The interconnection queue was the headline binding constraint on US clean power buildout for most of the back half of the 2010s and the first half of the 2020s. Lawrence Berkeley National Laboratory’s annual queue report tracked the count from roughly 1 terawatt of generation and storage in active interconnection queues nationally at the end of 2020 to more than 2.6 terawatts by the end of 2024. The historical clearance ratio, projects that signed an interconnection agreement and reached commercial operation as a share of projects that entered the queue, sat in the 15 to 25 percent range across most RTOs. The withdrawal rate was the mirror image of that ratio, with 70 to 85 percent of queued projects exiting before completing the study cycle.
FERC Order 2023, issued in July 2023, was the federal response to that pattern. The order required every transmission provider to file compliance revisions to its open access transmission tariff implementing first-ready-first-served cluster studies, financial commitment deposits scaled to project size, commercial readiness criteria covering site control and offtake, withdrawal penalties indexed to the network upgrade cost burden the withdrawal placed on the cluster, and study deadlines with financial penalties to the transmission provider for missed milestones. The compliance plans cleared FERC across 2024, and the first full cluster cycles under the reformed rules began posting results in late 2025 and into the first half of 2026.
The question on the table at mid-2026 is not whether the reformed process is faster. The question is whether the reformed process is sorting the queue toward the projects that need to clear for the 2027 to 2032 reliability and clean capacity stack.
What the first cluster cycles actually delivered
The cluster cycle outcomes are best read by what the published study reports show on three metrics: total megawatts entering the cycle, total megawatts clearing the cycle with a signed interconnection agreement, and the network upgrade cost per cleared megawatt assigned to the cluster.
PJM’s transition cluster, which closed its application window in 2024 and posted system impact study results across late 2025 and the first quarter of 2026, took in applications totaling roughly 130 to 140 gigawatts of generation and storage. The cluster cleared roughly 35 to 40 percent of that nameplate through to the interconnection agreement stage, with the remainder either withdrawing during the readiness deposit window or being moved into the subsequent cluster. The cleared mix shifted toward battery storage and storage-plus-solar hybrids and away from standalone solar relative to the pre-reform 2022 queue snapshot.
MISO’s second cluster under the reformed rules cleared in late 2025, with a similar pattern. The total nameplate entering the cluster was lower than PJM’s, in the 60 to 75 gigawatt range. The clearance ratio was higher, roughly 45 percent, reflecting MISO’s earlier move toward cluster studies before Order 2023 codified the federal floor. The cleared mix included a meaningful share of natural gas combined-cycle additions on top of the storage and renewables base, a pattern that diverges from PJM’s where the new gas pipeline has been thin.
CAISO’s 2024 cluster closed its application window in April 2024 and was the first major RTO cluster to apply the Order 2023 commercial readiness criteria from the start. CAISO took in roughly 90 gigawatts of nameplate, applied stricter site control documentation requirements than PJM had used, and cleared a smaller share, roughly 25 to 30 percent, through to the interconnection agreement stage. The CAISO outcome included an unusually high concentration of storage and load-paired generation, with several large data center load applicants pairing their interconnection requests with co-located gas peakers and behind-the-meter storage.
ISO-NE and NYISO ran smaller cluster cycles with similar pattern shifts. SPP, which historically had a less congested queue than the eastern RTOs, ran its first full Order 2023 cluster with a clearance ratio above 50 percent on a smaller absolute nameplate base.
The aggregate across all RTOs is a clearance ratio that has roughly doubled relative to the pre-reform serial study process, off a queue base that has shrunk because the deposit and readiness criteria filtered out speculative applications before the studies began.
The deposit and readiness criteria did the work
The single most important design choice in Order 2023 was the requirement that transmission providers escalate financial deposits at each study milestone and assess withdrawal penalties scaled to the cluster network upgrade cost. The pre-reform queue had been filled with applications that cost the applicant roughly $10,000 to $50,000 to file and could be withdrawn at any point with no material penalty. The reformed queue requires deposits in the $500,000 to multi-million range scaled to project nameplate, with the deposit forfeited and additional withdrawal penalties assessed if the project exits after triggering re-studies that shift cost allocation across the remaining cluster members.
