Designing of Fresnel Lenses for Solar Concentrators
Date Issued
2010
Date
2010
Author(s)
Huang, Pei-Yu
Abstract
This study analyzes the designs and properties of flat Fresnel lenses applied in refractive concentrator systems. For a high concentration ratio, the Fresnel lens design for III-V multi-junction solar cells uses a 625× geometrical concentration ratio. We use the square light tube as a secondary optical element to increase the acceptance angle and the energy distribution. The working distance is 95 mm, and the ideal optical efficiency achieves 87.5％ in ±1.265 incident degrees. Secondly, the lens for the 100× geometrical concentration ratio is applied to thin-film solar cells. We divide the lens into three cyclic zones, and each part has a different focal plane to increase the uniformity of light distribution. The acceptance angle in this medium concentration system is ±1 degree, and the ideal optical efficiency is 95％ in ±1.265 degrees with a 66 mm working distance. For the final part which uses a 3× geometrical concentration ratio, the system is designed for applications in silicon solar cells. Considering the loss of optical efficiency caused by the draft angle of the vertical facets and the roundness of vertices, we use wide prism pitches to reduce the fidelity loss of fabrication. This system’s focal length is 90 mm, and the acceptance angle is ±4 degrees.
Subjects
Fresnel lens
concentrator
concentration ratio
F-number
secondary optical element
Type
thesis
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