Photovoltaic (PV) devices based on arrays of silicon wires with diameters in the nanometer to micron range have sparked considerable interest due to their attractive light trapping characteristics and the prospects to enhance carrier collection in radial junction structures. This chapter reviews fabrication techniques, design and testing considerations, and the PV performance of silicon wire devices. Common bottom-up and top-down wire fabrication methods are initially reviewed including vapor–liquid–solid growth, metal-assisted chemical etching, and deep reactive ion etching. Design considerations for wire array solar cells are discussed such as the impact of wire array geometry on light absorption and the effects of wire diameter and doping on PV performance. Device results for three common wire junction geometries are then reviewed including radial and axial junction wire structures and planar junctions with nanowire surface texturing. Methods to form radial junctions in silicon wires are compared such as the use of an electrolyte, thermal diffusion of dopants, and wire-coating techniques based on chemical vapor deposition. Applications for nanowire texturing of silicon monocrystalline and multicrystalline cells are described. The advances in device design and processing have resulted in continual improvements in the PV performance of silicon wire array devices to the point where efficiencies ranging from ~ 10% for radial junction cells up to as high as 22.1% for nanowire-textured devices have been reported.