[P.O.E.]

At year end 2010, the U.S. had 2,593 megawatts (MW) of installed solar electric capacity. This included about 2,086 MW of photovoltaics (PV) and 507 MW of utility-scale concentrating solar power.

Per wikipedia US uses 3.7 B megawatts per year. I've looked to find basic data on this but google searches seem clogged with solar- and wind-power sites.

http://en.wikipedia.org/wiki/List_of_countries_by_electricity_consumption

Anyhoo, it looks like solar is less than 1%, and this doesn't take into account it's the low-hanging fruit - the tough questions are transportation, cost/mW, etc.

[P.O.E.]

Sorry, I did my maths wrong. US uses 3.7 Trillion mW. Which puts solar at 0.0001%.