Influence of power converters on PV maximum power point tracking efficiency

Photovoltaic maximum power point tracker (MPPT) systems are commonly employed to maximize the photovoltaic output power, since it is strongly affected in accordance to the incident solar radiation, surface temperature and load-type changes. Basically, a MPPT system consists on a dc-dc converter (hardware) controlled by a tracking algorithm (software) and the combination of both, hardware and software, defines the tracking efficiency. This paper shows that even when the most accurate algorithm is employed, the maximum power point cannot be found, since its imposition as operation point depends on the dc-dc converter static feature and the load-type connected to the system output. For validating the concept, the main dc-dc converters, i.e., Boost, Buck-Boost, Cuk, SEPIC and Zeta are analyzed considering two load-types: resistive voltage regulated dc bus. Simulation and experimental results are included for validating the theoretical analysis.