Just over a year ago I finished installing a fully DIY (with the help of an electrician and a trenching guy) grid-tied residential rooftop solar install. Some day I'll make a post that covers all of that, because it was pretty interesting. But this post is just to discuss production data after a year.
I installed 27 panels across 3 arrays, as seen below:
North is up, so the garage array, outlined in red, faces southwest. The front array, outlined in green, faces southeast. The back array, outlined in blue, faces northwest. There is significant partial shade from trees on both front arrays at different times of year and day. I also roof-raked the front and garage arrays in the winter, but not the back arrays, which were covered with snow pretty continuously in january and february
Ultimately, all of the panels performed well. The overall average production was 305kwh per panel. The back side panels generated 82% of the per-panel power that the front arrays generated, and the worst panel (248kwh) generated 75% of the power that the best panel (328kwh) generated. I found this interesting, because while everybody says north-facing panels are bad, its very hard to get real-world numbers on HOW bad. Standard deviations across each array were small, under 5%, despite variable and uneven partial shading.
All in all, I am quite pleased with the performance of the system, and the amount of power it generates. We are moving to a new house soon, and I am strongly considering building a 36-panel array there.
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