These rates are supply is provisional - Eversource states Basic Service rates are subject to change pending final regulatory approval. They are what the utility bills today, and they are not final.
Source
NSTAR Electric Company d/b/a Eversource Energy, Rate R-1HP (M.D.P.U. No. 85), priced in M.D.P.U. No. 1-26-E 'Summary of Electric Service Delivery Rates', Part A, effective 07-01-26
Effective
2026-07-01
Structure
time-of-use
· 2 rate periods
Covers
delivery and default supply — delivery plus the utility's default supply; a customer who buys supply elsewhere pays the delivery part only
Transcription notes recorded when this tariff was encoded, including anything deliberately left out.
NSTAR Electric Company d/b/a Eversource Energy, Massachusetts. A SEPARATE operating company from The Connecticut Light and Power Company, which is also Eversource and files an entirely different tariff: CL&P puts delivery and supply on one sheet, NSTAR files delivery only.
Rates are built from the components filed in M.D.P.U. No. 1-26-E, 'Summary of Electric Service Delivery Rates', Part A, and each is asserted at build time against the Total Delivery column the tariff prints on the same row. The published total is a check, never the source.
M.D.P.U. No. 1 is the authority, NOT the customer-facing 'Summary of Electric Rates' PDFs published per service area. The filed R-1HP schedule (M.D.P.U. No. 85) carries no numbers at all - every line reads 'As per M.D.P.U. No. 1 as in effect from time to time' - which is what identifies No. 1 as the source.
TRAP in the customer-facing summary: it lists 'Energy Efficiency Charge $0.02292' as one of eleven components. In M.D.P.U. No. 1 that figure is a SUBTOTAL of System Benefits $0.00250 and the Energy Efficiency Reconciling Factor $0.02042, printed beside the two columns that actually add. The additive components are used here.
TWO RATE SETS, not four service areas. M.D.P.U. No. 1 groups them BOST/CAMB/SOUTH/WMA and CAPE. Greater Boston, Cambridge, South Shore and Western Massachusetts are identical on every component; Cape Cod & Martha's Vineyard differs in exactly one, the energy efficiency reconciling factor, by $0.01446/kWh. Service areas map to rate sets in data/current/nstar_service_areas.json.
Western Massachusetts - the former WMECO territory - shares the mainland rates. The customer-facing summary pages offer only the four Eastern Massachusetts areas and would have left WMA out silently.
Revenue Decoupling is the one component that varies BETWEEN schedules: R-1 $0.00539, R-3 $0.00527, R-1HP $0.00443. Copying a component list between schedules produces a rate that is wrong and still looks plausible.
EXCLUDED: Massachusetts state and local taxes.
Rate set 'cape', which is the filed grouping for: Cape Cod & Martha's Vineyard.
SEASONAL, unlike R-1 and R-3. M.D.P.U. No. 1 labels the rows 'Energy (kWh) - Summer' and 'Energy (kWh) - Winter', which is what fixes the pairing: SUMMER is the expensive block ($0.19717) and WINTER the discounted one ($0.11985, 61% of summer). The customer-facing summary prints the two blocks with their season labels rendered as column headers away from the data, where the pairing is not recoverable.
MONTH BOUNDARIES ARE NOT IN A FILED TARIFF. M.D.P.U. No. 1 names the seasons without stating their months; No. 85 does not mention seasons at all; No. 3 defines no residential season. May-October and November-April come from Eversource's customer-facing summary, which is the utility's own published statement but is not a filed document. Encoded on that basis, and recorded here rather than presented as filed.
Available only to customers who qualify for R-1 and who affirm ownership of an installed heat pump. /compare cannot check that.
BUNDLED. Adds Basic Service residential fixed supply of $0.17323/kWh to every delivery rate.
Basic Service is repriced every February 1 and August 1. The rate used here covers 2026-08-01 to 2027-01-31; the preceding period was $0.15629, 11% lower. This tariff has a known expiry.
Eversource states that final Basic Service rates are subject to change and await final regulatory approval. The supply half of this rate is provisional; the delivery half is filed and final.
The FIXED Basic Service rate is used because it is the default - 'upon opening your account, all residential customers are placed on a fixed rate'. A Monthly Variable option exists and a customer may switch to it once. Customers on a competitive supplier pay neither; for them the delivery-only tariff is correct.
The supply rate is filed for Rates R1, R2, R3 and R4. R-1HP is not named in that list, and is priced here at the same Basic Service rate as R-1 on the basis that R-1HP customers qualify under R-1. That is an inference, not a filing.
NOT ENCODED: R-2 (M.D.P.U. No. 8), R-2HP (No. 86) and R-4 (No. 10), the income-qualified assistance versions of R-1, R-1HP and R-3. They are filed in the same table and readable the same way, but this encoding cannot express eligibility, so /compare would recommend them to people who cannot have them. They belong in the CARE-style discount machinery in rategrid/care.py rather than as separate tariffs.
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Change history
The source document is fetched daily and every version is kept.
Utilities do not publish superseded rates, so this record does not exist
elsewhere once a rate changes.
No changes detected since monitoring began. The source sheet is checked daily.