has an article about photovoltaic solar panel prices dropping below $1 Watt
. While good news they look at the raw materials required to manufacture the panels and conclude that looking for less efficient, but more abundant and easier to process materials is the key to success.
... Wadia and his colleagues found that iron pyrite—better known as fool's gold—was several orders of magnitude better than any of the alternatives, based on both cost and abundance. Copper sulfide and copper oxide were also attractive candidates. The problem with these materials is that they're less efficient in converting the sun's rays to electricity, and as a result have been the focus of considerably less research.
I personally take the view that photovoltaic is a solution for small private installations. Larger solar power production efforts will probably succeed on concentrating solar thermal approaches. Popular Mechanics also has an article on solar thermal technology
On a crisp morning this past January, Andraka and his colleagues fired up Dish No. 3. The temperature was around freezing, and the sky was 8 percent brighter than average—the contrast between the cold air and the hot sun helps the engine run more efficiently. When power began to flow from the 25-kilowatt system, it did so with the highest conversion efficiency ever recorded in a commercial solar device: 31.25 percent of the energy shining onto the giant dish flowed into the grid.
For more information visit Wikipedia