Dual-Junction Solar Cell Breaks Efficiency Record
Jan 7, 2016 James Morra | Electronic Design
A research team based out of the U.S. National Renewable Energy Laboratory (NREL), has developed a multi-junction solar cell that it says has broken an efficiency record. The research team partnered with the Swiss Center for Electronics and Microtechnology (CSEM) to create the so-called tandem solar cell, combining two layers of semiconductor material to absorb more of the solar spectrum.
In laboratory tests, the research team demonstrated that the solar cell could convert direct sunlight into electricity at 29.8% efficiency. David Young, a senior researcher at the NREL, points out that these results edged out the theoretical limit of 29.4% for mechanically stacked cells. In addition, the device works without having to concentrate sunlight with reflectors, which can increase efficiency in certain solar cells.
Each research center contributed part of the dual-junction solar cell, which combines III-V and crystalline silicon semiconductors. CSEM scientists developed a silicon sub-cell, on which NREL stacked a layer of gallium-indium phosphide (GaInP). The resulting device has a higher efficiency than either material by itself. The record efficiency for an individual crystalline silicon cell is 25.6%, and 20.8% for single-junction GaInP.
http://electronicdesign.com/power/du...iciency-record
I'm a bit confused by the headline though, because according to the NREL efficiency chart, the current record for a two junction solar cell is 31.1%.