PJM Interconnection, which operates the nation’s largest regional grid, stretching from Illinois to New Jersey, has been so inundated by connection requests that last year it announced a freeze on new applications until 2026, so that it can work through a backlog of thousands of proposals, mostly for renewable energy.

It now takes roughly four years, on average, for developers to get approval, double the time it took a decade ago.

And when companies finally get their projects reviewed, they often face another hurdle: the local grid is at capacity, and they are required to spend much more than they planned for new transmission lines and other upgrades.