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​If you have already received a completed SIA from the IESO, proceed to register with the IESO through the Registration process at least eight months prior to the project's in-service date.


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System Impact Assessment

The System Impact Assessment (SIA) steps are outlined on this page. More detailed information on each step is available in Market Manual 2.10, section 8.

Follow the System Impact Assessment process (for typical and renewable generation facilities), from SIA application to notification of conditional approval from the IESO.


Step 1 - Submit SIA Application Package

To begin the process, the applicant must submit an SIA application package to the IESO for:

The application package must include the completed SIA application form, appropriate supporting documentation and deposit as described in Market Manual 2.10, section 8.4. Note that a deposit may not be needed if the IESO determines an Expedited SIA is applicable. For applicants who have already received a completed SIA from the IESO, proceed to register with the IESO through the Market Registration process at least eight months prior to the project's in-service date.


Step 2 - Execute SIA Agreement

After the IESO receives the completed SIA application package, the IESO and the applicant negotiate a Scope of Work and execute an SIA agreement. The Scope of Work is attached as Schedule 1 to the SIA agreement.

The Scope of Work for Renewable Energy application is different than the standard Scope of Work.


Step 3 - SIA Studies and Report Production

An SIA consists of a review of the proposed connection arrangement and its impact on the reliability of the integrated power system. A draft SIA report is issued to both the applicant and the transmitter summarizing the results of the IESO assessment for the project. After receiving the applicant and transmitter feedback on the draft report, the IESO will produce the final SIA report.

Note: The connection applicant can opt to engage a consultant to perform the connection assessment studies.


Step 4 - Notification of Conditional Approval/Disapproval and Publication of SIA Report

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


Step 5 - Transmitter Customer Connection Process

Concurrent with an SIA application, applicants must apply for a Customer Impact Assessment from their applicable transmitter. For a list of licensed transmitters in Ontario and their contact information, visit the Ontario Energy Board - Issued Licenses.

The Customer Impact Assessment process is described in the Ontario Energy Board's Transmission System Code.