OATT & ISO Tariff Frequently Asked Questions

OATT is an acronym for Open Access Transmission Tariff. Regional Network Service (RNS) is a transmission service offered under Schedule 9 of the ISO New England OATT. Network Customers purchase RNS in order to serve their Regional Network Load in the New England Control Area.

Reference: Open Access Transmission Tariff (OATT).

Any customer with a Monthly Regional Network Load will be charged for RNS.

Your Regional Network Load value, as submitted to ISO New England by the Transmission Owner (TO) of your local network is multiplied by the RNS rate to determine your monthly charge. The RNS rate is determined based on the annual revenue requirements of the Transmission Owners (TOs), and is the amount of revenue needed to cover the TOs' costs of owning the Pool Transmission Facilities (PTF). The RNS charges collected from Regional Network Load Customers are allocated pro-rata to the TOs based on their shares of the total revenue requirement.

The total monthly RNS bill also includes a charge for OATT Schedule 1 Service. This charge recovers the Scheduling, System Control and Dispatch costs incurred by the TOs and are distributed pro-rata to the TOs based on their shares of these costs. Your Network Load value is multiplied by the OATT Schedule 1 rate to determine your monthly charge for this component of the RNS bill.

Yes, all customers are slated to pay the same RNS rate regardless of Regional Network Load location.

OATT is the acronym for Open Access Transmission Tariff. Through or Out Service (TOUT) is a transmission service offered under Schedule 8 of the ISO New England OATT. Transmission customers use TOUT in order move power through or out of the New England Control Area.

Transmission Customers who have requested TOUT from ISO New England will be charged for the service. TOUT charges are incurred based on the MW of Reserved Transmission Capacity as submitted to the Open Access Same Time Information System (OASIS).

Your MW of Reserved Transmission Capacity for each hourly TOUT purchase is multiplied by the TOUT hourly rate to determine the charge. Your total charge for the month is the sum of the TOUT charges associated with all of your transmission reservations. The TOUT revenues are distributed among the Transmission Owners (TOs).

The total monthly TOUT bill also includes a charge for OATT Schedule 1 Service. This charge recovers the Scheduling, System Control and Dispatch costs incurred by the TOs, and are distributed pro-rata to the TOs based on their shares of these costs. Your MW of Reserved Transmission Capacity for each hourly TOUT purchase is multiplied by the OATT Schedule 1 rate to determine your monthly charge for this component of the TOUT bill.

OATT Schedule 2 is Reactive Supply and Voltage Control from Generation Sources Service. ISO New England operates generation facilities to produce or absorb reactive power as necessary to maintain transmission voltages within acceptable limits. Schedule 2 charges are collected to compensate generating facilities that provide the service each month.

Any Transmission Customer who uses Regional Network Service or Through or Out Service during the month will incur the charge.

Generating resources that provide reactive supply to the transmission system are compensated
by different mechanisms, as applicable:

  • Capacity Payment: A $/kVar-year rate, subject to adjustment as detailed in the Tariff.
  • Lost Opportunity Payment: Compensation for backing down in-merit generation.
  • Cost of Energy Produced: Compensation for running out-of-merit generation.
  • Cost of Energy Consumed: Compensation for electric supply to motor hydro generation.

The total Schedule 2 charges for any month are the sum of all of these payments.

An hourly determinant is calculated for each Transmission Customer as the sum of the Customer's Monthly Regional Network Load plus the Customer's Through or Out Service Reservation (if any) for the hour. The hourly Schedule 2 charges are allocated to all Transmission Customers based on their pro-rata share of the total of the determinants. Hours flagged for High Voltage VAR Support are charged to the Reliability region that was supported.

Hourly Schedule 2 payments and charges are included in the MIS report prefixed with the name AD_VARSC2. Access the OATT and ISO New England Tariff rates.

Reference: OATT Schedule 2 - VAR reports.

OATT is the acronym for Open Access Transmission Tariff. Schedule 16 is Blackstart Service. Blackstart Service is necessary to facilitate a stable and orderly system restoration following a partial or complete shutdown of the New England Transmission System. Resources are offered by Blackstart Owners to provide Blackstart Service. The ISO shall select those resources whose locations and capabilities support the New England System Restoration Plan. Following agreement between the owner and the ISO, such selected resources ("Designated Blackstart Resources") shall provide and are eligible to receive compensation for providing Blackstart Service.

