[Christ]

Eh, I didn't really research it, that's why I said "probably". Imagination takes a large part in that consideration, when you stop and think about exactly how many Federal and Corporate controlled buildings there are in the US, regardless of their positions relative to prime Solar PV real estate.

Imagine McDonalds having solar shingles... (yes, they exist)
Imagine if 25% of the glass panels on buildings were actually solar panels (the approx. percent of glass panels that were covered on the back side by something non-clear on the last building I worked in professionally, a State Court house, the "Pennsylvania Judicial Center" in HBG on Commonwealth St.)

The windows are especially my favorite, since they do nothing as it is... they just look pretty. They add to the visual flair of an "all glass" building, but they don't aid light transfer, they don't allow for heating or cooling of the building (see: potential for greenhouse heating in buildings' crawlspaces) they're purely aesthetic.

And frankly, they don't look all that great to begin with. I think a touch of blue every other set of windows would be excellent aesthetically, would it not?

etc and so on... it's not just roof tops... it's just about everything that has already displaced wildlife and ecology in general... how can we justify taking away more space without utilizing what is already there? (2 years ago, I would have slapped myself silly for saying something like that... and I just looked at myself funny in my reflection on the brand new LCD TV that isn't running right now.)