Full modeling and experimental validation of cylindrical holographic lenses recorded in Bayfol HX photopolymer and partly operating in the transition regime for solar concentration

Abstract

Concentrating photovoltaics for building integration can be successfully carried out with Holographic Optical Elements (HOEs) because of their behavior analogous to refractive optical elements and their tuning ability to the spectral range that the photovoltaic (PV) cell is sensitive to. That way, concentration of spectral ranges that would cause overheating of the cell is avoided. Volume HOEs are usually chosen because they provide high efficiencies. However, their chromatic selectivity is also very high, and only a small part of the desired spectral range reaches the PV cell. A novel approach is theoretically and experimentally explored to overcome this problem: the use of HOEs operating in the transition regime, which yield lower chromatic selectivity while keeping rather high efficiencies. A model that considers the recording material's response, by determining the index modulation reached for each spatial frequency and exposure dosage, has been developed. It has been validated with experimental measurements of three cylindrical holographic lenses with different spatial frequency ranges recorded in Bayfol HX photopolymer. Simulations of systems comprising two lenses and a mono-c Si PV cell are carried out with the standard AM 1.5D solar spectrum. Promising results are obtained when using the system with lower spatial frequencies lenses: a total current intensity equal to 3.72 times the one that would be reached without the concentrator.

Volume Holographic Optical Elements as Solar Concentrators: An Overview

“…Recently, Marin-Saez et al [57] theoretically and experimentally explored a novel approach to overcoming the problem related to the V-HOEs chromatic selectivity by using HOEs operating in the transition regime, which led to a lower chromatic selectivity while maintaining rather high efficiencies.…”

“…When a 2 mm thick holographic recording material (phenanthrenequinone doped PMMA photopolymer) was used to record the proposed architecture, the collection angle from increases 0.01° to 6°. Recently, Marin-Saez et al [57] theoretically and experimentally explored a novel approach to overcoming the problem related to the V-HOEs chromatic selectivity by using HOEs operating in the transition regime, which led to a lower chromatic selectivity while maintaining rather high efficiencies. In particular, they developed a model that takes into account the recording material's response to evaluate the index modulation reached for different spatial frequency and exposure dosage.…”

Application of Photopolymer Materials in Holographic Technologies

“…The main requirement for holographic solar concentrators is a combination of high diffraction efficiency with a wide range of angles of radiation incidence. In the literature are considered the processes of fabrication and properties of diffraction deflectors based on volume [22][23][24][25] or relief structures [26] and also focusing elements [27][28][29][30] as components of solar concentrators. In this section, we consider the properties of structures in Bayfol HX materials and acrylate compositions as applied to the problem of obtaining diffraction deflectors of holographic solar concentrators.…”

Wide-Band High Concentration-Ratio Volume-Holographic Grating for Solar Concentration

“…None of the aforementioned studies have comprehensively considered these four factors. Inspired by the previous work, we use the Kogelnik coupled-wave theory [20,21,23] and the first-order monomer diffusion model proposed by Piazzolla et al [24] to achieve comprehensive consideration of the four factors and design and fabricate a volume-holographic concentrator, which possesses the characteristics of wide band, large angle, and high diffraction efficiency. For recording volume holographic gratings with high spatial frequency, the non-local diffusion model is recommended because a non-local material response function is introduced [25].…”