Numerical Investigation on the Thermo-Mechanical Performance and Structural Mechanisms of Glass–Glass PV Modules in Standard Fire Conditions

Abstract

The use of glass–glass photovoltaic (PV) technologies for building integrated (BIPV) solutions is continuously increasing in constructions, for several positive aspects. Besides, the optimal design of these new multi-functional components requires the technical knowledge of several experts, due to the combination of electrical, structural-mechanical, and architectural needs, and others. In parallel, methodologies in support of design should be specifically elaborated to account for the intrinsic features of PVs. Structurally speaking, the glass covers are expected to sustain ordinary and accidental actions that are typical of buildings, including superimposed thermal and mechanical loads. Often, this task is more challenging as a consequence of architectural needs that promote the use of a reduced number of mechanical fasteners to preserve high aesthetic levels. Extreme scenarios such as fire events, in this context, represent one of the critical conditions to verify. This study presents an in-depth assessment of glass–glass PV performances in fire, with a careful consideration for the analysis of the expected resisting mechanisms and load-bearing capacity. A primary advantage is taken from the use of Finite Element (FE) numerical models validated to literature. As an example, a 400 × 400 mm glass–glass PV with metal point-fixings is investigated under standard fire exposure, accounting for the effect of possible superimposed mechanical loads. Compared to structural needs under ordinary loads, the fire performance is highly demanding and requires appropriate modeling assumptions, as well as sound performance limits. The thermo-mechanical response is addressed based on a combination of indicators that are typically used for glass or construction members in fire, such as the temperature peaks and differences, the associated thermal and mechanical stress peaks, the maximum deflection, and the corresponding deflection-rate. The parametric results, as shown, highlight the vulnerability of glass covers and highlight the lack of robust limit conditions for fire resistance assessment, which would be of rather practical and efficient use but should be properly calibrated for structural safety purposes.