Solar Air Collector is an apparatus that can be applied to convert solar radiation to be thermal energy. To increase the thermal efficiency of solar air collector, modification is needed by constructing the absorption area wider using v-corrugated plate absorber and adding prismatic triangle fin. Experimental sets to test the effect of fin addition to solar collector's performance and efficiency. The experiment uses v-corrugated absorber plate and 30°bill shaped obstacle with fin addition. The geometry of the fins is prismatic triangle fin. Fin thickness of 3 mm, with 0.5L, spacing between the obstacle and fin angle to air flow 67.5°. Intensity of radiation are varied from 431; 575; 719 W/m2 respectively, and mass flow rate are varied from 0.002; 0.004; 0.006; 0.008 kg/s, respectively. The result of experimental study, the highest efficiency is 92.6% achieved by 0.008 kg/s mass flow rate and radiation intensity 431.372 W/m2.