A massive switch from coal, oil, natural gas and nuclear power plants to solar power plants could supply 69 percent of the U.S.’s electricity and 35 percent of its total energy by 2050.
A vast area of photovoltaic cells would have to be erected in the Southwest. Excess daytime energy would be stored as compressed air in underground caverns to be tapped during nighttime hours.
Large solar concentrator power plants would be built as well.
A new direct-current power transmission backbone would deliver solar electricity across the country.
But $420 billion in subsidies from 2011 to 2050 would be required to fund the infrastructure and make it cost-competitive.

source: http://www.sciam.com/article.cfm?id=a-solar-grand-plan