20240305PAC to Staff 17 Supplemental.pdf

1407 W North Temple, Suite 330 Salt Lake City, Utah 84116
March 5, 2024
Monica Barrios-Sanchez Commission Secretary
Idaho Public Utilities Commission 11331 W. Chinden Blvd. Bldg. 8, Ste. 201-A Boise, ID 83714
[e-mail]
[e-mail]
RE: ID PAC-E-23-24 IPUC Set 1 (1-24)
Please find enclosed Rocky Mountain Power’s 1st Supplemental Response to IPUC 1st Set Data
Request 17. Also provided is Attachment IPUC Audit 17 1st Supplemental.
If you have any questions, please feel free to call me at [phone].
Sincerely,
____/s/____ J.Ted Weston
Manager, Regulation
Enclosures
RECEIVED
Tuesday, March 5, 2024 12:19PM
IDAHO PUBLIC
UTILITIES COMMISSION
PAC-E-23-24 / Rocky Mountain Power March 5, 2024 IPUC Data Request 17 – 1st Supplemental
IPUC Data Request 17 Please respond to the following regarding Table F.7 on Page 150 of the FRS.
(a) Please explain what the percentages on the y-axis represent;
(b) Please explain the relationship between the Wind Capacity (MW) and the percentages (%) on the y-axis;

(c) On the y-axis, if 1,575 MW is 100%, please explain why 166% results in 3,024 MW; (d) Please explain what the percentages on the x-axis represent;
(e) Please explain the relationship between the Solar Capacity (MW) and the
percentages (%) on the x-axis; (f) On the x-axis, if 855 MW is 100%, please explain why 166% results in 1,462
MW;
(g) Please explain how percentage intervals are determined on the x-axis and the y axis; and (h) Please explain how the starting point of 788 MW for wind and the starting
point of 428 MW for solar are determined. Supplemental request received from Idaho Public Utilities Commission (IPUC) staff on February 26, 2024:

1. Referencing the Company’s response to subpart (a) which concluded by stating “There may also be an error in the calculation”. Please explain what the error was. Did the error mean the mismatch between the megawatt (MW) amounts and the percentages on X-axis and Y-axis? Did the error affect the final integration charges? If so, why?

2. Referencing the Company’s response to subpart (h) which states “The starting point for the analysis was the 2018-2019 actual wind and solar levels, designated as 100 percent”. Based on Table F.7 and Table F. 8, the starting wind level is 2301 MW (1575+726). However, Table F.1 shows the actual
wind during 2018-2019 is 2745MW. Please reconcile the difference. 1st Supplemental Response to IPUC Data Request 17 Further to the Company’s response to IPUC Data Request 17 dated February 2,
2024 and to the follow-up requests received from Idaho Public Utilities
PAC-E-23-24 / Rocky Mountain Power March 5, 2024 IPUC Data Request 17 – 1st Supplemental
Commission (IPUC) staff on February 26, 2024, the Company responds as follows: 1. The “error” just refers to the confusing labels and does not impact the
calculation of the integration cost. Please refer to Attachment IPUC 17 1st
Supplemental which provides a calculation of the referenced percentages. As shown in the provided attachment, the percentages refer to PacifiCorp’s share of the system totals including both East and West. This is not an error, but the
values when considering the East only or the West only vary. The calculation
of the megawatt (MW) levels for each step was provided with the Company’s response to IPUC Data Request 6, specifically Confidential Attachment IPUC 6-2, in columns S:AE on tabs “PACE” and “PACW” and was intended to evenly cover the maximum interconnection potential for each area, doing either all wind or all solar. Note: since the time the Flexible Reserve Study
(FRS) was prepared, integrated resource plan (IRP) modeling has evolved to
allow for hybrid resources, that include both wind and solar, and potentially storage, behind the same interconnection. The IRP also allows for expansion in combination with existing resources, known as “Surplus Interconnection”,
adding wind or solar at existing thermal resources, and the cluster study
generation interconnection process has identified transmission solutions for an even larger amount of potential wind and solar resources. 2. The 2018-2019 actual data includes all resources within the PacifiCorp East (PACE) and PacifiCorp West (PACW) balancing authority areas (BAA), so it
has resources that are not owned by the Company or purchased by the
Company for serving retail customers. These “third-party” resources purchase transmission and ancillary services. These are held constant at the historical levels for the FRS.

Recordholder: Dan MacNeil Sponsor: Dan MacNeil