Connecticut regulators have required utilities Eversource and United Illuminating to offer scheduled flexible interconnection for solar and storage projects on their most constrained distribution circuits by next May, and progress to dynamic flexible interconnection statewide by late 2030.
The order is a victory for the Connecticut Solar & Storage Association that was years in the making.
Mike Trahan, the group’s executive director, said the decision addresses “three big threats to project viability: time-to-interconnection, project-level capital expenditure, and revenue loss from over-curtailment.”
In regulatory proceedings, the trade group had “pushed back at the notion that solar developers must wait two to four years for utilities to deploy DERMS before shovel-ready jobs could flexibly interconnect.” The acronym DERMS refers to distributed energy resource management systems that can control a project’s exports.
The group told state regulators that a two- to four-year timeline “put private capital, site control leases, and federal investment tax credits at risk,” Trahan said, adding that regulators “agreed” in their decision.
Scheduled flexible interconnection, an approach pioneered in California, allows electricity export in amounts that vary based on the forecasted minimum hosting capacity within defined time windows.
Starting in May 2028, utilities must offer dynamic flexible interconnection at the most constrained substations, and offer it statewide by late 2030. Under this approach, exports are subject to dynamic limits that the utility can adjust automatically based on real-time system conditions.
To implement dynamic flexible interconnection, both an Advanced Distribution Management System (ADMS) and grid-scale DERMS are required, the regulatory order says.
The two utilities must also establish provisions for converting from scheduled to dynamic flexible interconnection, and from flexible to firm interconnection.
Curtailment
The Connecticut Solar & Storage Association had argued that flexible developers who are “the first to commit a project need protection from curtailment creep that can happen as more solar or storage projects connect to the same substation.”
The group obtained that protection in the decision as well, Trahan said.
The regulatory order establishes “vintages” of projects, with each vintage to have a target for maximum curtailment. Projects enrolling in the first vintage will have a target of no more than 5% annual MWh curtailment. The order says the target “is intended as a basis for establishing the vintage and is not a guarantee or hard limit on the actual curtailment experienced by an individual project.”
The Connecticut Solar & Storage Association has long pursued flexible interconnection, starting with its work to launch a state-sponsored interconnection working group five years ago.
Consumer savings
Connecticut Public Utilities Regulatory Authority Commissioner David Arconti said in a social media post that the decision will enable faster interconnection, better utility utilization, and potential savings for utility customers.
The Brattle Group has projected that achieving flexible interconnection nationwide would yield $39 billion in savings through 2050.
The order was published as a November 4 final decision in PURA docket 25-01-27.
At least seven other states require utilities to offer some form of flexible interconnection, or are considering doing so.
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