Maximum power point tracking (MPPT) techniques are used in photovoltaic systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panel's temperature and irradiance conditions. The issue of MPPT techniques has been addressed in different literature. Among all these strategies, maximum power point tracker based on single variable are recently had a great attention due to its simplicity and ease in implementation than the other tracking techniques. In this paper a variable step size based on single current sensor MPPT has been proposed. The proposed algorithm automatically adjusts the step size to track the array maximum power point (MPP). Compared with the conventional fixed step size method, the proposed algorithm can effectively improve not only the steady state performance but also the dynamic response of the PV system. Detailed analysis and the flowchart of the suggested algorithm are included. PSIM simulation results and experimental results are also provided to highlight the usefulness of the scheme.