Enphase inverters: Pigtails on BOTH AC connectors?

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RegGuheert
RegGuheert Solar Expert Posts: 102 ✭✭✭✭
in Grid Tie and Grid Interactive Systems #1
It seems that Enphase may have made an ECO on their inverters since all of their literature was created. Specifically, I was surprised to see that my inverters have TWO AC pigtails instead of one pigtail with a long wire on one side and a connector on the other side.

All of the product literature I've seen from Enphase including the current datasheet and user manual shows these inverters with one AC connector integrated into the side of the inverter. You can see this on their microenverter product page as well.

By contrast, you can see the new arrangement of the connectors in these excellent pictures by Mr. Radon.

I can see that having the connector on the side of the unit may have posed two problems:
1) It does not allow the wire/connector to make a right-angle bend for an additional four inches, which may have been an issue in some installations, and
2) More importantly, having a four-inch rigid connector cantilevered off the side of the unit may have led to excessive stress on solder connections inside the unit.

Thoughts?

Reg
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  • drees
    drees Solar Expert Posts: 482 ✭✭✭
    #2
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    Re: Enphase inverters: Pigtails on BOTH AC connectors?

    The M190 inverters all have 2 pigtails - one for "input" from the grid, one for "output" to the next inverter.

    The one in their picture has the 2nd pigtail, it's just not visible for whatever reason.

    Now, the D380 does only have 1 pigtail for AC as it plugs into a special trunk cable.

    Just another helpful hint while you are working on your system:

    Enphase actually recommends getting two pigtails per branch and then tying into the branch in the "middle" of each string - this way you cut voltage/power losses by a decent amount for modules near the end of the string. By center feeding the branch you can cut about 0.5-1% of voltage loss for half the panels of each branch (assuming a 15 panel string).

    http://www.enphaseenergy.com/downloads/EnphaseAppNote_Vdrop_Calculations.pdf
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  • RegGuheert
    RegGuheert Solar Expert Posts: 102 ✭✭✭✭
    #3
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    Re: Enphase inverters: Pigtails on BOTH AC connectors?
    drees wrote: »
    The M190 inverters all have 2 pigtails - one for "input" from the grid, one for "output" to the next inverter.

    The one in their picture has the 2nd pigtail, it's just not visible for whatever reason.
    The ones in their literature have one long wire on the left and a connector on the right. You can see this clearly if you look at a larger picture, such as the one on the front of the user manual.
    drees wrote: »
    Just another helpful hint while you are working on your system:

    Enphase actually recommends getting two pigtails per branch and then tying into the branch in the "middle" of each string - this way you cut voltage/power losses by a decent amount for modules near the end of the string. By center feeding the branch you can cut about 0.5-1% of voltage loss for half the panels of each branch (assuming a 15 panel string).
    Thanks! Yes, I am planning to use six branches of 7 panels each in order to limit the branch voltage drops to less than one volt.
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