Thermal and mechanical evaluation on integration of GFRP and thin-film flexible PV cells for building applications

Building-integrated photovoltaics (BIPV) are multifunctional building components using exterior surfaces not subjected to structural loads to generate electricity by solar cells; while a few types of PV cells with higher flexibility have shown potentials to extend the application of BIPV components to load-carrying scenarios. In this paper thin-film flexible amorphous silicon (a-Si) PV cells and organic PV cells are adhesively bonded to glass fibre reinforced polymer (GFRP) sections to develop BIPV integrations. Such integrations and GFRP sections are then exposed to artificial sunlight with various intensities from 200 to 1000 W/m². An approximate linear increase in the surface temperature with the sunlight intensity is observed and quantified, and such thermal responses are also explained by thermomechanical analysis. Open-circuit voltage (V_OC) of the integrated a-Si PV cell decreases almost linearly at 0.40% for an increase of 1 °C until the maximum temperature (91.5 °C) in the experiments; while V_OC of the integrated organic PV cells decreases at 0.12% for an increase of 1 °C first until a significant degradation occurred at 78 °C. Such GFRP sections with PV cells are further examined under tensile or compressive loadings. The tensile results show that both types of PV cells can normally function up to GFRP breakage at about 1% strain. However, in compression, obvious decreases in V_OC are witnessed when a compressive strain of 0.23% on average is reached for the integrated a-Si PV cells. Such a critical compressive strain for the integrated organic PV cells is 0.25% on average.