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NREL and Partners to Compare High-Efficiency Solar Cells from Three Nations at Sites in Colorado and Yokohama, Japan

April 4, 2011

Golden, Colo., April 4, 2011 – The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) is partnering with major international industrial technology and solar research organizations to test how solar cells from three manufacturers perform in two geographic locations with different lighting conditions. A primary goal of the study is to assess how panels from three different manufacturers – from the United States, Japan and Germany – perform under different average lighting conditions characteristic of the study’s test sites in Aurora, Colo., and Okayama, Japan.

Concentrator photovoltaic (CPV) solar systems – which use lenses to multiply the sun’s intensity, reduce the area of the solar cells needed to convert sunlight to electricity and improve the efficiency of conventional photovoltaics – have been installed at sites in Aurora and Okayama, in part, to measure how well the same cells perform in the high-altitude sunshine of Colorado in comparison with those in cloudier, lower-altitude Japan.

NREL teamed with Japan’s National Institute of Advanced Industrial Science and Technology (AIST) to install 25 kilowatts of CPV systems at the Solar Technology Acceleration Center (SolarTAC) in Aurora, Colo. SolarTAC provides a venue for researching, demonstrating, testing, and validating a broad range of solar technologies at the early commercial or near-commercial stage of development. Concentrator Photovoltaic systems made by Daido Steel, a Japanese manufacturer, are installed at both sites and are designed to compare solar cells made by Spectrolab of the United States, Sharp of Japan, and Azur Space of Germany.

Daido’s CPV design uses a dome-shaped Fresnel lens and concentrator solar cells with efficiencies approaching 40 percent – meaning that 40 percent of the energy in the sunlight that hits the solar cells is converted into usable electricity – resulting in module efficiencies of about 30 percent. By contrast, most of the PV panels on rooftops today have an efficiency rating of 20 percent or less. The output of the CPV systems will be compared with conventional silicon PV modules.

The study will also test high efficiency, advanced versions of the Gallium-Indium-Phosphorous/Galium-Arsenic solar cells originally invented and developed at NREL, which are now widely used for space exploration applications, such as the Mars rovers. The high efficiencies of these cells, coupled with system designs that greatly reduce the area that needs to be covered by solar cells, have attracted growing interest in recent years. In the modules being tested, solar cells cover 1 one-thousandth of the space covered by similar conventional solar modules.

The project is primarily funded by AIST as a part of the "R&D on Innovative Solar Cells” project, which in turn is funded by Japan’s New Energy and Industrial Technology Development Organization (NEDO).
SolarTAC, the largest test facility for solar technologies in the United States, is managed and operated by MRIGlobal and supports proprietary research, testing and demonstration by member companies, as well as collaborative activities between the members, to support the overall growth of the industry. NREL, a member of SolarTAC, plans to host multiple projects there. SolarTAC originated in 2008 when six public and private sector entities – Xcel Energy (the original founding member), Abengoa Solar, the City of Aurora, the Colorado Renewable Energy Collaboratory, MRIGlobal, and SunEdison – joined forces to establish a large site where cutting-edge solar technologies could be tested and demonstrated at a utility scale and under actual field conditions. For more information, please visit

AIST is the largest research organization in the area of industrial science and technology in Japan. Its headquarters are in Tokyo and Tsukuba with nine regional centers throughout the country from Hokkaido to Kyushu.

NEDO was established by the Japanese government in 1980 to develop new oil-alternative energy technologies. Activities to promote new energy and energy conservation technology were subsequently added in 1993. NEDO is now also responsible for R&D project planning and formation, project management and post-project technology evaluation functions in Japan.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by the Alliance for Sustainable Energy, LLC.


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—William Scanlon