ISO-NE's interconnection queue holds 127 active generator projects totaling 14,541 MW. Less than 5,000 MW is likely to get built by 2029. Just 57 projects, 5,952 MW at nameplate, have executed interconnection agreements (IAs) and target commercial operation by 2029. But that nameplate figure overstates expected build. Build-through rates by technology, detailed below, cut the realistic outcome by 26% to 4,395 MW of expected build, 97% of it wind, solar, storage, or hydro.

State policy explains what projects enter the queue and where, whether through offshore wind state contracts, Massachusetts batteries earning Clean Peak Energy Certificates (CPECs), or solar dependent on RPS carve-outs.

Applying historical derating with project-specific overrides to the active pipeline with IAs, we have an expected build of 1,793 MW BESS, 1,741 MW offshore wind, 643 MW solar, and 103 MW onshore wind through 2029.

Key takeaways

• 57 projects and 5,952 MW nameplate have an executed IA and target 2029. Build-through rates cut expected capacity of batteries from 2,233 to 1,793 MW and solar from 1,162 to 643 MW.
• Offshore wind (2,295 MW, three projects) and batteries dominate the projects with IAs.
• Massachusetts batteries earn additional revenue through CPECs, leading to 76% of committed battery capacity in ISO-NE landing there.
• ISO-NE replaced its serial queue in October 2025, transitioning to a cluster study approach to the queue where projects are processed simultaneously.

Receiving an Interconnection Agreement defines committed projects but does not guarantee construction

ISO-NE's interconnection queue tracks a project's progress toward grid connection, including System Impact Study completion and proposed plan approval. But the IA is the defining gate. Projects without an executed IA will not build. Projects with an executed IA are what we call committed here, though an IA alone does not guarantee the project gets built.

ISO-NE's interconnection queue tracks a project's progress toward grid connection, including System Impact Study completion and proposed plan approval. But the IA is the defining gate. Without an IA, a project will not build. We consider a project with IA committed here, though there is no guarantee it gets built.

Of 127 active generators, 59 have executed an IA. Two target commercial operation beyond 2029, leaving 57 committed through the planning horizon.

Solar completes IAs but builds through at roughly 50%: an IA does not substitute for a MA SMART or RPS contract. After IA batteries have construction rates of 78%, onshore wind has 81%, and gas has 86%. Hydro builds through at close to 100% historically.

Named projects under construction override historical rates and count as built. Offshore wind's three near-term projects each carry their own assessed probability instead of a pooled rate.

The IA filter reveals which technologies have state support

No market mechanism in ISO-NE automatically advances projects through the interconnection process. IA execution instead tracks which technologies have secured state contracts or policy support.

All five active offshore projects in the queue (4,695 MW combined) have received an IA and carry state contracts. Gas and dual-fuel are predominantly merchant. Lacking offtake, 1,780 MW of active thermal nameplate falls to 106 MW committed, a 94% reduction. The last new thermal build in ISO-NE was Canal 3 (350 MW gas turbine) in 2019, and the gas in the queue currently reflects upgrades to existing gas generators.

BESS clears IAs at just 40%, but its active queue is the largest in the ISO at 5,616 MW. Solar has a higher rate of IAs at 79%, while onshore wind clears at just 16%.

By state, Massachusetts leads with 3,306 MW IA'd, followed by Rhode Island (982 MW), Connecticut (781 MW), and Maine (744 MW).

Offshore wind and batteries account for 76% of committed nameplate

Offshore wind contributes 2,295 MW across three projects. Vineyard Wind 1 (800 MW) and Revolution Wind (704 MW) are both delivering power. New England Wind 1 (791 MW) holds a Massachusetts contract and full federal approval from BOEM, but carries just a 30% probability given its pending PPA and a December 2025 Department of the Interior remand motion. That mix, not a flat rate, produces 1,741 MW of expected offshore build.

Queue status reflects interconnection readiness, not construction certainty, as the table below shows. Vineyard Wind 1 is complete but in financial distress amid a payment dispute with GE Vernova.

Two wind projects with executed IAs target dates beyond 2029, while no project directly targets a 2030 build date. SouthCoast Wind 1 (2031) lost its Rhode Island offtake contract in November 2025 and has been delayed four times. Bay State Wind 4 (2033) remains in early development with no confirmed state contract. Federal obstructions and developer risk concerns have effectively halted both projects' realization despite their executed IAs.

Massachusetts CPEC creates a battery revenue structure no other New England state replicates

Batteries contribute 2,233 MW nameplate across ISO-NE, with an expected build of 1,793 MW when including Taft BESS, which is under construction. 55% of committed battery expected capacity sits in the Boston Area (989 MW). Another 19% is in Southeast MA (337 MW).

Massachusetts is contracting 5,000 MW of storage (83E RFPs) by July 2030. That offtake floor makes project finance viable. The Clean Peak Energy Standard adds CPECs for batteries charging on renewable energy and discharging during peak hours, providing a second revenue stream on top of energy market income. Connecticut, Rhode Island, and Maine all have storage mandates but no CPEC equivalent.

The 83E RFP Round 1 winners have not executed IAs yet. Holding a state contract does not grant queue priority, and the four selected projects must complete the queue before they can sign one.​

BESS dominates the transitional cluster study

The projects committed today cleared ISO-NE's old serial interconnection queue, a process now replaced by cluster studies under FERC Order 2023 that allocate network upgrade costs by each project's relative system impact.

The transitional cluster study, launched October 2025, evaluates 25 projects. Three already hold executed IAs: SouthCoast Wind 1, Lite Brite Battery Storage, and Twin Energy Wind. The remaining 17 have no IA yet: 15 battery projects totaling 3,383 MW and two solar projects totaling 280 MW, no wind.

Applying this piece's build-through rates, battery at 78% and solar at 50%, to the cluster's pending capacity gives an illustrative ceiling of about 2,780 MW. That ceiling assumes every pending project executes an IA, which is unlikely. ISO-NE must graduate the cluster by August 2026, and the next entry window opens October 5 through November 19, 2026.

State incentives will continue to determine pipeline under cluster study

Under the old serial process, developers could sit in queue for years before learning their network upgrade costs. The cluster model surfaces those costs earlier.

New England's active queue is almost entirely wind, solar, and storage. No new thermal or nuclear capacity is in development. That leaves firm capacity scarce just as the region's winter peak is expected to grow.

The queue shows which projects are ready to connect, while state policy effectively determines which get built. The TCS results, due August 2026, will define which New England projects are committed next.