Optimization of Multiplexed Wide-angle Solar Concentrators with High Diffraction Efficiency

Abstract

The main objective of the work was to obtain a versatile holographic element to concentrate sunlight from different relative positions of the Sun during the day, avoiding the need for expensive tracking systems. For this purpose, symmetric and asymmetric holographic lenses of negative focal length were stored using peristrophic holographic multiplexing techniques to obtain holographic optical elements of width angular response and high diffraction efficiency. For this purpose, a low-toxicity photopolymer called Biophotopol whose dye was photosensitive at the recording wavelength of 473 nm was used. The holographic behavior of the solar concentrators (HSC) was studied by measuring the angular diffraction efficiency at 633 nm (near the maximum response of silicon cells). The efficiency of the complete HSC-solar cell system has been studied in short-circuit under solar illumination, using a solar simulator, at different incidence angles. In addition, the relationship between the angular separation between multiplexed HLs and the efficiency of the complete system has also been studied.