Polymer-based solar cells consisting of ZnO nanorods and poly(1-methoxy-4-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) are investigated by current−voltage characterization and intensity modulated photovoltage spectroscopy (IMVS). The high quality ZnO nanorod arrays were prepared by electrodeposition, in which the length (Ln) and the concentration of deep level defects of ZnO nanorods were controlled by deposition time (Td). Results show that increasing Td leads to ZnO nanorods with linearly increased Ln but differently increased defect concentration for the MEH-PPV/ZnO solar cells, providing a peak device power conversion efficiency of 0.34% at AM 1.5 illumination (100 mW/cm2) for Td = 10 min. The electron lifetimes in MEH-PPV/ZnO nanorod devices at open circuit were studied by means of IMVS for the first time, and the influences of Ln and defect concentration on the charge recombination kinetics and device performance were revealed. It is found that, in the MEH-PPV/ZnO devices with high quality ZnO nanorods with rather low defect concentration, both photocurrent and recombination rate are mainly dependent on the Ln value as a result of the exponential attenuation of incident light intensity in the device, but the open circuit voltage Voc is more sensitive to the defect concentration. The present study provides new insights into designing the nanostructures for the hybrid photovoltaic devices based on vertically aligned one-dimensional nanoarrays.