City Hall 35% more efficient than Ypsi Food Coop

One of my goals for SolarYpsi.org is to compare solar installation. I’m expecting the City Hall installation to be much better than the Ypsi Food Coop, since those panels are higher and have no shading. The Coop get’s shaded in the late afternoon. City Hall’s panels should also be cooler since there is more breeze blowing across/through them. The Coop also has an older less efficient inverter.

Looking at the monthly data and normalizing the energy production on a per watt basis I get these numbers.


City Hall(2.46kw) Ypsi Food Coop(2.28kw)

Month KWH KWH/w KWH KWH/w
Apr 251.0 102.0 159.7 70.0
May 204.0 82.9 159.6 70.0
Jun 82.6 33.6 232.0 101.7
Jul 341.3 138.7 246.8 108.2
Aug 331.1 134.6 220.4 96.7
Sep 262.4 106.7 179.4 78.7
Oct 296.8 120.7 211.6 92.8

Since both installation are more-or-less in the same location, they should get the same amount of solar radiation. So if I divide one by the other I should see the ratio of energy efficiency.

ratio

Month City Hall / Co-op
Apr 1.46
May 1.18
Jun 0.33
Jul 1.28
Aug 1.39
Sep 1.36
Oct 1.30

I’m not sure what happened in May/June, but ignoring those months, I would say that City Hall is about 35% more efficient at making power. I suspect we lost some data in May/June and that’s why those numbers
are off.