New house, new solar installation!
I used an Emporia Vue again to get an idea of the baseline consumption and where it’s coming from and how we might upgrade in the future. The data didn’t include my electric car, so I had to rely on consumption data from the other house for a year, but that was skewed from the anticipated new usage patterns, so there was some guesswork. Where I settled was a 6kW system composed of 14 SilFab 430W panels backed by IQ8 Enphase microinverters, going into an Enphase combiner box outside, through a disconnect, and into the house. The house only had 100 Amp service, and a panel that was too small, so we paid $5000 to upgrade the service. This was done mostly in a single day. I considered doing it myself, but the code requirements and the amount of labor and tools required were all a little outside my experience and I didn’t want the house to be without electricity for an extended period if I screwed up.
Coordinating everything was challenging. I had the permits to acquire while I was waiting for the service upgrade to happen, and once the permits were approved I had to order materials. With my previous installation I had paid extra for a planset to be created. With the amount of corrections and back and forth and materials I had to provide, I figured I might as well just do this set on my own. I used the previous one to generate a template and filled out all the new relevant details that were different. The roof was a truss rather than rafters, so that part was different, but fortunately I didn’t need to sister rafters to improve the strength for weeks, and the space was tall enough to mostly stand. I did need to offset my attachment feet, but that’s normal. Ultimately the plan was approved without much hassle (the calculations I had done were on an older version of a spreadsheet that the city had upgraded since my last time, and MGE had a new process for submitting that required things in a different format than I had generated). But with the approvals granted I was able to order parts. I ordered from two different companies, which both shipped quickly. The rail was complicated because I didn’t want to pay a ridiculous fee for shipping, so I had Wes order them from a local place that delivered for free, and they were cheaper, too. After the service upgrade I got started on the installation.
The previous installation was on a metal roof with a shallow pitch. This was an asphalt roof with a 6:12 pitch, so I had to be more careful, and I had to do roof penetrations for the attachments. Fortunately I only missed a stud twice; once on finding the first stud, and once towards the end when some 2′ measurements compounded errors and I was just off. But otherwise it went smoothly. I had a new 24′ ladder to get up to the roof, and I used my rock climbing harness and a new rope thrown over a tree that hung over the back of the roof to have a secure safety line. Once the rail was in place, I recruited a friend for a day to come and help lift the panels in place. I pulled up on a rope while he pushed up from underneath, and we managed to get all 14 panels up in a few hours. This was the only time I had help.
Next was the wiring. I drilled a hole through the roof and put in a junction box and conduit to go through the attic to the back of the house, and then out the soffit in the back and straight down. From there it went to the combiner box. Finding a stud to mount to was challenging and the wall was just aluminum siding in front of styrofoam with no sheathing. I decided to just put it above the meter, where I knew there was a stud. I had to pull four wires through the conduit, which was challenging but I was ultimately successful. Then the disconnect and conduit down into the basement, where I had to drill another hole in the house. Finally it went into the new box. The conduit ended up looking pretty clean, and I had close to the exact lengths of wire that I needed.
It was finally time for inspections. The building inspector didn’t even stop by the house to talk to me; he just drove by and approved the work and I had to call to find out that it was already done. The electrical inspection didn’t go great. I didn’t make any of the same mistakes as last time, but I made some new ones. First, I didn’t have a sticker of the right color for one of the boxes. Second, I had the combiner box too high. While it was at eye level when standing on the deck, because the box was over the meter it was technically above the ground more than the limit, even though everybody would access it while standing on the deck. Third, I had put the backfed breaker in the middle of the panel instead of the bottom. Finally, when I had pulled the wires through the conduit, I used one black, one red, one white taped black, and one white taped red. This would have been ok to do if it was Romex and in a bundle, but you can’t do it with just regular conduit with THHN running through it. I could have done this with other color wires, but it wasn’t ok to do it with white or green or gray. I needed to pull new wire through because it was the wrong color. D’oh. I fixed the problems within a couple days and easily passed the second inspection. Then it was a matter of waiting for MGE to sign the power contract so that we could turn it on.
When it was finally approved, we had a small ceremony to flip the disconnect and start generating power. It’s been running great since then, though we have unfortunately turned it on during the fall when sunlight is fading and we can only expect to match our consumption, not produce more like we will in the summer. Still, electricity bills have dropped substantially, so that’s cool. Total cost on the project was $9366, not including the $5000 for the service upgrade, and not including the tax discount.