Micro-optic solar concentration and next-generation prototypes

Abstract

We recently proposed a micro-optic solar concentrator using a two-dimensional array of small-aperture lenses focusing into a planar slab waveguide. By placing mirrors at each lens focus, light collected by the lens array reflects into a common slab waveguide at angles which guide by total internal reflection. Coupled sunlight propagates within the slab until reaching a photovoltaic cell mounted along the edge(s). Simulations of this geometry reveal designs with 89% and 81.9% optical efficiency at 100x and 300x geometric concentrations respectively. The micro-optic concentrator was previously fabricated as a proof-of-concept, but exhibited poor performance due to lens aberrations. Here, we present a 2nd-generation system using a better-suited lens array and achieve >52% measured efficiency. We also discuss performance tradeoffs associated with micro-optic concentration and explore secondary coupler designs as a means to increase both efficiency and concentration.