Several users wrote to tell us that Dow Chemical plans on selling solar shingles
as early as next year. The solar version can be integrated with normal asphalt shingling and will be introduced in 2010, with a wider roll-out scheduled for 2011. "The shingle will use thin-film cells of copper indium gallium diselenide (CIGS), a photovoltaic material that typically is more efficient at turning sunlight into electricity than traditional polysilicon cells. Dow is using CIGS cells that operate at higher than 10 percent efficiency, below the efficiencies for the top polysilicon cells -- but would cost 10 to 15 percent less on a per-watt basis."