Grid Forming Inverter

A grid forming inverter sets its own voltage and frequency and can hold up a microgrid alone, while a grid following inverter synchronizes to a voltage that already exists.

Nearly all solar inverters are grid following: they lock onto the grid’s waveform and inject current into it. A grid forming inverter, usually on a battery, behaves like a generator and creates the reference the other equipment follows. That capability is what lets a storage system black start a site and run it in island mode. Grid forming behavior is becoming an interconnection expectation for large inverter based resources as synchronous generation retires.

Also called: Grid following inverter, Voltage source inverter