III-V semiconductor nanowires behave as optical antennae because of their shape anisotropy and high refractive index. The antennae like behavior modifies the absorption and emission properties of nanowires compared to planar materials. Nanowires absorb light more efficiently compared to an equivalent volume planar material, leading to higher short circuit current densities. The modified emission from the nanowires has the potential to increase the open circuit voltage from nanowire solar cells compared to planar solar cells. In order to achieve high efficiency nanowire solar cells it is essential to control the surface state density and doping in nanowires. We review the physics of nanowire solar cells and progress made in addressing the surface recombination and doping of nanowires, with emphasis on GaAs and InP materials.