A photovoltaic power conversion system with flat efficiency curve over a wide load range

This paper proposes a modular power conditioning unit (PCU) that is intended to improve light load efficiency of photovoltaic (PV) generation systems. The proposed PCU topology consists of many modules in parallel with lower power rating, rather than a single module with power rating matching with PV panels. The new structure features high efficiency over a wide load range. Equalizing of utilization rate among PCU modules and maximum power point tracking control are presented. A case study of a 5 kW PV system demonstrates the superior efficiency performance of the proposed PCU structure and verifies the control strategy.