Comparison of iterative and fuzzy logic based Maximum Power Point Tracking (MPPT) algorithms

Voltage – current characteristics of photovoltaic (PV) generators rely on many auxiliary conditions as irradiance, temperature or load profile. Independently on the type of installation (stand-alone, grid connected, hybrid) a solar panel generation system should always be operated at it's maximum electrical power point under defined conditions. Many algorithms have been proposed as maximum power point seeking techniques. A comparison of two methods is described considering an iterative approach and a fuzzy logic controller. Both dynamical properties and tracking accuracy are analyzed based on laboratory experiments and measurements led on an exemplary installation. In addition a misinterpretation avoidance apparatus is proposed for flat-topped power characteristics under partial shading or low irradiance. Power electronic system is described as well as the control system prototype based on a fixed-point microcontroller. Measurement results are presented and conclusions are given.