NREL and partners to compare efficiency of III-V solar cells
The three manufacturers whose cells will be compared are Spectrolab of the United States, Sharp of Japan, and Azur Space of Germany. The CPV cell efficiencies will be tested in sites in Colorado, USA and Yokohama, Japan.
The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) is partnering with major international industrial technology and solar research organisations 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, Colorado, 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 Centre (SolarTAC) in Aurora, Colorado.
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.
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 multi-junction III-V solar cells with efficiencies approaching 40 %, meaning that 40 % of the energy in the sunlight that hits the solar cells is converted into usable electricity. This results in module efficiencies of about 30 %. By contrast, most of the PV panels on rooftops today have an efficiency rating of 20 % 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 InGaP/GaAs 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 Organisation (NEDO).