Currently, a significant amount of photovoltaic device cost is related to its requirement of high-quality absorber materials, especially in the case of III-V solar cells. Therefore, a technology that can transform a low cost, low minority carrier lifetime material into an efficient solar cell can be beneficial for future applications. Here, we transform an inefficient p-type InP substrate with a minority carrier lifetime less than 100 ps into an efficient solar cell by utilizing a radial p-n junction nanowire architecture. We fabricate a p-InP/n-ZnO/AZO radial heterojunction nanowire solar cell to achieve a photovoltaic conversion efficiency of 17.1%, the best reported value for radial junction nanowire solar cells. The quantum efficiency of ~ 95 % (between 550 - 750 nm) and short circuit current density of 31.3 mA/cm are amongst the best for InP solar cells. Besides, we also perform an advanced loss analysis of proposed solar cell to assess different loss mechanisms in the solar cell.