A Massachusetts interconnection application follows the utility’s DG tariff, not the town building department. National Grid, Eversource, and Unitil each implement DPU-approved Standards for Interconnection of Distributed Generation. The tracks you will hear in kickoff meetings are Simplified, Expedited, and Standard. Pick the wrong one and completeness review sends you back before anyone looks at a feeder.
This is a checklist for installer PMs. Confirm cutoffs and fees on the live M.D.P.U. tariff and the utility’s DG portal. Those documents update.
Simplified vs Expedited vs Standard
National Grid’s Massachusetts DG process page is the plain-language version. Simplified is for small listed inverter-based facilities on radial circuits that meet the size and screen tests. The page currently describes Simplified as a single UL 1741 listed inverter path at or below 15 kW for single-phase service and 25 kW for three-phase. Expedited is available when you do not qualify for Simplified. Standard is the track National Grid recommends for non-inverter DG and large (they cite ≥500 kW) inverter-based systems.
Eversource Massachusetts uses the same three-track idea under its own tariff. Do not assume a National Grid Simplified exhibit is accepted as-is in Eversource’s portal.
Municipal light plants are not these tariffs. If the bill says a town department of public utilities, call them. Do not file Gridforce and hope.
Before you apply
- Confirm IOU vs MLP.
- Confirm single-phase vs three-phase service. A three-phase inverter on a single-phase service is a service upgrade, not a Simplified trick.
- If aggregate nameplate is 250 kW or greater, National Grid requires a Pre-Application Report. Below 250 kW the report is optional and paid. Skipping a mandatory pre-application makes the interconnection application incomplete by definition.
- Freeze module, inverter, and storage SKUs. SMART equipment lists and the interconnection application should describe the same machine.
- Pull the electric bill. Account number errors are the most common “incomplete” we still see.
Packet checklist (Simplified)
National Grid’s Simplified flow uses Exhibit A / portal fields plus attachments. At minimum have:
- Legal customer name matching the account
- Service address
- kW AC, DC STC, configuration
- UL 1741 confirmation
- Fuel source and incentive flags (net metering vs qualifying facility language in the portal). National Grid’s Simplified article notes net metering selection is limited by system size in the form; oversize and the form routes you elsewhere.
- SMART enrollment question answered honestly. SMART is not PTO. It is a checkbox and a separate program.
- One-line: utility side, meter, disconnect, inverter, grounding as they want it drawn
- Cut sheets
- Signed terms
Then pay whatever fee the current tariff assigns to Simplified. Do not copy a 2024 fee into a 2026 bid without looking.
Packet checklist (Expedited / Standard)
Add what Simplified skipped:
- Pre-application if required
- Three-line or more detail if the utility asks
- Relay, transformer, or storage operating modes
- Possible study and ISA (Interconnection Service Agreement)
- Witness test language in the closeout
MassACA’s ISA guidance is a reminder that Simplified “agreements” and full ISAs are different documents. If you need an ISA for net metering cap allocation, a Simplified countersigned Exhibit A may still need the extra pages MassACA lists. That is incentive administration riding on interconnection paperwork. It is not a second physics review.
Completeness, screening, construct, PTO
National Grid’s Simplified article currently cites 10 business days for document review, then 15 business days for Simplified screening after a clean package. If they find issues, the case goes on hold. Those are tariff-adjacent clocks from the company’s own help article. If your job is Expedited, use the tariff tables, not this Simplified paragraph.
Conditional approval means build. The Massachusetts building permit is a parallel clock. See our 2026 Massachusetts permit guide for AHJ documents. Do not wait for PTO to pull a building permit, and do not treat the building permit as the Massachusetts interconnection application.
Closeout: completion documents, any witness test the ISA requires, meter work, then National Grid’s interconnect email. That email is permission to operate. PPO and permit to operate mean the same closeout. Do not export the Friday the inspector left if the email is not in the inbox.
Moving forward when MA jobs stall
If screening fails, you are usually looking at a different process, not a pep talk. If completion fails, it is often a mismatched nameplate or a missing form. Upload as-builts when the array is not the approved layout.
Athol Energy prepares Massachusetts interconnection applications against the same permit design model, with PE stamps when the drawing needs a Massachusetts PE in responsible charge. For statewide design context see Massachusetts solar design services.
Sources: National Grid MA process, Submitting MA Simplified Application, MassACA ISA requirements.