The experimental study conducted on a novel frustum roughened solar air heater reveals its thermal performance. This experiment took place on outdoors setup at MANIT, Bhopal. Key roughness parameters included the height-to-base diameter ratio (e/d1), relative roughness pitch (p/e), height (e/Dh), and relative diametral ratio (d1/d2). The primary flow parameter was the Reynolds number (Re), which varied from 2500 to 12,500. The findings indicate that thermal efficiency improves as the Reynolds number increases across all roughness parameters. The highest thermal efficiency, reaching 78%, was observed at p/e = 12, e/Dh = 0.040, e/d1 = 0.75, and d1/d2 = 3.