Study Of A Hybrid Solar CPV/T System Using Compact Linear Fresnel Reflector And Spectral Beam Splitting Technology

In solar photovoltaic(PV)applications,the invalid solar radiation increases the cell surface temperature and thus reduces the PV conversion efficiency.The spectral beam splitter can be used to solve this problem to a certain degree.Effective solar radiation will penetrate the beam splitter and then be absorbed by solar cells.Other solar radiation will be reflected to the solar thermal receiver tube for thermal utilizations by the beam splitter.A novel solar energy PVT system using compact linear Fresnel reflector(CLFR)concentrator and beam splitting technique is proposed in the current paper.Theoretical and simulation research works are conducted.Firstly,a complete type CLFR concentrator is proposed.Based on spectral beam splitting technology,a solar PVT system with solar cells coated by film-based beam splitter is proposed.By theoretical analysis and calculation,the structural parameters and mirror field configurations of the PVT system are obtained.In addition,the Matlab program is utilized to analysis the relationships of the geometrical and optical parameters.Secondly,based on the design theory of coating system and for monocrystalline silicon solar cells,the Needle method is used to design the beam splitter suitable for the PVT system.A film of 25 layer coatings is obtained,which had relatively high transmittance in the wavelength range of 380.0～1100.0 nm and relatively high reflectance in other spectrum ranges.Thirdly,the MCRT is employed to simulate the solar concentrating processes of the PVT system and the solar intensity distributions on solar cells as well as thermal receivers are obtained.Solar concentration processes at different thermal receiver tube heights and different tube diameters are simulated and the relevant optical efficiencies are calculated.Furthermore,the optical behavior of the PVT system under different sun tracking deviation angles is evaluated.The results demonstrate that the PVT system is sensitive to the sun tracking error.In practical applications,a two-axis solar tracker with relatively high tracking accuracy is needed.The interaction between geometrical and optical parameters of the PVT system is investigated,and the structural and optical characteristics of the PVT system are revealed.Finally,the thermodynamic analysis of the PVT system is launched.The radiation flux incident on the CLFR concentrator is obtained.Based on the transmission performance of the designed beam splitter as well as the performance parameters of solar cells and thermal receiver tube,energy conversion efficiencies and output powers of two subsystems and the whole PVT system are calculated.The results indicate that when the temperatures of solar cells and thermal receiver are 30.0 °C and 300.0 °C,the total output power of the PVT system is 7106.0 W.The PV conversion efficiency and the overall energy efficiency of the PVT system are 31.2% and26.7%,which are both greater than those of the concentrated solar PV system under the same condition.