Performance analysis of a directly coupled photovoltaic water-pumping system

The application of a stand-alone directly coupled photovoltaic (PV) electromechanical system for water pumping has increased in remote areas of developing countries. In this work, the performance of a PV-powered dc permanent-magnet (PM) motor coupled with a centrifugal pump has been analyzed at different solar intensities and corresponding cell temperature. The results obtained by experiments are compared with the calculated values, and it is observed that this system has a good match between the PV array and the electromechanical system characteristics. Through manual tracking (i.e., changing the orientation of PV array, three times a day to face the sun) the output obtained is 20% more compared to the fixed tilted PV array. It has been observed that the torque-speed curve at low solar intensities for a PV electromechanical system should be steeper than at higher solar intensities, and the load torque-speed curve should be as steep as possible in the operating region with low starting torque. The performance analysis will be helpful to select the suitable PV electromechanical system for water-pumping applications.