Design and implementation of a solar PV panel integrated inverter with multi-mode operation capability

Solar PV panel integrated systems which are in general referred to as micro-inverters provide a unique solution with high reliability and high average efficiency overcoming partial shading effect while delivering maximum available PV power. Micro-inverters are grid connected systems, which shut down in the event of grid failure. For residential as well as small commercial applications, this can be discouraging as no power is available during grid failure. By providing added features such as sustaining the operation under islanded conditions, acting as short-term back-up power supply (UPS) and reactive power support system can enhance the utility and popularity of such systems. The micro-inverter system proposed in this paper features multimode operation such as grid connected mode, standalone mode, UPS mode and VAR compensation mode. The circuit topology includes integrated isolated SEPIC converters feeding H-bridge inverter followed by EMI filter with grid interface circuit. The paper describes the design and implementation of the new multi-functional micro-inverter system.