In this paper a power management strategy for the stand alone PV based system for water pumping is proposed. The mentioned system is practical for off-grid rural areas. The main part of the system includes PV panels, three phase induction motor and the battery. PV panel voltage is delivered to the inverter by a boost converter. For the battery charging and discharging a simple bidirectional converter is used. Efficiency optimization of these systems is very important. In this paper the efficiency of motor in light loads is increased by Rosenbrock method. Also, the PV maximum power point Tracking (MPPT) is done by perturb and observe (P&O) algorithm. The mentioned system is evaluated under different conditions. This paper proposed a control strategy for power management. Simulation results, using MATLAB/SIMULINK, confirm the validity of the system, and verify MPPT, DC link voltage regulation and optimal charging/discharging of the battery.