Common metals promise electricity bounty

Less-expensive solar technology using common metals could cover America's rooftops and supply a significant part of the country's electricity, scientists say. With enough sunlight falling on home roofs to supply at least half of America's electricity, shingles that generate electricity from the sun and can be installed like traditional roofing could be a source of cheaper and more sustainable solar power, researchers reported at a meeting of the American Chemical Society in Philadelphia. Such shingles already are a commercial reality but they utilize so-called rare earth elements like indium, gallium and are expensive to produce. A new photovoltaic technology uses abundant, less-expensive materials like copper and zinc -- "earth-abundant materials" -- instead and would make the technology affordable and make possible the integration of photovoltaics into other parts of buildings, the scientists said. "Sustainability involves developing technology that can be productive over the long-term, using resources in ways that meet today's needs without jeopardizing the ability of future generations to meet their needs," materials scientist Harry A. Atwater of the California Institute of Technology said. "That's exactly what we are doing with these new solar-energy conversion devices." Devices made with zinc phosphide and copper oxide have broken records for both electrical current and voltage achieved by existing so-called thin-film solar energy conversion devices. Eventually, the researchers suggested, the technology could produce electricity at a cost approaching that of coal-fired power plants.