Standalone direct pumping photovoltaic system or energy storage in batteries for supplying irrigation networks. Cost analysis

Abstract

Solar photovoltaic systems have become one of the most popular topics in the water management industry. Moreover, irrigation networks are water- and energy-hungry, and utility managers are likely to adapt water consumption (and consequently energy demand) to the hours in which there is energy availability. In countries such as Spain (with high irradiance values), solar energy is an available green alternative characterised by zero electricity costs and significantly lower environmental impact. In this work, several types of irrigation scheduled programmes (according to different irrigation sectors) that minimise the number of photovoltaic solar panels to be installed are studied; moreover, the effects of the variable costs linked to energy (energy and emissions costs) are presented. Finally, the effect of incorporating batteries for storing energy to protect the system against emergencies, such as unfavourable weather, is proposed. The irrigation hours available to satisfy water demands are limited by sunlight; they are also limited by the condition that the irrigation schedule type has to be rigid (predetermined rotation) and that the pressure at any node has to be above minimum pressure required by standards. A real case study is performed, and the results obtained demonstrate that there is no universal solution; this is because the portfolio of alternatives is based on investments for purchasing equipment at present and also on future energy savings (revenues). Apart from these two values, there is an economic value (equivalent discontinuous discount rate), which also influences the final results.