**1. Introduction**

Due to the higher clean energy demands, many buildings nowadays are equipped with photovoltaic (PV) panels to convert solar radiation into electricity. While solar panels are generally adapted to the structure of a building in the form of façademounted and rooftop-mounted designs, the latter design is widespread. In the case of inclined roofs, the PV panels are installed at a distance on the surface of the roof. The gap between the panels and inclined roof surface is crucial to allow airflow to pass from the gap and cool down the PV from the backside, whether by passive cooling due to the formation of buoyant forces in the gap or forced convective cooling due to wind effects. Cooling of PV panels is crucial as their electrical efficiency and lifetime are adversely affected as they experience higher temperatures [1]. Research conducted by Ritzen et al. [2] on the performance of rooftop-mounted PV modules showed that the efficiency of non-ventilated modules degraded by 86% after 3 years.

Several studies have been conducted to appraise the performance of PV modules under wind or passive cooling effects. Chowdhury et al. [3] performed wind tunnel experiments and CFD simulations under different wind velocities and air gaps. Experiments by Mirzaei et al. [4] showed that higher wind velocities result in higher heat exchanges between the PV panel and airflow and consequently lower PV temperatures. They also suggested installing PV modules in a stepped open arrangement instead of a flat arrangement for better cooling. Lai and Hokoi [5] performed experimental and numerical studies on double-skin façade PVs and reported that the electrical efficiency of ventilated modules was higher by about 16–44% than the nonventilated ones. Within another numerical research, Gan [6] concluded that adequate spacing or gap between the modules and the surface of the wall is required to allow the air to pass and cool down the PVs and avoid the formation of hot spots in panels.

The current numerical study investigates the impacts of wind direction on the cooling rate of a PV panel installed on the surface of a slanted roof. The slanted structure has been studied in this research as it is a common configuration used in Australia. In the following section, the studied case and the numerical procedure have been explained. Then, the results have been presented and discussed.
