Control and interfacing of bi-directional inverters for off-grid and weak grid photovoltaic power systems

Photovoltaics (PV) is one of the most cost-effective, reliable and durable energy sources to provide electricity in remote areas not connected to a grid. In some parts of the world grid-connected PV systems also help utilities to alleviate the need to install or operate costly power plants by supplementing and meeting high peak hours of electricity demand. The key to the widespread application of PV power plants is the availability of efficient and low cost power electronic equipment. A photovoltaic generator is a current source depending on solar radiation intensity and temperature. Simple charge controllers and DC-DC converters with maximum power point tracking are used to interface solar panels with batteries. There are different types of inverters for converting the DC power from batteries and/or solar panels to AC power. This paper describes the application of bi-directional inverters for remote area power systems using PV, diesel generators and battery storage. Use of bidirectional inverters to improve power quality and reliability in weak grids is also presented