Optimum design of a photovoltaic powered pumping system

Abstract Photovoltaic (PV) powered pumping systems are relatively simple and reliable, hence they are applied worldwide. Two conventional techniques are curently in use; the first is the directly coupled technique where a PV array is directly coupled to a d.c. motor-pump group, and the second is the battery buffered PV pumping system where a battery is connected across the array to feed the d.c. motor driving a pump. Recently, a third system is proposed to make use of the advantages of the previously mentioned conventional systems. It is the switched mode PV powered pumping system. The switched mode PV powered pumping system couples the pumping system to the PV array directly when the storage battery is fully charged as explained in Ref. [5]. The objective of such a system is the maximum utilization of available solar radiation to minimize the cost per pumped cubic meter from a given water depth. For a given location, four main parameters affect the design of this system; (1) d.c. motor-pump group parameters, (2) PV array size, (3) battery storage size and (4) water storage tank size. The system designer has to determine the previously mentioned four parameters so that the minimum cost per pumped cubic meter is achieved. It is found that some factors are more effective in reducing the cost than others. The PV array size is the predominant factor, while the battery storage and water tank sizes have relatively less effect. The system installation cost is considered in the detailed economic analysis discussed in this work.