Progress in the manufacture of ultra flat optics for very high concentration flat panels

A very high concentration in photovoltaics has been achieved using systems based on GaAs solar cells and TIR-R lens working at very high concentration of incident light (1000/spl times/). The reasons for this renewed study is the potential for a drastic reduction of cost with concentration and the highly compact optics design suitable for flat panels. This paper deals with the design, manufacture and characterisation of the ultra-flat optics needed for collecting over the receiver, about 1000 Suns of concentrated sunlight. A description of the details related to the manufacturing of the moulds of the lens, plastic injection process and characterisation of the lens for achieving an acceptance angle (for 90% relative transmission) of /spl alpha/ = /spl plusmn/1.3/spl deg/, an optical efficiency (at /spl lambda/=630 nm) /spl eta//sub opt/ = 86.5% and a peak irradiance on cell surface (at 850 W/m/sup 2/) < 6000, is presented. The goal of this optics is a geometrical concentration of 1250/spl times/.