TECHNOLOGYNEWS CIGS record improved
WITH an efficiency of 20.1 percent, scientists at the Zentrum für Sonnenenergie- und Wasserstoff- Forschung Baden-Württemberg, Germany (Centre for Solar Energy and Hydrogen Research, ZSW) have achieved a new benchmark for the yield of solar cells.
The Stuttgart researchers produced thin- film solar cells with a top efficiency of 20.3 percent. With this performance, they exceed their own world record, and minimize to only 0.1 percent the advance of the multi-crystalline solar cells still dominating the market.
The new record-breaking solar cells from ZSW are made of extremely thin layers of copper, indium, gallium and diselenide (CIGS). This saves materials and costs. The new results should significantly improve the cost-effectiveness of CIGS thin-film photovoltaics over the medium term. The area of the world record cell is
0.5 square centimetres. The semiconducting CIGS layer and the contact layers have a total thickness of only four thousandths of a millimetre, making them 50 times thinner than standard silicon cells.
“Our researchers have made the cells in a CIGS laboratory coating plant using a modified co-evaporation process, which in principle can be scaled up to commercial production processes,” says Dr. Michael Powalla, Member of the Board and Head of the Photovoltaics Division at ZSW. The Fraunhofer ISE in Freiburg, Germany has confirmed the new results. However, it would take a while before the increased efficiency of CIGS solar cells can be commercially utilised, Powalla said.
Innovative research and the improvement of production will further increase the efficiency of thin-film solar modules.
Collecting approval
KALAHARI GREENTECH have released a statement detailing a report prepared by the Georgia Institute of Technology’s Engineering Experiment Station, which found Kalahari Greentech’s Solar Collector to be up to 74% efficient; that is up to four times the efficiency of commercial photovoltaic cells. The Georgia Institute of Technology is one of the nation’s top research universities, distinguished by its commitment to improving the human condition through advanced science and technology.
Georgia Tech’s campus occupies 400 acres in the heart of the city of Atlanta, where 20,000 undergraduate and graduate students receive a focused, technologically based education.
The collector was tested in accordance with procedures outlined by the National Bureau of Standards, and provides the results of the tests along with some general observations made while conducting the test.
The study remarks that, “These tests indicate this collector to be capable of
reflected back into the atmosphere. During the 4 hour test, the lowest recorded efficiency of the Kalahari Solar Collector was 50%, still 300% more power than the average photovoltaic solution. This increase in efficiency allows Kalahari to produce power in a smaller unit and at a lower cost.
performing quite well and to compare favourably with high quality competitive collectors.”
The reason that the Kalahari Solar Collector is more efficient is because it uses all available wavelengths of light in its conversion process, whereas photovoltaic cells can only convert specific ranges of light into electricity. An average photovoltaic panel converts 15% of the light it absorbs into electricity. The rest is converted into wasted heating or
The Efficiency of a power generator system directly corresponds to the size of a typical installation. These test results imply that the Solar Tri-Brid will be 1/4 the size of current photovoltaic solar power systems. Based on the encouraging results of this independent test, Kalahari has begun the development of the Solar Tri-Brid system. The Tri-Brid is a standalone power generator, which will reliably produce electricity from sun power gathered by the Solar Collector.
Designed to be an ideal solution for rural homes and farms, where power infrastructure is limited or impractical to install, The “Tri-Brid” is designed around the goal of providing continuous, usable power without necessary grid power during non-peak times.
Within a few years, the efficiency of the relatively low-priced CIGS thin-film solar modules will rise from about 11 percent to about 15 percent, experts say. Higher efficiencies improve the electrical power output and thus the financial returns delivered by photovoltaic systems.
Experts assume that the CIGS thin-film technology is facing a great commercial future. Compared to 2008, in 2012 the market share of thin-film power plants is expected to double to around 30 percent.
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www.solar-pv-management.com Issue VI 2010
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