Roll-to-Roll Embossing of Optical Radial Fresnel Lenses on Polymer Film for Concentrator Photovoltaics: A Feasibility Study

Abstract

Fresnel-based concentrated photovoltaic (CPV) solar power systems have been proven effective to significantly enhance the photoelectric conversion efficiency, but a standard-size solar plant will require an extremely large amount of polymer radial Fresnel lenses. Roll-to-roll (R2R) manufacturing is a high-throughput technology to mass produce high-quality functional optical polymer film. In this paper, we have firstly studied a complete manufacturing cycle for R2R embossing of radial Fresnel lens polymer film for CPV systems, in terms of polymer lens design, roller mold machining, R2R embossing and optical performance test. Instead of wrapping an electroplated metal sheet onto the roller in conventional R2R process, the lens pattern array is directly machined using a 5-axis ultra-precision machining system to guarantee its surface quality and accuracy. Optical performance evaluation for the manufactured polymer film using a reference solar cell is conducted, and results have shown that radial Fresnel lens on the polymer film can achieve a sunlight concentration ratio 3.9 × times that of linear lenses with a much smaller receiving area. This study has explored the feasibility for R2R embossing of optical polymer film, an industry-applicable and cost-effective technology for mass production of high-quality Fresnel lenses to be used in high-efficiency CPV systems.