Influence of Air Layer Characteristics on the Heat Transfer Performance of Photovoltaic Dairy Barn Roofs

To enhance energy utilization efficiency, dairy farmers have increasingly adopted photovoltaic (PV) panels on barn roofs. However, there is currently a general separation between the barn construction and the additional aspects of the PV system. It is unclear to dairy farmers whether rooftop PV panels will have an impact on the dairy barn, particularly on the thermal environment. This study investigated the influence of air layer properties, specifically thickness and ventilation conditions, on the thermal performance of PV dairy barn roofs. Utilizing the harmonic analysis method, the study quantified its dynamic thermal properties. The results demonstrated that increasing the air layer thickness in ventilated roofs decreases heat flux and improves thermal resistance (1.67–2.15 times higher than non-PV roofs). In contrast, sealed air layers exhibit consistently high thermal resistance (up to 3.33 times higher). Optimizing ventilated air layer thickness (0.20–0.30 m) effectively minimizes heat ingress and prevents PV efficiency degradation. These results provide valuable insights for optimizing the design of energy-efficient PV dairy barns, enhancing thermal comfort, and contributing to low-carbon energy solutions in livestock facilities.