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Sierra 2021 RFP Documents

Sierra 2021 Battery Storage RFP

Solar Generation Profile for Retrofit Alternative

Apache Station Solis

Power Purchase Agreement Evaluation Form for Energy Storage Resources

Bidder Registration Form

Confidentiality Agreement

Sierra Southwest Audit 2018

Sierra Southwest Audit 2019

Sierra Southwest Audit 2020

Sierra 2021 RFP Schedule

RFP Issued

April 21, 2021

Q&A on Substantive RFP Issues (email)

April 21, 2021 –
May 24, 2021

Open Period for Submission of Bidder Registration Forms

April 21, 2021 –
April 30, 2021

Deadline for Submission of Bidder Registration Forms
(Appendix F) at 5:00 p.m. MST

April 30, 2021

Open Period for Submission of Proposals

May 1, 2021 –
May 24, 2021

Proposals (Appendices) Deadline at 5:00 p.m. MST

May 24, 2021

Bid Screening and Analysis Period

May 24, 2021 –
June 30, 2021

Notification of RFP Shortlist

July 1, 2021

Open Period for Best and Final Offers

July 2, 2021 –
July 16, 2021

Final Bid Analysis Period

July 18, 2021 –
July 30, 2021

Notification to Bidders of Recommendation of Award(s)

August 2, 2021

Finalize Mutually Agreeable Term Sheet (subject to
AEPCO and participating members’ Board of Directors approval)

November 5, 2021


Questions and Responses

Responses to all relevant questions submitted to or through the contact form on this page will be provided below

Relevant questions and responses related to the Sierra 2021 RFP will be posted on this page. 

Yes, so long as they are relevant to the RFP.

Responses to questions will be provided as soon as practical. Response times will vary depending upon the complexity of the question.

No, submitting a Notice of Intent does not obligate your company to submit an offer. However, a Notice of Intent is required to be able to submit an offer on behalf of your organization for this RFP. 

Sierra Southwest will be respecting the confidentiality of our Respondents and not be sharing these prices. 

We do not have the specific site selected and it may depend on the alternative chosen. However, there is plenty of available space and you can assume a mostly flat site. Though, in general, arrangements should minimize the area required, including site shape, for all the equipment meeting standards (NEC, IEEE, etc.) for proper clearance.

Sierra will only request a Confidentiality Agreement be signed and submitted if the need arises, so there is no specific deadline, and it may not be submitted at all. All proposals will be treated as confidential, and all RFP documentation will be made public unless a special circumstance arises between Sierra and a bidder that requires separate, confidential information sharing. 

Sierra has more flexibility with this configuration since it would charge from the grid, specifically early morning hours instead of just midday from a solar array’s output. There are also some use cases that require sustained charge (black start, regulation up, and contingency reserve). While we would be able to operate flexibly within whatever the contract limit ends up being, there could be value in having a higher average state of charge (40%-60%). Sierra requests whatever assumption the bidder makes be defined in Appendix C. If there would be a material price difference between an average SOC of 40% and 60%, the bidder can choose to submit two separate tabs in Appendix C or denote the price sensitivity to that value in the proposal for potential further refinement in the best and final offer round. 

AEPCO cannot provide a parental guarantee; however, the PPA between the energy provider and Sierra would be secured by the PPA between Sierra and AEPCO. AEPCO has an obligation to purchase all output and cover all costs from Sierra. 

Sierra’s bylaws provide that there is one class of Membership consisting of electric utilities which have agreements with Sierra with terms of five years or more, whereby electric power or energy related products and services are acquired from Sierra. As described in more detail in the RFP, AEPCO is Sierra’s sole member, and Sierra develops renewable energy projects for AEPCO, pursuant to various contracts between the two parties.     

The solar array is located at 32°3’58″N, 109°53’25″W at the site. The Apache site is not limited to that small area, there is plenty of room and a specific location has not been chosen yet. It will depend which alternative and what capacity is selected. Sierra will work with the bidder to select a specific location at the Apache site based on design criteria. 

Bidders will own the storage project and be responsible for any potential tax liability and tax credits. Sierra cannot provide tax guidance and requests bidders consult their own tax council for applicability. 

Sierra expects there could be varying contract arrangements for battery operation that may or may not involve direct, real-time control. However, Sierra would prefer to have the flexibility to determine how to operate the battery each day throughout the year and not include fixed charging and discharging times in the contract. 

Bidders should propose timelines they are comfortable with meeting within the COD range of June 2022 through May 2023. June 2022 is the preferred COD and the proposed COD will be part of the overall evaluation of each proposal as listed in Section 3.8. 

The solar array is located at 32°3’58″N, 109°53’25″W at the site.  The soil data that has been provided is from random locations throughout the Apache Solar Facility. 

The confidentiality agreement is not needed unless a special circumstance arises that requires confidential communication between Sierra and bidder (see Section 3.10 of the RFP for more detail). In the instance Sierra determines a confidentiality agreement is needed, there could be the opportunity to provide redlines to get to an agreement. 

Sierra is requesting that the bidder’s project boundary stop at 34.5kV; however, that is not the point of interconnection to the broader grid. Sierra will then take responsibility to complete the interconnection with AEPCO at the interconnection voltage of 69kV. Bidders can assume 2.5% losses from 34.5kV to the point of interconnection at 69kV. 

The generator interconnection states the Generating Facility will maintain a composite power delivery at continuous rated power output at the Point of Interconnection at a power factor within the range of 0.95 leading to 0.95 lagging. However, Sierra is newer to battery technology and anything the bidder can provide regarding the ability of the facility to provide voltage support as another value stream would be beneficial (e.g. D-curves or general descriptions of voltage support capabilities to consider). 

It would not be in addition, Sierra expects any of the power options for Design Alternative 1, 25 MW being the lowest, could support its black start instantaneous power needs as long as the requisite energy is kept in reserve in the battery (5 MWh). 

Sierra 2021 RFP Contact