Beam Splitting System for the Development of a Concentrating Linear Fresnel Solar Hybrid PV/T Collector

Abstract

Investigations are underway around the world to make solar energy more competitive in the energy market [1–3]. One approach is to develop solar hybrid photovoltaic/thermal (PV/T) technologies which allow for maximal utilization of incident sunlight by integrating a PV cell and a thermal receiver in the same collector [4,5]. In this study, we will present a new PV/T design based on a compact linear Fresnel concentrator (LFC) coupled with a spectral beam-splitter. The beam-splitting approach avoids the efficiency drop in the PV cell while still obtaining high temperature thermal output. The design is analyzed numerically with respect to a worth factor which considers the intrinsically higher economic value of electrical energy at ∼3 times thermal energy. In order to predict optical performance, the geometry of this hybrid concentrating collector, which achieves 10–15 suns concentration, is modeled at various incident angles using the ray tracing software Zemax. Three different PV cells are considered (Si, GaAs and GaInP/GaAs). The reported spectral response of these cells is used to determine the optimal wavelength split for the fraction of the solar spectrum directed to the various PV cells. The results indicate that such designs can achieve 20–51% greater value of the power outputs — PV electrical power plus heat produced — relative to a stand-alone PV system.