We report the investigation of the photovoltaic properties of core-shell GaN/InGaN wires. The radial structure is grown on m-plane {11 ̅00} facets of self-assembled c ̅-axis GaN wires elaborated by MOVPE on sapphire substrates. The conversion efficiency of wires with radial shell composed of thick In0.1Ga0.9N layers and of 30x In0.18Ga0.82N/GaN quantum wells are compared. We also investigate the impact of the contact nature and layout on the carrier collection and photovoltaic performances. The contact optimization results in an improved conversion efficiency of 0.33 % and a fill factor of 83 % under 1 sun (AM1.5G) on single wires with a quantum well-based active region. Photocurrent spectroscopy demonstrates that the response ascribed to the absorption of InGaN/GaN quantum wells appears at wavelengths shorter than 440 nm.