Well nut size for large solar panels?

Thanks rjxj! I know these brackets are overkill, but it makes me more secure for my 72"x40" panels. With luck I'll get them all mounted in the 16th.

Yeah, those will be more than enough.

Tip: If you spin a fastener (sheet metal screw through bracket) through Eternabond tape, the adhesive layer of the tape will be drawn up the threads of the fastener and envelop the screw head. This seals any fastener with the Eternabond adhesive and also activates the micro-beads within the tape. Eternabond had a video of this using Eternabond Doublestick tape but I found both Eternabond Roof tape and Eternabond Webseal do the same sealing. If you use the Doublestick tape, you'll get the added benefit of the adhesive on both the bracket and the roof membrane. Using these tapes is a lot more elegant than slathering tube- delivered sealants.

BTW, I'd suggest to orient the bracket bases so the angle base is outside the panel (flipped from what you have) so that installation is easier. Also, add a second bolt into the upright of the angle to mate with the piece attached to the module. Doing it like I describe will allow you to attach the whole bracket system to the panel and install the fasteners into the roof. If you use the brackets as pictured in your above post, installation will be difficult.