With the cost decreasing of photovoltaic (PV) system, the conversion of solar energy to electric energy is increasing becoming economical. In order to increase the efficiency of PV system, it is generally used dynamic sun-tracking system. The goal of the dynamic sun-tracking system is to make PV plates face the sun directly for capturing the maximum irradiation and promoting the system efficiency. This paper presents a dynamic tracker that has an active control strategy of a two-axis sun-tracking system. This control strategy is able to follow the sun with high accuracy without the necessity of either a precise procedure of installation or recalibration. The paper focuses on the analysis and control of hybrid stepper motors to operate in full-step mode with average torque higher than that obtained in classical full-step mode. This has been achieved using the idea of a half-step firing technique. This overcomes the instability associated with half-step mode. The control strategy is executed using a microcontroller and the simulation results are given to verify the validity
and reliability of the proposed active sun-tracking system.