Photovoltaic powered pumps are becoming popular. Their operation differs from that of the AC Mains powered pump, as they work under varying input power conditions. The efficiency figures of different subsystems will keep changing due to varying solar radiation conditions, causing the variations in overall efficiency under partial load operating conditions of the pump. The aim of this work is to study the performance of the various subsystems under these operating conditions. The system developed here consists of a Photovoltaic (PV) array of 900 Wp with 72 V nominal DC bus, a DC to DC Converter, a Variable Frequency Drive (VFD) and a three phase induction motor driven submersible pump. Maximum Power Point Tracking (MPPT) algorithm has been developed and implemented to maximize the use of PV power generated at any given instant. The system was installed and tested at Indian Institute of Technology Madras in Chennai, where daily average Peak Sun Hours is 5.6. Ambient temperature, total pressure head, water flow and power levels at different points starting from the output of the PV array upto the electrical power equivalent of water delivery were determined under varying solar radiation levels from sunrise to sunset. Continuously varying power efficiency figures of the subsystems were determined and power budget prepared. Wire to Water Energy Efficiency figures as well as System Performance Indices were determined. © 2013 IEEE.