Research On Fabrication Of Fresnel Lens Using In The Concentrator Photovoltaic Systems

With the non-renewable resources about coal, oil and natural gas, etc in the decades to be constantly consumed, solar energy will eventually replace other resources to be main stream. It should be selected in accordance with the appropriate solar energy equipment in order to use solar energy effectively. As the power efficiency of traditional silicon-based solar cell is low and also it costs high, concentrator photovoltaic systems with high conversion efficiency will become the main direction.In concentrator photovoltaic systems, Fresnel lens concentrator is one of the most important parts and its quality requirements is to improve incident light intensity of per unit area in solar cells, while it should exactly match with the system. With the development of concentrator photovoltaic systems is high efficiency, high condensing rate and lower costs, the cost and technical requirements are high of Fresnel lens concentrator. As a result, the research on design and fabrication methods of Fresnel lens is very important.In this paper, the structure and optical design principle of Fresnel lens is analyzed in detail. The Fresnel lens with the knowledge of geometrical optics is designed and the formula is derived. This paper is focused on UV-nanoimprint lithography. It is discussed about UV-nanoimprint lithography key technique (mold production, roll-to-roll ultraviolet nanoimprint lithography and stripping), on which each step process is analyzed in detail with theoretical and experimental research. Fresnel lens concentrator mold is fabricated by precision turning technology. The eigenstructure of Fresnel lens is transferred to the Ni mold by precision micro- electroforming in order to facilitate the roll-to-roll imprint. The Ni mold of Fresnel lens is imprinted by the roll-to-roll ultraviolet nanoimprint lithography. And after employing UV light to cure the resin, the Fresnel lens collector on the PC substrate is fabricated.The Fresnel lens collector on PC substrate is tested in the sunshine. Results show that the focal length, the spot diameter in focal point and the collector rate is 145mm, 4mm and 225 respectively. Its optical efficiency can reach more than 75%. It is consistent with design requirements of solar collector. The Fresnel lens collector has much notable feature with ultra-thin, low cost, high condensing rate and easy-to-batch production. Also it can improve the distribution of light intensity heterogeneity.Finally, a summary of this research is made and the direction for further work has been pointed out.