World-Record Solar Cell a Step Closer to Cheap Solar Energy

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George Douglas (303) 275-4096

Golden, Colo., Feb. 25, 1999 — Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) recently took another step toward reduced costs and increased competitiveness for solar energy by setting a world record for thin-film solar cell efficiency.

The measurement of 18.8 percent efficiency for the copper indium gallium diselenide (CIS) cell topped the previous record, also set at NREL, by more than 1 percent. The efficiency of a solar cell is the percentage of available sunlight converted by the photovoltaic cell into electricity.

"As the scientists and researchers at the National Center for Photovoltaics (NCPV) push the envelope of solar-cell efficiency, we can begin to visualize the day when energy from the sun will be generating a significant portion of country's electric power demand," said NCPV Director Larry Kazmerski. "The technology has been proven. The task before us now is to lower the cost, and improved cell efficiency is one of the most effective ways of doing that. With this advancement, we take another step toward that goal."

Thin-film photovoltaics use very thin layers of semiconductor material applied to a low-cost backing, such as glass or flexible plastic or stainless steel. CIS thin-film technology, in particular, demonstrates remarkable outdoor reliability and stable conversion efficiencies over time. Thin films are a promising path to low-cost photovoltaics, because less of the expensive semiconductor material needed to convert light into electricity is used in manufacturing the thin-film solar cells. And, the huge jump in efficiency reported by the NREL researchers suggests that there is even more room for improvement.

"This marks a new high for polycrystalline thin films. The cell's record-breaking efficiency demonstrates to the photovoltaic industry the great potential thin films have for terrestrial and space applications," CIS team leader Rommel Noufi said. "Each increase in efficiency translates into lower costs for harnessing energy from the sun. The cell's excellent performance also is significant for space applications, where high-efficiency, light-weight power sources are essential."

The team of record-setting NREL researchers in the National Center for Photovoltaics includes Senior Scientist Miguel Contreras, Kannan Ramanathan, James Keane, Brian Egaas, Falah Hasoon, James Dolan, Jeff Alleman, Holm Wiesner and Noufi.

DOE created the National Center for Photovoltaics in 1996 to provide a focal point for technology development and information about photovoltaics in the United States. The center, a collaborative effort of NREL and Sandia National Laboratories, helps the nation's photovoltaics industry improve the cost-effectiveness, performance and reliability of its products. For more information on photovoltaics, visit the National Center for Photovoltaics Web site.