Walking the Wire

First off,the back of the main house has all its solar tiles! Well, technically there’s a little piecing they still need to do but it’s looking great!

Oh, before I go further, a PSA: If you get a solar roof, prepare to find a LOT of asphalt bits all over the place in your attic! When they replace the decking it all just sprinkles on in there. In our case it’s all over the junk in our attic; luckily most of that is in boxes and plastic tubs so we can just sweep it off later.

Meanwhile, I think I’ve figured out the flow of the power cables they’ve strung up in our attics. Here’s a diagram — I’ll explain what it all means below.

The yellow icons represent the wiring from all the solar tiles coming through the roof decking into the attic. Photo 1 here (taken from around the location of the circle with a 1 in it in the diagram) shows the wiring in the “main” attic:

The cables from the solar tiles come in via those flexible metal conduits; you can see the one on the left coming through the decking (and through the reflective radiant heat barrier). The cables from the roof go into two emergency cutoff boxes — the two boxes you can see in the photo, which are labeled “Cut” in the diagram. Then another flexible conduit carries cables from each cutoff to a junction box (“Jct” in the diagram) next to the left-hand cutoff (which you can’t see in the photo because it’s behind the cutoff box). The conduit that looks like it’s coming out of the bottom of the cutoff box and curving to the left is actually coming out of the junction box; that conduit goes into the wall with the attic fan on it, which is the wall that abutts the garage attic.

Photo 2 here shows that conduit coming through on the other side of the wall (and down several feet — they had to fish it down inside the wall):

The flexible conduit couples to a straight metal conduit that’s screwed to the vertical roof supports well above head level; that conduit runs almost to the other end of the attic (Photo 3, facing the opposite direction):

Near the brighter lightbulb in Photo 3 above you can see the metal conduit curves to the right around the vertical support. (Those guys do a great job of bending those conduits!) The next few photos are all taken from location 4 in the diagram. In location 4 I’m standing in what was the right-hand half of the attic in the above photo. In this next photo my finger is blocking the same lightbulb I just mentioned. You can see the conduit (remember, this is carrying the power from both halves of the “top roof”) come down into a junction box that’s mounted to a piece of OSB stuck to the sides of the vertical supports. The boxes to either side of it are the cutoffs for the cables coming from the two halves of the garage roof. You can see the cable from the back half of the garage roof in this photo, at the very top edge on the right, and going into the right-hand cutoff; the other half of the roof comes down in a spot obscured by my finger and you can see it corkscrewing toward the camera and going into the left-hand cutoff.

The two cutoffs go straight into the junction box — so that’s all the power from the roof now coming into the junction box. (I assume there’s no problem with one box handling all that given all the different wire terminals inside the junction box.) You can see a flexible metal conduit comes out of the bottom of the junction box; this goes under the insulation right below the box and then comes back up just above “floor” level a couple feet away. The next photo is still standing in location 4 but I’ve turned to the right a bit:

You can ignore most of what you’re seeing there — the electical panel is right under that lower area, and those cables coming out of it are all the electrical circuits in my house. The thing to focus on here is the flexible metal conduit that comes up out of the insulation and connects to a oval-shaped metal box; the lid on that box is currently swiveled open and a mess of wires are hanging out. Directly underneath the box is the top end of a piece of straight metal conduit; you can just barely see it peeking out between tufts of torn up insulation. This metal conduit goes through the ceiling of the garage and comes down right next to the inverters, as you can see in the photo below:

And then it runs past both inverters (“Inv” in the diagram) with the appropriate wires inside the conduit branching off to connect to the appropriate inverter for the half of the roof they came from:

So there you have it! That’s how the power gets from our roof to our inverters.