Check out this Cool Video—a compelling five minute articulation of a vision to cover various surfaces, like roads, driveways, and parking lots with solar panels. It pulls together various technologies that already exist.
Some critics worry about the materials to be used, or the efficiency of photovoltaic cells or the practicality of covering roads that are jammed with vehicles or that do not receive much sunlight. Others are concerned by the costs.
While some of the social and technological obstacles are formidable, they appear to be surmountable, especially in the context of continued technological improvement and economies of scale helping to lower costs. Some observers are worried about the price of the construction, but few critics seem to consider the cost of alternatives, including the continued use of asphalt.
The initial implementation will be on a small scale, like driveways or parking lots. Success will breed duplication. What is proposed here is a modular system that can become part of Smart Grid that also generates more electricity. I only recently came across this, but the Solar Roadway proposal won first place honors in GE's Ecomagination Challenge for "Powering the Grid" in 2010 and took first place honors again in GE's 2011 Ecomagination Challenge for "Powering the Home".
One of the most successful New Deal programs in the US was the WPA (Works Progress Administration, later renamed to Work Projects Administration). At its peak it put millions of people to work building infrastructure, like roads, bridges and schools. Almost every community had a WPA project. The initial appropriation in 1935 was 6.7% of GDP. The WPA would be 80 years old next year. Time for a new one?