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Design of compound Fresnel-R lenses for new high-efficient concentrator

A new design of compound Fresnel-R concentrator is presented which is composed of two lenses: a primary lens (Fresnel lens) that works by total internal reflection at outer facets but refraction at inner facets, and a secondary lens that works by refraction. In contrast to previous Fresnel lens concentrator, this design increases the acceptance angle, improves the irradiance uniformity on the solar cell, and reduces the aspect ratio significantly. Another outstanding advantage of this concentrator is the fact that it mainly works by performing total internal reflection, reducing chromatic dependence as well as Fresnel losses. An optical efficiency more than 80% can be achieved. Moreover, in order to reduce the influence of manufacture accuracy and to increase the optical efficiency further, the central part of the bottom of the secondary lens which directly adhered to the solar cell is designed as a cone-shaped prism to collect the sunlight that doesn't reach the solar cell.