EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Photovoltaic solar energy is a clean, abundant, and highly promising green energy source, tackling CO2 generation and climate change. Light concentration can improve solar cell efficiency and reduce raw materials consumption by focusing the light in a much smaller cell. This study aims to develop and produce a micro-lens array to increase the efficiency of micro-concentrator solar cells by micro-hot embossing. Optical simulation with Zemax®OpticStudio software was used to simulate the performance of the lens using polymethyl methacrylate (PMMA) as material and its data was supplied by the library of the software, e.g., refractive index (na) of 1.49 and Abbot Number (Vb) 55.31. The geometry of convex-plane lens was simulated changing the parameters of the software, e.g., entrance pupil diameter, lens diameter, wavelengths, lens thickness, focal length, and receiver diameter. The geometry chosen was the one that allows the maximization of the flux and a better distribution of light in the final diameter. The design of metallic mould insert used to replicate the lens array was developed concerning the data obtained from the Zemax®OpticStudio and according to the characteristics of a micro-concentrator solar cell. Three different metallic mould inserts, manufactured by different routes, having different costs and different finishing characteristics, were tested and compared during micro-hot embossing process. Critical parameters (pressure, dwell time, temperature and cooling) were optimized for each metallic mould insert used. The accuracy and the surface texture of the metallic mould inserts and the lenses array were measured by digital DVM6 microscopy using Las X and Leica Map start software according with the standard ISO 25178. The metallic mould insert with higher accuracy and lower roughness promoted the best accuracy and the smother surface in lens array, influencing optical characteristics increasing efficiency. For the three lens array produced using different metallic mould inserts, efficiency has increased.