The U.S. research institute NREL held the conversion efficiency record for copper, indium, gallium, and selenium (CIGS) solar cells for 16 years but has lost this accolade to scientists at the Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg, Germany (Centre for Solar Energy and Hydrogen Research, ZSW). ZSW, based in Stuttgart, has demonstrated CIGS cell efficiency of 20.1% on a 0.5-square-centimetre cell. The Fraunhofer ISE in Freiburg, Germany has confirmed the new results.
“This record is for thin-film technology in general and not just CIGS solar cells,” noted Dr. Michael Powalla, member of the board and head of the photovoltaics division at ZSW. “It is the result of continuous systematic research which has been supported for years by the Federal Ministry of the Environment, Nature Conservation and Nuclear Safety, the Baden-Württemberg Ministry of Economics and the European Community. A major factor in achieving this top position was the close cooperation between basic research at the university, applied research at the ZSW, and production development at our industrial partner Würth Solar.”
The solar cell consists of the semiconducting CIGS layer and contact layers. It has a total thickness of only four thousandths of a millimetre.
The new efficiency record shows the great potential of CIGS technology for lower-cost, efficient photovoltaic systems. Michael Powalla assumes that efficiency levels of up to 15% can also be achieved in commercial modules within the next few years.
The ZSW is the R&D partner of Würth Solar.