After analyzing the effect of perforation in a single pass solar air heater in part A, an experimental comparative study was performed on a Double Pass Parallel Flow Solar Air Heater (DPPFSAH) roughened with continuous and perforated multi-V rib roughness. In DPPFSAH, for perforated rib roughness, the gain in Nu/Nus, f/fs, and Thermo-hydraulic performance parameter (THPP) for W/w = 6 are 8.33, 9.09, and 2.97, respectively. While for continuous rib for W/w = 6 the values of Nu/Nus, f/fs, and THPP are 5.93, 10.83, and 1.82, respectively, as compared to the smooth plate. The results strongly support the application of perforation in artificial roughness. [ABSTRACT FROM AUTHOR]