We report the performance of Silicon Nanowire Arrays (SiNWA) with two different lengths (30 m and 50 m) for both p- and n-type Si(100) as a material applied for thermoelectric power harvesting, followed by comparing the recorded performance to that bulk Si. Heat flow from top to the bottom Cu sheet had noticeably decreased in SiNWA samples, resulting in a higher temperature difference, T and Seebeck voltage, Voc than in bulk Si. The results suggested that both p- and n-type SiNWA samples (50 m) have achieved 100 and 80% increase in T, respectively, relative to the bulk Si.