Why do Boston and Worcester sites model so differently?

Two filed rate designs. Eversource's Boston G-2 is flat energy against about $36 per kilowatt-month of demand — the heaviest in the covered set; National Grid's Worcester G-3 is about $11 per kilowatt-month against higher time-of-use energy. Same state, opposite shapes — utilization and TOU mix decide which book prices a given load better, and the model runs both from the address.

ForgeAsset / Supercharger ROI / Massachusetts

Tesla Supercharger ROI in Massachusetts

Massachusetts prices the same charging load two very different ways. National Grid's G-3 around Worcester bills a comparatively light demand charge — about $11 per kilowatt-month, only inside a weekday-daytime window and with no ratchet clause at all — against energy near 19¢ once the quarterly default-supply strip folds in. Eversource's G-2 in Boston inverts the shape: flat energy near 16.7¢ against roughly $36 per kilowatt-month of distribution and transmission demand, the heaviest demand charge in the covered set. Both books re-price supply quarterly, and the modeled rows carry the published August-through-October 2026 strips.

Model a Massachusetts site

What makes Massachusetts economics distinct

The heaviest demand charge in the covered set

Eversource's Boston-area G-2 bills about $36 per kilowatt-month across distribution and transmission — at a multi-megawatt billed peak that is the dominant line on the bill. One structural relief: demand recorded during off-peak hours bills at 45%, so if a site's monthly peak ever fell outside the peak window the actual bill would run below the modeled line, not above it.

A demand window with no ratchet

National Grid's G-3 measures demand only inside an 8 a.m.–9 p.m. weekday window — thirteen hours, five days, the widest such window in the covered set — and its filed tariff carries no ratchet clause of any kind. For a charging site that draws its hardware peak daily, the window contains the peak and the model prices the charge exactly.

Supply re-prices every quarter

Both utilities' default Basic Service is procured on quarterly fixed-price strips — the modeled rows seed from the published August–October 2026 strips and the library re-derives each quarter. Eversource's fixed price is an election with a twelve-month term and six months' notice to exit; supply zones move the energy rate a few tenths of a cent between Boston, Worcester, and the southeast.

A sales-tax exemption a small operator might actually hold

Massachusetts levies 6.25% sales tax on commercial electricity, folded into the modeled rates as the conservative default. A genuine exemption exists for businesses with five or fewer employees and under $1 million of gross income — a single-site entity can qualify, and the certificate removes the entire fold, worth roughly $10,000 to $15,000 per year at default volumes.

Utilities and tariffs modeled in Massachusetts

Utility & tariff	Energy	Demand
National Grid MA G-3	18.8¢/kWh–19.0¢/kWh by time of day	$11.13/kW of monthly peak
Eversource MA Rate G-2	16.7¢/kWh flat	$36.07/kW of monthly peak

Rates are digit-verified against each utility's own filed sheets and update within two weeks of any revision. Full derivations are on the methodology page.

Massachusetts tax profile

Sales tax on hardware: 6.25%
Business personal property tax: 2.6% of equipment value (example rate)
Clean-fuels credit: no program
Per-kWh charging excise: none

Massachusetts tax defaults applied: no clean-fuels credit program exists in Massachusetts (the LCFS revenue line is $0; a clean-fuel-standard bill sits in committee). LLC costs use the $500 annual report — the largest fixed entity cost in the covered set after California. Sales tax is the statewide 6.25% on hardware with separately stated installation labor untaxed; the electricity sales tax is already inside the modeled utility rates, and a small-business exemption (five or fewer employees and under $1 million of gross income) can remove it for a qualifying single-site entity — the conservative default models the tax. Business personal property bills at Boston's $25.96 per $1,000 of fair cash value — about 2.6% per year, with Worcester running higher; the field is editable by municipality.

Massachusetts programs and incentives

Utility make-ready programs (DPU 21-90/21-91)

Roughly $400 million approved across Eversource and National Grid for 2023–2026 make-ready infrastructure and charger rebates; 2026 is the current program term's final year, and successor-term filings were unresolved as of the research date. A specific award enters the model through the grant inputs.

NEVI (federal, MassDOT-administered)

Federal corridor DC fast-charging funding along I-90, I-95, and I-93, administered in award rounds.

Massachusetts charging market

Massachusetts carries roughly 62 Supercharger stations across the I-90/I-95/I-93 corridors and the Boston metro. Eversource serves Boston and Cambridge; National Grid serves Worcester and much of central Massachusetts. Municipal light plants — Braintree, Taunton, and dozens more — run their own systems the model does not cover; addresses there see a named-utility notice rather than a wrong auto-selection.

Massachusetts Supercharger ROI — questions

Why do Boston and Worcester sites model so differently?: Two filed rate designs. Eversource's Boston G-2 is flat energy against about $36 per kilowatt-month of demand — the heaviest in the covered set; National Grid's Worcester G-3 is about $11 per kilowatt-month against higher time-of-use energy. Same state, opposite shapes — utilization and TOU mix decide which book prices a given load better, and the model runs both from the address.
How stable are the Massachusetts rates?: The delivery components move on commission-approved schedules, but default supply re-prices every quarter — the modeled rows carry the published August–October 2026 strips, and the library re-derives at each reset. Eversource's fixed supply price is also an election with a twelve-month term and six months' notice, which the tariff note states.
Does Massachusetts tax EV charging per kilowatt-hour?: No per-kWh charging tax exists and none was found pending. The 6.25% sales tax on commercial electricity is folded into the modeled rates; a small-business exemption — five or fewer employees and under $1 million of gross income — can remove it for a qualifying single-site entity. A charger registration mandate exists in statute but no fee schedule had been issued as of the research date.

Sources

Model a Tesla V4 Supercharger site in Massachusetts — payback, NPV, IRR, and a 15-year cash flow from your own inputs.

Run a Massachusetts scenario

Other states: California, North Carolina, Georgia, Oregon, Pennsylvania, Florida, Arizona, Texas, Virginia, Illinois, Michigan, Tennessee, Montana, Idaho, Kansas, Nebraska, North Dakota, South Dakota, Wyoming, New Mexico, Oklahoma, Alabama, Missouri, Wisconsin, Iowa, Indiana, Louisiana, Nevada, Washington, Ohio, Utah, New Hampshire, Kentucky, South Carolina, Minnesota, New Jersey, Colorado, Maryland. Coverage spans thirty-nine states in total — see the full list.

ForgeAsset is software, not investment, tax, or legal advice — outputs are model estimates from your inputs, not guarantees. Rates and programs current as of research; verify current terms with each source before committing capital.