Gaps and challenges in modelling the structural response of Building Integrated Photovoltaic (BIPV) assemblies in fire conditions

Building integrated photovoltaic (BIPV) systems represent an innovative solution for renewable energy, combining efficiency and sustainability. However, a realistic numerical analysis of the most important phenomena in their multifunctional response is rather challenging. Their structural safety, particularly in fire conditions, requires expensive experiments but could be supported by rather complex numerical analyses, such as Finite Element (FE) thermo-mechanical simulations. In doing so, careful consideration should be spent for the thermo-physical and mechanical characterization of its constituent materials, including the glass covers, the encapsulants, the embedded solar cells and the fixing systems. Among several associated phenomena that can take place when BIPV systems (i.e., facades or roofs) are subjected to accidental loads of typical interest for building structural design, the resisitng and failure mechanisms are a critical aspect to verify. The objective of this study is to numerically assess the potential of FE predictions for the first glass crack detection (i.e., thermal shock) of a given BIPV in fire, and for the study of the expected structural failure mechanisms. A numerical parametric analysis is carried out in ABAQUS, considering possible influencing parameters superimposed to fire. As shown, many critical aspects should be carefully considered in the numerical analysis of similar systems, due to the complexity of the intrinsically associated phenomena. Besides, FE simulations can offer important support for their multidisciplinary assessment, in particular for their structural analysis under unfavourable operational conditions. In this regard, from the study also emerges that (similarly to the consolidated standardized procedures that are used for the analysis of traditional building components in fire conditions) robust performance indicators are needed for the structural evaluation of BIPVs, and these indicators should be efficently calibrated (with the support of a variety of configurations and scenarios of technical interest) to account for their implicit mechanisms.