Maximum power point tracking system is widely used to maximise output power of photovoltaic array. A crucial issue of this system is an algorithm of maximum power point seeking. Well–known perturb and observe technique is optimal solution in terms of the ratio of cost and efficiency. However, this algorithm has some disadvantages such as oscillation around a maximum power point and decrease in efficiency occurring under low level of solar irradiance. In this paper, an improved perturb and observe method has been proposed. It is based on combination of conventional perturb and observe and constant voltage algorithms. According to this technique, a simple constant voltage method is implemented in case of low levels of solar irradiations otherwise the system operates under conventional perturb and observe algorithm. A case study described in this paper demonstrates that the total efficiency of proposed method is higher than conventional one, especially in cloudy weather.
Keywords: maximum power point, MPP tracking, MPPT, perturb and observe, constant voltage, photovoltaics, solar energy, solar power, photovoltaic arrays, solar radiation, cloudy weather