Researchers increase efficiency of solar cells to 46 percent

The German Fraunhofer Institute and the French research institute CEA-Leti say they have achieved a new record for converting sunlight into electricity using solar cells. The new record is an efficiency of 46 percent and 50 is considered achievable.

The researchers use so-called multi-junction solar cells, in which each subcell converts a quarter of the incident light into electricity. These are photons with a wavelength of 300 to 1750nm. Concentrating the light using a Fresnel lens achieved an efficiency of 46 percent at 50.8W/cm², breaking the old record of 44.7 percent set by the same researchers in September last year. For the record, sunlight was concentrated to an intensity equivalent to 508 “suns,” Fraunhofer reports. The results have been confirmed by the independent Japanese AIST research institute.

According to the French and German scientists, correctly distributing the photons over the four subcells of the multijunction cell was the most difficult hurdle to overcome. By changing the thickness of each layer within the solar cell and by adapting the material composition, a higher efficiency would have been achieved compared to previous designs.

Fraunhofer and CEA-Leti claim that their concentrator photovoltaic technology is the most efficient and is of particular interest for areas where the sun has intensive radiation. In addition, the researchers expect that returns of 50 percent can be achieved in the near future. The developed cells are produced by Soitec.