Any Transmission Customer purchasing Regional Network Service (RNS) under the OATT will also be billed for Schedule 16 Blackstart Service.

The total of the Schedule 16 payments made to all Designated Blackstart Resources is allocated pro-rata among Transmission Customers based on their Monthly Regional Network Load.

Special Constraint Resource Service is provided under Schedule 19 of the ISO New England Open Access Transmission Tariff (OATT). In order to maintain reliability, Transmission Owners or distribution companies can request that ISO New England commit out-of-merit generation to provide relief for thermal, voltage, or stability constraints on a local area network. Schedule 19 charges are collected to compensate these generators.

Reference:

The Transmission Owner or distribution company making the request, or on whose behalf of a Local Control Center (LCC) makes a request, shall be charged for this service.

Hourly Black Start payments are included in the MIS report prefixed with the name AD_BLACKSTART. Access additional Schedule 16 - Black Start details.

Read Section II.4 and Schedule 19 of the ISO OATT.

The Transmission Owner or distribution company making the request, or on whose behalf an Local Control Center (LCC) makes a request, shall be charged an amount equal to the Net Commitment Period Compensation (NCPC) credited to the SCR Resource.

Reference:

Schedule 1 is an Ancillary Service provided by ISO New England for scheduling the movement of power through, out of, within or into the New England Control Area. RNS is an acronym for Regional Network Service, which is transmission service that Network Customers purchase in order to serve their Regional Network Load in the New England Control Area. Customers who purchase RNS also pay for Schedule 1 service. The rate for ISO New England Schedule 1 service is established each year, effective January 1st.

All RNS customers pay for Schedule 1 Service each month. Charges are determined for each customer based on their Monthly Regional Network Load.

Your Regional Network Load value, as submitted to ISO New England by the Participant Transmission Owner of your local network, is multiplied by the monthly ISO New England Schedule 1 rate to determine your monthly charge.

Schedule 1 is an Ancillary Service provided by ISO New England for scheduling the movement of power through, out of, within or into of the New England Control Area. TOUT is an acronym for Through or Out Service, which is transmission service that Transmission Customers purchase from ISO New England to move power through or out of the New England Control Area. Customers who purchase TOUT also pay for Schedule 1 service. The rate for ISO New England Schedule 1 service is established each year effective January 1st.

Any Transmission Customer with a reservation during the month for TOUT pays for Schedule 1 service. Charges are determined for each customer based on their TOUT capacity reservation(s).

The Reserved Capacity as submitted to the Open Access Same Time Information System (OASIS) for each hourly TOUT purchase is multiplied by the ISO New England Schedule 1 hourly rate to determine the charge. Your total charge for the month is the sum of the Schedule 1 charges associated with all of your TOUT reservations. The total charges collected for ISO New England Schedule 1 for TOUT are allocated as credits to all Regional Network Load customers based on their pro-rata share of the total NEPOOL Monthly Regional Network Load.

Energy Administration Service (EAS) is the service provided by ISO New England to administer the Energy Market. This administration includes the core operation of the Energy Market, generation dispatch, and energy accounting. The charge is a part of the recovery of costs to operate ISO New England. The rates for ISO New England Schedule 2 are established each year effective Jan 1st.

Reference:

Any Market Participant with an account for Energy that is settled by ISO New England for the month.

EAS is allocated based on different billing units: Energy Transaction Units (TUs) and Volumetric Measure (VM). Customers accrue a TU for every hour that a transaction is in place during the month; where transactions are contracts, demand bids, supply offers, non-zero spot market energy settlements. The VM billing units are equal to the amount of Real-Time load and generation obligation MW in a Customer's settlement each month. There are also billing units for increment offers and decrement bids submitted and cleared, and FTRs submitted and cleared.

Market Information Server (MIS) report data are available to the Market Participants via the ISO New England FTP file server. The MIS Report Description document contains field descriptions of all of the report data and the templates provide descriptive headers for these data. A summary of TU and VM data is included in the MIS report prefixed with the file name TR_SCH2DT. A summary of the ISO Schedule 2 EAS charges as determined by the ISO New England.

Reliability Administration Service (RAS) is the service provided by ISO New England to administer the Reliability Markets, and to provide other reliability and informational services. The charge is a part of the recovery of costs to operate ISO New England. The rates for ISO New England Schedule 3 are established each year effective Jan 1st.

Reference: OATT & ISO Tariff Rate Schedules.

