With all of the concern for the environment, why aren't rich people of the world (home owners in the U.S. for example) covering their roofs with solar panels?

With all of the concern for the environment, why aren't rich people of the world (home owners in the U.S. for example) covering their roofs with solar panels? To me, this is the best solution because we still get our comforts (computers, air conditioning), but decrease coal, gas and oil usage. It's still expensive, but would be a good option if we figured all of the long term costs in.