Metal oxide (MO) semiconductors hold the promise for the development of high efficiency solar cells with low cost. Currently heterostructure type MO solar cells have been theoretically and experimentally studied, demonstrated their potential for applications. This paper highlights a numerical investigation on Schottky type MO solar cells using CuO as the absorption layer. It is shown that the doping concentration, absorption layer thickness, barrier height and back surface field have significant effects on the performance of the devices. Under the optimal structure and doping, the Schottky barrier solar cells, if can be fabricated with suitable techniques, can have a conversion efficiency up to 18.5%, comparable to MO heterojunction solar cells, but at a much simpler structure and lower cost. Some guidelines about the materials selection and structure design for MO Schottky barrier solar cells are summarized.