Step 3: Undergo the Interconnection Study Process

In this section

Preparing for the Interconnection Study Scoping Meeting

Now that your project has received a queue position, the ISO will work with you, the ITO, and affected parties to schedule a scoping meeting.

Timing of Scoping Meeting

The ISO will work with you, the ITO, and any affected parties as appropriate, to set a mutually agreeable time for the scoping meeting. Unless otherwise agreed on, the scoping meeting will be held as follows:

For large generators and ETUs—within 30 calendar days after the interconnection request (IR) is deemed valid and you have received a queue position
For small generators—within 10 business days after the IR is deemed valid and you have received a queue position

Purpose of Scoping Meeting

The purpose of the scoping meeting is to discuss the interconnection study process and the details of your project and to identify any known issues in the area in which your project aims to interconnect. The meeting will include the following tasks:

Discussion of the estimated timeline for completing all applicable interconnection studies
Exchange information on transmission data and local distribution system, including potential reliability issues or challenges
Determination of the primary and alternative points of interconnection (POIs)
Discussion of any other information necessary to facilitate the administration of the interconnection procedures and development of the study agreement

Technical Expertise for Scoping Meeting

Personnel and others with relevant technical knowledge of the project design and area of the system relevant to the point of interconnection should attend the scoping meeting. Attendees should bring the following types of information to the meeting, as applicable:

The primary and any alternative POIs for discussion
General facility loadings and general instability issues
General short-circuit, voltage, and reliability issues, as may be reasonably required for scoping out the project to accomplish the purpose of the meeting

Study Decision Notification

Within five business days of the scoping meeting, you must notify the ISO in writing (unless the IR has been identified to be included in a cluster study) of the following:

Your study decision—see the interconnection studies page for information on study options
The name and title of the signatory for the agreement and state of incorporation
The selected POI and any reasonable alternatives

The Interconnection Study Process

The ISO’s consideration of a valid interconnection request involves performing various studies—some required and some optional. The studies your project requires will be discussed with you at the scoping meeting. You’ll need to be mindful of deadlines for study deposits, data, and model submissions, and elections you can make.

Interconnection Studies and Options

Interconnection studies and options

Study Deposit and Data Submittal

Deposit—As the interconnection customer, you’re responsible for all study-related deposits. You will be refunded any difference when the deposit is greater than the actual cost, except as noted in Schedule 22, Schedule 23, and Schedule 25. All deposits must be submitted electronically.
Data submittal—You must use the ISO Interconnection Request Tracking Tool (IRTT) to submit all data and attachments associated with your interconnection studies.
Questions—Email IRTT Participant Support at irtt@iso-ne.com.

Feasibility Study

Unless determined otherwise at the scoping meeting, all IRs require a feasibility study (FS), a preliminary evaluation of the system impact and cost of interconnecting your facility to the transmission system. If your project is eligible for study in a cluster, the ISO will let you know.

FS Governing Tariff Rules

The requirements and scope of the FS are included in Schedule 22, Section 6, Interconnection Feasibility Study, for large generators; Schedule 25 for ETUs; and Schedule 23, Section 3, Study Process, for small generators. A summary of key points follows.

FS Timeframe and Options

Within five business days of your scoping meeting, email your choice to your assigned ISO project manager the following decisions:
- Study choice as discussed in the scoping meeting:
  - FS or SIS—Chose to have the FS as a separate and distinct study, or chose to go straight to the SIS to help expedite the process.
  - Alternative feasibility study (AFS)—When the FS is performed as a separate study, you can choose a limited subset of analyses focusing on the issues expected to be the most significant for your interconnection. For this option, you must provide all the technical data called for in an SIS.
- Point of interconnection (POI)—You must designate your project’s point of interconnection and, if desired, up to two reasonable alternative points of interconnection. If you chose one or more alternate POI, but no issues are uncovered during study of the main POI, you will receive a report for the main POI only, not multiple POIs.
Within five business days of receiving your elections of the FS, the ISO will provide you with the Feasibility Study Agreement (FSA) including a good-faith estimate of the cost for completing the study.
You must return the fully executed agreement and required data to the ISO and pay the deposit within 30 calendar days after receipt of the FSA.
If you’re requesting capacity network service and aim to qualify for a Forward Capacity Auction (FCA), you may opt for a preliminary, nonbinding analysis to identify potentially needed upgrades based on a limited set of assumptions you specify. This requires an additional deposit and is performed in the October to February timeframe.

