What is the solar interconnection process? It is the utility’s path from a complete interconnection application to written permission to operate. Town permitting is a separate path. Incentive programs are a third. If you explain only “we file with the utility and then you turn it on,” customers will call the week the roof is done asking why the app is not producing.
Here is the process as it actually runs in Massachusetts, Rhode Island, Connecticut, New York, and Pennsylvania, without inventing day counts the current tariff does not publish for your job.
Step 0: Know which rulebook you are in
- Massachusetts investor-owned utilities: DPU DG interconnection tariffs (National Grid’s is the M.D.P.U. Standards for Interconnection of Distributed Generation; Eversource and Unitil have parallel tariffs). Municipal light plants are their own world.
- Rhode Island Energy: Standards for Connecting Distributed Generation.
- Connecticut: PURA interconnection guidelines, implemented by Eversource and UI in separate PowerClerk sites.
- New York: Standardized Interconnection Requirements (SIR) for DG and storage 5 MW or less. The February 9, 2026 SIR is on the Department of Public Service site.
- Pennsylvania: 52 Pa. Code Chapter 75, Levels 1 to 4, implemented by each EDC (PECO, PPL, FirstEnergy companies, Duquesne Light, and others).
The solar interconnection process is not “one national form.”
Step 1: Pre-application when the tariff requires it
National Grid Massachusetts requires a Pre-Application Report at 250 kW aggregate nameplate; smaller jobs may request one for a fee. New York’s SIR uses a $750 pre-application on the large-DG side, credited in defined cases toward the later application fee. Skipping a mandatory pre-application is how a 300 kW roof gets bounced on day one.
Hosting capacity maps (Eversource CT publishes one; other EDCs have their own) are reconnaissance. They are not approval.
Step 2: File the interconnection application
This is the solar interconnection application: account data, nameplate, UL 1741 inverters, one-line, site plan, fee, signed terms. Completeness review is its own event. National Grid MA Simplified documentation review, Rhode Island Energy’s 10-business-day completeness notice in the tariff, Pennsylvania Level 1’s 10-business-day receipt window in section 75.37: different numbers, same idea. Incomplete means the process has not started.
How do you apply? Through the utility portal. National Grid and Rhode Island Energy use Gridforce-style accounts. Connecticut and many New York utilities use PowerClerk. PECO uses MyGeneration. Mail-in still exists on some PECO instructions as a backup. Production companies should not rely on mail.
Step 3: Screens, Fast Track, Expedited, SIR, or study
Small listed inverter jobs try to pass screens (Simplified in MA/RI, 25 kW-or-less inverter guidelines in CT, SIR 50 kW-or-less in NY, Chapter 75 Level 1 at 10 kW or less in PA). Fail a screen and you are not “denied forever.” You are usually moved to Expedited, Fast Track, Level 2, CESIR, or Study, with more time and cost.
Con Edison’s public interconnection page: no application fee at or below 50 kW; $750 above 50 kW up to 5 MW, plus CESIR and construction if triggered. Eversource CT publishes $200 / $500 / $1,000 application fees by track and notes Fast Track study time versus Study Process in business days. Use the live table. Do not copy this paragraph into a bid as a guaranteed price.
Step 4: Agreement and permission to construct
You receive conditional approval, a countersigned Exhibit A, or an Interconnection Service Agreement. That is your construction baseline. Change the inverter after this and you reopen the interconnection application.
Build. Call for AHJ inspection. Do not treat the inspector as the utility.
Step 5: Completion, meter, witness test, PTO
Rhode Island Energy: completion documents, then meter, then Authorization to Interconnect. National Grid MA Simplified: completion package, then interconnect email. PECO: Permission to Operate letter plus meters. SIR jobs may include verification testing. As-builts show up when the field does not match the approved one-line.
PTO, PPO, and permit to operate all mean this written closeout. Moving forward after inspection is this step, not a pep talk.
Where jobs actually stall
The solar interconnection process rarely dies on “the utility hates solar.” It dies on:
- Account number typos
- One-line that does not match the permit set
- Wrong process track
- Equipment swap after approval
- Completion packet missing the certificate of completion
- Energizing before PTO and then arguing about it
Athol Energy’s interconnection work is the application packet and drawings. Permit design is the AHJ set. PE stamping is responsible charge where the state requires it. As-built drawings are for closeout when the roof changed. Keep those four labeled correctly in your own shop or you will file the wrong PDF in the wrong portal.
Sources: NY DPS SIR (effective February 9, 2026), 52 Pa. Code Chapter 75, National Grid MA process, Eversource CT Application to Connect, RI Energy interconnection process.