The fluid flow characteristics and heat transfer in triangular duct solar air heater (SAH) have been studied experimentally and numerically for Reynolds number range from 4000 to 18,000. In the present paper, three different models of triangular duct solar air heater were considered, namely, model 1 with simple triangular duct, model 2 with rounded corner on one side of the triangle with fixed radius of curvature of 0.39 times the duct height as flow passage, and model 3 with rounded corner on one side of the triangular duct with roughness on the absorber plate of SAH. The absorber plate and apex angle values are assumed as constant in all the three models of SAH, i.e., 160 mm and 60 deg, respectively. The three-dimensional numerical simulations were performed by discretization of computational domain using finite volume method (FVM) and are analyzed with the help of computational fluid dynamics (CFD) code. Experiments were performed to validate numerical results by comparing absorber plate temperature along the length of the SAH. A detailed analysis of different models of solar air heater was carried out by solving flow governing equations numerically on ansys fluent 12.1. A close match has been observed between the simulated and experimental results of SAH with maximum percentage deviation of approximately ±5% in absorber plate temperature. The rounded apex improves velocity distribution near the corner region and helps in improving heat transfer. In the three studied models of solar air heater, the best performance is observed in the case of model 3.