Using a multi-junction cell receiver as self-detector for spectrally-resolved optical efficiency measurement of concentrators

An optical characterization technique is introduced for the measurement of the spectrally-resolved optical efficiency of concentrators that employ multi-junction cells. The method takes into account the optical coupling between any secondary optic and its multi-junction cell receiver and allows the latter to be used as light detector for the first time. A series of band pass filters are used to isolate the optical performance of different narrow spectral bands throughout the spectrum of interest. The subcell with a response in each narrow band is used as a light sensor. A high-intensity filtered broad band light is cast on the receiver surroundings to avoid the other subcells to limit the current. The technique presented has been key to identify solarization effects in molded soda-lime glass secondary optics exposed to outdoor operation during several months.