# McFarland B Solar and Storage

CAISO Batteries, Solar Photovoltaic · https://askthegrid.com/assets/facilities/mcfarland-b-solar-and-storage

McFarland B Solar and Storage is a hybrid solar and battery storage facility with 450 MW of EIA-reported operating capacity in Yuma County, Arizona, registered as EIA Plant ID 66637. AES Clean Energy owns and operates the plant. An EIA-based plant record ranks McFarland B Solar and Storage as the #52 power plant in the United States and #4 in Arizona by capacity, at 450 MW.

## Key facts

- Technology: Batteries, Solar Photovoltaic
- Power capacity: 450 MW
- Operating status: operating

## Grid and market context

- ISO/RTO: CAISO
- Balancing authority: California Independent System Operator (CAISO/CISO)
- Substation: Hoodoo Wash 500 kV Switchyard
- Point of interconnection: Hoodoo Wash 500 kV Switchyard
- Transmission owner: Arizona Public Service Company (APS), with the Hoodoo Wash switchyard co-owned by APS, San Diego Gas & Electric (SDG&E), and Imperial Irrigation District (IID)
- Interconnection voltage: 500 kV

## Source-backed facts

- Owner logo domain: aes.com — AES | Accelerating the Future of Global Energy · confidence: medium
- Identifiers: [{"value":"66637","system":"EIA plant ID"},{"value":"BESS","system":"EIA generator ID"},{"value":"MCFRB","system":"EIA generator ID"},{"value":"MCFLND_5_MSBBX2","system":"CAISO market resource — McFarland Solar B BESS"},{"value":"MCFLND_5_MSBSX2","system":"CAISO market resource — McFarland Solar B PV"},{"value":"23NGR27334","system":"CAISO network-model resource identifier — BESS"},{"value":"23GEN27333","system":"CAISO network-model resource identifier — PV"},{"value":"ER22-516-000","system":"FERC docket"},{"value":"APS Service Agreement No. 396","system":"APS OATT interconnection agreement"},{"value":"CAISO Service Agreement No. 7003","system":"CAISO interconnection agreement"}] — Curtailed · confidence: medium
- Identifiers: [{"value":"66637","system":"EIA plant ID"},{"value":"BESS","system":"EIA generator ID"},{"value":"MCFRB","system":"EIA generator ID"},{"value":"MCFLND_5_MSBBX2","system":"CAISO market resource — McFarland Solar B BESS"},{"value":"MCFLND_5_MSBSX2","system":"CAISO market resource — McFarland Solar B PV"},{"value":"23NGR27334","system":"CAISO network-model resource identifier — BESS"},{"value":"23GEN27333","system":"CAISO network-model resource identifier — PV"},{"value":"ER22-516-000","system":"FERC docket"},{"value":"APS Service Agreement No. 396","system":"APS OATT interconnection agreement"},{"value":"CAISO Service Agreement No. 7003","system":"CAISO interconnection agreement"}] — NRI · confidence: medium
- Description: McFarland B Solar and Storage is EIA plant 66637 in Yuma County, Arizona, with two generators: a 300 MW solar photovoltaic unit identified by EIA as MCFRB and a 150 MW battery unit identified as BESS, for 450 MW total. Its CAISO resources are MCFLND_5_MSBSX2 for the PV facility and MCFLND_5_MSBBX2 for the BESS. AES lists McFarland B as a 300 MW solar asset with a 75% AES equity interest, commercial operations in 2023–2024, and Amazon as the customer. — Curtailed · confidence: medium
- Description: McFarland B Solar and Storage is EIA plant 66637 in Yuma County, Arizona, with two generators: a 300 MW solar photovoltaic unit identified by EIA as MCFRB and a 150 MW battery unit identified as BESS, for 450 MW total. Its CAISO resources are MCFLND_5_MSBSX2 for the PV facility and MCFLND_5_MSBBX2 for the BESS. AES lists McFarland B as a 300 MW solar asset with a 75% AES equity interest, commercial operations in 2023–2024, and Amazon as the customer. — Source · confidence: medium
- Identifiers.1: {"value":"BESS","system":"EIA generator ID"} — MBR | Index · confidence: high
- Identifiers.2: {"value":"MCFRB","system":"EIA generator ID"} — MBR | Index · confidence: high
- Identifiers.3: {"value":"MCFLND_5_MSBBX2","system":"CAISO market resource — McFarland Solar B BESS"} — Curtailed · confidence: high
- Identifiers.4: {"value":"MCFLND_5_MSBSX2","system":"CAISO market resource — McFarland Solar B PV"} — Curtailed · confidence: high
- Identifiers.5: {"value":"23NGR27334","system":"CAISO network-model resource identifier — BESS"} — NRI · confidence: medium
- Identifiers.6: {"value":"23GEN27333","system":"CAISO network-model resource identifier — PV"} — NRI · confidence: medium
- Parties.0: {"relationship":"Owner and operator / parent operating platform","name":"AES Clean Energy","official_url":"https://www.aes.com/"} — AES | Accelerating the Future of Global Energy · confidence: medium
