May 5th, 2014
Semprius demonstrates proprietary four-junction, four-terminal stacked solar cell reaching a world-class efficiency level of 43.9 Percent
Semprius, Inc., an innovator in high concentration photovoltaic (HCPV) solar modules, has manufactured the first four-junction, four-terminal stacked solar cell using its proprietary micro transfer printing process.
In this effort, Semprius worked in collaboration with Professor John Rogers and his team at the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign and researchers at Solar Junction, a leading III-V high-efficiency solar cell manufacturer and important Semprius partner.
The new stacked solar cell is comprised of a three-junction microcell that is stacked on top of a single-junction germanium microcell using Semprius’ high-speed micro transfer printing process, which enables the simultaneous formation of thousands of stacked microcells with very high yields. By using four junctions, the stacked cell is able to capture light across a broader portion of the solar spectrum and therefore achieve efficiencies much higher than conventional silicon and thin-film single-junction solar cells. Initial trials yielded solar cells with measured efficiencies up to 43.9 percent. This process is capable of achieving solar cell efficiencies greater than 50 percent in the near future.
Fig: Entegris Completes Acquisition of ATMI• Cost pyramid for HCPV system with cost elements related to the number of HCPV cells per nominal system power installed. Source: Yole Développement
As detailed in the Yole’s High-Concentration Photovoltaics Business and Technology Update report, a high cell efficiency is crucial to compete with conventional flat-plate PV technologies.
A key achievement of this project was the development of a new interfacial material that is placed between the top and bottom cell to minimize optical losses within the stack and thereby optimize overall conversion efficiency. In addition, the new stacked cell has four terminals, rather than the standard two. This reduces the spectral dependence of the solar cell and increases the solar cell’s energy yield under normal operation in the field.
Semprius is a graduate of the U.S. Department of Energy’s SunShot Incubator Program.
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