MCRT-FDTD investigation of the solar-plasmonic-electrical conversion for uniform irradiation in a spectral splitting CPVT system

Abstract

Concentrating photovoltaic-thermal systems with the spectral splitting technology are promising methods for full-spectral use of solar energy, but the nonuniform irradiation on solar cells are the main problem for their applications. To improve the uniformity of solar irradiation, the distribution features with combined spectral splitting and energy fitting are explored. A parabolic concentrating photovoltaic-thermal system, which has two symmetrical spectral splitting filters and one primary concentrator, is proposed for full-spectral solar utilization. A multiscale-multiphysics MCRT-FDTD model has been built for solar-plasmonic-electrical conversion containing concentrated sunlight propagation and plasmonic photoelectrical conversion. The proposed model has been validated by the local concentration ratio with a photovoltaic/thermochemical hybrid system. The system energy distribution was obtained by conducting a Monte-Carlo ray-trace method, and the finite-difference-time domain method is applied to the plasmonic solar cell for wavelength-dependent absorption. The position relationships between the reflector elements (primary concentrator, spectral splitting filter) and the energy conversion elements (solar cell, thermal absorber) have been thoroughly investigated. Results show that the shading loss is found to be the dominant energy loss. For the solar cell, the local concentration ratio presents peak, linear decrease, sharp decrease, and flat regions. For the absorber, the local concentration ratio presents an “M” profile with five irradiation regions. High and uniform concentrating irradiation is achieved for the solar cell with the improved linear decrease region. The electrical efficiency and fill factor of the plasmonic solar cell are obtained, and a maximum electrical efficiency of 22.64% is achieved. This work provides a theoretical guidance for improved plasmonic solar cells with the uniform irradiation in concentrating photovoltaic-thermal systems.