- Parties.2: {"relationship":"Site-preparation contractor","name":"WW Clyde","official_url":"https://wwclyde.net/"} — McFarland Solar Phase B - WW Clyde · confidence: high
- Parties.7: {"relationship":"Customer / offtaker identified in AES portfolio materials","name":"Amazon","official_url":"https://www.amazon.com/"} — Source · confidence: high
- Interconnection: Hoodoo Wash 500 kV Switchyard; interconnection involves APS and the CAISO system, with the switchyard co-owned by APS, SDG&E, and IID. — Source · confidence: medium
- Site acres: 1800 — McFarland Solar Phase B - W.W. Clyde · confidence: medium
- Unit configuration: Two generating units: one 300 MW solar photovoltaic generator (MCFRB) and one 150 MW battery energy-storage unit (BESS), for 450 MW total. — MBR | Index · confidence: high
- Commercial operation date: 2023-11-01 — MBR | Index · confidence: medium
- Power mw: 450 — MBR | Index · confidence: medium
- Unit count: 2 — MBR | Index · confidence: medium
- Battery units: 1 — Source · confidence: medium
- Equipment models: [] — Special Use Permit Application · confidence: medium
- Equipment models: [] — Special Use Permit Application · confidence: medium
- Equipment models: [] — McFarland Solar Phase B · confidence: medium
- Description: McFarland B Solar and Storage is a 450 MW hybrid plant in Yuma County, Arizona, comprising a 300 MW photovoltaic unit and a 150 MW battery unit; AES Clean Energy operates the two-unit facility. AES portfolio materials list McFarland B as a 300 MW solar asset with a 75% AES interest, 2023–2024 commercial operations, and Amazon as the customer, alongside third-party tax-equity investors with variable ownership interests. The project was originally proposed in June 2016 by Sustainable Power Group, or sPower, doing business as McFarland Solar LLC, as an 85 MW solar project. WW Clyde completed site-preparation work for the built Phase B facility on November 1, 2023, and the first unit came online on December 1, 2024. — Fact Sheet - The AES Corporation · confidence: medium
- Description: McFarland B Solar and Storage is a 450 MW hybrid plant in Yuma County, Arizona, comprising a 300 MW photovoltaic unit and a 150 MW battery unit; AES Clean Energy operates the two-unit facility. AES portfolio materials list McFarland B as a 300 MW solar asset with a 75% AES interest, 2023–2024 commercial operations, and Amazon as the customer, alongside third-party tax-equity investors with variable ownership interests. The project was originally proposed in June 2016 by Sustainable Power Group, or sPower, doing business as McFarland Solar LLC, as an 85 MW solar project. WW Clyde completed site-preparation work for the built Phase B facility on November 1, 2023, and the first unit came online on December 1, 2024. — McFarland Solar Phase B - WW Clyde · confidence: medium
- Description: McFarland B Solar and Storage is a 450 MW hybrid plant in Yuma County, Arizona, comprising a 300 MW photovoltaic unit and a 150 MW battery unit; AES Clean Energy operates the two-unit facility. AES portfolio materials list McFarland B as a 300 MW solar asset with a 75% AES interest, 2023–2024 commercial operations, and Amazon as the customer, alongside third-party tax-equity investors with variable ownership interests. The project was originally proposed in June 2016 by Sustainable Power Group, or sPower, doing business as McFarland Solar LLC, as an 85 MW solar project. WW Clyde completed site-preparation work for the built Phase B facility on November 1, 2023, and the first unit came online on December 1, 2024. — Special Use Permit Application · confidence: medium
- Quality notes: ["The August 2017 transaction was a platform-level acquisition of sPower by AES and AIMCo from Fir Tree Partners, not documented project-specific sale consideration for McFarland B.","The June 2016 sPower permit application described an 85 MW solar proposal, while the operating EIA plant is 300 MW of photovoltaic capacity plus 150 MW of battery capacity; the cited record does not document one formal expansion or repowering event connecting those configurations.","The November 1, 2023 contractor milestone is identified as site-preparation completion, not full-plant commercial operation. The EIA-derived operating record reports the first unit online on December 1, 2024.","No retirement event is shown in the cited operating record; the plant is listed as operational as of the latest available record."] — Special Use Permit Application · confidence: medium
