Performance evaluation of a low power solar-PV energy system with SEPIC converter

This paper presents the design and performance of a low power stand-alone solar photovoltaic (PV) energy generating system. The system is designed considering solar-PV panels of 750W to feed an average load demand of 250W for a rural household. The system includes series-parallel combination of solar panels, MPPT (maximum power point tracking) controller, a dc-dc converter, an energy storage system and a single-phase VSI (voltage source inverter). A dc-dc converter is providing a constant dc bus voltage and its duty cycle is controlled by the MPPT controller. A modified incremental conductance approach is utilized for MPPT. In this approach, MPPT controller automatically generates a PWM signal for the dc-dc converter to extract maximum power. To maintain the power quality a feedback control is used in the VSI. The complete system is designed, and modeled to evaluate its performance. Simulated results are presented to demonstrate the performance of the MPPT controller and designed system for varying atmosphere conditions and load disturbances.