Independent system operator tariff

Independent system operator tariff


The AUC released Decision 22942-D02-2019 on the Alberta Electric System Operator (AESO)’s 2018 Independent System Operator (ISO) tariff on September 22, 2019. ​The ISO tariff sets out the rates to be charged for, and the terms and conditions that apply to, each class of system access service provided by the AESO.

The AUC has examined and reviewed the billing and cost allocation approaches of the AESO, who plans and runs Alberta’s transmission system. As Alberta’s independent utilities regulator, the AUC reviews the AESO’s tariff to ensure the billing and cost-allocation approaches are fair and just and serve the public interest of Alberta by promoting a fair, efficient and openly competitive system.

The AUC's decision, based on submissions made to it and in-depth review of the evidence, reduces certain overall customer contribution costs for connecting distribution to transmission that are ultimately borne by ratepayers. This is expected to save Alberta ratepayers approximately $40 million over five years. 

Additionally, changes to the AESO’s terms and conditions will exert greater discipline on decisions to build transmission. Further, changes to metering of distributed generation projects will level the playing field between distribution- and transmission-connected generation.

The decision represents significant progress on mitigating or improving AESO practices or approaches that had previously raised concerns of the AUC.

Directionally, the decision also reduces costs that are ultimately paid for by ratepayers by:

  • Ensuring fewer transmission-distribution connection projects are classified as system related and as a result are paid for by all ratepayers. 
  • Requiring payments by generation developers, called a generation unit owner’s contribution (GUOC) to be made earlier.
  • Denying $20 million in costs requested by TransAlta for reliability compliance costs.

General information on the ISO tariff can be found on the transmission rates page.

Accessing proceeding documents

The eFiling System can be accessed to view the applications and the other documents that were considered in this proceeding. The system is also used to file submissions and evidence to participate in the proceeding.

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Documents being considered in this proceeding can be found in the eFiling System (which requires log in). Once you have logged in, enter 22942 in the "go to" section at the top left corner of your screen.

Proceeding 22942      Register

Application status: completed

Decision: 22942-D02-2019, issued September 22, 2019 

AESO Application amendment filed: August 17, 2018 

Hearing dates: March 18 - 22, 2019

Hearing location: William Andrew Grieve Hearing Room


AUC contact: Jay Halls
 403-592-4426 or  

AUC contact: Salma Karim
 403-592-4436 or  

 Alberta Electric System Operator contact: Brenda Hill

403-539-2948 or  

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