Rules by state

Solar and battery interconnection rules in Massachusetts

Massachusetts standards for interconnection of distributed generation. Every threshold below was read out of the document linked at the bottom of this page, and the same rules answer the free screening check.

Who this binds: investor owned utilities. A utility outside that list sets its own terms, so confirm who serves the address first.

Check a Massachusetts address free
How the size is measured

nameplate, design or generation capacity or rating: the maximum continuous power output in alternating current listed by the manufacturer. This is the cleanest basis definition found in the northeastern states.

Size bands and what each one obliges

Simplified process Size 0 to 25 kW

Listed inverter based facilities of 25 kW or less, single phase on single phase secondary service or three phase on a three phase transformer configuration, on a radial system where aggregate generating capacity is under 15 percent of feeder or circuit annual peak load. The application fee is zero and the witness test is free. No insurance is required for a facility eligible for Class 1 net metering, meaning 60 kW or less.

  • No application fee
  • Net metering cap allocation from the System of Assurance
  • No insurance at or below 60 kW
Expedited process Size 25.001 to 1000 kW

Facilities that do not qualify for the simplified process must pass screens one through ten. The application fee is $4.50 per kW with a $300 minimum and a $7,500 maximum. Insurance is $500,000 above 10 kW to 100 kW and $1,000,000 above 100 kW to 1 MW, but nothing is required at or below 60 kW under the net metering exemption.

  • $4.50 per kW application fee, minimum $300 and maximum $7,500
  • $500,000 insurance above 100 kW, $1,000,000 above 100 kW to 1 MW
Standard process Size 1000.001 kW and above

Facilities that do not qualify for simplified or expedited treatment. Insurance is $2,000,000 per occurrence with $5,000,000 aggregate above 1 MW to 5 MW, and $5,000,000 above 5 MW. Group study timelines run to 160 days for the largest cases.

  • $2,000,000 per occurrence and $5,000,000 aggregate above 1 MW to 5 MW
  • Impact and detailed studies at actual cost

The screens that decide it

Ask the utility this, before you sell it

  1. Is this address served by a municipal light plant? If so none of this applies, the utility sets its own terms, and the state net metering caps do not reach it.
  2. What net metering cap allocation is available from the System of Assurance for this project? Massachusetts rations allocation through that queue and the tariff requires an allocation as compliance documentation, so it is a real gate on a sale.
  3. Is a pre application report required here? It is mandatory at 250 kW and above, at $100 below 250 kW, $250 from 250 to 500 kW and $750 above 500 kW.

Worth knowing before you quote

Massachusetts caps aggregate net metering at 7 percent of the distribution company peak load for private facilities and 8 percent for municipal and other governmental facilities, administered through the System of Assurance. Whether a particular allocation bucket is exhausted is a live queue figure rather than a published rule, so it must be asked. Simplified review completes in 25 business days, or 30 where the fault current screen fails; expedited in 45 or 65 with supplemental review. Permission to operate follows within 5 business days of the customer satisfying the connection requirements and the meter being installed. The tariff still references IEEE 1547-2003 throughout and contains no reference to the 2018 revision.

Source

Massachusetts standards for interconnection of distributed generation, NSTAR Electric doing business as Eversource, M.D.P.U. No. 55G, effective 20 August 2026, with net metering caps at Massachusetts General Laws Chapter 164 Section 139

Read and recorded 2026-09-12. A Department of Public Utilities model tariff implemented as each distribution company own tariff, so it is statewide in substance rather than a codified rule. National Grid and Unitil file counterparts. Municipal light plants are outside it, because the net metering caps run against a distribution company and roughly forty one Massachusetts towns are served by a municipal light plant instead.

What to do with this

Check a real address

The rules below are the general case. Run the free check to see which utility serves a specific address, which tier the system lands in, and what to ask.

Run the free check
Installers: keep the answer with the job

GridProjeX holds the project from here, with every value tied to the document it came from and the utility and permit tracks run to permission to operate.

How it works for installers
Utilities: see what applicants are told

The same published rules your applicants read here are the ones your queue sees. GridProjeX is the record both sides work from.

How it works for utilities

Also from CivyxIQ, if they fit what you already do: SolarProjeX for running the crews and the jobs, and Solar Home so the homeowner can follow their own project. Neither is needed to use the checker.