High-efficiency Köhler photovoltaic concentrators with external light confinement

Descripción (resumen): 

Metal grid lines are a vital element in multijunction solar cells in order to take out from the cell the generated photocurrent. Nevertheless all this implies certain shadowing factor and thus certain reflectivity on cells surface that lowers its light absorption. This reflectivity produces a loss in electrical efficiency and thus a loss in global energy production for CPV systems. We present here an optical design for recovering this portion of reflected light, and thus leading to a system efficiency increase. This new design is based on an external confinement cavity, an optical element able to redirect the light reflected by the cell towards its surface again. It has been possible thanks to the recent invention of the advanced Köhler concentrators by LPI, likely to integrate one of these cavities easily. We have proven the excellent performance of these cavities integrated in this kind of CPV modules offering outstanding results: 33.2% module electrical efficiency @Tcell=25ºC and relative efficiency and Isc gains of over 6%.

Tipo publicación: 
Publicado en: 
Nonimaging Optics: Efficient Design for Illumination and Solar Concentration VIII San Diego, CA (USA). Proceedings SPIE Vol. 8124 http://dx.doi.org/10.1117/12.894414
Ingeniería óptica
Fecha de Publicacion: 
Agosto 2011
Autores CeDInt: 
Otros Autores: 
Yang Li