Design and implementation of a micro-inverter for single PV panel based solar home system

This paper presents the design and implementation of a complete prototype of a low powered (25-30 watts), portable and cost effective micro-inverter specially designed for rural areas of developing countries where a single solar module will be able to run AC loads along with DC loads. The system consists of a switch mode power supply, DC-DC push-pull converter, DCAC H-bridge inverter, LC filter and finally the test load. The power supply supplies the DC voltage needed to activate the DCDC push pull converter and the optocouplers. The push-pull converter and optocouplers are directly connected to the switches of the full bridge circuitry. The optocouplers work as an isolation for the full bridge circuit and the DC-DC push pull converter boosts the input DC voltage into the desired rated input voltage of the inverter. High frequency Pulse Width Modulated (PWM) pulses are generated by a microcontroller (PIC18F4431) and provided to the switches of full bridge connection. The full bridge inverter outputs a 220V PWM sine wave which is later conditioned to pure sine wave by an L-C filter. Finally, the output is connected to the test load (Table fan) and the test load works in desired speed.