




            • #7
              Hi Gary,

              Thanks for sharing the links and linking to our forum as well.

              It's greatly appreciated!


              • #8
                Hi Gary! Like the boss (Jason) says - A big welcome to Solar Panel Talk and thank you for sharing the links.