ZSW (Zentrum für Sonnenenergie- und Wasserstoff-Forschung — or Center for Solar Energy and Hydrogen Research — Baden-Württemberg) in Stuttgart, Germany has raised its energy conversion efficiency record for thin-film solar cells from 20.3% to 20.8%, as confirmed by the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg. This is also the first time that a CIGS PV cell has exceeded the laboratory efficiency levels of existing widely used polycrystalline solar cells (which have held an advantage for nearly 30 years), overcoming the remaining disadvantage of using cost-efficient thin-film PV technology, it is reckoned.
Covering an area of 0.5cm2 (normal for experimental cells), the record copper indium gallium diselenide (CIGS) cell was manufactured in a laboratory coating system using the co-evaporation method which is capable of being transferred into industrial production processes, and which was developed further and patented jointly by ZSW and industrial partner Manz AG of Reutlingen, Germany (a supplier of integrated production lines for crystalline silicon solar cells and thin-film solar modules). The latest record is the result of joint research by ZSW and Manz. The goal of the partnership is to cut the cost of solar power more rapidly. With the latest efficiency record, the two firms reckons they have moved a large step closer to this goal. Manz holds the exclusive rights to use the record technology, and will now transition it from laboratory-scale cells into mass-production modules.
"With a record module efficiency of 14.6% we have already caught up with polycrystalline technology last year," notes Manz's founder & CEO Dieter Manz. "The research result of the world record cell will help us speed up the increase in efficiency on production-size modules," he adds. Manz has its CIGS innovation line in Schw?bisch-Hall, where it produces modules on a large scale and transfers knowledge gained in the lab to mass production. "Customers of our CIGSfab - the fully integrated, turnkey production line for CIGS thin-film solar panels [which uses ZSW technology] - will see the greatest benefit from this achievement," says Manz. "We are going to offer them exclusive access to the world's leading world-record technology."
CIGS production costs are already considerably more favourable, reckons Manz. "On top of that, the technology has the greatest potential for further efficiency increases," he adds. "Production lines can be scaled as desired and, thanks to the comparatively low initial investment, they are perfect for manufacturing panels locally in the large growth markets of PV with local content requirements. These markets are characterized by an energy demand that is constantly increasing, which cannot be covered by fossil fuels. Due to the high level of integration compared to crystalline production, the CIGS PV production process is much simpler, more affordable and can thus be realized much faster, Manz claims. In addition, most of the materials needed can be sourced locally, strengthening the local economy.
Existing market-standard CIGS PV modules have efficiencies of 14-15%. Manz has a roadmap for its solar business that plans to offer CIGSfab customers solar panel efficiency increases of up to 16% and more within the next four years. Professor Michael Powalla, board member and head of the photovoltaics division at ZSW, believes that 16-18% in commercial modules is possible over the next few years.
It is reckoned that the latest efficiency record will help technologies 'made in Baden-Württemberg' to compete against Asian rivals. ZSW's research has been supported for many years by both the German Federal Environment Ministry and the state of Baden-Württemberg.
