Solar energy converter and elongated fresnel lens element

Abstract

A solar energy concentrating and collecting assembly including a formed synthetic resin radiation concentrator having a series of elongated, generally rectilinear, side-by-side, parallel solar ray focusing surfaces that extend in a direction which is at an angle relative to the side margins of the focusing area but are of helical configuration longitudinally thereof in order to focus the solar radiation onto a narrow zone spaced from the concentrator which is parallel with the side margins of the focusing area. In its preferred form, the focusing surfaces define a Fresnel-type concentrator. A relatively large number of focusing surfaces are provided per unit width of the concentrator to minimize the effective thickness thereof and the accuracy and integrity of the focusing surfaces is obtained and preserved in the focusing unit by forming thereof from a sheet of synthetic resin material which has been forced against a cylindrical die having a continuous, helical, focusing surface defining groove in the circumference thereof which thereby causes such surfaces to be at an angle relative to the direction of travel of the sheet during forming and thereby in the final product, but with a built-in warp in such surfaces longitudinally thereof to maintain a nonangular focusing zone spaced from the concentrator. Forming of the concentrator against a continuous surface die permits fabrication of a radiation energy focusing sheet of any desired length having a series of repeat pattern Fresnel surfaces which merge smoothly and uninterruptedly one into another with the effective focus thereof extending longitudinally of the sheet even though the focusing surfaces are at an angle relative to the focus zone.