Mechanical-Electric Behaviors Of Composites Of Flexible Thin Film Solar Cells And PVC Coated Fabrics

With the continuous development of solar photovoltaic building integration,the application of solar cells combined with building structures(components)is becoming more and more widespread.Compared with the traditional structure,the tensioned membrane structure has the advantages of unique shape,light weight and soft beauty,and good seismic performance.It creates unique conditions for the integration of flexible thin film solar cells and tensioned membrane structures.In practical membrane structure engineering,as a typical composite material,the mechanical properties of coated fabrics are significantly affected by the load level.The solar cells also inevitably withstand the load from the membrane surface.The interaction mechanism of the two materials after integration is not clear yet.Therefore,it is necessary to study the mechanical properties of composites of flexible film solar cells and coated fabrics(PV-PVC composites),and the variation law of photoelectric performance of solar cells under load.It can provide theoretical reference for the integrated photovoltaic design of tensioned membrane structure.In this paper,Mechanical-electric behaviors of coated fabrics,flexible film solar cells and PV-PVC composites are studied by a series of uniaxial and cyclic tensile tests.The effects of tensile direction,stress level and composite mode are discussed.The nonlinear damage constitutive model for PVC coated fabrics is proposed.The main contents and conclusions are as follows:(1)The off-axial tensile tests of PVC coated fabrics under different conditions were carried out,in which the effects of specimen shape,clamping mode and tensile direction were analyzed.Distribution and variation of strains of coated fabrics during tension were obtained by means of DIC measurement system.The results show that the mechanical properties of coated fabrics exhibit obvious nonlinearity and anisotropy.With the increase of the deviation from the warp and weft angle,Longitudinal strains decreases and shear strains increases gradually.(2)The uniaxial tensile tests of flexible thin film solar cells and PV-PVC composites were carried out.The mechanical properties and failure modes of flexible thin film solar cells were studied.The composite method of flexible thin film solar cell and PVC coated fabrics was designed,and the effects of composite mode,tensile direction and specimen size on the mechanical and electrical properties of the composites were analyzed.It was found that the solar cells should be forced in the direction of parallel cell strips as much as possible to avoid tearing damage when subjected to large tensile forces in the direction of vertical cell strips.(3)The uniaxial cyclic tensile tests of PVC coated fabrics and PV-PVC composites were carried out.The photoelectric performance of solar cells under cyclic loading was analyzed.loading The elastic modulus,ratcheting strain and hysteresis loop area of PVC coated fabrics and PV-PVC composites were compared.The ratcheting behaviors of PV-PVC composites were obviously weakened,and under the stress level of common design strength of PVC coated fabrics,solar cells can maintain good photoelectric performance.(4)According to the tensile curve characteristics of PVC coated fabrics,the nonlinear damage constitutive model and damage evolution equation of coated fabrics were established,which based on the continuum damage mechanics theory.By compiling the MATLAB program of the constitutive model,the parameters were obtained,and the off-axial tensile curves of coated fabrics were predicted.The model was realized by ABAQUS software.The constitutive model was validated by static loading tests of tensioned membrane structures.It show that the calculation results are in good agreement with the experimental results.There are 102 pictures,18 tables and 116 references in this paper.