The paper deals with the determination of the optimal control tuning of small Vertical Axis Wind Turbines (up to 10kW), in order to maximize the energy harvesting in urban environment. Because of the highly variable wind speed profiles, it is hard to obtain an optimal set up of the parameters of the system control algorithm. A suitable model including system losses is presented in the paper then, with the aims of maximizing the aerodynamic efficiency of the wind turbine and minimizing the whole system losses, a performance comparison is performed using different control parameters arrangements. Exploiting a precise power flow analysis, the proposed model-based procedure allows us to determine the best tuning configuration of the system.