Progress in development of all-glass terrestrial concentrator modules based on composite Fresnel lenses and III-V solar cells

This paper describes an approach in designing of concentrator modules which is very similar to that for flat PV panels. Small-size submodules, each with 4×4 cm² aperture and 7.5 cm focusing distance, are integrated in a fully hermetic module which is resistant to the environmental influences. Panels of concentrating Fresnel lenses have a composite structure and consist of a silicate glass superstrate and a thin (~0.2 mm in average) refractive profile made of transparent silicone. An optical efficiency of the lenses as high as 91.5% was measured. The geometrical concentration ratio of the all-glass module is 130×. The solar cells are mounted on copper heat-spreaders which are glued to a bottom glass plate. The module cabinet has glass walls sealed to the lens and solar cell panels by means of silicone. The outdoor module efficiencies of 19.3% in the case of single-junction AlGaAs-GaAs cells and 24.8% in the case of two-junction GaInP-GaInAs solar cells were measured