The growth of ZnO nanowires (NWs) on a zinc oxide (ZnO)/textured crystalline-Si (c-Si) photovoltaic device via the hydrothermal method is investigated. The average length and diameter of the ZnO NWs are around 0.65μm and 70–100nm, respectively. Experimental results indicate that a ZnO/textured c-Si photovoltaic device with ZnO NWs has the lowest reflectance among the tested substrates, especially in the range of ultraviolet (UV) and green light (350nm to 590nm). Compared to SiNx/textured c-Si and ZnO/textured c-Si photovoltaic devices, the proposed device exhibits photovoltaic conversion efficiency improvements of around 7% and 6.3%, respectively. After encapsulation, the ZnO NWs/ZnO/textured c-Si photovoltaic device has the lowest drop in conversion efficiency. Furthermore, a small NW diameter increases light absorption.