ENERGY  ALTERNATIVES: RENEWABLE
ENERGY AND ENERGY CONSERVATION
TECHNOLOGIES



  (b)  Solar Pumps :
  Recent  technological  progress  makes solar energy for water 
  lifting,  in  the  100-800 W  range, a realistic option under 
  certain  conditions.  The  solar  pump  system  consists of a 
  photovoltaic  array, a motor  and a pump.  Particularly,  the 
  pump efficiencies have been improved up to 65 to 70  per cent, 
  and the overall costs have been reduced. Typical applications 
  are irrigation of  landholdings up to two hectares with 60 m3 
  of water  per  day through  static heads of 2 to 10 m, or the 
  supply of some 20 m3 of drinking water per day through static 
  heads of  10 to 30 m  for a  village of  up to  1,500  people.  
  However, solar pumps are still expensive,  which implies that 
  this  technology is attractive only when alternatives (diesel, 
  wind, etc.) are lacking. Investment costs are still such that 
  pay back periods may exceed 5 years. It is expected that in a 
  few  years  time the  costs will  fall  further so as to make 
  solar pumps more competitive among prevailing alternatives.