An innovative electronic system for testing the performance of wind turbines is presented. The main goal of the system is to increase the accuracy in the measurements of torque and speed for each steady-state point of the turbine characteristic power curve. Another useful advantage provided by the electronic control is given by the possibility of fine timing the load in order to obtain a large number of steady state experimental points describing the characteristic curve of the turbine. Moreover the system is suitable for integration into an automatic data acquisition and control system. In the paper the main characteristics of the electronic system are described and compared with a traditional system. This electronic control system is used for testing a small Vertical Axis Wind Turbine in a wind tunnel. The wind turbine is directly coupled to a direct current electric generator and a chopper, electronically controlled by means of a Pulse Width Modulator is used to supply the circuit. The electric generator is used for braking the wind turbine at various speeds during the performance test. The experimental results obtained through the proposed system are presented and discussed.