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.

2 thoughts on “City Hall 35% more efficient than Ypsi Food Coop”

  1. Have you seen pvoutput.org? It’s pretty slick for comparisons between sites, or between days on the same site. For example, here is my array on a sunny day in May compared to a sunny day in September:

    http://pvoutput.org/comparelive.jsp?sid=1384&df=20110517&dt=20110915

    (I was trying to find a very hot day vs. a cool day, but I guess those two are about the same; you can see how the sun came up a bit earlier in May, though!)

    It’s really easy to send data there, either live or in batches, and it’s free. You might consider adding it as another destination for your data?

  2. because no one who places reesll values on their home would ever vent through the wall with an open hole with wire sticking out, this is? great way to go as a survivalist but as a common person that may move one day would never sell a house looking like that

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