A Solar Chimney Power Plant (SCPP) consists of three cardinal elements - collector, chimney, and turbine(s). In collector, there can be natural and artificial roughness such as the surface of the earth and the energy storage system, respectively. In this paper, using a three-dimensional simulation, the performance of SCPP with and without artificial roughness has been investigated for the weather conditions of Semnan. Also, the dimensions of Manzanares power plant were considered, and the simulated SCPP, without roughness, was validated based on it. Simulation results reveal that, Semnan (53.23 degrees E, 35.34 degrees N), has a good potential for using SCPP. Without roughness, the maximum power of SCPP was 50.81 kW for April. It is found that the artificial roughness in SCPP improves heat transfer, but reduces velocity; therefore, there is an optimal dimension and location for it. Geometrically, the location of this roughness near the collector entrance has a better performance than other locations, but this change of locations has little impact on the performance of SCPP.