ABSTRACT Heat transfer augmentation of counterflow double-pass (DP) solar air heater (SAH) was investigated experimentally. Best artificial roughness was selected from previous work and it experimented with porous screen matrix of different porosity range from 0.74 to 0.9. Counterflow DP arrangement gives the best results with the combination of porous screen matrix. Correlations for Colburn factor, Nusselt number, friction factor, and thermal efficiency were developed over a wide range of geometrical configurations of porous media, i.e. wire diameters ranging from 1.06 to 1.4 mm, pitch ranging from 2.54 to 3.01 mm, and layer count ranging from 2 to 9. Correlations have been discovered to predict experimental values accurately.