Optimization of an isolated photovoltaic water pumping system with technical–economic criteria in a water users association

Abstract

With proper management, the modernization of irrigation systems makes it possible to improve the efficiency of application and use of water at the cost of an increase in pumping needs and, therefore, an increment of the energy consumed. The recent drastic price increase for energy put the viability of many farms at risk. In this context, using photovoltaic solar energy to power pumping stations has become an increasingly attractive alternative and a cheap and reliable option. The dimensioning of pumping systems powered by photovoltaic solar energy must be done considering the variability of solar radiation to take advantage of the available photovoltaic energy, especially during periods of less irradiation. By investigating a particular case, this paper studies the effect of increasing the number of pumps in parallel while maintaining the total power, as well as the relationship between the installed photovoltaic capacity and the power of the pumping system, to meet pumping requirements throughout the year. The pumped volume increased as the number of pumps installed in parallel increased for the same photovoltaic power generator. Although this increment has a limit, beyond which no greater significant rise in volume is achieved, installation costs increase. In addition, for the same pumping power installed, the required photovoltaic generator power decreases as the number of pumps in parallel increases. In the case studied, a 27% increase in the annual pumped volume was achieved by incrementing the number of pumps in parallel from one to five, thus leading to a 44.1% reduction in the size of the photovoltaic generator and a 13.3% reduction in the cost of installation compared with a system with only one pump. The procedure used to determine the most appropriate number of pumps to install in parallel when pumping water between two tanks, which minimizes the photovoltaic generator's size while guaranteeing pumping requirements, is easily generalizable for sizing isolated photovoltaic water pumping systems.