Towards sustainable solar energy: optimization of a holographic concentrator in a green photopolymer

Nowadays, one of the challenges in obtaining competitive photovoltaics is to achieve lightweight, low-cost, and free-tracking systems. It is also desired to eliminate wavelengths that can damage the photovoltaic cell by overheating. To this end, volume holographic lenses (HLs) allow controlling the solar radiation that hits the photocell, avoiding harmful radiation that can damage photocells, such as infrared radiation, which heats the solar cells, but does not efficiently convert solar energy into electrical energy. In addition, holographic solar concentrators based on multiplexed HLs have the advantage that they do not require any solar tracker. In this work, we present the optimization of the relevant conditions in the fabrication of multiplexed HLs stored in Biophotopol. These parameters refer to both the material factors (optimal concentrations of dye and monomer, thickness) and the optical recording factors (optimal number of multiplexed HLs, angular distance peak-to-peak, and exposure times). Finally, a theoretical study of the exposure times has been done using the exposure schedule method (ESM) to improve the average diffraction efficiency.