Single elemental planar light concentrator using skewed V-groove optics

Abstract

Light concentrators are widely used to address the challenges of solar radiation's limited energy density. However, traditional light concentrators suffer from bulkiness, higher focal length, low solar acceptance, and cost factor due to the usage of large imaging optics elements. Waveguide-based planar light concentrators (PLC) have been engineered as a solution to these challenges. They work by collecting light at the incident face and channeling it to the lateral face of the waveguides. However, the existing PLC designs mostly consist of multiple optics elements, resulting in the need for precise positioning and point-to-point solar tracking. Addressing these complexities, a new design for waveguide-based PLC is presented. It features a simplified array of skewed V-grooves within an optical slab, essentially creating a single elemental optics. This novel skewed V-groove-based PLC (SV-PLC) introduces a low-concentration (i.e., <10X geometric concentration (GC)) solution that offers high angular acceptance along one axis. The current study aims to establish the novel design concept, validate, optimize, and assess the design through the Ray-tracing simulation. Further, based on the simulation results, a functional prototype was successfully fabricated in PMMA using laser machining. The results of the optical characterization of the SV-PLC showed that the Optical Efficiency (OE) was approximately around half the theoretical OE. Angular-dependent ray trace results showed a lower OE drop (<10 %) for incident angles less than 15°, and a maximum drop of 30 % (for a 10X GC design) for an incident angle of 23.5° (i.e., half the angle shift of the sun through seasons).