Marco- You should not transition to THHN wire at all for the DC run. The PV wire is double insulated for a good reason- the transformerless inverters are such suckers for a ground fault that they need the extra protection. That's why the NEC specifies PV wire.
I recently did an installation like you wrote, with a transition at the j-box. This developed an intermittent ground fault when wet, and when the P1 inverter failed it was deemed out of warranty. Learn from my mistake-- use PV wire all the way to the inverter.
That said, does anyone know where to get 1000 volt PV wire in colors other than red, black, and white?
It would be nice to color code the positive runs like is possible with colors of THHN.
I'm thinking of buying spools of white and spraying plastic paint on them for a striped color coding.
Don Barch
Energy Solar
Message: 3
Date: Mon, 23 Sep 2013 09:27:30 -1000
From: "Marco Mangelsdorf" <[email protected]>
To: "'RE-wrenches'" <[email protected]>
Subject: [RE-wrenches] transformerless inverters and conductor colors
Message-ID: <000001ceb892$f3e41470$dbac3d50$@com>
Content-Type: text/plain; charset="us-ascii"
Hi all,
We're doing more and more installs with TL inverters (SMA and P1).
I'm using double-insulated wire from the array string to the first
enclosure, as in j-box, and then transitioning to standard THHN/THWN wire.
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