Obtaining A Connection Assessment

Anyone planning to construct a new connection or modify an existing connection to the IESO-controlled grid is required to complete the IESO connection assessment and approval (CAA) process for their project.

Upon receiving an application for connection approval from a connection applicant, the IESO will conduct a connection assessment, with input from the affected transmitter(s) and in consultation with the connection applicant. This process will identify any required changes to the connection proposal or enhancements to the transmission system that will mitigate any potential adverse impact.

The CAA process applies to:

  • Generation facilities
  • Embedded generation facilities greater than 10 MW
  • Transmission facilities
  • Load facilities or a one-time addition of load greater than 10 MW
  • Ancillary services, such as frequency control, black start capability, voltage control, reactive power, operating reserve, etc.
    Protection Systems

Completing an optional technical feasibility study

Before conducting a connection assessment, a connection applicant may request an optional technical feasibility study. The purpose of this study is to determine the technical acceptability of a new or modified connection to the IESO-controlled grid and to identify alternate connection options. See Technical Feasibility Study for steps to be followed.

Transferring a project

If the connection applicant wishes to transfer a project to another party, the original and the new connection applicants (buyer/assignee) are required to execute an asset transfer agreement with the IESO. Please contact the IESO at connection.assessments@ieso.ca for more details on how to transfer a project to another party.  

Before you apply

A connection applicant planning a new connection to a transmission system should first consult with the applicable transmitter for advice regarding the preferred point of connection. This is particularly important in situations where:

  • Physical constraints may influence the point of connection
  • New equipment is required to be installed within transmitter-owned facilities

A connection applicant must have a detailed project design in place before beginning the IESO connection assessment and approval (CAA) process.

Renewable energy projects that are required to complete the CAA process must have an executed contract with the IESO.

In the case of an embedded generation facility greater 10 MW, the applicable distributor that owns the distribution system where the embedded generation facility is to connect to, must apply on behalf of the proponent of the project.  

Step 1 - Submit connection assessment application package

To begin the process, the connection applicant must submit a connection assessment application package to the IESO at connection.assessments@ieso.ca using the applicable form:

*If the transmitter is not HONI or Hydro One SSM, please contact the IESO at connection.assessments@ieso.ca.

The application package must include the completed application form and applicable supporting documentation. The completed form application as well as any design-related documentation must be stamped by a Professional Engineer who is active and registered in Ontario.

A system impact assessment (SIA) is required for connection proposals that result in a new connection on the IESO-controlled grid. An SIA may not be necessary for connection proposals that do not represent major system changes, or for connection proposals that would not have a major impact on the reliability of the integrated power system. In these cases, an expedited SIA (ESIA) is conducted. The IESO typically reviews the application package within five business days and will determine if an SIA or an ESIA is appropriate. A CAA identification number will be assigned to the project.

If the IESO determines that an ESIA is applicable, please proceed with steps for Expedited System Impact Assessment.

Step 2 – Submit deposit

The connection applicant must submit the appropriate deposit based on project type as outlined in Market Manual 2.10, section 8.4.

Step 3 - Execute SIA agreement

The IESO and the connection applicant execute an SIA agreement. The standard scope of work is attached as schedule 1 to the SIA agreement. Please note the scope of work for a renewable energy project is different than the standard scope of work.

Step 4 – Complete SIA studies and produce report

The IESO completes the applicable studies to assess the project’s impact on reliability using the Ontario Resource and Transmission Assessment Criteria as per scope of work. A draft SIA report is issued to both the connection applicant and the transmitter summarizing the project details, findings, applicable connection requirements and applicable recommendations.

After receiving feedback on the draft report from the connection applicant and the transmitter, the IESO will produce the final SIA report.

Step 5 – Issue SIA report with notification of conditional approval/disapproval

The IESO issues the final SIA report with either a notification of conditional approval, or a notification of disapproval with reasons, to the connection applicant and the transmitter. The final SIA report is posted to the Application Status table.

Step 6 – Apply for customer impact assessment

Concurrent with completing the SIA, the connection applicant must apply for a customer impact assessment (CIA) with the applicable transmitter who will determine if a CIA is required.

The customer impact assessment process is described in the Ontario Energy Board's Transmission System Code.

Next step – Market registration

After completing the IESO CAA process, the connection applicant must initiate and complete the IESO market registration process at least eight months prior to the project's in-service date, before energization to the IESO-controlled grid, and prior to the commencement of any project-related outages, in order to obtain the IESO's final approval for connection. See Registration for more information.


Related Information

Market Rules, Chapter 4, Section 6 – rules for establishing or modifying IESO-controlled grid facilities and connections

Market Manual 2.10 - Connection Assessment and Approval – provides detailed procedures for connection applicants that wish to establish or modify a connection to the IESO-controlled grid

Market Rules - Appendices 4.1-4.7 – provides grid connection requirements

Ontario Resource and Transmission Assessment Criteria – identifies technical criteria for use in the assessment of the adequacy and security of the IESO-controlled grid