Numerical Analysis of the Thermal and Mechanical Performance of Photovoltaic Supports with Rainwater Harvesting

The increasing demand for sustainable infrastructure has encouraged the development of multifunctional engineering solutions capable of simultaneously addressing renewable energy production and efficient water management. In this context, photovoltaic support structures provide an opportunity to integrate rainwater harvesting without requiring additional land occupation or independent collection systems. However, incorporating drainage functions into cold-formed steel support members may influence both their mechanical behavior and thermal response, requiring a comprehensive assessment of the proposed solution. This paper presents complementary numerical investigations into the mechanical and thermal behavior of a photovoltaic support system incorporating rainwater harvesting. The mechanical investigation focuses on a full-scale ground-mounted steel support structure in which conventional secondary members are replaced by cold-formed omega profiles acting simultaneously as photovoltaic module supports and longitudinal rainwater collection channels. Three-dimensional finite element analyses and structural verification procedures are employed to assess the global load-transfer mechanism, stresses, displacements, and compliance with the relevant Ultimate Limit State and Serviceability Limit State requirements. The thermal investigation addresses a representative cold-formed steel profile subjected to realistic outdoor environmental conditions. A sequential ANSYS Fluent-Mechanical framework is adopted, combining a calibrated Solar Ray Tracing model with transient heat-transfer analyses accounting for short-wave solar radiation, long-wave thermal radiation, and convection. The numerical thermal response is assessed against temperatures recorded during an experimental monitoring campaign. The mechanical analyses demonstrate that the rainwater harvesting functionality can be incorporated without compromising the global structural performance of the photovoltaic support system when the structural members are appropriately designed. The thermal model accurately reproduces the mean temperature evolution of the monitored profile, while also highlighting the development of transient and spatially non-uniform temperature distributions. Together, the two investigations demonstrate the structural feasibility of the proposed multifunctional support concept and establish a sound basis for future fully coupled thermo-mechanical analyses under realistic environmental and structural loading conditions.