We carried out experimental and simulative investigations of the electrical and optical characteristics of radial p-n junction Si microwire (MW) array solar cells (diameter: 4 mu m, height: 12 mu m, and period: 12 mu m) prepared by electroless etching (EE) methods. Due to its unique geometry, the MW array had an enlarged junction area, enabling efficient carrier collection and optical reflectance in the wavelength range from 400 to 1000 nm, which is lower than that of its planar counterpart. Despite these advantages, the energy conversion efficiency (CE) of the MW array solar cell (3.2%) was lower than that of a planar solar cell (4.2%). This comparative study clearly reveals the inherent potential of MW-based solar cells and the importance of extrinsic trap state control to realize low-cost, high-efficiency devices. (C) 2012 Elsevier B.V. All rights reserved.