ISO-NE

Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont, United States.

Wholesale design: nodal energy and ancillary-services markets with a Forward Capacity Market transitioning toward a prompt seasonal design.

Operator
ISO New England
Nominal frequency
60 Hz
Where energy trades

Where does energy trade in ISO-NE?

Energy in ISO-NE trades in 2 layers: Day-Ahead Energy and Ancillary Services Market and Real-Time Energy and Reserve Market. Participation in Real-Time Energy and Reserve Market is mandatory. Scheduling and settlement, where the official sources state them, are in the table below.

Layer Scheduling Settlement
Day-Ahead Energy and Ancillary Services Market hourly day-ahead locational marginal pricing and day-ahead ancillary-service clearing prices
Real-Time Energy and Reserve Market (mandatory) five-minute real-time dispatch and pricing real-time locational marginal pricing and reserve clearing prices
What a battery can sell

What ancillary services can a battery sell in ISO-NE?

ISO-NE has 7 ancillary-service products, across 5 families — regulation, contingency reserve, replacement reserve, reactive power & voltage and other services: Blackstart Service, Energy Imbalance Reserve, Regulation Service, Ten-Minute Non-Spinning Reserve, Thirty-Minute Operating Reserve, Ten-Minute Spinning Reserve, Voltage Support Service. Response timing, direction and eligibility for each are in the cards below, as the official sources state them.

Facts below are stated as the official sources state them. A missing line means the source does not state that value — never that the value is zero.

Regulation

  • Regulation Service

    Correct area-control error and maintain interconnection frequency through automatic resource movement.

    Activation
    automatic generation control signal sent every four seconds
    Stated response
    Four seconds is the control-signal interval, not a universal full-response requirement.
    Trigger / range
    continuous movement within each resource's assigned regulation range
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    regulation capacity and service/performance compensation under Market Rule 1

Contingency reserve

  • Energy Imbalance Reserve

    Compensate resources positioned day ahead to preserve upward capability for forecast energy imbalance in real time.

    Activation
    day-ahead co-optimization positions eligible resources; any later energy deployment occurs through real-time dispatch
    Trigger / range
    forecast real-time energy requirement above the day-ahead cleared energy position
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    day-ahead EIR clearing price with settlement interactions defined in Market Rule 1

    EIR began with DASI on 2025-03-01 and is distinct from ten- and thirty-minute contingency reserve.

  • Ten-Minute Non-Spinning Reserve

    Provide qualified non-synchronized contingency response to replace the first resource contingency.

    Activation
    ISO New England instruction
    Expected within
    10 minutes
    Trigger / range
    qualified capability able to start, synchronize, and reach the reserve amount within ten minutes; participates in both day-ahead and real-time reserve procurement
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    day-ahead or real-time reserve clearing price, as applicable

  • Ten-Minute Spinning Reserve

    Provide synchronized contingency response to replace the first resource contingency.

    Activation
    automatic response and ISO New England instruction
    Expected within
    10 minutes
    Trigger / range
    online synchronized capability deliverable within ten minutes; participates in both day-ahead and real-time reserve procurement
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    day-ahead or real-time reserve clearing price, as applicable

Replacement reserve

  • Thirty-Minute Operating Reserve

    Provide replacement reserve within thirty minutes and support recovery for a second contingency.

    Activation
    ISO New England instruction
    Expected within
    30 minutes
    Trigger / range
    qualified online or offline capability deliverable within thirty minutes; system requirements include additional reserve associated with one-half of the second-largest contingency, with locational requirements when needed
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    day-ahead or real-time reserve clearing price, as applicable

Reactive power & voltage

  • Voltage Support Service

    Maintain voltage and reactive-power capability on the transmission system.

    Activation
    automatic voltage control and ISO New England instruction
    Trigger / range
    facility-specific voltage schedule and reactive capability
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    tariff-defined compensation, not a co-optimized reserve price

Other services

  • Blackstart Service

    Start without external station power and support restoration of the New England transmission system.

    Activation
    ISO New England restoration instruction
    Trigger / range
    restoration-plan and facility-specific capability
    Typical procurement
    Dynamic or not publicly stated
    Pricing
    tariff-defined cost recovery
Getting paid to exist

Does ISO-NE have a capacity mechanism?

Yes — Forward Capacity Market is a central capacity market.

Forward Capacity Market

No primary Forward Capacity Auction was conducted in calendar 2025 because FCA 19 was delayed during the transition toward a prompt seasonal capacity design. Three annual and twelve monthly secondary reconfiguration-auction results published during 2025 are included below. FERC accepted the prompt-market design filing on 2026-03-30; the seasonal/accreditation reform track remained pending at the cutoff.

Unit of obligation
MW of capacity supply obligation
Auction held in 2025
Yes () — Dated from the publication of the auction results.
Where this comes from

Official sources

Rules

Market explainer

Capacity-mechanism explainer

Capacity result

Current as of · from the Global Electricity Market Catalogue v1.2.0 (compiled to , CC BY 4.0). Facts belong to the linked official authorities; verify the current rules before design or bidding decisions.

Questions

Common questions about ISO-NE

Who operates ISO-NE?
ISO New England operates ISO-NE, covering Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont, United States.
Was a qualifying capacity event held in ISO-NE in 2025?
Yes. Forward Capacity Market: a qualifying 2025 event is recorded (2025-07-02). Dated from the publication of the auction results.
How is energy traded, priced and settled in ISO-NE?
ISO-NE: nodal energy and ancillary-services markets with a Forward Capacity Market transitioning toward a prompt seasonal design.
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