Page 256 - Applied Photovoltaics
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Chapter
12
PV WATER PUMPING
SYSTEM DESIGN
12.1 INTRODUCTION
Considerable emphasis in this book is placed on the design of photovoltaic water
pumping systems, firstly because water pumping is a major application for
photovoltaics and secondly because the design of each system is considerably more
complicated than most applications, owing to the large range of water source types,
consumer requirements and system configurations. Where batteries are required for
storage, design procedures are relatively straightforward and follow the design
principles outlined in earlier chapters for stand-alone systems. However, direct
interfacing between photovoltaic panels and the water pump motor introduces
significant mismatch problems as the light intensity varies. This leads to large
variations in overall system efficiency throughout each day and between ‘sunny’ and
‘cloudy’ weather, making it inappropriate to assume that the power delivered to the
load is directly related to the light energy incident on the solar panels. It is therefore
necessary to process insolation data differently for directly-coupled systems. The
basic design principles are covered in this chapter, with worked examples given in
Appendix H.
