Grid-Forming Inverters Show They Can Steady Clean Power Grids

New field results from 2025 and early 2026 suggest grid-forming inverters can keep renewable-heavy power systems stable as fossil plants retire

6 Feb 2026

A quiet shift is underway in the US power system, far from Wall Street and Washington. As solar panels and batteries spread across the grid, a long-held belief is starting to wobble. Reliability, it turns out, may not depend on massive, spinning power plants after all.

For decades, coal and gas generators offered more than electricity. Their physical bulk helped steady the grid when things went wrong, smoothing out sudden changes in voltage and frequency. As those plants retire, grids rich in renewables are learning a tough lesson. Speed alone does not guarantee stability.

One of the clearest examples comes from Kauaʻi. The Hawaiian island runs one of the most renewable-heavy systems in the country, with solar and batteries supplying much of its power. When a conventional generator suddenly went offline, batteries responded in a flash. Yet the grid began to wobble, and the disturbance refused to settle. Fast action, it turned out, was not enough.

That moment forced a rethink. Kauaʻi Island Utility Cooperative partnered with the National Laboratory of the Rockies to upgrade parts of its solar and battery fleet with grid-forming inverter controls. Unlike standard inverters that follow the grid, these systems help create it, actively setting voltage and frequency much like traditional generators once did.

The payoff was clear. Results released through 2025 and into early 2026 showed that during follow-up outage tests, the grid stayed steady. The wild swings seen before were gone. The system rode through disruptions even with fewer fuel-based generators online.

This lesson matters far beyond one island. Utilities across the US are wrestling with how to retire aging plants without putting reliability at risk. Field data, peer-reviewed research, and national lab studies are all pointing in the same direction. Grid-forming inverters can take on part of the stabilizing role long handled by fossil machines.

Challenges remain. The technology is complex, standards are still taking shape, and coordination across devices is crucial. Still, theory is giving way to experience. Kauaʻi’s story suggests the future grid will depend not just on cleaner power, but on smarter control of it.