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Interconnection Standards

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Massachusetts' interconnection standards apply to all forms of distributed generation (DG), including renewables, and to all customers of the state's three investor-owned utilities (Unitil, Eversource, and National Grid).

Massachusetts requires investor-owned utilities to have standard interconnection tariffs. There are three basic paths for interconnection in the state:

  • The Simplified interconnection process applies to IEE 1547.1-certified, inverter-based facilities with: 
  1. A power rating of 15 kW or less for single-phase systems located on a radial distribution circuit, 
  2. A power rating of 25 kW or less for three-phase systems located on a radial distribution circuit (where the facility capacity is less than 15% of the feeder/circuit annual peak load, and if available, line segment), 
  3. A power rating of less than 1/15 of the customer's minimum load and located on a spot network, or 
  4. A power rating of less than 1/15 of the customer's minimum load and 15 kW or less and located on an area network. 
  • The Expedited interconnection process applies to:
    • 1) Inverter-based facilities 15 kW or greater for single-phase systems, 
    • 2) Inverter-based facilities 25 kW or greater for 3-phase systems, and 
    • 3) Other systems of all sizes that are served by radial systems and meet certain other requirements. 
  • The Standard process is for all other facilities that do not meet the specifications of the Simplified or Expedited process, including systems on all networks. 
  • The issue of interconnection to network systems is particularly important in Massachusetts because network systems are commonly used in dense urban areas, such as Boston. Order 11-75-E implemented a more transparent Supplemental Review screen process for projects that fail the initial Simplified and Expedited screens. If a project fails the Simplified and Expedited screens, it must pass three supplemental review screens, otherwise it must go through the full standard review process. Massachusetts uses a 100% of minimum load penetration screen in the supplemental review process. If the generating capacity is less than 100% of minimum load, it  may not require a detailed study. In addition to these different paths, for all systems 500 kW or greater, facility owners must request and receive a pre-application report from the utility. The pre-application report is optional for facilities less than 500 kW; no fee is charged for this report.

    For the simplified and expedited interconnection paths, technical requirements are based on the IEEE 1547 and UL 1741 standards. A manual external disconnect switch may be required at the discretion of the utility (project-specific, not required in the tariffs). Utilities must collect and track information on the interconnection process. This information will be used in revising and updating the standards.


    In August 2011, the Department of Energy Resources (DOER) submitted the Massachusetts Distributed Generation Interconnection Report to the DPU outlining its recommendations for improved interconnection policies and processes based on its research, which included an extensive stakeholder survey, conducted in April 2011. In September 2012, the Massachusetts Distributed Generation Interconnection Working Group submitted its final report recommending changes to the state's interconnection standards. DPU incorporated changes from comments submitted in Docket 11-75, and adopted the report those changes in March 2013.