Investigation of ventilation and thermal performance of monitor roofs equipped with internally mounted PV-powered fans

• Numerically examines how PV-powered internal fans affect monitor-roof ventilation. • Fan assistance markedly enhances ventilation performance under low-wind conditions. • Presents a resilient hybrid ventilation concept integrating PV power and battery storage. • Provides PV–battery sizing and fan-operation guidance for hybrid monitor roofs. This study aims at improving the ventilation performance of a monitor roof by integrating renewable energy applications. Photovoltaic-powered fans are incorporated into the design, and Computational Fluid Dynamics (CFD) simulations are employed to systematically evaluate their impact on natural ventilation effectiveness. The monitor roof is 1.2 m wide and 1.2 m high, with an eave overhang length of 0.3 m. Twenty inner fans are installed on the central axis of the horizontal opening of the monitor roof. The flow area of each inner fan is set to be 0.3 × 0.3 m or 0.6 × 0.6 m. The fan operates with outlet wind speeds of 0.5 m/s and 2 m/s. A power-law exponent of 0.143 is applied to represent the approaching wind profile over open terrain. The prescribed velocity range (0.01–3 m/s) corresponds to the reference wind speed at a height of 10 m. The results show that, under low wind speeds or no wind conditions (such as sweltering summer mornings or nights), the installation of inner fans on the monitor roof can enhance ventilation. Detailed descriptions of the basic flow patterns of key cases and design suggestions for solar PV power systems that meet the requirements of common usage modes are provided.