Refractive spectrum splitting optics for use with photovoltaic cells

Abstract

A new optical design is proposed that refractively disperses sunlight and concentrates different portions of the spectrum onto an array of photovoltaic cells with suitable band gaps. Splitting the solar spectrum allows each photovoltaic cell to operate at higher efficiency. The configuration presented here consists of two 200 mm wide linear arrays of 1 mm wide prisms. Dispersing prisms, whose apex angles vary from 35/spl deg/ to 30/spl deg/ across the array, are immediately followed by concentrating prisms, whose apex angles are chosen to focus 1.64 eV photons from the center of the solar disk onto a line 500 mm from the center of the prism arrays. The dispersed solar spectrum falls on four photovoltaic cells with band gaps ranging from 0.65 to 2.45 eV. A ray tracing simulation predicts 23% more electrical output from the present design compared to a single lens of the same aperture focusing light on a single photovoltaic cell.