The best location for covering a large area of land for purposes of solar energy would arguably be a desert. "90% of the world’s population lives within range of a desert and could be supplied with solar electricity from there", says this article, which also shows you how much needs to be covered to supply the entire globe in theory: http://cleantechnica.com/2009/06/22/half-a-trillion-dollars-...
There is some type of coating that doesn't allow anything to stick to it. That is a start. I think is called enduroshield. It is not a permanent solution because it wears down but it would help.
