Page - 48 - in Clean Water Using Solar and Wind - Outside the Power Grid

48 Clean Water Using Solar and Wind: Outside the Power Grid pumping for irrigation is most essential. Pumping, for water supply, reuse and treatment of used water, is typically the major use of electric power in rural areas. Energy consumption is generally the largest cost in the lifecycle costs of a pump system, where pumps often run for more than 2,000 hours per year. To provide electric energy for pumping in rural areas of developing countries is not trivial. However, interesting products based on solar energy are now available. For a small-scale water supply the water distribution pressure can be obtained either by a pump or by an elevated storage where the potential energy can provide the water supply pressure. If contaminated water is treated by desalination, there is a significant need for pumping energy; see 5.3 and 8.5. Any used water treatment or water reuse will use pumping energy (Chapter 7). It is apparent that pumping technology is an essential component of any water system, and having efficient pumping is crucial for any operation. Among the advantages of solar PV pumping there are four often emphasised: unattended operation, low maintenance cost, easy installation and a long life. Both technology and economic viability have been considered in comprehensive literature reviews of solar pumping technology (Chandel et  al., 2017; Sontake & Kalamkar, 2016; Varadi et  al., 2018, Chapter 5.2). The authors have identified factors affecting performance of solar PV pumping systems and the degradation of PV modules as well as efficiency-improving techniques. It has been verified that solar pumping systems are more economically viable than diesel-based systems for irrigation and water supplies in rural, remote and urban regions (IRENA, 2016e). The investment payback time for some solar PV water-pumping systems has been found to be four to six years. This depends of course on local conditions, as shown below. The costs of the systems are significantly different depending on their scale, purpose and configuration. It may be more meaningful to calculate the cost of the energy services provided and compare that to the existing costs that the user will pay for energy services off-grid. 4.2 PUMPING IN DEVELOPING REGIONS The electric energy required for pumping is dramatically illustrated by the situation in India, where nearly 20% of electricity generation Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user