Solar cell efficiency approaches 50%

I just saw an announcement from the Fraunhofer Institute for Solar Energy Systems, Soitec, CEA-Leti and the Helmholtz Center Berlin jointly for having achieved a new world record for efficiency of 44.7% (measured at a concentration of 297 suns) for the conversion of sunlight into electricity. The team developed a multi-junction solar cell with several cells made out of different semiconductor materials are stacked on top of each other. The single subcells absorb different wavelength ranges of the solar spectrum.  These so-called III-V multi-junction solar cells originally were used in space.  These solar cells are used in concentrator photovoltaics (CPV), a technology which achieves more than twice the efficiency of conventional PV power plants in sun-rich locations by concentrating sunlight.

NREL has maintained a chart of the efficiencies of research photovoltaics for several years.  Most commercial solar cells are closer to 10-20% efficient.  Single junction solar cells are limited to about 33% efficiency maximum.  The combination of multi-junction and CPV is required to reach the nearly 50% efficiency that Fraunhofer at al. have announced.