The result, visible in the application-stage withdrawal rates, is that roughly half of the speculative applications that would have entered the pre-reform queue never reach the cluster study under the reformed rules. They are filtered out at the application screening and readiness deposit stages. The cluster studies themselves are then running on a smaller and more committed applicant pool, which is the precondition for finishing the studies faster.
The commercial readiness criteria are doing complementary work on the demand side of the queue. Site control documentation requirements have eliminated the placeholder applications that historically tied up queue positions with no underlying real estate transaction. Offtake commitment requirements at the second and third study milestones have pushed merchant developers to secure power purchase agreements earlier in the development cycle, which has favored utility-led and corporate-PPA-backed projects over speculative merchant projects.
The downstream effect is a queue that resembles a development pipeline, not an option-value lottery. That is the shift the reform was designed to deliver.
What the cleared mix says about the next reliability window
The interconnection queue is a forward indicator for the dispatchable and clean capacity stack that will be available in the late 2020s and early 2030s. The composition of the cleared projects from the first reformed cluster cycles tells you what the reformed process is actually surfacing.
The headline composition shift is the rise of storage and storage-paired hybrid projects as the dominant cleared category. Standalone four-hour lithium-ion battery storage and solar-plus-storage hybrids together account for roughly half to two-thirds of the cleared nameplate in the PJM, MISO, and CAISO clusters that have posted final results. The four-lever framing for the 2027 to 2029 reliability window has storage as the first lever for a reason: the cleared interconnection queue confirms the buildout pipeline.
The second observation is that pure standalone solar without storage is a smaller share of the cleared queue than it was of the pre-reform queue. This reflects a combination of pressure from the readiness criteria, capacity market price signals that are rewarding firm capacity over energy-only output, and corporate PPA terms that are increasingly demanding the storage hybrid configuration. The pure solar queue thinning is not a failure of the reform. It is the reform surfacing the projects that have a clear path to commercial operation under current market conditions.
The third observation is that natural gas combined-cycle and simple-cycle additions are clearing in MISO and SPP in larger nameplate than they are in PJM, ISO-NE, and CAISO. The MISO gas pipeline is the most active in the country among the cleared cluster results, with several utility-led combined-cycle projects in the 1 to 2 gigawatt range moving through the study cycle for late-decade commercial operation. This is consistent with the gas turbine OEM backlog analysis: the OEM order books have absorbed the demand signal, and the RTO interconnection queue is now confirming the demand signal on the wires side.
The fourth observation is the rise of load-paired and behind-the-meter applications, particularly in CAISO and PJM. Data center developers are submitting interconnection requests that pair their large load with co-located generation and storage as a single integrated package. This pattern is the inverse of the historical queue, where generation requests and load requests entered separate processes. The Order 2023 framework did not explicitly enable load-paired generation, but the readiness criteria favor it because the load offtake provides the commercial readiness documentation the criteria require.
Where the reform is not delivering
The reformed process has not delivered the headline outcome the policy community hoped for, which was a meaningful acceleration of clean firm generation through the queue. Nuclear restarts, small modular reactor first deployments, and enhanced geothermal projects are clearing the queue at a pace that reflects their development timelines, not at a pace that reflects the reformed study process. The Order 2023 queue reform is a necessary but not sufficient condition for accelerating clean firm capacity onto the grid. The binding constraints on clean firm are still the technology readiness curves, the equipment supply chains, and the offtake market design questions, not the interconnection study process.
The reformed process has also not yet meaningfully reduced the network upgrade cost burden assigned to cleared projects. The cluster studies are surfacing the same large network upgrade costs that the pre-reform studies were surfacing, in the $50 to $250 per kilowatt range depending on the cluster, with some projects facing assignments above $500 per kilowatt. The Order 1920 transmission planning framework, which requires regional transmission planning over a 20-year horizon and includes cost allocation rules for projects that deliver multi-value benefits, is the policy lever that is meant to bring network upgrade costs down by enabling proactive transmission buildout. Order 1920 is still in its implementation window, and the network upgrade cost effects will show up in cluster studies one to two cycles from now, not in the first reformed cluster.
