This paper presents the design configuration with the least components to realize highly efficient solar energy battery charger with PWM based voltage controlled buck converter. PWM power converter is designed to use the power MOSFET as a switching switch and be operated in a switching on and switching off model to control the power MOSFET duty cycle to achieve the buck/boost topology. PWM power converters enhance the low efficiency shortcoming of the conventionally adopted linear power converter with increasing converter switching frequency. In proposed method, a change in solar energy input is considered and control loop of converter is then designed in a way that output is constant.