Purpose

We invite all interested stakeholders to provide feedback on the interim draft Cost of Service study report published on Nov. 17, 2025. We are sharing questions in advance to allow stakeholders to prepare and resource adequately, however feedback will be open from Dec. 5, 2025 - Jan. 21, 2026.

Instructions

1. This feedback form is open to all industry stakeholders.
2. Please fill out the sections below as indicated.
3. Only one completed feedback form will be accepted per organization.
4. To upload your your feedback, click on the "Submit Stakeholder Feedback" box below.

All responses are due by January 21, 2026, and will be shared on AESO Engage in their original format. If you have any questions, please email stakeholderrelations@aeso.ca

Stakeholder Questions

Performance review of Rate DTS

12CP charge

Cost-reflectivity at a system-wide level

1. Do you agree with our assessment that in peak seasons the 12CP charge signals to load the drivers of system-wide network investment by encouraging load reduction across periods of high system-wide load? Please provide rationale for your response.

Cost-reflectivity at a planning area level

2. Do you agree with our assessment that the 12CP charge provides little incentive to reduce load in periods of stress on the local transmission network for many areas in the Province? Please provide rationale for your response.

Combing both cost drivers

3. Do you agree with our assessment that in other parts of the year the 12CP charge likely triggers inefficient price response by encouraging a reduction in load in periods when there is spare transmission capacity? Please provide rationale for your response. 

Billing capacity charge

Cost-reflectivity at a system-wide level

4. Do you agree with our assessment that the billing charge likely does not lead to a reduction in system-level network stress due to the low level of synchronicity of load across the entire Province? Please provide rationale for your response.

Cost-reflectivity at a system-wide and area-planning level

5. Do you agree with our assessment that the billing charge likely results in reduced local line stress for some planning areas, i.e., those with high synchronized load? Please provide rationale for your response.

6. Do you agree with our assessment that for areas with asynchronous load, the billing charge likely triggers inefficient price response with limited impact on system-wide or local line stress? Please provide rationale for your response.

Scope and framework for rate review

7. Do you agree with the scope, i.e., the focus on 12CP and the billing capacity? Please provide rationale for your response.

8. Do you agree with the questions investigated in the analytical framework (see Figure 4-17 of the Report)? Would you remove or add other questions? Please provide rationale for your response.

Embedded cost of service (ECOS) study

Identified structural issues with the existing ECOS methodology

9. Do you agree with our assessment that the high-voltage 500 kV assets have complex cost drivers that are attributable to both load and generation, rather than entirely one or the other? Please provide rationale for your response.

10. Do you agree with our assessment that as well as load, generation has also been a driver of historically incurred network costs for network elements operating at voltage levels lower than 500kV? Please provide rationale for your response.

11. Do you agree with our assessment that regional load peaks are an important driver of local transmission investment that is currently not adequately captured by the existing ECOS methodology? Please provide rationale for your response. 

12. Do you agree with our assessment that Point of Supply (POS) costs should not be functionalized as part of the bulk system, given load cannot influence these costs? Please provide rationale for your response. 

13. Do you agree that since the current ECOSS methodology was introduced in 2013, the functional distinction between assets operating at different voltages has become increasingly blurred due to the evolving use of the transmission network? Please provide rationale for your response. 

14. Do you agree with our assessment that the current ‘all-or-nothing’ approach to functionalizing substations as point of connection is likely not durable to future grid developments? Please provide rationale for your response. 

15. Are there any other structural issues with the existing ECOS methodology that we should consider further in our assessment?

 Proposed approach to address the identified shortcomings of the existing ECOS methodology

16. Do you agree with our proposed approach to perform a separate functionalization of the 500 kV assets and classify costs 50/50 between load and generation? Please provide rationale for your response.

17. Do you agree with our proposed approach to recognize generation as a cost driver for System costs by classifying costs in each planning area based on a comparison of peak load and peak generation? Please provide rationale for your response. 

18. Do you agree with our proposed approach to capture system and regional load peaks as cost drivers by allocating a proportion of costs to ‘peak and ‘shoulder’ periods? Please provide rationale for your response.

19. Do you agree with our proposed approach to recognize that a proportion of network costs are incurred to support non-peak use of the system and allocate a proportion of costs to a ‘baseload’ period? Please provide rationale for your response. 

20. Do you agree with our proposed approach to separately functionalize Point of Connection (POC) costs, and to separate POC into POS and Point of Delivery (POD) by assuming POS is fully netted off by deducting customer contributions from POC, and the residual is POD? Please provide rationale for your response.

21. Do you agree with our proposal to merge the former Bulk and Regional functions (other than the 500 kV assets) into a combined ‘System’ function, or are there materially different cost drivers between the asset voltage levels that should be captured? Please provide rationale for your response.

22. Do you agree with our proposal to recognize the dual function of some substations by applying the ‘substation fraction’ methodology? Please provide rationale for your response. 

23. Are there any structural issues with the proposed ECOS methodology that we should consider further in our assessment?

Marginal Cost of Service Study (MCOSS)

24. Do you agree with our proposal to use a regression approach in the MCOSS? Please provide rationale for your response. 

25. Do you agree with the set of variables we have considered in the regression approach? Please provide rationale for your response.

26. Do you agree with the way we determined the acquisition value of transmission assets? Please provide rationale or share an alternative and explain.

27. Do you agree with our assumed asset life for transmission lines and substations? Please provide rationale or share an alternative and explain.

28. Do you agree with the use of Canadian Producer Price Index (PPI) for inflating grid costs? Please provide rationale or share an alternative and explain.

29. Do you agree with our identification of peak load and peak generation as key underlying drivers of network investment? Please provide rationale for your response.

30. Do you agree that the estimates of the long-run marginal cost (LRMC) of the grid with respect to peak load should be generalizable in future grid planning scenarios? Please provide rationale for your response 

31. Do you have any other remarks on the MCOSS?

Conclusions across the three studies

32. How should the studies inform rate design options?

33. Is there any information missing and/or required before we move into rate design?