The research explores the characteristics of heat transfer and fluid flow in a solar air heater (SAH) duct, where transverse inverted-Y-shaped ribs are used. The study's key findings regarding friction factor, Nusselt number, and visualizations of flow parameters within the SAH are presented. To predict the heat transfer rate in rectangular SAH, the analysis incorporates various dimensionless parameters, such as relative roughness pitch (P/e), and Reynolds number (Re). This study examines a range of relative roughness pitch values (9.4 to 25.86) and Reynolds numbers (5243 to 18,000) with variation in relative roughness height. A two-dimensional computational domain features an aluminum absorber plate with a uniform heat flow of 1000 W/m2. The study significantly improves heat transfer by incorporating an inverted Y-shaped ribbed absorber plate in SAH. This indicates a substantial enhancement in the overall efficiency of heat transfer within the solar air heater.