Utility Scale

U.S. interconnection queues, already jammed, grew 30% in 2023

U.S. interconnection queues, already jammed, grew 30% in 2023
(Photo by Jonathan Hanna on Unsplash)

The backlog of new power generation and energy storage seeking transmission connections across the U.S. grew again in 2023, with nearly 2,600 GW of generation and storage capacity now actively seeking grid interconnection, according to new research from Lawrence Berkeley National Laboratory (Berkeley Lab).

Active capacity in U.S. interconnection queues increased nearly eight-fold over the last decade, and is now more than twice the total installed capacity of the existing U.S. power plant fleet. The queues indicate particularly strong interest in solar, battery storage, and wind energy, which together accounted for over 95% of all active capacity at the end of 2023.

Active capacity in U.S. interconnection queues increased nearly eight-fold over the last decade, and is now more than twice the total installed capacity of the existing U.S. power plant fleet. The queues indicate particularly strong interest in solar, battery storage, and wind energy, which together accounted for over 95% of all active capacity at the end of 2023.

The Federal Energy Regulatory Commission (FERC) adopted major interconnection reforms in 2023 that have not yet taken effect in most regions; project developers continue to cite grid interconnection as a leading cause of project delays and cancellations.

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Berkeley Lab compiled and analyzed data from the seven organized electricity markets (RTO / ISOs) in the US and an additional 44 balancing areas outside of RTO / ISOs, which collectively represent over 95% of currently installed U.S. electricity generation. 

“It is promising to see the unprecedented interest and investment in new energy and storage development across the U.S., but the latest queue data also affirm that grid interconnection remains a persistent bottleneck,” said Joseph Rand, an Energy Policy Researcher at Berkeley Lab, and lead author of the study. “The new rules from FERC will be a step in the right direction when implemented, but it is increasingly clear that additional solutions to interconnection problems are essential to maintain grid system reliability amidst rising electricity demand and utility- and state-level clean energy goals”, added Rand.

The total capacity in the queue at the end of 2023, nearly 2.6 Terawatts (TW), is more than twice the current U.S. generating capacity of 1.28 TW, and roughly eight times larger than the queue in 2014.

Figure 1: Installed U.S. electric generating capacity compared to interconnection queue capacity (2010 and 2023) (Credit: Berkeley Lab)

Solar (1,080 GW) accounts for the majority of generation capacity in the queues. Substantial wind (366 GW) capacity is also actively seeking grid connection. The amount of offshore wind capacity in the queues (120 GW) represents four times the Biden Administration’s goal of 30 GW installed by 2030. Developer interest in electricity storage ballooned in recent years, with capacity in the queues growing more than 50% in the past year to roughly 1,030 GW.

Figure 2: Active capacity in interconnection queues by transmission grid operating region (Credit: Berkeley Lab)

The overall growth of capacity in the queues occurred despite major slowdowns in two of the largest grid operating regions: MISO and PJM. Due to the large influx of new interconnection requests in 2022, MISO did not accept any new requests in 2023 as it sought approval for procedural reforms. Similarly, PJM announced that it would not review any new requests until at least 2025, resulting in relatively few new requests in 2023. Yet, these slowdowns were more than offset by growth in other regions – particularly CAISO (which had a record-breaking number and capacity of new requests in 2023), the non-ISO West, and ERCOT. CAISO since proposed to delay its 2024 application window to the following year.

With falling battery prices and the growth of variable renewable generation, there has been a surge of interest in “hybrid” power plants that typically combine generating capacity with co-located batteries. 571 GW of solar capacity in the queues are proposed as hybrid plants (53% of all solar in the queues), as is 49 GW of wind (13% of all wind in the queues). Over half of all storage capacity in the queues is proposed in hybrid configurations with generation (525 GW).

Interest in hybrid projects is especially strong in CAISO and the non-ISO West, where 98% and 81% of all proposed solar is in a hybrid configuration, respectively.

Figure 4: Total and hybrid capacity in interconnection queues over time. *Hybrid storage capacity was estimated for some projects using known generator:storage ratios and was not estimated for years prior to 2020. (Credit: Berkeley Lab)

However, the report has one big caveat: much of the proposed capacity in the queues will not ultimately be built since projects may not come to fruition for a variety of reasons. Only 19% of the projects (and just 14% of capacity) that submitted interconnection requests from 2000 to 2018 reached commercial operations by the end of 2023.

Another trend is that interconnection wait times are on the rise. Interconnection requests now typically take more than 3 years to complete the requisite grid impact studies in most regions, though some – like ERCOT in Texas – are processing requests more quickly. The timeline from the initial connection request to having a fully built and operational plant has increased from <2 years for projects built in 2000-2007 to more than 4 years for those built in 2018-2023. 

Figure 5: Completion rates (for requests from 2000-2018) and typical duration to reach commercial operations for projects in the queues. Capacity-weighted completion rates shown in brackets [X%] (Credit: Berkeley Lab)

The full study is available here.

Originally published in POWERGRID International.