This paper examines the effects of applying three Savonius wind turbines with different mounting positions, including lateral spacing, on power coefficients by conducting high-fidelity three-dimensional numerical simulations, i.e., based on the Reynolds-Averaged Navier-Stokes (RANS) method. The first validation case of the single Savonius wind turbine located on the fixed step height, and a flat surface is found to be in good agreement with that reported in the literature. Then the model is expanded to study the performances of three laterally aligned Savonius wind turbines by placing them above a flat surface and a forward facing step. When the three laterally placed turbines are on a flat surface, an increase of approximately 5% of the maximum mean power coefficient is observed compared to that of a single turbine. Next, the effect of implementing the three turbines at different positions on a fixed step is investigated, where the maximum mean power coefficient improvement for the three turbines can be as high as 230%. Finally, the effect of the lateral spacing distance between the two adjacent turbines is examined. It has been shown that there is an optimal spacing if the maximum mean power coefficient is concerned. •Savonius wind turbine is numerically investigated by the three-dimensional aerodynamics simulations.•Installation of such a turbine on a step significantly increases its aerodynamics power coefficient.•Laterally aligned turbines offer further power coefficient gains over an isolated turbine.•Arrayed turbines have an optimal spacing considering the maximum mean power coefficient.