Solar Water Pumping Systems: A Tool to Assist in Sizing and Optimization

The United Nations estimates that about 25% of the earth's population will live in countries where access to water will be a recurrent problem by 2025. This article proposes a methodology and open-access software tool for rural off-grid communities and users with little knowledge about solar photovoltaic water pumping systems (SPVWPS) to provide access to safe water for consumption. The proposed methodology assists in all stages of the project: conducting a prefeasibility study, sizing and optimizing, maintenance and financial analysis. It includes components selection, optimal dimensioning of the SPVWPS, behavior prediction, yearly distribution of the water shortage probability (WSP) and a basic financial analysis. The tool suggests a water tariff to help ensure the project's financial viability. The most interesting findings of this research is that the size - hence the feasabilty - of a project depends mostly on the population tolerance to water shortage. The concept of water shortage probability (WSP) is introduced to help in defining the appropriate size and cost of the systems. This WSP is calculated for each day of the year. A comprehensive literature review is presented and two case studies were used to validate its potential. It is found that only about 10% of the total energy produced by the PV modules is effectively used to fulfill the water needs.