23 August 2010


ZSW raises its thin-film solar cell efficiency record to 20.3%

Scientists at the Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (Centre for Solar Energy and Hydrogen Research, ZSW) in Stuttgart, Germany have raised their thin-film solar cell efficiency record to 20.3%. ZSW’s prior record of 20.1% (achieved in April) had surpassed the US Department of Energy’s National Renewable Energy Laboratory (NREL), which had held the record for the previous 16 years (latterly 19.9%, achieved in March 2008).

ZSW’s latest record copper indium gallium di-selenide (CIGS) thin-film solar cells shrink the efficiency advantage of multi-crystalline solar cells (still dominating the market) to just 0.1%. The increased efficiency should significantly improve the cost-effectiveness of CIGS thin-film photovoltaics over the medium term, it is claimed.

The ZSW solar cell has an area of 0.5cm2, and the semiconducting CIGS layer and the contact layers have a total thickness of just 4 microns, 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 at ZSW and head of its Photovoltaics Division. The latest efficiency figures have been confirmed by Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany. However, it will be some time before the increased efficiency of the CIGS solar cells can be utilized commercially, Powalla cautions.

Experts reckon that, within the next years, the efficiency of the relatively low-priced CIGS thin-film solar modules will rise from about 11% to about 15%. Compared to 2008, the market share of thin-film power plants is expected to double by 2012, reaching about 30%.

Together with industrial partner Würth Solar, ZSW has developed its CIGS thin-film solar module technology to enable industrial production. In 2006, Würth launched what is claimed to be the world’s first mass production of CIGS solar modules (in Schwäbisch Hall, Germany).

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ZSW sets thin-film PV cell efficiency record of 20.1%

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