Single nanowire radial junction solar cell devices were fabricated using Si nanowires synthesized by Al-catalyzed vapor-liquid-solid growth of the p(+) core (Al auto-doping) and thin film deposition of the n(+)-shell at temperatures below 650 °C. Short circuit current densities of 11.7 mA cm(-2) were measured under 1-sun AM1.5G illumination, showing enhanced optical absorption. The power conversion efficiencies were limited to < 1% by the low open circuit voltage and fill factor of the devices, which was attributed to junction shunt leakage promoted by the high p(+)/n(+) doping. This demonstration of a radial junction device represents an important advance in the use of Al-catalyzed Si nanowire growth for low cost photovoltaics.