NREL Achieves Solar-Electric Record

New Technology Could Spur Growth in Photovoltaic Panels

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Golden, Colo., Apr. 24, 2001 - Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory have surpassed a record for electricity produced by solar cells made from cadmium telluride—a development that could help meet expanding demand for solar systems.

The measurement of 16.4 percent efficiency bested the previous threshold of 15.8 percent efficiency for a cadmium telluride cell—a record that has stood since 1992. The efficiency of a solar cell is calculated as the percentage of available sunlight the device converts into electricity.

The record-setting cadmium telluride process developed by NREL is different from previous cells and benefits from a number of new insights in understanding of the operation of these solar cells. The cell utilizes new materials that interact chemically with the CdTe to improve adhesion, light collection, and electronic properties, NREL researchers report.

"This technology offers the prospect of getting a better product to customers," said NREL research manager John Benner. "Our industry partners can use this technology in expanding capacity to meet the rapidly mounting demand for PV."

In 2000, the photovoltaic industry increased production by 29 percent in the United States and 39 percent worldwide. In recent months the rising cost of fuels and the California power crisis have spurred an even greater surge in installation of solar electric systems for homes and businesses, with the solar industry expanding to meet the rising demand.

Two of the largest new photovoltaic plants in the U.S. are producing thin-film panels made from cadmium telluride. Benner said these and other plants may adopt all or part of the new NREL-developed process for their next generation of expansion.

Cadmium telluride represents one of the most promising technologies for so-called thin-film solar cells. In the thin-film manufacturing process, layers of differing electricity-producing materials are applied sequentially to a glass, plastic or steel backing.

Many experts believe thin-film cells are the wave of the future, because thin-films use materials that are less expensive than the materials used in earlier, conventional solar panels.

Of the several materials that can be used for thin-film panels, cadmium telluride yields higher wattage per square foot, at a lower price per watt of capacity. Increasing efficiency and lowering costs have been the two overarching goals during the two-plus decades the national laboratory has been conducting research on improving photovoltaic systems.

Over that time, NREL has developed new materials and processes that have helped reduce the cost of solar electric systems by some ten fold. Earlier this year the lab embarked on a program to reduce photovoltaic prices by another 50 percent by the end of the decade.

The NREL team that produced the record-setting solar cell works within the National Center for Photovoltaics in collaboration with the National CdTe Team that also includes scientist from universities and industry.

DOE established the National Center for Photovoltaics at NREL in 1996 to provide for coordinated research and development to improve the cost-effectiveness, performance and reliability of solar-electric technologies. Sandia National Laboratories also participates in the center.

NREL is a national laboratory managed by Midwest Research Institute, Battelle and Bechtel. In addition to its work in photovoltaics, the lab is a leading center for research into wind energy, plant- and waste-derived fuels and chemicals, energy-efficient buildings, advanced vehicle design, geothermal energy and hydrogen fuel cell

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