[bennelson]

Steve, do you have any photos inside your junction boxes, or photos of how they are mounted?

You just screwed the boxes straight into the racking? So the box must be sideways and parallel to the racking then to do that.

The best I can think of so far for mounting junction boxes is to get some sort of larger aluminum L, mount that to the back of the box, and then drill a hole through the other leg of the L and mount that to the rack with a bolt. It would be pretty simple and repositionable.

My Combiner/Disconnect needs to be on the outside of the building, as required by the power utility. I did design this so that it's physically close to the building breaker panel (about 2 feet away) just on the other side of the wall. This allows a Utility worker to disconnect the solar even if I wasn't home and the garage was locked. (Although the safety features built into the inverters means they stop producing power just by disconnecting grid power to the building.)

The detached garage is 25' from my house, and there's a direct line of sight between the main utility meter and where the solar disconnect will be.

As for Voltage Rise, it looks like it's really an issue when you max out a string. With the Enphase inverters, I could have 16 (17 w M215 inverters) in a string.
It's that total current in series that causes the problem. Since I will have three rows of 8 panels, having a combiner box at the end of two of the rows, (where both rows go into one box) I've just center-fed a string of 16 down to two legs of 8. Half the current now means one quarter the losses.
This also physically puts the combiner box at the END of the row.

If I ever need to get to that combiner box again, it would be accessible from the end of the roof via a ladder. The box could be either right on the end, or under the end panel. I like the idea of it being under the panel in terms of protection from the elements AND looks. I like the idea of it NOT being under a panel because I'm pretty sure I never want to ever have to take off any of these solar panels ever again.

The third row of panels would just be it's own string. That gives me one circuit of 8 panels, and one circuit of 16 panels (but center fed on the Enphase cable.)

My combiner box has space for three circuit breakers. This gives me room for expansion. For example, I might be able to put a couple solar panels in the back yard. (I don't have ideal solar back there, but I might for example put up a couple "EXTRA" panels with cheap salvaged inverters.)

One other thing that I've thought of is that I guess I'm not exactly sure of requirements for supporting conduit. I know it has to be spaced off the roof. (Mostly to keep the roof from heating the conduit.)

My racking will be running horizontal, and the conduit connecting the strings of solar will need to run vertical. I suppose the easiest way to support it is just to have it run over the top of the racking. Racking will be about every three feet. I could use a conduit strap straight to a bolt into the top of the racking.

However, I couldn't have the conduit go over the racking where ever there is the top or bottom end of a solar panel. I could go over the racking at the ENDs of the rack, where the racking extends past the solar panels. (The racking needs to be wider than the solar panels by at least one inch minimum on either end for the panel end clamps. I can always make it a little longer as needed.)

Any thoughts on plastic versus metal conduit? I noticed that on my house, the service entrance, and anywhere else that has conduit is plastic. Plastic never rusts. It is floppier than metal. I will also need a piece of conduit that bends around the edge of my roof to get the conduit down the wall to the disconnect. Metal conduit can be bent, but I think it that case, I'll be going beyond the "180 Rule" and will need a pulling body anyways, so several plastic parts glued together should probably work just fine to make the "Get off the Roof" bend.