An ultra-efficient maximum power point tracking circuit for photovoltaic inverters

This paper deals with a new ultra-efficient circuit for the individual maximum power point (MPP) tracking of an unlimited number of photovoltaic strings. The circuit generates a DC output voltage and can be combined with common DC-AC solar inverter circuits. The necessary blocking voltages of the transistors are far below the maximum string voltages, which yields to low losses and small passive components. An appropriate controller structure is developed and a prototype is built up, that reaches a maximum efficiency of 99.85 percent.