The reformed process has not solved the small project burden problem. Projects under 20 megawatts are now waived from many of the cluster study requirements through the small generator interconnection process revisions FERC included in Order 2023, but the practical experience is that small projects are still facing study delays and cost allocation surprises in the post-application phase. The state-level interconnection rules for distribution-connected small generation, which sit outside FERC jurisdiction, remain a separate bottleneck.
What to watch in the next cluster cycle
The first reformed cluster cycles have established the new baseline. The question for the second and third reformed cycles is whether the pattern holds and whether the process timelines tighten further.
Three concrete questions will be answered in the next 12 to 18 months.
The first question is whether the cluster cycle calendars hold to the published milestones. The financial penalty provisions for missed study deadlines kicked in on the first cluster cycles. The penalty assessments, if any, will be the clearest signal of whether the RTOs are staffing the study queue adequately. The PJM compliance plan has been particularly contentious on this point, and the PJM transition cluster is the first major test of whether the penalty framework changes the RTO’s resource allocation to studies.
The second question is whether the withdrawal rates after the readiness deposit stabilize at a new lower level or whether they creep back toward the pre-reform pattern. The first cluster withdrawal rates benefited from the filtering effect of the deposit requirements. The second cluster is the test of whether the filtered queue holds together through to commercial operation, or whether the structural pressures that drove pre-reform withdrawals (financing market shifts, equipment cost changes, offtake price re-negotiation) reassert themselves at later stages.
The third question is whether the network upgrade cost per cleared megawatt comes down with the rollout of Order 1920 regional transmission planning. The Order 1920 compliance plans were filed in 2025 and 2026, and the regional transmission plans they enable will start producing transmission project approvals in 2027 and 2028. The interaction between regional transmission planning and the cluster study cost assignment is the structural reform that, if it works, brings the network upgrade cost burden down to a level that supports a larger fraction of the queue clearing economically.
Where this leaves the four-lever and five-lever frame
The four-lever framing for the 2027 to 2029 reliability window covered storage, coal life-extension, demand-side reliability, and grid-enhancing technologies, with enhanced geothermal added as the fifth lever for the 2030 to 2032 window. The Order 2023 cluster study results are the supply-side confirmation that the storage lever is delivering at scale, the demand-side reliability lever is being surfaced through load-paired applications, and the dispatchable clean generation lever is still constrained by technology readiness rather than queue throughput.
The reformed queue is not the binding constraint on the 2027 to 2029 reliability window. The gas turbine OEM order book is. The reformed queue is not the binding constraint on the 2030 to 2032 clean firm window either. The drilling cost curve at Cape Station and the small modular reactor first-of-a-kind cost curve are. The reformed queue is, however, the necessary infrastructure that allows the projects clearing those upstream constraints to actually reach commercial operation in the timelines that capacity planning assumes.
The honest summary for utility integrated resource planning is that interconnection queue clearance is no longer the planning risk it was three years ago. The planning risk has moved upstream into the equipment supply chain and the development capital stack. The reformed queue is doing its job. The rest of the stack has to catch up.
Sources and references
- FERC Order 2023, issued July 28, 2023, and the compliance filings of PJM, MISO, CAISO, ISO-NE, NYISO, and SPP
- Lawrence Berkeley National Laboratory annual queued generation reports, 2021 through 2025 editions
- PJM transition cluster system impact study reports, late 2025 and Q1 2026
- MISO Definitive Planning Phase cluster reports, 2025 cycle
- CAISO 2024 cluster study reports
- FERC Order 1920 regional transmission planning final rule, May 2024
- Heavy-duty gas turbine OEM Q1 2026 earnings disclosures (GE Vernova, Siemens Energy, Mitsubishi Heavy Industries)