By giving the absorber plate artificial roughness, the efficacy of a solar air heater may be increased. A mathematical study has been performed on solar air heaters roughened with Z-shaped baffles. With the help of MATLAB code, an exergy analysis, estimation of exergetic losses and efficiency have been made. The effect of relative pitch ratio for 45° zig-zag structured baffles with a fixed relative blockage height of 0.3 on various exergy parameters has also been studied. The current study has been done for Reynolds numbers ranging from 3000 to 14 000 and for 1100 W/m² of solar radiation. It is deduced that with the increase in Reynolds number, the effective efficiency enhances up to a certain point, beyond which it begins to decline. Moreover, the pitch ratio of 1.5 has shown the best performance up to the Reynolds number of 5000, while at higher Reynolds numbers, the pitch ratio of 3 has produced better results.