We measure the Seebeck coefficient S in large arrays of lightly doped n-Si nanowires (SiNWs). Our samples consist of ∼107 NWs in parallel, forming a “bulk” nano-structured material. We find that the phonon drag component of S, a manifestation of electron-phonon scattering in the sample, is heavily suppressed due to surface scattering, and that there is a “universal” temperature dependence for S. Furthermore, at room temperature, S is enhanced in the arrays by up to ∼3 times in comparison to bulk Si.