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Abstract

We disclose here a new type of solar generator using an optical concentrator in which sunlight is concentrated successively in each of two dimensions. Sunlight is first reflected toward a linear focus by a large, deeply-curved, cylindrical trough reflector of parabolic shape. Before the reflected light comes to the focus, it passes through smaller, regularly spaced toroidal arc lenses which further concentrate it in the orthogonal direction. The lenses have the two-dimensional cross section of a convex lens, extended into a toroid by rotation about an axis parallel to the line focus. The toroidal arc lenses operate to efficiently focus at very high-concentration converging rays that are incident from a wide range of directions, from the deeply curved primary reflector. The foci formed by the toroidal arc lenses are formed at regular intervals, spaced along a line parallel to and close to the primary linear trough focus. The concentrated sunlight at these foci is converted into electricity preferably by multi junction photovoltaic cells of very high efficiency, configured in short, parallel-connected linear arrays. In one embodiment, tolerance to off-axis pointing and uniformity of illumination is improved with an additional refractive element in the form of a rod lens, introduced close to and parallel to each cell array, so as to image the outline of the toroidal arc lenses onto the cells.

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First Claim