FS Deposit

A refundable deposit is required for the Feasibility Study:

For large generators and ETUs—100% of the estimated study costs
For small generators—the lesser of 50% of the good-faith estimated study costs or earnest money of $1,000

FS Required Technical Data

Large generators and ETUs—
- See Attachment B to Appendix 1, Technical Data Required for Interconnection Feasibility Study, for information on the technical data you must provide.
- For alternative FS, see Attachment A to Appendix 1 and Attachment A-1.
Small generators—You should have already met the technical data requirements with your interconnection request submission.

FS Results

If you opted to have the Feasibility Study performed as a separate study:

Reasonable effort will be made to complete the FS within 90 calendar days after the ISO receives a fully executed study agreement, study deposit, and required technical data.
The FS report will provide the study findings and a nonbinding good-faith estimate of the costs and construction time for the facilities and upgrades needed for the interconnection.
Within 10 business days of providing the FS report, the ISO, interconnection transmission owner, and affected parties will convene a meeting to discuss the results.
The report will provide a preliminary nonbinding analysis regarding capacity market participation (if requested).

System Impact Study (SIS)

All interconnection requests require a System Impact Study—an engineering study that evaluates the impact of the proposed interconnection on the safety and reliability of the transmission system. If your project is eligible for study in a cluster, the ISO will let you know.

SIS Governing Tariff Rules

The requirements and scope of the SIS are included in Schedule 22, Section 7, Interconnection System Impact Study, for large generators; Schedule 25 for ETUs; and Schedule 23, Section 3, Study Process, for small generators. A summary of key points follows.

SIS Timeframe and Options

The ISO will issue the System Impact Study Agreement to you within five business days after one of the following:

The ISO’s receipt of your written election to proceed with a System Impact Study, along with your designated point of interconnection
Your Feasibility Study results meeting, if you chose to have a separate FS

You must return the fully executed agreement, demonstration of site control (if applicable), the required technical data, and the deposit within 30 calendar days.

If you’re requesting capacity network service and aim to qualify for a Forward Capacity Auction (FCA), you may opt for a preliminary, nonbinding analysis to identify potentially needed upgrades based on a limited set of assumptions you specify. This requires an additional deposit and is performed in the October to February timeframe.

SIS Deposit

A refundable deposit is required for the SIS:

For large generators—the greater of 100% of the estimated study costs or $250,000. However, the deposit can be reduced to the lesser of the estimated cost of the study or $50,000 in any of these cases:
- You provide evidence of major permit applications.
- You demonstrate “at-risk” expenditures in at least the amount of 100% of study costs or $250,000.
- Your generating facility is not increasing its energy or capacity output.
For small generators—50% of the estimated cost for the transmission portion of the study and 100% of the estimated cost for the distribution portion, if applicable
For elective transmission upgrades—the greater of 100% of the estimated study costs or $250,000

SIS Required Technical Data

Small generators must submit the required technical data with their interconnection request. Large generators and ETUs must submit the technical data called for in Appendix 1, Attachment A of Schedules 22 and 25, respectively. Large wind or inverter-based generating facilities must supply a completed Attachment A-1 Supplementary Wind and Inverter-Based Generating Facility Form.

Keep in mind these power system simulation model requirements:

Power flow model—Submit a completed, fully functioning standard library model in Power System Simulation for Engineers (PSSE) or other compatible format. User models will not be accepted.
Power System Computer-Aided Design (PSCAD) model—Submit a PSCAD model if your interconnection request is for an inverter-based generator (wind, solar, battery) or was otherwise deemed necessary at your scoping meeting. Conventional generators and ETUs have 90 calendar days from the execution of the System Impact Study Agreement to submit the PSCAD model.
A benchmarking analysis—Provide this along with your PSCAD model to confirm acceptable performance compared with the PSSE model.

Learn more in ISO Planning Procedure No. 5-6, Interconnection Planning Procedure for Generation and Elective Transmission Upgrades, Appendix B, Requirements of PSSE Models, and Appendix C, Requirements of PSCAD Models.

SIS Results

Reasonable effort will be made to complete the System Impact Study within 270 calendar days after the ISO receives a fully executed study agreement, deposit, demonstration of site control (if applicable), and required technical data. Within 10 business days of providing the SIS report, the ISO will convene a meeting to discuss the results. The SIS report will provide the following elements:

A list of the facilities necessary for interconnection
A nonbinding good-faith estimate of the cost responsibility and construction time
An assessment to determine the required protection upgrades
A preliminary, nonbinding analysis regarding capacity market participation (if requested)

Important milestones are as follows:

Within 10 business days following the study results meeting, you must provide the ISO written notice that you will either pursue the Facilities Study or waive it and elect an expedited interconnection. Your election cannot be changed once you have notified the ISO of your decision.
Within 30 calendar days of receiving the SIS report, you will provide comments on the report or written notice of no comments.
Within 30 calendar days from the end of the comment process, you must submit a Proposed Plan Application in accordance with Planning Procedure 5-1.
Within five business days after the study results meeting, you may request in writing an Optional Interconnection Study (OIS) for a large generator or ETU—not a small generator.

