Power production of a wind turbine system is strongly dependent on both the wind regime at the site and the operating parameters of the wind turbine (design parameters). In order to evaluate the performance of a wind turbine in a given location, an accurate estimation of the turbine's Capacity Factor (CF) is required. This parameter shows the degree of match between the characteristics of the turbine andthe wind patterns on the site. In this paper, four widely used empirical models are presented and compared using the method of bins, which is based on the manufacturer-provided power curves. The generic models considered in this paper are Linear Model (LM), Quadratic Model (QM), Cubic Model (CM), and General Model (GM). The validity of these models was investigated using a case study of four locations across Morocco which are namely: Tetouan, Essaouira, Taza and Ouarzazate. Four small scale wind turbines presenting different ranges of characteristic speeds and rated powers (10 kW, 20 kW, and 50 kW) were used to conduct the comparative study. From the obtained results, the recommended models are the Quadratic and the Cubic models. These two models present a good description of the turbines' power curves.