<p>A numerical investigation of a solar air heater system (SAHsys) equipped with transverse C-wave-shaped ribs on the absorber plate is presented. Two-dimensional steady-state simulations were carried out under turbulent flow conditions for Reynolds numbers ranging from 3800 to 18,000. The influence of non-dimensional rib pitch (<i>P</i>/<i>c</i>) and rib height (<i>c</i>/<i>D</i>) on the thermal and hydraulic behavior of the system was examined. The governing equations were solved using the finite volume method, and turbulence was modeled using the RNG <i>k</i>–<i>ε</i> model with enhanced wall treatment. The numerical approach was validated by comparison with available experimental data and well-established correlations for smooth ducts. The results show that the presence of C-wave-shaped ribs promotes flow separation and recirculation, leading to enhanced convective heat transfer, accompanied by an increase in pressure losses. The thermal and hydraulic performances were evaluated in terms of the Nusselt number, skin friction factor, thermal performance, and thermo-hydraulic performance factor (THPF). An optimal configuration was identified at <i>c</i>/<i>D</i> = 0.063 and <i>P</i>/<i>c</i> = 21.42, providing a maximum THPF of 1.78 at Re = 3800. In addition, empirical correlations for the Nusselt number and skin friction factor were developed based on the numerical results.</p>