Line Side Taps - Any experts out there?

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Line Side Taps - Any experts out there?

Postby pgrovetom » Tue Jun 16, 2009 5:02 pm

I'm installing a 12kw ( 56 Kyocera 210w and 2x SB7000US Inverters) system and want to make sure I connect my line side tap properly. I have a Square D 200A side by side combo meter and service main panel. The 56 Kyocera's are in 4 strings of 14 each with 2 per SB7000. They are connected on the AC side to a Square D 6/12 panel with 2 40A breakers from the inverters and an 80A breaker to a Square D AC disconnect with RK5 fuses. The fuses then are to be tied into my Square D main panel at either the meter socket or at the service side #6AWG pairs of cables to the 200A service disconnect switch.

The Squared D main panel has spare wire holes and set screws on each leg perfect and probably for a solar tap. Why else have 3 set screws per leg when only 2 are needed. They are hot and to safely connect to them, I would need to remove the meter. That is ideal and very clean. Is it ok? Does it impact the UL rating? How could any change not impact UL? Anywhere, meter or cables to the disconnect? How would I find out?

Ok that is downright ideal! Spare set screws on the meter lugs identical to the ones used to feed my main breaker. It couldn't be done cleaner.

The main panel is a top or bottom utility service so there is a spare ground and neutral lug also. Its not accessible without removing the meter but its perfect. There is also a screw that holds the ground bar going across to the service side which I could change to stainless and add a lock washer and lug with set screw also. Not as ideal but easily accessible.

I've read all Wiles papers and there is no formula except changing to a 400A panel (yuck) or finding higher rated buses for the Square D so it becomes capable of the extra 80A. Yuck.

How are line side taps actually done when the panel supplier is UL rated and anything would void that! There are so many main panel models that it would be virtually impossible to verify every one's UL rating is ok with a change anywhere on the line side. How are line side taps done as a practical matter and is my using the spare set screws on the 2 hot legs and either using the existing screw upgraded plus a lug with set screw for the neutral and ground. The hot line tap wires are #4 AWG THWN-2 and the neutral/ground are #6 AWG according to my solar suppliers calcs.

Any comments appreciated!
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