ISO-NE begins interconnection Transitional Cluster Study

ISO New England has begun its Transitional Cluster Study, an important milestone in a yearslong reform effort that will create a more efficient process for new generating facilities and elective transmission upgrades to interconnect with the regional power grid.

A total of 26 interconnection requests qualified to be included in the study. That includes 21 battery energy storage, two solar photovoltaic, and three wind projects. Most of the interconnection requests are in Massachusetts, with two each in Connecticut, Maine, and Vermont, as well as one in New Hampshire. There are none in Rhode Island.

More than 50 other requests with previously completed studies, most of which have signed interconnection agreements, remain in the queue and can continue working toward completing the interconnection process. Information on interconnection requests is available via the ISO’s public queue data.

ISO-NE must perform technical studies to ensure each new resource can connect to the grid safely and reliably. Until now, interconnection requests have been studied one by one on a “first-come, first-served” basis, outside of specific circumstances.

The cluster-study-based interconnection process was developed as a result of Federal Energy Regulatory Commission (FERC) Order Nos. 2023 and 2023-A. The orders sought to address interconnection queue backlogs across the United States by prioritizing projects with a high likelihood of development and deterring speculative ventures.

The new process institutes a “first-ready, first-served” process, studying all interconnection requests as a group, or cluster. Additionally, developers must meet increased financial and site control requirements, and face potential penalties for withdrawing projects from the queue. The ISO and transmission owners would face penalties for any delays in future cluster studies.

The Transitional Cluster Study is the ISO’s first under the new framework. It is scheduled to be completed by Aug. 6, 2026, as required by the ISO’s tariff. The cluster request window for the ISO’s first full cluster study will open in October 2026.