Operation analysis of photovoltaic modules with partially connected DC-DC converters

DC-DC converters are commonly used as an interface between a photovoltaic (PV) module and a load because the characteristics of PV modules vary with environmental conditions. In a conventional system, all the power extracted from the PV modules is transferred through the converter with an efficiency penalty; thus, the converter must operate as efficiently as possible. This paper proposes a novel PV system in which a dc-dc converter is partially connected to series-connected PV modules. Only part of the generated power is delivered via the converter, and the rest is directly transferred to the load. Thus, the total efficiency can be higher than that of a conventional system. The operating principles of the partial converter and PV modules and an optimum design procedure are presented. Experimental tests were performed on both the conventional and proposed systems with the same buck converter to demonstrate their operating characteristics and total efficiency performance. The results showed that the proposed system could realize a higher total efficiency, and high utilization of the PV modules was also achieved by the optimum design procedure.