Energy Collection Efficiency of Low Concentration Holographic Planar Concentrators

In this presentation we evaluate the energy collection efficiency and energy yield of different holographic planar concentrator designs. The holographic planar concentrator replaces expensive photovoltaic cell material with holographic collectors that cost approximately 1% of the photovoltaic material. An analysis is performed using a combination of raytracing and coupled wave theory. Other loss factors such as Fresnel reflection and polarization are also incorporated. The performance of single gratings is optimized to maximize the spectral and angular bandwidth that matches the spectral responsivity of different photovoltaic devices. Multiple grating collectors are also modeled to maximize energy collection over the course of a year accommodating the movement of the sun. The results show that approximately half of the light illuminating the hologram can directly be collected by diffraction and directed to the photovoltaic cell. A test system is evaluated and the experimental results compare well with the analysis.