A grid tied or utility-interactive system is a PV system that operates in parallel with and is connected to the electric utility grid. These systems are the simplest and least expensive PV systems that produce AC power because they require the fewest components and do not use batteries. The primary component in a grid tied system is the inverter, which directly interfaces to the array and the electric utility network and converts DC output from an array to AC power that is synchronous with the utility grid. Grid tied systems are modular, so large systems can be designed as several smaller systems with individual inverters and then connected together.
Grid tied systems make a bidirectional interface with the utility at the distribution panel or electrical service entrance. When the PV system does not produce enough power to meet the system loads, additional power is imported from the utility. If there is an excess of PV power, the excess is fed back (exported) to the grid.