In this Work, control strategies are proposed for photovoltaic systems connected to the DC load. The solar panel is connected to DC load through power converters. Control methods of perturb and observe (P&O)-proportional-integral (PI) MPPT control of photovoltaic generator (PV generator) are developed. Simulation results under different environmental and operating conditions are presented and discussed to verify the satisfactory performance of the developed P&O based PI MPPT control.