Facilities Study

A facilities study (FAC) determines the equipment and electrical switching configuration necessary to accomplish the interconnection and estimates the cost, construction, and installation times.

FAC Governing Tariff Rules

The requirements and scope of the FAC are included in Schedule 22, Section 8, Interconnection Facilities Study, for large generators; Schedule 25 for ETUs; and Schedule 23, Section 3, Study Process, for small generators. A summary of key points follows.

FAC Timeframe and Options

Within three business days following the System Impact Study results meeting, if requested, the ISO will provide you with a nonbinding good-faith estimate of the cost for completing the facilities study. The FAC will offer two options: a good-faith cost estimate of ±20% or ±10% (see below).
You must return the executed agreement within 30 calendar days after receiving it, together with the required technical data and deposit.
Within 10 business days following your SIS results meeting, you must provide the ISO written notice if you wish to waive the FAC and elect an expedited interconnection or pursue a FAC. Keep the following in mind:
- If you waive the FAC, you assume all risks and costs associated with the equipment, engineering, procurement, and construction work typically covered by the FAC. If the FAC is waived, you and the ITO can enter into a separate Engineering and Procurement Agreement in its place.
- This election cannot be reversed.

FAC Deposit

A refundable deposit is required for the FAC:

For large generators—the greater of 25% of the estimated cost of the study or $250,000. However, the deposit can be reduced to the greater of $100,000 or one month’s estimated study costs in any of these cases:
- You can provide evidence of major permit applications—or certification that they’re not required.
- You demonstrate “at-risk” expenditures (excluding study costs) in at least the amount of 100% of study costs or $250,000, not including the same at-risk expenditures demonstrated for the SIS.
For small generators—100% of the estimated study cost
For ETUs—the greater of 25% of the estimated cost of the study or $250,000

FAC Required Technical Data

In Schedule 22 for large generators, Schedule 25 for ETUs, or Schedule 23 for small generators, see the Data Form to Be Provided by Interconnection Customer with the Interconnection Facilities Study Agreement.

FAC Results

The ISO will make reasonable efforts to provide a draft study report within the following timeframe, depending on the good-faith estimate you requested:

±20% = 90 calendar days
±10% = 180 calendar days

Within 10 business days of providing the draft report, the ISO will convene a meeting with you to discuss the study results.

Optional Interconnection Study

The ISO conducts the Optional Interconnection Study (OIS) at your discretion. The study is a sensitivity analysis based on the assumption that one or more earlier-queued resources are removed. This study can be requested for large generators and ETUs only, not small generators.

OIS Governing Tariff Rules

The requirements and scope of the OIS are included in Schedule 22, Section 10, Optional Interconnection Study, for large generators or Schedule 25 for ETUs. A summary of key points follows.

OIS Deposit

The deposit required for the OIS is 100% of estimated study costs.

OIS Timeframe

You may request this report in writing, specifying the assumptions you want studied, on or after the date you receive your System Impact Study and within five business days after the study results meeting. Key milestones are as follows:

Within five business days after receipt of this request, the ISO will provide you with the study agreement.
Within 10 business days of receiving it from the ISO, you must return a fully executed study agreement, along with the required technical data and the refundable deposit.

OIS Required Technical Data

The study agreement will specify the technical data required, which will depend on the study assumptions you specify.

OIS Results

The ISO will make a reasonable effort to complete the study within a mutually agreed upon time. Within 10 business days of providing you with your study report, the ISO will convene a meeting to discuss the results.

Clustering

Where certain conditions are present in the interconnection queue, certain Interconnection Requests will be subject to clustering instead of undergoing a System Impact Study and Facilities Study for your project alone.

Clustering Governing Tariff Rules

The requirements and scope of clustering are included in Schedule 22, Section 4.2, Clustering, for large generators; Schedule 25 for ETUs; and Schedule 23, Section 1.5.3, Clustering, for small generators. A summary of key points follows.

Clustering Triggers

At the discretion of the ISO, clustering is triggered when both of the following conditions exist:

There’s a backlog of two or more interconnection requests in the same part of the transmission system.
The ISO has determined that none of these IRs will be able to interconnect, either individually or in a cluster, without the use of common significant new transmission line infrastructure.

