Interconnection filings and tariffs

Here, you can find a list of interconnection filings and electric company interconnection tariffs.

1. Policy investigations

Case number	Subject of investigation
D.P.U. 25-48	Investigation into the interconnection implementation review group’s proposed revisions to the distributed generation tariff
D.P.U. 20-75	Investigation of distributed generation interconnection cost allocation
D.P.U. 19-55	Investigation on distributed generation interconnection D.P.U. 19-55-B Interim guidance for interconnection of qualifying facilities D.P.U. 19-55-C Affected system operator studies D.P.U. 19-55-D Management of high-volume queues
D.P.U. 11-75	Investigation on distributed generation interconnection

2. Customer petitions

Case number	Subject of investigation	Notice issued
D.P.U. 24-186	Petition of Allco Renewable Energy Limited and Allco Finance Limited for an adjudicatory hearing regarding interconnection disputes with National Grid	yes
D.P.U. 21-102	Petition of Allco Renewable Energy Limited and Allco Finance Limited for an adjudicatory hearing regarding interconnection disputes with National Grid	yes
D.P.U. 21-16	Petition of Eversource Energy for an adjudicatory proceeding pursuant to Section 9.3 of the standards for interconnection of distributed generation	yes
D.P.U. 21-13	Petition of Allco Renewable Energy Limited and Allco Finance Limited for an adjudicatory hearing and emergency injunctive relief regarding interconnection disputes with National Grid	N/A
D.P.U. 19-08	Petition of Sippican Community Solar Garden, LLC, for an interconnection adjudicatory proceeding with Eversource East	yes

3. Electric company petitions

Case number	Subject of investigation
D.P.U. 25-20	Petition for approval of the long-term system planning process proposal
D.P.U. 17-164	Petition for approval of a proposed revision of Section 3.4.1 of the distributed generation tariff D.P.U. 17-164 Revisions to Section 3.4.1 of the standards of interconnection of distributed generation tariff D.P.U. 17-164-A Model compliance filing

4. Distributed generation (DG) guidelines

This document is applicable to the obligations and responsibilities of the Distribution Companies and interconnecting customers. Users of each Distribution Company’s DG interconnection tariff also should refer to the Department DG Guidelines.

DG guidelines

5. Tariffs

Interconnection tariff

• Eversource Energy interconnection tariff
• National Grid interconnection tariff
• Unitil interconnection tariff

Provisional system planning tariff

• Eversource provisional system planning tariff
• National Grid provisional system planning tariff

6. Other DG filings

Case number	Summary of information in filing
XX-DG	Filings included: electric company bi-monthly affected system operator study report

To access all document filings, please visit the file room and type the case number, replacing the first two digits in a case number with the relevant year’s last two digits.  For example, type 25-DG for 2025 DG filings.  

Last updated:	November 20, 2025