Economic Sizing of a Water Pumping System Powered by an On-Grid Photovoltaic System

Objective: The objective of this study is to propose complementary sizing techniques to increase the economic efficiency of water pumping systems. Theoretical Framework: This study is based on cost analysis using the trial and error method for the economic sizing of water pipelines, on the Bresse equation as an initial diameter estimate, on the standards of regulatory agencies and energy distributors on pricing, supply and distributed generation, and on the integration of power factor correction and photovoltaic systems as techniques to reduce operating costs and increase energy efficiency. Method: The methodology was used in three main stages: application of the trial and error method for the economic sizing of the pipeline, based on speed ranges and calculation of the total annual cost; sizing of an on-grid photovoltaic system to supply part of the energy demand and estimate savings and payback; and power factor correction, with sizing of a capacitor bank, to reduce electrical losses and improve energy efficiency. Results and Discussion: The economic dimensioning resulted in the selection of a PVC pipeline with a nominal diameter of 150 and a motor pump with a power of 75 hp. It was found that the cost of electricity represents the largest portion of the total annual cost, corresponding to 79% of the value. In order to reduce this cost, an on-grid photovoltaic system capable of supplying 43% of the energy consumed was dimensioned. Induction motors used in motor pumps need to have their power factor corrected to avoid fines on the electricity bill. The installation of an on-grid photovoltaic system also causes a sharp drop in the installation's power factor. Power factor correction also contributes to energy efficiency and the quality of electricity. Considering an annual interest rate of 12% and a system lifespan of 20 years, the viability of electricity generation and power factor correction was proven by the reduction in the total annual cost of 14.7% and the payback period with a discount of 3.09 years Research Implications: The results demonstrate the economic viability of investing in on-grid photovoltaic systems. The alternative sizing techniques proposed in this research can be applied both in the design of new systems and in the renovation of existing systems, with the aim of maximizing economic efficiency. Originality/Value: The sizing of water pumping systems is a multidisciplinary activity that requires the association of hydraulic, economic and electrical concepts. Considering that the cost of electrical energy represents the largest portion of the total annual cost of operation, the adoption of techniques such as power factor correction and the sizing of on-grid photovoltaic systems becomes essential for economic optimization. However, the literature does not yet comprehensively cover the simultaneous use of these approaches in the context of the sizing of these systems.