Interconnection Queue Backlog

As of 2023, over 2,000 GW of generation projects were waiting in US interconnection queues. Total US installed capacity is roughly 1,300 GW. The queue contains more proposed generation than the entire existing grid, and the average wait time has stretched to five years.

The interconnection queue backlog is the accumulation of proposed generation projects (predominantly solar, wind, and storage) awaiting grid connection studies, which take years to complete because each project's impact must be studied sequentially and each withdrawal triggers restudies for remaining projects. The backlog is the single largest bottleneck to clean energy deployment in the US.

The bottleneck is not construction. It is study capacity. RTOs have a limited number of engineers to perform interconnection studies. Each study must model how a new project affects power flows, voltage, and reliability across the entire transmission network. When one project drops out (and roughly 80% do), remaining projects must be restudied because the grid conditions have changed.

The withdrawal cascade. A developer in MISO files for interconnection. After 3 years of study, two projects ahead in the queue withdraw. MISO must restudy the developer's project under the new grid configuration.

How does the withdrawal of unrelated projects delay this developer?

Each withdrawal changes the grid model. Power flows and upgrade requirements shift when projects enter or leave the queue. Restudying means the developer's 3-year wait restarts, potentially adding 1-2 more years. The sequential study process means one project's decision affects every project behind it.

FERC Order 2023 (finalized 2023) attempts to fix this by moving to cluster-based studies that process groups of projects simultaneously.

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