# Grid-following inverter

Canonical URL: https://eloragrid.ai/symbols/grid-following-inverter
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: GFL
Drawing use: SLD
Reference families: IEC, IEEE / ANSI

An inverter that tracks an existing network voltage with a phase-locked loop and injects controlled current into it.

## In plain English

### What does Grid-following inverter mean?

A grid-following inverter measures the network voltage, locks to it with a phase-locked loop and injects a controlled current. Most rooftop and utility-scale solar inverters work this way. They need a stable voltage from the grid, a synchronous machine or a grid-forming inverter to operate, and they disconnect when that reference is lost.

### A simple example

Drawings use the standard inverter symbol with a GFL note or a current-source annotation. Anti-islanding protection, often shown as a protection relay or a function list, is associated with this type so that it does not energise a dead network.

### What the drawings help you do

In weak networks with high converter penetration, grid-following control can become unstable, so system strength studies are needed. The symbol does not show the phase-locked loop settings or the reactive power mode.

### This particular reference

An inverter that tracks an existing network voltage with a phase-locked loop and injects controlled current into it. A grid-following inverter needs an external voltage reference; a grid-forming inverter provides that reference.

### Terms

- Coil: A wound conductor that can produce a magnetic field when energised.
- Phase: One of the related AC waveforms in a power system.
- Rating: A value stating the conditions for which equipment is specified.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [Photovoltaic technology and inverter functions](https://www.electrical-installation.org/enwiki/Photovoltaic_background%2C_technology)
- [Solar electrical system architecture](https://www.ti.com/applications/industrial/energy-infrastructure/solar-energy/overview.html)


## What it represents

A grid-following inverter measures the network voltage, locks to it with a phase-locked loop and injects a controlled current. Most rooftop and utility-scale solar inverters work this way. They need a stable voltage from the grid, a synchronous machine or a grid-forming inverter to operate, and they disconnect when that reference is lost.
Drawings use the standard inverter symbol with a GFL note or a current-source annotation. Anti-islanding protection, often shown as a protection relay or a function list, is associated with this type so that it does not energise a dead network.
In weak networks with high converter penetration, grid-following control can become unstable, so system strength studies are needed. The symbol does not show the phase-locked loop settings or the reactive power mode.

## How to read it

- Check that a forming source exists if the inverter is expected to run in an island.
- Anti-islanding settings are often listed as protection functions next to the inverter.

## Information to show or reference

- State reactive power mode and ride-through settings.
- Show anti-islanding protection.
- Reference system strength assessment.

## Important distinction

A grid-following inverter needs an external voltage reference; a grid-forming inverter provides that reference.

## Facts

- Control behaviour: Current source synchronised by PLL
- Islanding: Disconnects without external reference
- Typical use: Solar and wind plant inverters
- Preview: Independent educational illustration; consult the applicable standard and project legend for the exact graphic

## Public references

- [Photovoltaic technology and inverter functions](https://www.electrical-installation.org/enwiki/Photovoltaic_background%2C_technology) — Schneider Electric. Public photovoltaic inverter function context.
- [Solar electrical system architecture](https://www.ti.com/applications/industrial/energy-infrastructure/solar-energy/overview.html) — Texas Instruments. Public solar electrical system architecture context.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.