Utilities · Massachusetts

Eversource Massachusetts: solar economics on a 36 cent grid

SLWritten by the Solar Learning Lab research desk·Updated August 18, 2026·9 min read

Eversource is the utility most Massachusetts solar quotes are built against, and most of those quotes are already stale. The supply price reset on August 1, 2026, up about 11 percent in the east and 16 percent in the west, and the delivery side changed five weeks before that. A Greater Boston household on default service now pays roughly 35.7 cents per kilowatt-hour all-in. Cape Cod pays more. That number is brutal on a winter bill and it is exactly why solar payback in this territory keeps getting shorter.

What exports are worth

Massachusetts net metering is set by state rules, and the residential deal is stronger than most homeowners realize. A Class I facility of 25 kW AC or less is Nameplate Cap Exempt, which means it earns the standard credit at 100 percent of the basic service, distribution, transmission, and transition charges combined. The 25 kW threshold came from a 2022 law; before that, single-phase systems capped out at 10 kW for the exemption. Larger systems between 25 and 60 kW fall to the market credit at 60 percent of the same value.

Running the current components through the state formula, we get roughly 31.4 cents per exported kWh in Eastern Massachusetts and 30.0 cents in the west. Treat both as an upper-bound approximation: Eversource does not publish a single credit rate, and whether every distribution sub-factor counts in the credit is not spelled out on the pages we read. Even discounted, an export credit near 30 cents is more than double what most Sun Belt utilities pay, and it is the single biggest reason Massachusetts payback math survives its cloudy winters. The customer charge, energy efficiency, and renewable energy charges are never offset, so no system zeroes a bill entirely.

Do the caps matter for a rooftop? No. Cap-exempt means what it says, and even for larger private projects Eversource had 87,689 kW of private cap available with no waiting list as of the April 17, 2026 allocation report. The pressure point is on public-entity projects and, as our National Grid guide covers, on the other utility's side of the ledger.

Sources: Mass.gov net metering guide, net metering laws and regulations, and the MassACA cap allocation report of April 17, 2026. Export values are our sums of the cited tariff components.

Interconnection, step by step

Your installer files the application in Eversource's PowerClerk portal, and for the path nearly every house takes, a UL-listed inverter system of 25 kW AC or less on a radial circuit, the application fee is zero. Eversource describes the review as generally one to three weeks, installation as one to two days, and then the sequence runs municipal inspection, meter swap, permission to operate. Do not let anyone energize the system before that letter arrives.

The 25 kW Simplified threshold is itself new. The state model tariff approved February 10, 2026 raised it from 15 kW, part of an interconnection reform docket that also produced stamp-approved tariffs for all three utilities on April 27, 2026. One proposal to watch: a March 2026 joint filing would add a non-refundable $225 fee for all Simplified applicants to fund system upgrades. It was not approved as of our review date, and we flag it because a free process that becomes a $225 process changes quotes at the margin. Area network locations, mostly dense urban grids, pay $100 to $300 today. Larger or non-inverter projects pay $4.50 per kW between a $300 floor and a $7,500 cap.

Sources: Eversource application to interconnect, Eversource solar project timeline, Mass.gov utility interconnection, and the D.P.U. 26-57 notice on the proposed $225 fee.

Who should do the work is its own question. We grade every major Massachusetts installer on documentation, complaint history, and verifiable volume on our installer pages, and the Massachusetts guide carries the statewide picture, including the SMART history and the payback math these rates produce.

What we could not verify

As of August 18, 2026: a published Eversource residential net metering credit rate in cents per kWh, so our export figures are sums of tariff components, not a utility number; whether the proposed $225 interconnection fee in D.P.U. 26-57 was approved; whether Eversource's own SMART 3.0 tariff is on file and paying after the May 19 approval; any general residential EV time-of-use tariff; and an end-to-end interconnection timeline in business days beyond the one-to-three-week review estimate. Where we could not read a source, we did not print a number. Our editorial policy explains how corrections work if you hold a document that settles any of these.