Once you have decided that you are ready to interconnect to the transmission system, you can begin the process.

Pursuant to the Tariff, transmission interconnection requests are submitted through ISO New England’s cluster‑based interconnection process and accepted only during designated request windows.

After an interconnection request is accepted by ISO New England, projects proceed through the cluster study process.

Project Phase

The interconnection project phase starts when you submit an interconnection request during an active cluster request window to ISO New England via the Interconnection Request Tracking Tool (IRTT).

More information is also available on the  Undergo the Interconnection Study Process page of the ISO New England Interconnection Process Guide.

Facility study

Upon completion of the ISO New England Cluster Study, a facility study is performed by Eversource, in coordination with ISO New England. The purpose of the facility study is to further refine the scope of work and cost estimates associated with the interconnection facilities and any required system upgrades.

At the interconnection customer's discretion, the facility study will result in a +/-20% or +/-10% cost estimate.

The study will include the following:

• Siting and permitting desktop review
• Real estate rights review
• Environmental justice review
• Preliminary surveying
• Environmental mapping
• Preliminary soil borings
• Substation(s) and transmission line(s) preliminary engineering
• Constructability review
• Outage and energization plan(s)

The estimate does not include the following:

• Real estate rights acquisition costs
• The return and tax elements of the revenue requirements associated with transmission owner funded projects and allocation of interconnection operation and maintenance related charges.

For more detail, read ISO NE's interconnection process guide.

Early assessment

Pursuant to Schedule 23 of the Open Access Transmission Tariff (OATT), prospective interconnection customers (for small generating facilities <=20MW ) have the option to submit a formal pre-application request to ISO-NE to obtain a pre-application report on a proposed project in question at a specific site.

We will generate a report using existing system data that reflects the best available information at the time of reporting. The items to be included in this report include but are not limited to:

• Total capacity of the substation or transmission line based on normal operating ratings, pursuant to operating and planning manuals and procedures likely to serve the proposed point of interconnection (POI)
• Existing aggregate generation capacity (in MW) interconnected to a substation or transmission line likely to serve the proposed POI
• Approximate transmission line distance between the proposed POI and the substation in question

This report is non-binding and does not confer any rights to any of the parties involved, as the interconnection customer must still successfully apply to interconnect with the New England transmission system during an ISO New England Cluster Request Window.

The deposit for the pre-application is $500.

A full comprehensive list of all items pursuant to Schedule 23 pre-application can be found in the pertinent schedule of the tariff.

Infrastructure Coordination

Once an interconnection agreement has been signed, the infrastructure coordination phase will begin.

During this time, we will conduct periodic coordination meetings between Eversource and the interconnection customer.

The first meeting will be a kick-off to discuss the project construction timeline as identified in the interconnection agreement.

In addition to project construction, the following occurs at this time:

• Financial assurance, as identified in Schedule 11, 22 ,23, or 25 of the OATT, will be assessed (see Supplemental Manual for Credit and Security Requirements for Generator Interconnections for details) .
• Discussions regarding siting expectations. We will coordinate with the customer early in the process to develop an overall project siting plan that encompasses both interconnecting customer interconnection facilities as well as interconnecting transmission owner transmission facilities. Please contact us for additional questions or details.
• Operation and Maintenance (O&M) assigned to the project will be calculated based on FERC Form 1 Data and the estimated investment cost of facilities.

We will provide cost details during construction. By request, we can break out the cost into the following categories:

• Labor
• Materials
• Contractor Services
• Engineering Services
• Other Outside Services
• Contractor Labor
• Environmental Outside Services
• Licensing and Permitting