Buljan, Marina and Benitez Gimenez, Pablo and Mohedano del Pozo, Raúl and Miñano Dominguez, Juan Carlos and Sun, Y. and Falicoff, W. and Vilaplana, J. and Chaves, Julio and Biot Marí, Guillermo and López, J.
Free-form Fresnel RXI-RR Köhler design for high-concentration photovoltaics with spectrum-splitting.
In: "Nonimaging Optics: Efficient Design for Illumination and Solar Concentration VIII", 21/08/2011 - 22/08/2011, San Diego, EEUU.
Development of a novel HCPV nonimaging concentrator with high concentration (>500x) and built-in spectrum splitting concept is presented. It uses the combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-Point-Contact (BPC) silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell's reflection. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded in it - Both the POE and SOE performing Köhler integration to produce light homogenization on the receiver. The band-pass filter transmits the IR photons in the 900-1200 nm band to the silicon cell. A design target of an "equivalent" cell efficiency ~46% is predicted using commercial 39% 3J and 26% Si cells. A projected CPV module efficiency of greater than 38% is achievable at a concentration level larger than 500X with a wide acceptance angle of ±1°. A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ~100x and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J cell with a peak efficiency of 36.9%.