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 that is heavily utilized with underground utility feed.
The 56 Kyocera's are in 4 strings of 14 each with 2 per SB7000 Inverter. They are connected on the AC side to a Square D 100A 6/12 current combining panels with 2 40A breakers from the inverters and an 80A breaker to a Square D AC disconnect with RK5 fuses toward the main panel line tap. The fuses then are to be tied into my Square D main panel at either the meter socket or at the two legs service side pairs of cables to the 200A service disconnect switch on service side through 4 grommets.
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 and 1 on each side unused. They are hot and to safely connect to them, I would need to remove the meter of course. That is ideal and very clean. The tap is identical to how the main disconnects are wired. 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? Would Square D actually tell me?
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. Push in the wires and tighten the screws and the two hot 80A taps are done. Then there is the neutral and ground.
The main panel is a top or bottom utility service so there is a spare ground and neutral lug also above the meter. Its not accessible without removing the meter but its perfect except very large. There are also screws 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 and bullet proof and 1 inch from the ground point.
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 lug and set 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 THN-2 according to my solar suppliers calcs.
My concern is not electrical integrity but how even touching the line side on any panel impacts UL and how the building department and NEC and PG&E would see that. I designed Telecom systems and we couldn't touch any OEM UL or agency approved electronics in any way or the UL testing was voided.
How does he real world work?
Just remove the meter, intall the taps and se what happens when the inspector looks at it? I know its electrically bulletproof since I'm using the exact hardware and not adding any current to any bus bar.
Any comments appreciated!