Stage 2 - Obtain conditional approval to connect

Prepare Application Design and Build Authorize Market and Program Participation Register Equipment Commission Equipment and Validate Performance
Contact IESO Connection Assessments at or your transmitter or distributor for questions about this stage of the process.

If you determined during the previous stage that your organization is required to participate in the IESO’s and transmitter's connection assessment and approval (CAA) process, you need to consider the following.

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, and operating reserve

Please contact the IESO if you have questions about the CAA process.

Pre-application meeting

The IESO strongly recommends that your organization hold a pre-application face-to-face meeting with your consultants, the IESO and the transmitter in order to:

  • Form a partnership between your organization, the IESO and the transmitter to help navigate through the connection process
  • Discuss the project, its proposed location, the connection area, and limitations that could impact your requirements for connection
  • Learn about the key steps of the connection assessment process, as well as the roles and responsibilities of the parties involved
  • Confirm the application forms and data that will be required
  • Discuss your timelines and expectations
  • Discuss a communication plan and frequency of updates.


Step 1 – Submit application and deposit


As the connection applicant, your organization must file an application form that applies to your facility from the table below. The authorized representative (organization’s contact responsible for contractually binding the organization with the IESO) must sign the SIA form. For existing Market Participants, please ensure that the authorized representative signing the SIA application form matches the authorized representative registered in Online IESO. For more details, see roles and responsibilities.


Upon receipt, the IESO will determine if the application qualifies for a system impact assessment (SIA) or an expedited system impact assessment (ESIA) and will assign a unique CAA ID.

Modifications that qualifies for an expedited SIA under section 9.2 of Market Manual 1.4, do not require a deposit. However, the IESO will enter into a Cost Recovery Agreement (CRA) with your organization. Once a CRA is executed, the cost of the assessment will be invoiced quarterly to your company. If a CRA between the IESO and your organization already exists, the assessment engineer will confirm the validity of this agreement.

For SIAs, the connection applicant must submit the appropriate deposit as outlined in Market Manual 1.4. The preferred method of payment is electronic or direct deposit (e.g., Wire, EDI and EFT). You must include the assigned CAA ID with the deposit and send a notification that the deposit has been made to the following IESO groups:

The IESO’s account for SIA deposits is:

Independent Electricity System Operator


Account Number: 0429444

Transit Number:10202

Bank ID Number:004

TD Bank – 55 King Street West, Toronto, Ontario M5K 1A2

Application Forms

Transmission Facilities (must be a licensed transmitter)

Generation and Electricity Storage Facilities

Load Facilities

Ancillary Services (regulation, reactive support, voltage control and black start capability)

The IESO will work with your organization and the transmitter to confirm that all information required for the connection assessment has been included.

Step 2 – Execute the system impact assessment (SIA) agreement

After receiving your application and associated deposit for a connection assessment, the IESO will prepare an SIA agreement in accordance with section of chapter 4 of the Market Rules for execution by your authorized representative.

Step 3 – IESO completes SIA studies and produces draft report

Once you have provided all of the required information, the IESO will assess the impact of your proposed new or modified connection on the reliability of the integrated power system and issue a draft SIA report to your organization and the transmitter for review and comments. The draft SIA report gives your organization the opportunity to verify that the information used in the SIA is accurate, the connection requirements are understood and acceptable, and the report does not contain any information that your organization deems confidential or commercially sensitive.

The transmitter generally initiates the customer impact assessment (CIA) after the draft SIA report from the IESO. A CIA agreement between the connection applicant and transmitter is also needed as part of the transmitter’s CIA process.

If modifications to the draft SIA report are required, the IESO will prepare a revised draft SIA report for final review by your organization and the transmitter.

Step 4 – IESO issues final SIA report

After addressing comments received from your organization and the transmitter on the draft or revised draft SIA report, the IESO sends the final SIA report and one of the following to both parties:

  • Notification of conditional approval (NoCA)
  • Notification of final approval (NoFA - applicable only for changes to protective relays)
  • Notification of disapproval with reasons (NoDR)

The final SIA report will be published on the IESO website in the Application Status table at the end of the month in which it was finalized.

Any changes to a final SIA report after publication will be included as an addendum. Addendums to the final SIA report can result from:

  • Changes made by the applicant to the proposed connection before it came into service
  • Changes made by transmitter to their transmission system
  • Changes to the IESO's projected system conditions

If the IESO becomes aware of changes that trigger the need for an addendum to your SIA, it will promptly notify your organization.

Addendums could also include the issuance of a notification of conditional approval, final approval (applicable only for changes to protective relays) or disapproval with reasons of your connection request.


Transferring a project

If your organization wishes to transfer a project to another organization during the SIA process (which includes the production of the final SIA report and any required addendum to the final SIA report), the original and the new connection applicants (buyer/assignee) are required to execute an asset transfer agreement for the SIA agreement with the IESO. Please contact the IESO for details on how to transfer your project to another organization.

The IESO’s connection assessment and approval process is governed by section 6 of Chapter 4 of the Market Rules. The detailed process to obtain an SIA is described in Market Manual 1.4.