Wiring for Solar

by Ben N on June 2, 2017

We got the wiring for the solar done!

My electrician, Ross, came over and we set to work on the wiring. I already had mounted electrical boxes to the racking on the roof and connected the Enphase Engage cable to the boxes with liquid-tight cable strain reliefs. I also made the conduit connections from the boxes down to the edge of the roof. However, I still needed to run conduit from the edge of the roof down to where the disconnect would be. Since I didn’t know EXACTLY where the box would be, I hadn’t done that section of conduit.

IMG_4920My brother had made a block which matched the garage trim on which I could install the disconnect box. This would provide a solid raised surface to install the box and a place for the siding (still to be installed) to run in to. I centered the box on the wood blocking and marked where the knock-out on the back would go. I then drilled that 1 inch hole with a Forstner Bit. On the SIDE of The MidNite Solar disconnect box there is a  1/2″ knockout for the incoming wire, but we are using 3/4″ conduit. So, Ross pulled out his step bit, and we drilled out the box for a 3/4″ connection for the wiring from the roof.

We screwed the blocking and box to the side of the building, using a short level, to ensure both were plumb (mostly to look nice.) We then ran the conduit down so that a 90 degree elbow would be directly horizontal from the hole in the side of the box. The hole in the disconnect is actually out from the wall just a bit, so we needed an offset. I already experimented with heating PVC conduit to shape it, but hadn’t done a particularly good job. Ross showed me how to measure the offset. We then cut a piece of conduit the right length and stacked up scrap wood to the same height as our offset. We then heated the PCV and put one end on the pavement, the other end on top of the scrap wood, and then just pushed and held the ends down. This made a very nice custom offset. That piece then went into the side of the box with a gasket.

We ran a short piece of conduit through the wall and installed a pulling body on the backside. It turned out that we ended up needing a short conduit extension on BOTH sides of the elbow to reach the main electric panel! I was so concerned with the box on the outside (being at the right height, meeting code in various ways, etc.) that I missed simplifying the installation on the inside of the wall by just lining it up with stock conduit components! Oh well.

IMG_4923At this point, all the conduit was complete, and we could start the actual wiring pull. This project is two 20 amp 240V circuits. That’s a hot, hot, and neutral for each of the two, plus a ground wire, 7 wires total. Ross set up several rolls of wire on an extra wide reel. The plan was to feed the wiring in a straight line from the bottom box up to the middle box, and then pull just the top circuit to the top box. One of the hot wires used purple insulation (instead of the typical red) so that we had the “Purple wire group” and the “Red wire group”. This made it a little easier to keep the two circuits straight.

The top box was pretty straight forward. I simply used wire nuts to connect the four wires from the Enphase cable to the four wires I pulled through the conduit to the box. I put a small dab of No-Ox in each nut before making the connection.

Next, at the middle box, I needed to splice the ground, and connect the Enphase cable to the wires of the second circuit. This circuit would be the middle and bottom rows of solar panels.

At the bottom box, I pulled out a loop of the second circuit wiring, cut it and then spliced it together with the bottom row Enphase cable. The “Purple wire group” was only connected to the top row of panels, and simply passed through the middle and bottom junction boxes.

IMG_4929Ross cut the wires on the ground to a length long enough to wind their way through the conduit down to the disconnect box. I pulled up the wires, taped the ends together, and then pushed them down through the conduit to the disconnect box. Ross made the electrical connection at the box and already ran and connected the 10 gauge wiring from the disconnect box to the main breaker panel.

After that, the electrician packed up and left. (Good! They get paid by the hour! My plan with building the junction boxes and installing them and the conduit on the roof was to minimize how long I’d have an electrician there. Gotta stay on budget!)

I checked over everything on the roof and closed up the weatherproof junction boxes.

At the MidNite Solar AC Disconnect, I installed the inside cover and the slider that connects the two circuit breakers to the big red lever on the face of the box exterior. One of the few things that my Utility specifies is the exact wording on the box. I mail-ordered a red plastic sign earlier in the week, and it happened to show up that morning! I peeled off wax paper from the sticky-back tape and applied the sign to the box. I had also ordered a placard from my utility meter. My Utility didn’t specify that I need it, but many utility companies do. It didn’t cost much more to have a second sign in the same order, so I purchased that second sign and put it on my meter.

IMG_4935Other than just a little clean-up, the wiring was now complete. Frankly, I COULD have done it all by myself. I already used a wiring calculator, and double-checked which size conduit to use, etc. I really wanted an electrician there because I was required to have an electrical permit, which specified a particular master electricians license. I also wanted a little advice just to make sure everything was to code, and lastly, what I really wanted was just the confidence that I was doing everything right. (Which I was, but I didn’t know that for sure.) It was also nice to have somebody there for advice and if I ran into any problems.

It was also good to have an electrician because he has all the spare odd electrical bits in his truck (instead of yet ANOTHER run to the store) and he had the large reels of wire (which are very expensive to buy from the big box home improvement store.)

Still, I was the guy designing the system, and the guy up on the roof pulling the cable and making connections, so I WAS getting real experience building a solar system.

Later in the day, Wayne stopped over, and we got some of the siding started.

The roofer is supposed to come this Monday with his lift. This project really requires some power equipment to get the solar panels onto the roof. The guy that I hired to roof the garage has a nice lift along with a trailer to deliver it and the experience to operate it. Between the two of us and one person on the ground, we SHOULD be able to make pretty quick work of installing the solar panels.

Until next time, stay charged up!


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