Sizing optimisation under irradiance uncertainty of irrigation systems powered by off-grid solar panels

Abstract

Sizing a photovoltaic installation is crucial for decision-makers, researchers and practitioners managing pressurised irrigation networks powered by solar panels. Photovoltaic off-grid installations offer energy efficiency, lower operation costs, environmental benefits and economic profitability. Network managers must strategically account for the energy limitations of solar installations when irrigating. Moreover, the manager has the challenge of synchronising energy production with the energy consumption of the pumping equipment that supplies water to crops. We propose a technique to optimise the sizing of photovoltaic installations to maximise energy consumption in pumps, thereby meeting the water demands of crops while considering the uncertainties associated with non-clear sky conditions. This approach enhances the management of installations and can schedule the opening and closing of hydrants and irrigation intakes to supply water to crops efficiently. Finally, a real case study in the University of Alicante irrigation network was conducted for two scenarios. The first is to calculate irradiance and the electrical production curve using a theoretical model (very close to reality in latitudes like Alicante, Spain). Real data obtained from a nearby meteorological station is used for the second scenario. In both cases, non-clear sky conditions are considered to establish a relationship between the probability of clear sky ($\alpha$=1) and the minimum number of PV modules (537 or 509 for the theoretical model and real data, respectively). For days without direct normal irradiance ($\alpha$=0), the minimum number of modules is 2145 and 991. Practitioners or decision-makers must find a compromise that meets water demands while minimising the size of the installation.