Aspects of solar water pumping in remote regions

Abstract

Solar water pumping is applied on an increasing scale where other energy sources are not available. For cost reasons, the range within which solar photovoltaic (PV) pumps present a viable alternative is limited. Most pumps installed operate in the range of a few hundred watts to some kilowatts; the demands of economic viability become more stringent for larger systems. Thus, this paper deals with the benefits and disadvantages of solar pumping for applications, preferably, where distances from the grid exceed a few kilometres, and where autonomous operation is practical. Drinking water supply in remote regions, watering of cattle or drainage tasks in low-lying fields present good examples of such appliances. The technique of utilising solar radiation as a source of energy for pumping is described, and means of reaching a satisfactory degree of maturity and reliability are presented. The documentation includes a review of the state of the art of the technology and the basic physical laws controlling energy demand and the performance of water pumping. The importance of efficiency for a satisfactory operation is emphasized, and design methods and procedures to reach a precise prediction of yield explained. As a basis for the assessment, typical characteristics of pumps and motors are presented, and the results confirmed by experimental data from field trials. Last, but not least, the issue of economics is discussed, on the basis of comparison between PV and conventional fossil fuel-powered pumps. High investment costs are identified as the most important limiting factor for more widespread application. Despite this fact, an increasing number of PV pumps have been installed and operated successfully in many countries in the “solar” region. Since in these regions the import of products is often hampered by lack of funds, the issue of local production of components for solar pumps is also discussed.