Shading and bypass diode impacts to energy extraction of PV arrays under different converter configurations

A solar photovoltaic (PV) energy conversion system requires power converters for maximum power extraction and grid integration. At present, typical converter configurations used in a solar PV system include central, string and micro-converter based PV systems. In order to develop efficient and reliable photovoltaic energy conversion technologies, this paper compares the energy extraction characteristics of a PV system for different converter schemes. The paper particularly focuses on how energy extraction characteristics of a PV array are affected by uneven shading and how different bypass diode arrangements improve and affect PV system energy extraction characteristics under different converter configurations. A detailed comparison study is conducted for central, string and micro-converter based PV systems. It is found that compared to micro-converter based PV systems, the central converter PV systems with large-scale distributed bypass diode connections could be an economic solution to enhance PV system efficiency, reliability and performance, in particular for utility-scale PV generators.