- Quality notes: ["The August 2017 transaction was a platform-level acquisition of sPower by AES and AIMCo from Fir Tree Partners, not documented project-specific sale consideration for McFarland B.","The June 2016 sPower permit application described an 85 MW solar proposal, while the operating EIA plant is 300 MW of photovoltaic capacity plus 150 MW of battery capacity; the cited record does not document one formal expansion or repowering event connecting those configurations.","The November 1, 2023 contractor milestone is identified as site-preparation completion, not full-plant commercial operation. The EIA-derived operating record reports the first unit online on December 1, 2024.","No retirement event is shown in the cited operating record; the plant is listed as operational as of the latest available record."] — McFarland Solar Phase B - WW Clyde · confidence: medium
- Financing summary: AES identifies McFarland B (OpCo D) as owned together with third-party tax-equity investors with variable ownership interests, but the cited disclosures do not assign a project-specific debt, tax-equity, or construction-financing amount. Separately, AES and AIMCo completed the August 2017 acquisition of sPower from Fir Tree Partners for $853 million in cash plus assumed debt reported at $712 million; AES's SEC acquisition disclosure described $90 million of subordinated debt and $763 million of equity funding. Those figures relate to the sPower platform acquisition, not McFarland B project financing. — Fact Sheet - The AES Corporation · confidence: medium
- Financing summary: AES identifies McFarland B (OpCo D) as owned together with third-party tax-equity investors with variable ownership interests, but the cited disclosures do not assign a project-specific debt, tax-equity, or construction-financing amount. Separately, AES and AIMCo completed the August 2017 acquisition of sPower from Fir Tree Partners for $853 million in cash plus assumed debt reported at $712 million; AES's SEC acquisition disclosure described $90 million of subordinated debt and $763 million of equity funding. Those figures relate to the sPower platform acquisition, not McFarland B project financing. — Source · confidence: medium
- Timeline.0: {"event":"Original project proposal and permit application","date":"2016-06","detail":"Sustainable Power Group, doing business as McFarland Solar LLC, submitted the McFarland B Solar Project application for a proposed facility of up to 85 MW in Yuma County; the application estimated construction in 2017–2018."} — Special Use Permit Application · confidence: medium
- Timeline.4: {"event":"Market-based-rate filing","date":"2023-07","detail":"McFarland Solar B LLC received notice of its initial market-based-rate filing, including a request for blanket Section 204 authorization."} — McFarland Solar B, LLC; Supplemental Notice That Initial... · confidence: high
- Timeline.5: {"event":"Site-preparation completion","date":"2023-11-01","detail":"WW Clyde reported completion of site-preparation work for AES's 300 MW solar and BESS Phase B facility, including earthwork, access roads, and inverter/BESS foundations."} — McFarland Solar Phase B - WW Clyde · confidence: high
- Timeline.6: {"event":"Pre-operation CAISO resource listing","date":"2024-05-08","detail":"CAISO listed the McFarland Solar B PV resource at 300 MW and the BESS resource at 150 MW as forced non-operational resources in its report."} — Curtailed · confidence: high
- Commercial parties.0: {"relationship":"Owner, operator, and parent operating platform","name":"AES Clean Energy","detail":"AES portfolio materials list McFarland B as a 300 MW solar asset with a 75% AES interest; the EIA-derived plant record identifies AES Clean Energy as operator.","official_url":"https://www.aes.com/"} — Fact Sheet - The AES Corporation · confidence: medium
- Commercial parties.2: {"relationship":"Predecessor developer and original applicant","name":"Sustainable Power Group (sPower)","detail":"Submitted the June 2016 McFarland B Solar Project application under the name McFarland Solar LLC.","official_url":null} — Special Use Permit Application · confidence: high
- Commercial parties.5: {"relationship":"Site-preparation contractor","name":"WW Clyde","detail":"Performed site clearing, grading, access-road installation, and inverter/BESS foundation work for the AES Phase B facility.","official_url":"https://wwclyde.net/"} — McFarland Solar Phase B - WW Clyde · confidence: high
- Commercial parties.10: {"relationship":"Customer identified in AES portfolio materials","name":"Amazon","detail":"AES identifies Amazon in the customer column for McFarland B; the cited material does not specify the contract form or offtake terms.","official_url":"https://www.amazon.com/"} — Fact Sheet - The AES Corporation · confidence: medium

