We already could put have solar panels on every roof. Could have for decades. What is the cost compared to building and power plants and transmission line? And the fuel for those power plants?

I looked into using these. The problems were that the cost to actually use the power was high (the batteries and such) and that it was difficult to impossible to hook up to the electrical coop where I was building. :-(

These are all really great dreams. Now. What is the *real* cost of each of them? I mean, starting from the design in someone's head and going all the way through tossing them away at the end of their useful life.

"tossing them away at the end of their useful life."

.... the length of which is probably MUCH shorter than traditional asphalt shingles....

Why do you assume they have a shorter useful life than asphalt shingles? If light is quickly converted into electricity, the degradation that normally comes from sun exposure might be slowed down. I live in the desert where nothing lasts long in the sun but depending on how the panels are constructed they may last as long or longer.