Any non-Market Participant Transmission Customer taking Point-to-Point Service, any Market Participant with a Non-Coincidental Peak (NCP) Real-Time Load Obligation for the month, or any Market Participant having exports in the month.

A Non-Market Participant Transmission Customer is charged for Schedule 3 based on its number of hours of Point-to-Point Transmission Service for the month.

Market Participants are charged for Schedule 3 based on their NCPC Real-Time Load Obligations (RTLO) for the month, or their MW of Exports.

A summary of the ISO New England Schedule 3 calculations is included in the MIS report prefixed with the file name TR_SCH3P2.

There is no Day Ahead Internal Bilateral for Load (IBL). All IBL can only be submitted in the Real Time Market.

IBL will incur Schedule 2 Transactional Units (TU) charges for Bilateral Contract Block-Hours. IBL will also incur Schedule 2 Volumetric Measures (VM) charges as it affects the Real Time Load Obligation. IBL may possibly incur a Schedule 3 charge if the IBL coincides with non-coincidental peak load obligation.

Reference: Manual 28 section 3.1.2 "Market Participants may enter into Internal Bilaterals for Load for the Real-Time Energy Market only."

The Day Ahead Internal Bilateral for Market (IBM) always flows in Real Time . As a result, the Day Ahead IBM will accrue Schedule 2 TU charges for each Bilateral Contract Block-Hours. More importantly, IBM transactions that flow from DA to RT are only counted once, in RT, even though their origin may have been DA.

DA IBM does not incur Schedule 2 VM or Schedule 3 charges. This is because the IBM only affects Day-Ahead or Real-Time Adjusted Load Obligation, which is not a billing determinant used in the calculation for those charges.

Reference: Manual 28 section 3.1.2 "Market Participants may enter into Internal Bilaterals for Market associated with Energy in either the Day-Ahead Energy Market, in which case the transaction automatically carries forward into the Real-Time Energy Market, or just the Real-Time Energy Market."

ISO Tariff Schedule 2 charges that a generator may be subject to:
Transaction Units (TUs) as applicable.
A transaction unit is accrued for each hour that a transaction is in place.
Possible transaction units:

  • Transaction Units for Schedule Block Hours
  • Transaction Units for Non-Zero ANI
  • Transaction Units for Bilateral Transactions

Volumetric Measure (VMs) Charges for Real Time Generation Obligation
ISO Tariff Schedule 3
Charges for Non-coincident peak load obligation for Station Service Load (If generator owns the Station Service Load Asset).

What is the potential Tariff costs associated with external transactions?
Potential Tariff costs for External Sales transactions could be:

  • ISO Tariff Schedule 1 for Through or Out Service rates)
  • OATT Schedule 8 Through or Out Service ("TOUT") (Note: The OATT Schedule 1 for Through or Out Service charge is included in the OATT TOUT line item charge on the ISO-New England invoice.)
  • OATT Schedule 2 ("VAR") Charges are possible. VAR charges are allocated hourly; the determinant is the Participant's Network Load + TOUT hourly reservation. If VAR charges accrue in the Control Area during the hour that an external sale is in place, the Participant will receive an allocation of the hourly charge.
  • ISO Tariff Schedule 3: Additional charges are possible.
    • Schedule 3 is billed on monthly Exports.

External Sales or Purchase transactions:

  • ISO Tariff Schedule 2
    • A Transaction Unit (TU) is incurred for each hour that an external contract is in place.
    • Volumetric Charges (VMs) are incurred for external contract MW.

The ISO acts as the billing and collection agent for the New England States' Committee on Electricity (NESCOE) for recovery of amounts reflected in the annual NESCOE budget.

All RNS customers pay for Schedule 5 each month. Charges are determined for each customer based on their Monthly Regional Network Load.

Reference: Open Access Transmission Tariff (OATT).

Read Schedule 5 of the ISO New England Self-Funding Tariff. View Schedule 1 rates.

Your Network Load value, as submitted to ISO New England by the Participant Transmission Owner of your local network, is multiplied by the monthly ISO New England Schedule 5 rate to determine your monthly charge.

Reference: Open Access Transmission Tariff (OATT).
ActivityOATTOATT Schedule 2OATT Schedule 8OATT Schedule 9OATT Schedule 16
Schedule 1
RNSTOUTVARTOUTRNSBlack Start
Regional Network Load x   x   x x
External Transaction Through   x x x    
External Transaction Export   x x x    
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