A novel analog maximum power point tracker for low-cost and low-power distributed PV systems

The main disadvantage of the voltage-based maximum power point tracking (VMPPT) method is in the way the photovoltaic (PV) array is disconnected from the load when sampling open-circuit voltage, which inevitably results in power loss. Another disadvantage is in case of rapid irradiance variation, where the duration between two successive samplings is too long, leading to considerable loss. To overcome these problems, this paper proposes a low-cost analog VMPPT circuit that is designed on the basis of an ultralow-power sample-and-hold circuit with the least hardware complexity, which has not been reported before. Furthermore, the method of determining the sampling frequency and time interval of the sampling mode is investigated. Experimental verification with a series of different PV power sources is likewise conducted. The experimental results confirm that the proposed MPPT circuit can operate over a wide range of PV power and can adapt quickly to the changing environment. The disconnection energy loss is reduced significantly, with a high system efficiency of up to 95.9%. (c) 2015 Institute of Electrical Engineers of Japan. Published by John Wiley Sons, Inc