High efficiency glass waveguiding solar concentrator

A new waveguiding concentrator design is presented that does not suffer from decoupling losses common to other waveguiding architectures. The geometric optical efficiency (η
_geo
), before considering absorption and scattering, is higher than 99.9%. For a tracking (incidence) angle tolerance of ±0.8°, the efficiency only drops to 95.6%. The concentration optics are transparent, allowing collection of the diffuse sunlight with a low-cost single-junction solar cell. Glass waveguides are used so that absorption losses are minimized and the design can be scaled to large areas. We present simulation results using Zemax and TracePro to achieve high optical path efficiencies for both concentrated (direct) and diffuse light and energy harvesting efficiencies over 30% in both high and low DNI conditions using currently achievable PV cell efficiencies. We also discuss our first measurement results on fabricated glass waveguides and for a first prototype measurement with an efficiency of 90% for a single lens-to-waveguide optical path.