  A common configuration for a stand-alone PV power system may consist of three
converters: a buck converter for the PV panelto charge the battery, a boost
converter for the battery to discharge to the load and one for the load voltage
regulation. Such a systemrequires a coordinated control scheme for three
converters which can be complicated. A simple structure for a stand-alone PV
plantconsists of a PV array, a battery unit, and its associated bidirectional
converter which is a combination of a buck and boost converter.When controlled
properly the system can provide uninterrupted power to the load, despite the
intermittent availability of sunlight. Inthis paper complete design of the
converter is carried out and the simulation has been performed using Psim. From
the simulation,the graphs are presented to show the converter working in buck
mode and boost mode. Controller is designed to take care of modetransition,
buck to boost and boost to buck mode automatically based on source voltage.
Hardware implementation has been doneusing microcontroller (8051).