## Timeline

- 2016-06 — Original project proposal and permit application
  Sustainable Power Group, doing business as McFarland Solar LLC, submitted the McFarland B Solar Project application for a proposed facility of up to 85 MW in Yuma County; the application estimated construction in 2017–2018.
  Source: Special Use Permit Application (https://public.destinyhosted.com/yumacdocs/2016/BOSREG/20161121_975/7217_McFarland%20B%20SUP%20Application.pdf)
- 2021-11-29 — Interconnection agreement effective
  The CAISO tariff record adopting the non-conforming Large Generator Interconnection Agreement for McFarland Solar A and B became effective, covering the CAISO, APS, SDG&E, IID, and the project companies.
  Source: Source (https://www.caiso.com/documents/may6-2022-orderacceptingcertificateofconcurrence-largegeneratorinterconnectionagreement-mcfarlandsolar-er22-875.pdf)
- 2023-11-01 — Site-preparation completion
  WW Clyde reported completion of site-preparation work for AES's 300 MW solar and BESS Phase B facility, including earthwork, access roads, and inverter/BESS foundations.
  Source: McFarland Solar Phase B - WW Clyde (https://wwclyde.net/project/mcfarland-solar-phase-b/)

## Sources

- [AES | Accelerating the Future of Global Energy](https://www.aes.com/) — aes.com · tier other
- [MBR | Index](https://mbrweb.ferc.gov/SearchlkpEIA/Index?page=775) — mbrweb.ferc.gov · tier regulatory
- [Curtailed](https://www.caiso.com/documents/curtailed-non-operational-generator-am-report-20240508.xlsx) — caiso.com · tier other
- [NRI](https://www.caiso.com/documents/fullnetworkmodel_workscope_db23m8.xlsx) — caiso.com · tier other
- [Source](https://www.caiso.com/documents/jan24-2022-certificateofconcurrence-largegeneratorinterconnectionagmtlgia-mcfarlandsolar-er22-875.pdf) — caiso.com · tier other
- [McFarland Solar Phase B](https://wwclyde.net/project/mcfarland-solar-phase-b/) — wwclyde.net · tier other
- [Fact Sheet - The AES Corporation](https://www.aes.com/sites/vault/files/2025-04/AES-Q4-FY24-Fact-Sheet-03-03-25.pdf) — aes.com · tier other
- [wwwww@ww@w@w HHHHHHHHHHHH](https://www.aps.com/-/media/APS/APSCOM-PDFs/About/Construction-and-Power-Line-Siting/Power-Line-Siting/Power-Line-Siting-Projects/Hoodoo/AmendedCEC_52.pdf?la=en&sc_lang=en&hash=6B8FB659826331623ED289509896B7E4) — aps.com · tier other
- [Source](https://wwclyde.net/project/mcfarland-solar-phase-b) — wwclyde.net · tier other
- [Special Use Permit Application](https://public.destinyhosted.com/yumacdocs/2016/BOSREG/20161121_975/7217_McFarland%20B%20SUP%20Application.pdf) — public.destinyhosted.com · tier other
- [03-03-25 Q4-FY 2024 Fact Sheet_FINAL](https://aes.com/sites/vault/files/2025-04/AES-Q4-FY24-Fact-Sheet-03-03-25.pdf) — aes.com · tier other
- [Source](https://www.sec.gov/Archives/edgar/data/874761/000114420417010800/v460369_8k.htm) — sec.gov · tier regulatory
- [Source](https://www.caiso.com/documents/may6-2022-orderacceptingcertificateofconcurrence-largegeneratorinterconnectionagreement-mcfarlandsolar-er22-875.pdf) — caiso.com · tier other
- [Federal Register :: McFarland Solar B, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization](https://www.federalregister.gov/documents/2023/07/26/2023-15833/mcfarland-solar-b-llc-supplemental-notice-that-initial-market-based-rate-filing-includes-request-for) — federalregister.gov · tier regulatory
- [2025](https://www.aes.com/sites/vault/files/2026-03/AES-Corp-2025-Annual-Report-03-20-2026.pdf) — aes.com · tier other
- [08-01-25 Q2 2025 Fact Sheet_FINAL](https://www.aes.com/sites/aesvault.com/files/2025-08/AES-Q2-2025-Fact-Sheet-08-01-25.pdf) — aes.com · tier other
- [McFarland B Solar and Storage solar farm](https://www.gem.wiki/McFarland_B_Solar_and_Storage_solar_farm) — gem.wiki · tier other
- [2025 NQC List](https://www.caiso.com/documents/final-net-qualifying-capacity-report-for-compliance-year-2025.xlsx) — caiso.com · tier other

## Data quality

- The August 2017 transaction was a platform-level acquisition of sPower by AES and AIMCo from Fir Tree Partners, not documented project-specific sale consideration for McFarland B. The EIA-derived operating record reports the first unit online on December 1, 2024. No retirement event is shown in the cited operating record; the plant is listed as operational as of the latest available record.

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