How Much Is Solar in Boston, MA? $2.91/W, 12.4-Yr Payback

Why this number

A kilowatt of panels in Boston produces about 1,257 kWh a year, the highest of the 3 Massachusetts cities modeled here — ahead of Worcester at 1,252, Springfield at 1,220. On an 8 kW system that is a payback of about 8.3 years, against 8.5 years in Springfield, on identical hardware at the same 30.49¢/kWh.

Boston against the rest of Massachusetts

Across the 3 Massachusetts cities with their own modeled figures, production spans 3.0% — Springfield at 1,220 kWh per kW to Boston at 1,257. Every column except production is identical down this table: same 30.5¢/kWh retail rate, same export regime, same $2.91/W installed cost. The payback differences are caused by weather and nothing else.

Against the state figure, Boston runs 0.6% above Massachusetts’s 1,250 kWh per kW — a payback 4.1 years longer than the statewide 8.3-year estimate on the same hardware at the same price.

What sets Boston apart

The reference point for Massachusetts, and close to the state figure — the state is small enough that its cities barely differ.

Your utility, officially

Massachusetts’s average residential rate is 30.5¢/kWh, but the bill in Boston comes from NSTAR Electric Company at 19.92¢ — 35% below the state figure. These are the residential figures Boston’s utility reported to the U.S. Energy Information Administration on Form EIA-861 for 2024 — computed as revenue ÷ sales from the official file, not estimated:

How exports are treated matters as much as the headline price: NSTAR Electric Company is modeled here under the state’s full-retail net metering rules, and that treatment is baked into every payback figure on this page.

Boston homes are billed by Eversource — on the EIA’s books still NSTAR Electric Company, the legacy name of the Boston-area utility Eversource absorbed — an investor-owned company with 1,303,076 residential customers and a 2024 EIA-861 average of 19.92¢/kWh. That is expensive by national standards and cheap by Massachusetts ones: drive forty miles west to Worcester and National Grid’s average is 23.07¢, a 3.15¢ spread inside one small state. High rates are the engine of Boston solar economics — at nearly 20¢, a mediocre production year still buys back a lot of bill — and they are why Massachusetts paybacks embarrass sunnier, cheaper states.

A Massachusetts bill splits into delivery and supply, and the supply side is where Boston gets complicated. Eversource’s Basic Service price resets on a schedule, many residents instead get supply through the city’s community-choice aggregation or a competitive supplier, and your effective rate depends on which of those you are on. Check the supplier line on your bill before trusting any average; Eversource’s current tariffs are published at eversource.com .

On exports, we owe you unusual candor. Massachusetts net metering (220 CMR 18.04) is commonly treated as full retail for home systems, and Eversource’s own overview is at eversource.com . But our review of the regulation could not resolve whether a 60% credit multiplier in the rule reaches residential behind-the-meter systems, so our Massachusetts page carries this at low confidence and so does this one: confirm your exact credit class with Eversource in writing before you sign. A payback built on the wrong multiplier is not a rounding error.

The fleet data suggests Bostonians have found the terms agreeable anyway: 80,111 residential net-metering customers and 579.848 MW reported to EIA for 2024 — about one Eversource home in sixteen, averaging 7.2 kW per system. That is one of the densest solar fleets in the eastern half of our dataset, in a city not famous for sunshine, which tells you the driver here was never the weather. It is the 19.92¢ rate, a crediting regime worth confirming but historically generous, and a state that has layered its own incentives on top — the combination that makes triple-decker roofs in Dorchester better investments than ranch houses in Georgia.

Source: EIA Form EIA-861, 2024 final release , accessed 2026-09-02. Average price is total residential revenue divided by total residential sales for the year — your own rate depends on your tariff and usage tier.

Who else serves the metro

NSTAR Electric covers most of Boston, yet its 11-county EIA-861 territory overlaps with other systems, including Massachusetts Electric Co at 23.1¢, the Town of Reading’s utility at 15.9¢, and Fitchburg Gas & Electric Light at 24.0¢. Against NSTAR’s 19.92¢, that’s roughly a 4.0¢ drop to Reading’s rate and about 4.1¢ higher to reach Fitchburg — a spread substantial enough that a payback calculated on NSTAR’s price and export rules would not carry over to either neighbor. Massachusetts’s July 2026 state average, 30.49¢, is a later, separately calculated figure, not directly comparable to these 2024 numbers. Whether a home sits on NSTAR, Reading, or another system is determined by ZIP code, not city.

The exact answer is a ZIP question, not a city question: look up your utility by ZIP . Candidates: utilities EIA-861 lists in 11 service counties of the metro’s main utility; prices are 2024 revenue ÷ sales from the official file.

An 8 kW system in Boston, priced out

Only the first two rows differ. Everything financial — rate, tariff, price per watt — is inherited from Massachusetts without change, which is the point: a city page that quietly used a different electricity rate from its state page would be guessing, not measuring.

Doing nothing is not free either. Twenty-five years of the electricity an 8 kW Boston array would produce, with rates rising at 2.5% a year, comes to roughly $94,241.

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Run it with your own bill