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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

 

Bidder/Stakeholder
Questions and Responses

Responses to all relevant questions submitted to Sierra2021RFP@acespower.com 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). 

For Design Alternative 1, there would not be as much individual priorities as the ability to stack multiple value streams and maximize the value of the BESS to the system. For design alternative 2 the priority is the peak shaving use case. 

Based on the priority of peak shaving for Design Alternative 2, Sierra is only requesting 4 hour duration. There is no preference between 2 or 4 hour for Design Alternative 1—it will be evaluated based on the additional cost versus value that a 4 hour duration might provide compared to 2 hours. 

The load information belongs to the distribution cooperatives, so it’s not something Sierra can share. 

Sierra will pick up from the BESS 34.5kV and route power to the 69kV interconnection point. Yes, the bidder is responsible for all costs from the BESS output voltage to 34.5kV and anything behind (on the BESS side) the 34.5kV transformation (e.g. station service voltage). 

Yes, putting them in one proposal is actually preferred. An Appendix C table is still needed for each proposed option which can be done by copying the sheet and submitting multiple tabs in the same Excel file. 

Yes, putting them in one proposal is actually preferred. An Appendix C table is still needed for each proposed option, which can be done by copying the sheet and submitting multiple tabs in the same Excel file. 

The Energy Storage Service Agreement will be the PPA-like contract that details the requirements of each party for the term of the agreement. There are usually many components to these agreements; however, some key items would be the descriptions of warranties and guarantees and operating requirements/limitations for Sierra to maintain warranties and guarantees. Any other terms that would be required in a final contract should also be included here if a full sample agreement is not provided. 

The Energy Storage Service Agreement will be the PPA-like contract that details the requirements of each party for the term of the agreement. There are usually many components to these agreements; however, some key items would be the descriptions of warranties and guarantees and operating requirements/limitations for Sierra to maintain warranties and guarantees. Any other terms that would be required in a final contract should also be included here if a full sample agreement is not provided. 

The solar facility will be separately owned from the BESS and therefore its existing tax treatment is also separate and not expected to directly impact the BESS project. The solar facility will just be providing energy to charge the BESS. 

Sierra would prefer to have the option to augment the BESS to maintain the power and capacity over the term; however, Sierra would also prefer to see this priced incrementally, given the uncertainty of long-term battery costs and the actual relationship between usage and degradation. Bidders should indicate if they have a preferred augmentation strategy and if those costs are included in the proposed price as either fixed or estimates of future augmentation costs. 

The combination of use cases described in Section 2.2 of the RFP. 

Yes, the optimal power/energy configuration will be identified based on the cost of the system and its ability to meet the use case needs identified. 

Nothing beyond the descriptions in Section 2.2 of the RFP. 

There is no more specific charging source information beyond what’s listed in Section 2.2 of the RFP. 

Sierra is not targeting a specific load shape for which to manage BESS dispatch, the use would be flexible between energy arbitrage, peak shaving, and/or the ancillary services identified in the case of Design Alternative 1. 

Yes, Sierra will require a capacity and degradation guarantee either with or without augmentation to determine the performance expectations for the life of the contract. 

There is not a specific load factor to be corrected by the BESS, either design may be operated for either peak shaving or energy arbitrage. 

Without knowing the exact metrics needed, Sierra requests the bidders to use the latitude, longitude, and elevation provided to determine the various environmental conditions. Bidders should provide their design specifications for heating, cooling, and battery condition temperature requirements. 

The BESS is not expected to be operated in a microgrid, the system should include any controls necessary to meet the use case needs at a utility scale.  

Sierra will be doing the interconnection with the grid, so a single-line diagram of the entire Apache site will not be provided at this time. 

The combination of use cases, including ancillary services, is described in Section 2.2 of the RFP. 

Bidders should assume no space constraints, there is no predetermined site layout. 

Yes, Sierra expects these will be needed. The system should include any equipment necessary to meet the use case needs at a utility scale up to the project boundary with Sierra at 34.5kV. 

A third-party financing firm owns the Apache Solar array, Sierra does not expect the BESS will have the same owner as the array. 

A third-party financing firm owns the Apache Solar array, Sierra does not expect the BESS will have the same owner as the array. Bidders should indicate in Appendix C if the BESS is not expected to be ITC eligible. 

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. 

Sierra will be doing the interconnection with the grid so a single-line diagram of the entire Apache site will not be provided at this time. 

The land will not be available for purchase. Sierra would like the option to be able to purchase the BESS or extend the contract, however BESS bidders should also consider the possibility of decommissioning the facility, equipment removal, and other end of life activities. 

The location provided is for the broader Apache Station site. Sierra has not chosen a specific location and it may depend on the design selected. However, Sierra expects the BESS would be located adjacent to the solar array for Design Alternative 2. 

There are no known limitations for size or setbacks that would impact this facility. Bidders should assume no permitting for BESS has been completed. 

As a percent, this can also be called turnaround efficiency. Revenue quality metering will measure what energy is used to charge and what is discharged. 

Sierra is interested in degradation of both the power capacity and energy capacity, if they are different the bidder should note it in the proposal. 

Yes, if there would be any limitation to charging times they should be noted. If there are no expected restrictions bidders can write N/A. 

Bidder will be responsible for obtaining Cochise County permits. 

The bidder will be responsible for obtaining all permits. 

Yes for personnel safety and must be in accordance with Cochise County dark skies requirements. 

The generator interconnection with the transmission provider states the Generating Facility 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. There will also need to be standard communication between the generator and the transmission operator as part of the LGIA. 

Yes, Sierra expects the energy will be a pass through. The method for accounting for aux load is negotiable; however, Sierra expects it would be included either directly in the BESS price or supplied independently by Sierra. Bidders may want to state their assumptions in the proposal. 

This is negotiable, as long as the BESS can deliver the contract power rating at 69kV. 

One cycle per day can be assumed for Design Alternative 2. The use cases are more detailed for Design Alternative 1, specifically the periodic use for Frequency Regulation. Sierra may need to understand how the cycles are calculated better to determine if the entire system could be limited to one cycle per day (e.g., is it an average over some time period or is it limited to each calendar day?). 

Sierra 2021 RFP Contact