What’s the Difference Between an Inverter That’s Grid-Following Versus Grid- Forming?

It feels like a day doesn’t go by without energy storage in the headlines. These systems are experiencing unprecedented adoption across residential, commercial, and utility-scale applications. As storage continues to become increasingly critical to the clean energy transition, design professionals need a solid understanding of system fundamentals. 

In the Design Considerations for Energy Storage Systems course, industry expert Ryan Mayfield of Mayfield Renewables guides professionals through the essential elements of designing effective energy storage, solar-plus-storage, and microgrid systems. This one-hour self-paced course covers system architectures, component parameters, and proper planning through feasibility studies. Below is an excerpt where Ryan explains the crucial difference between grid-following and grid-forming inverters—a technical distinction that significantly impacts system functionality and design decisions.

Transcript below.

What’s the difference between an inverter that’s grid-following versus grid-forming?

Is this grid-following versus grid-forming?

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 It’s an important aspect of understanding what can your inverter actually do.

Grid-following meaning exactly what it’s saying is that it is following the grid. It is going to mimic whatever the utility provides. This is what happens with our grid-direct inverters. Those inverters cannot create their own sine wave. They can only follow what the grid supplies to them, and so they’re grid-following. 

We do have battery systems that are grid-following. They’re only there to provide grid support services. Again, the demand charge management, energy arbitrage, maybe there’s some other features that the utility wants to have out of those inverters . There are inverters, I should say out there, that do not have the ability to form a sine wave, so those would be grid-following.

The grid-forming inverters, on the other hand, when you’re doing a resilient system, if you’re doing something with backup, your inverter has to be able to provide a sine wave and has to be grid-forming. So it has to be able to provide that output that the loads can run off of.

If you have those inverters, those PV inverters that are grid-following, that your AC coupling, that battery inverter has to be able to form that grid to allow the inverters to connect to it. 

So all important stuff to understand what their roles are and how they’re interacting with the utility or not – as the case may be – and what those functions are and how they’re going to be able to make sure that they are working properly.