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Chapter
11
PHOTOVOLTAIC
WATER PUMPING
SYSTEM
COMPONENTS
11.1 INTRODUCTION
Water pumping is essential world-wide for numerous purposes, including irrigation,
stock watering, village water supplies and domestic use. An estimated 1.2 billion
people do not have access to clean water (von Aichberger, 2003). However, the
pumping of groundwater can be done sustainably only to the extent that the extraction
rate equals the aquifer’s replenishment rate. Otherwise, a lowered water table leads to
dry wells, and ecological and social damage (Pearce, 2004). Harvesting rainwater can
be a better option in many cases. A wide variety of power sources are used for
pumping, depending on local conditions. The advantages and disadvantages of many
of these alternatives are listed in Appendix F.
Water pumping applications can vary widely, both in their requirements and in the
conditions under which the pumping must take place. Considerable variability exists
in volumes of water required, timing of water requirements, water source capacity,
depth from which it is to be pumped, replenishment rates of the source, seasonal
variability of static head, bore or well diameters, and solar insolation characteristics.
For instance, water pumping from a river for irrigation normally has no immediate
problems with the water source capacity or replenishment rate, although over-
exploitation can occur, and usually involves relatively low static heads. In
comparison, in some terrains deep bores are necessary and may be characterised by
low water capacities, slow replenishment rates, large seasonal variations in water
