A Grid-Tied Inverter with Renewable Energy Source Integration in an Off-Grid System with a Functional Experimental Prototype

Renewable energy implementation in residential-scale grid-connected systems is already popular, and the growth of such systems is increasing every year. Grid-connected solar systems are relatively simple to install and operate; in addition, such power plants are relatively inexpensive compared to other renewable sources and grid-connection options. However, most residential grid-connected system owners believe that they will become independent from a distribution system operator (DSO) once a renewable energy source (RES) becomes available. As a rule, after installation, without DSOs, grid-connected systems are typically shut down due to a faulty grid, despite RES availability; therefore, such RES grid-connected system owners at later phases aim to become at least partially independent of DSOs. After such a change, the importance of developing a grid-tied inverter connection to an off-grid system will increase. While developing such a system connection the main issue analyzed in this paper is to control the excess power without affecting the accumulated energy levels in a system. As a result, a solution for such a system structure is presented with its main advantage to control excess power without affecting the accumulated energy level.