Backlog of power plants seeking transmission grid connection eased somewhat in 2025 amidst high withdrawals
Annual Berkeley Lab data visualization slide deck illustrates over 2,000 gigawatts of generation and storage capacity active in U.S. interconnection queues
Generator interconnection queues across the U.S. are showing some signals of improvement as historical backlogs wane and the volume of newly executed interconnection agreements rises, though process timelines remain long.
The volume of new power generation and energy storage seeking transmission connection decreased 10% from 2024 to 2025, with 2,061 gigawatts (GW) of generation and storage capacity now actively seeking grid interconnection (Figure 1). The backlog of generator interconnection requests surged in the 2010s and early 2020s, reaching a peak of nearly 2,600 GW active at the end of 2023. The backlogged queues and lengthy connection approval processes became a major bottleneck slowing the build-out of the generation supply needed to meet future load growth, maintain grid reliability, and ensure energy affordability. In 2023, the Federal Energy Regulatory Commission (FERC) adopted major interconnection reforms that took effect the following year in most regions. Several grid operators have implemented additional process reforms as well. These reforms, alongside market conditions, may have played a role in the >750 GW of requests withdrawn in 2025.
A new slide deck, data file, and interactive visualization from Lawrence Berkeley National Laboratory (in partnership with Interconnection.fyi) synthesizes data from transmission interconnection queues throughout the U.S. to illustrate trends in proposed power plants across time, technologies, and regions. This latest edition of the annual “Queued Up” slide deck also includes new additions such as analysis of reliability-focused fast-track interconnection programs and an updated brief summary of key process updates and reforms at the federal and regional levels.
Figure 1: Year-over-year changes in U.S. generator interconnection queues (2024 to 2025)
Proposed large-scale electric generation and storage projects must apply for interconnection to the transmission system via interconnection queues. Many projects that apply for interconnection will not ultimately be built, since entering an interconnection queue is only one of many steps in the development process. Projects must also have agreements with landowners, land-use permits, power purchasers, equipment suppliers, and financiers, and may face transmission upgrade requirements. Data from these queues nonetheless provide a general indicator for trends in electric supply-side developer activity. In partnership with Interconnection.fyi, Berkeley Lab compiled and analyzed data from the seven organized electricity markets (RTOs / ISOs) in the U.S. and an additional 50 balancing areas outside of RTOs / ISOs, which collectively represent about 98% of currently installed U.S. electricity generation.
Active queue capacity is highest in the non-ISO West (567 GW), followed by ERCOT (408 GW). Capacity reduced in 2025 in all regions except ERCOT and SPP (Figure 2). Natural gas capacity (253 GW) in queues increased 86% year-over-year, while solar (773 GW, -19%), storage (749 GW, -16%), and wind (220 GW, -19%) all decreased in 2025.
Figure 2: Active capacity in interconnection queues by transmission grid operating region, 2014-2025
The generator interconnection process culminates in the execution of an interconnection agreement (IA). Effectively a contract between the transmission provider and the project developer, this agreement is a pre-requisite for connecting a new plant to the grid. More than a quarter (536 GW) of the active capacity in U.S. interconnection queues already has a draft of executed IA, including 18% of gas, 32% of solar, 22% of storage, and 33% of wind capacity. In a signal of positive progress, annual IA processing volume is on the rise in most regions with available data: CAISO, ERCOT, SPP, and MISO each signed a record capacity of IAs in 2025. Notably, CAISO and ERCOT both executed IAs last year amounting to >30 GW of capacity (Figure 3).
Figure 3: Annual capacity (GW) of newly-executed interconnection agreements in select regions
Despite these signals of potential improvement, some major challenges persist. Most interconnection requests are never actually built - proposed power plants may not come to fruition for a variety of reasons. Looking historically at interconnection requests submitted from 2000-2020, just 13% of capacity had come online by the end of 2025, while 75% had withdrawn (final outcome of more recent projects cannot yet be determined) (Figure 4A). Withdrawal rates are relatively high (>40%) even after signing an interconnection agreement, posing challenges for grid planners and operators. Additionally, interconnection process timelines remain high: the median duration from submitting a request to signing an IA was well over 3 years in 2025, while the timeline to reach commercial operations exceeds 5 years (for the subset of regions with available data) (Figure 4B).
Figure 4 (A): Historical completion rates by region for requests submitted 2000-2020 by % of capacity and [# of requests]. (B) Median (with 25th-75th percentile) duration (years) from interconnection request to commercial operations date.
These persistent grid connection challenges come at a time of unprecedented electric load growth, exacerbating concerns around grid reliability, resource adequacy, and electricity affordability. It remains too early to fully understand the effects of FERC Order 2023 and the various ISO process reforms, but analyses in this slide deck point to some progress reducing backlogs. In addition, many grid operators are adopting automation, advanced computing, and AI software resources to speed up interconnection procedures and studies, while several ISOs (MISO, SPP, and PJM) have also implemented new, limited-term “fast-track” interconnection programs in attempts to speed the processing and connection of new generation essential to reliability. Continuing to assess the impacts and effectiveness of these various reforms and programs is a priority for Berkeley Lab researchers.
More information, including a slide deck, complete data file, and an interactive data visualization, is available here: emp.lbl.gov/queues. The authors will be hosting a webinar to share the research and answer questions on Thursday July 16 at 1pm EDT / 10am PDT. Register here: https://lbnl.zoom.us/webinar/register/WN_AkkPNt0_S7CGMTL3ZqKfwQ
This work is supported by the U.S. Department of Energy’s Integrated Energy Systems Office (IESO), via the Interconnection Innovation eXchange (i2X) program.