U.S. renewables developers face daunting grid interconnection queues

Many grid operators are overwhelmed by projects, according to a report by Enverus.

May 9, 2025 Michael Puttré

Image: Standard Solar

Despite any uncertainty caused by the change in U.S. administrations, funding and tax credits for renewable energy projects under the Inflation Reduction Act and regulatory pressures to retire legacy fossil fuel generation have created interconnection backlogs for new solar, wind and battery storage facilities. A new report by Texas-based energy consultancy Enverus says grid operators interconnection queues are lengthening, leading to project delays and even suspensions.

The severity of the wait times vary by independent system operator (ISO) or non-ISO region and project type. For projects that became operational from 2022 through 2024, Enverus says project development timelines in California ISO (CAISO) were the longest with an average of 9.2 years for all project types, while ISO New England (ISO-NE) had the shortest, at about 3.8 years, followed by Electric Reliability Council of Texas (ERCOT) at about 4.5 years.

Moreover, Enverus says its research shows projects under New York ISO, Southwest Power Pool (SPP), Pennsylvania-New Jersey-Maryland (PJM) and ISO-NE have higher suspension rates later in the project cycle, with interconnection agreement suspension rates ranging from 46% to 79%, compared to around 20% in ERCOT, CAISO and Midcontinent ISO (MISO).

According to the report, one of the key factors determining project wait times and suspension rates is what technology is being integrated in what operating region. In NYISO, for example, high solar demand is responsible for a large backlog of projects in queue while there is uncertainty in contracts for offshore wind projects. For the 110 solar, wind and energy storage projects active in the traditional NYISO queue, the average current wait time is 6.53 years, the report said.

Meanwhile, in CAISO, Enverus reports that a total of 32 renewable and energy storage projects came online in 2024 with an average of 9.2 years in the queue. This is because the ISO is severely backlogged and has not approved any projects from 2022 or 2023. It shut down the approval process for 2024 entirely, Enverus reported. Thus, CAISO’s relatively low project suspension rate of 20% may in part be due to the fact projects aren’t being approved in the first place.

Yet progress is being made. Enverus reports that last year, NYISO embarked on a new “cluster study” that will group projects with the goal of expediting the interconnection study process. ERCOT’s benign regulatory environment – from a developer’s perspective – has resulted in its relatively short interconnection queues and is thus attracting more and larger renewable projects.

On the other side of the coin, “legislator meddling” in CAISO’s efforts to unblock project stoppage through queue reform measures is generating stakeholder concern, according to the Enverus report.

All of this is by way of saying that the interconnection outlook across U.S. grid operators is multifaceted and ever-changing. Enverus says its “2025 Interconnection Outlook Report” provides a comprehensive view of key variables, such as asset economics, power demand growth, existing and planned transmission lines, and substation-level available transfer capability to help developers maximize investment potential by minimizing project delays and increasing the odds of making it through the queue.

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