Studies in the past few years by the Lawrence Berkeley Lab (LBL) highlight a growing queue and grid connection bottlenecks due to clean energy surges.
In April 2024, an updated study on the grid connection backlog finds the following: Solar energy projects led the U.S. interconnection queues with a combined capacity of 1,080 GW, followed by wind energy projects at 366 GW. Notably, 571 GW of solar capacity in the queues were proposed as hybrid plants, driven by decreasing battery prices, making up 53% of all solar projects. Similarly, over half of the storage capacity (525 GW) was proposed in hybrid configurations with generation.
Despite slowdowns in the Midcontinent Independent System Operator (MISO) and PJM Interconnection regions, overall growth in the interconnection queue persisted in 2023. MISO halted new requests in 2022 to implement procedural reforms, while PJM announced a pause on new requests until at least 2025. Conversely, the California Independent System Operator (CAISO) received a record-breaking 523 GW of new requests, offsetting the slowdowns in other regions.
The Inflation Reduction Act (IRA) incentivized the entry of over 1,200 GW of capacity into the queues, including more than 500 GW of solar, 540 GW of storage, and 125 GW of wind. This surge reflects the IRA’s impact on stimulating the clean energy and storage development market. However, grid interconnection and permitting remain significant challenges.
The study highlights that over 70% of interconnection requests were withdrawn in previous years. From 2000 to 2018, only 19% of projects and 14% of capacity reached commercial operations by the end of 2023. Solar projects had even lower success rates, with only 13% of projects and 10% of capacity becoming operational. Additionally, interconnection requests typically take more than three years to complete grid impact studies, with the timeline from initial request to operational plant increasing from less than two years (2000-2007) to over four years (2018-2023).
According to LBL's research, the total generation and storage capacity seeking grid interconnection exceeds 2,500 GW, driven by strong interest in solar, battery storage, and wind energy. Combined solar and wind capacity in the queues (~1,250 GW) now equals the installed capacity of the entire U.S. power plant fleet. This backlog presents a major bottleneck for project development, as most interconnection requests are ultimately canceled and withdrawn.
While solar accounts for the largest share of generation capacity in the queues (947 GW), wind capacity also remains significant (300 GW), with offshore wind capacity (113 GW) far exceeding the Biden Administration’s goal of 30 GW by 2030. Developer interest in electricity storage has surged, with capacity reaching an estimated 1,030 GW by 2023. Combining generation with storage, hybrid projects have gained popularity, particularly in CAISO and the non-ISO West regions.
The increasing backlog and wait times highlight the need for improvements in the interconnection process. The Federal Energy Regulatory Commission (FERC) released a Notice of Proposed Rulemaking in 2022 to address these issues, and regional grid operators have initiated substantial reforms. The Department of Energy’s Interconnection Innovation Exchange (i2X) program aims to enhance interconnection process speed, fairness, and certainty.
The research reveals the opportunities and challenges of electric sector decarbonization in the U.S. The queues’ vast amount of solar, wind, and storage capacity indicates a strong developer interest in achieving a carbon pollution-free power sector by 2035. However, the delays and high withdrawal rates pose significant barriers. The findings from Lawrence Berkeley Lab, supported by the U.S. Department of Energy, provide critical insights and a roadmap for improving the interconnection process to facilitate the transition to clean energy.