The ISO conducts clustering in two phases:

First, the ISO performs a Cluster-Enabling Transmission Upgrade Regional Planning Study (CRPS) to identify the new transmission line infrastructure and associated system upgrades necessary to enable the interconnection of potentially all the proposed facilities triggering the study. This is called the cluster-enabling transmission upgrade (CETU).
Then, the ISO performs the Cluster-Interconnection System Impact Study (CSIS) and Cluster-Interconnection Facilities Study (CFAC). These studies collectively consider all the eligible interconnection customers who opted in, evaluating their impact on the safety and reliability of the ISO-administered transmission system and determining the equipment and electrical switching configurations the interconnections would need, along with estimated costs and construction and installation times.

Clustering Timeframe and Requirements

If your project is eligible for clustering, the ISO will notify you of the application deadline, which will be 30 calendar days from the ISO’s posting of the final CRPS report.
By the cluster deadline, you must communicate one of the following choices in writing to the ISO:
- Elect to join the cluster and submit a completed Cluster System Impact Study application in the IRTT and meet all CSIS entry requirements, including for the deposit.
- Elect not to join the cluster and be assigned a new queue position at the bottom of the Interconnection Request Queue relative to other cluster-eligible requests for projects that also have decided not to join the cluster.
- Withdraw your interconnection request.

If you fail to make an election—or if you apply for inclusion in the Cluster System Impact Study but fail to meet all requirements—your IR will be automatically withdrawn, and you will not have the opportunity to make any additional changes.

If you elect to participate in the Cluster Interconnection System Impact Study:
- Within 15 business days following the cluster entry deadline, the ISO will provide you with a study agreement, including a nonbinding good-faith estimate of the costs and timeframe for the CSIS. This will terminate any previously signed agreements for a noncluster study.
- You must return the executed agreement, deposit, and required data to the ISO within 30 calendar days after receipt.

Clustering Required Technical Data

If your project will be studied as part of the CRPS and you haven’t already done so, you must submit the data called for in Appendix 1, Attachment A of Schedules 22 and 25 for large generators and ETUs, respectively (and Attachment A-1, if applicable). (At this point in the process, small generators already have submitted their required data with their interconnection request.)
You must submit with your study agreement continued demonstration of site control.
If you elect to participate in clustering, you must submit technical data required for a System Impact Study.

Cluster Participation Deposit

By the cluster entry deadline, you must submit an initial cluster-participation deposit equal to 5% of your cost-allocation responsibility for the cluster-enabling transmission upgrade and associated system upgrades, to be determined on the basis of the cost estimates provided in the final CRPS report.
Within 30 calendar days after receipt of the final Cluster-Interconnection Facilities Study report, you must submit an additional cluster-participation deposit equal to 5% of your cost-allocation responsibility for the CETU and associated system upgrades, to be determined on the basis of the cost estimates provided in the final CFAC report.

See the applicable interconnection schedule for refund rules.

Submit Revised Data for an Interconnection Request

If, after submitting your interconnection request (IR), you make changes to your project’s design or operating characteristics, you must notify the ISO in writing.

Permitted Interconnection Request Modifications

During the course of the interconnection study process, you’re allowed the following nonmaterial modifications before the System Impact Study begins:

A decrease of up to 60% of electrical output in the capability of the project
Modifications to the technical parameters associated with the project or the step-up transformer impedance characteristics of a generator
Modifications to the interconnection configuration

Material Modifications that Would Require a New Interconnection Request

Before making any changes to your project, you may request that the ISO evaluate your proposed changes to determine whether they constitute a material modification. The ISO will work with you to prepare a submittal to best move the analysis forward.

The ISO would deem your modifications material if they result in any of the following:

Significant additional required study that could substantially change the interconnection design
A material impact on the cost or timing of any interconnection studies or upgrades associated with an interconnection request with a later queue priority date.
A proposed modification that could not be evaluated within 10 business days.
A significant adverse effect on the reliability or operating characteristics of the transmission system
A delay in the commercial operation, in-service, or initial synchronization date by more than three years from the original date submitted in the IR, unless allowed under Section 4.4.5 of Schedules 22 and 25.

Increases in energy or capacity capability, or a change from energy only to capacity interconnection service, require a new interconnection request.

Governing Documents

The interconnection process rules are detailed in the ISO’s Open Access Transmission Tariff (OATT). See the Scoping Meeting section in each of the applicable schedules: Also see the following section in each applicable schedule:

Schedule 22, Section 4.4, Modifications, for large generators, or Schedule 25 for elective transmission upgrades
Schedule 23, Section 3, Study Process, for small generators

Also see ISO Planning Procedure No. 5-6 (PP5-6), Interconnection Planning Procedure for Generation and Elective Transmission Upgrades, Appendix E, Procedures for Material Modification Determinations.

Reference I.3.9 Review of Market Participant’s Proposed Plans for more information.

Questions

Email IRTT Participant Support at irtt@iso-ne.com, or contact ISO Participant Support.

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