New inverters keep power grids stable without fossil fuels

Posted: January 20, 2026

A healthy grid, like a healthy heart, has a consistent frequency—and like a heart, sudden surges or drops in its rhythm can be catastrophic. Often, a grid gets out of whack when demand and power generation are mismatched: a surplus of electricity causes grid frequency to increase, and a deficit does the opposite. Either way, deviations can induce a system-wide collapse if not immediately addressed.

Fossil fuel generators address these deviations via their large, spinning turbines. Just like bicycle wheels that continue to propel you forward after you stop pedaling, the momentum of gigantic, spinning generators has long been tapped to avoid an energy emergency.

Gas turbines and other conventional generators spin at precise speeds—3,000 or 3,600 RPM—to produce the grid's required 50 or 60 Hz frequency. When demand suddenly spikes, the rotational inertia of thousands of synchronized generators acts as a buffer, slowing down slightly together and giving the system time to respond.

Renewables work differently. Solar panels produce direct current that must be converted to AC. Wind turbines do generate AC, but at variable frequencies that shift with wind speed, so their output is typically converted to DC and then back to grid-frequency AC. In both cases, power flows through inverters—and without spinning mass, there's no built-in buffer when supply and demand fall out of sync.

For grid operators who are increasingly dependent on renewable power generation, the absence of “inertia” (the technical term for the momentum of spinning turbines) has the potential to be the source of a major headache.

But there are ways of balancing a green grid. One piece of technology—the grid-forming inverter—is especially promising.

The grid’s heartbeat: frequency and load balancing

Wind farms, solar parks and battery systems are all fitted with inverters. These pieces of equipment serve a vital function: they transform direct current into grid-compatible alternating current. But if there’s a sudden drop or surge in grid frequency, inverters are powerless to help—indeed, in such an event they might even trip offline, making a bad problem worse.^[1]

Grid-forming inverters, however, can function independent of the rest of the grid, giving them the capacity to play an active role in stabilizing the grid when the system goes awry. If a grid's frequency is its heartbeat, grid-forming inverters are like pacemakers—monitoring constantly and stepping in to correct irregularities.

The real-world value of grid-forming inverters was vividly illustrated during an incident on the island of Kauai a few years ago.

For years, Kauai has been powered solely by renewables for several hours each day. But in the spring of 2023, a 26 MW generator began to fail right around sunset—just as solar power installations were coming offline for the night. The generator was supplying 60% of the island’s power; its failure could easily have brought down the entire grid.

Thankfully, Kauai was already equipped with a whole lot of battery storage, connected to grid-forming inverters. As the generator failed, these inverters dispatched power from batteries with 150 MWh of stored energy and prevented a blackout.

Grid-forming inverters might be better than inertia

Part of what makes grid-forming inverters so promising is that they aren’t mechanically any different from standard inverters—they are simply equipped with extra software. According to Ben Kroposki from the National Renewable Energy Lab (NREL), while retrofitting traditional inverters is difficult, the main challenge for deploying grid-forming inverters is establishing standards—not solving complex engineering problems.

Even more excitingly, the widespread deployment of grid-forming inverters has the potential to lend the grid even greater stability than that provided by the inertia of fossil fuel generators.

“Wind and solar plants either have no inertia or very little,” Antonio Gómez-Expósito, an electrical engineering professor at the University of Seville told NPR late last year. “But in return, they have infinitely greater response speeds.”

In a system where every second counts, response speeds are very important.

A report published by the NREL in 2020 concluded that inverter-based resources can respond much faster to contingencies than conventional methods. And as long as readily dispatchable power—like batteries—is built into the grid, less inertia does not impose a significant economic or technical barrier to wind, solar or storage developments.

Where grid-forming inverters are working today

It’s not just Kauai—grid-forming inverters are being deployed around the world.

In Australia, grid-scale batteries with grid-forming capabilities are already online, and there are more on the way. French renewable energy producer Neoen’s Western Downs Battery has 1,080 MWh online, and they’re working on installing 1,220 MWh of additional storage with grid-forming abilities by mid-2028.

A large battery storage system is underway in Europe, too. Blackhillock offers 200 MW of power for grid stabilization and 100 more megawatts are due to be installed in the next year. SMA, the German company behind Blackhillock, also designed the system to operate a blackstart sequence, meaning it can reconnect to the grid after a blackout. SMA anticipates Blackhillock will offer cheaper electricity for customers and save 2.3 million tons of CO2 after 15 years in operation. 

Renewable microgrids also depend on grid-forming inverters. The luxury resort AMAALA in Saudi Arabia will generate all of its power from renewables upon its expected completion in 2027. Sungrow inverters are behind AMAALA and the project boasts of avoiding the 350,000 tons of CO2 produced by similarly sized infrastructure running on fossil fuels.

Leading the inverter market is Huawei, which recently announced Fusion Solar 9.0, a kind of novel photovoltaic tech. Its grid-forming inverters incorporate AI and aim to offer grid-supporting solar to the market.

Around the world, inverters with grid-forming capabilities are taking hold. And as renewable power gains credibility for offering grid stability without inertia, the market is gaining some momentum of its own, too.

^{[1] https://spectrum.ieee.org/virtual-synchronous-machines}