Optimal Design Study Of Micro-lens Light Trapping Structure For Thin Film Solar Cells In BIPV

Building Integrated Photovoltaic(BIPV)combines photovoltaic modules with building skin,which has been recognized by more and more architectural designers and become a new research hotspot.Thin film solar cells stand out in BIPV because of their good performance under low light condition,flexibility and light weight.However,the reduction of photoelectric conversion efficiency caused by the decrease of the thickness of the absorption layer is also concerned.In this thesis,an optimal design method of micro-lens light trapping structure applied to BIPV is proposed.Under three common integrated scenes of BIPV,such as lighting roof,sunshade and building facade,the optimal design,optical and electrical properties and economy of micro-lens light trapping structure of thin film solar cell are studied.(1)Considering the micro-lens structure,solar motion and BIPV scene,the optical simulation and comparative analysis of V-shaped,semi cylindrical and concave micro-lens light trapping structure thin film solar cells are carried out by Trace Pro software.The simulation results show that the V-shaped micro-lens light trapping structure has the best light capture performance in all three BIPV scenarios.The V-shaped micro-lens light trapping structure with a top angle of 70°and a groove depth of 100μm has the best light capture performance in the application scenarios of lighting roof and sunshade,which can increase the annual radiation flux of the absorption layer incident surface by 4.45%and 2.84%respectively;the V-shaped micro-lens light trapping structure with a top angle of 60°and a groove depth of 200μm has the best light capture performance in the application scenarios of building facade,which can increase the annual radiation flux of the absorption layer incident surface by 7.63%.(2)The electrical properties of CIGS thin film solar cells with optimized V-shaped micro-lens light trapping structure are studied by FDTD Solutions.The results show that the short-circuit current density of CIGS thin film solar cells with 60°top angle and 200μm groove depth V-shaped micro-lens light trapping structure is 63.28m A/cm~2and the relative enhancement of short-circuit current density is 15.57%;the short-circuit current of CIGS thin film solar cells with 70°top angle and 100μm groove depth V-shaped micro-lens light trapping structure is 56.65 m A/cm~2 and the relative enhancement of short-circuit current density is 7.11%.(3)The optimized V-shaped micro-lens light trapping structure can improve the light capture performance of CIGS thin film solar cells for visible and infrared light.Among the three BIPV scenarios,when the micro-lens light trapping structure is applied to the building facade scene,it has the best light capture performance in the visible light segment.The difference between the light capture performance in the visible light segment and that in the infrared band is the largest.Therefore,the building facade scene is most suitable for the use of micro-lens light trapping structure.(4)Among the three kinds of BIPV scenes,the micro-lens light trapping structure has the best economy when applied to the building facade scene.Due to the high cost of micro-lens processing,the distributed photovoltaic power generation system with micro-lens light trapping structure can obtain higher total power generation income,but the system economy is worse than that without micro-lens light trapping structure.Cost analysis shows that 3D printing technology is an effective way to reduce the incremental cost of micro-lens.The research results of this thesis can provide design guidance for the design and application of micro-lens light trapping structure in BIPV.