# Sanborn BESS 3

CAISO Batteries · https://askthegrid.com/assets/facilities/sanborn-bess-3

Sanborn BESS 3 is a battery energy storage facility with 169 MW of EIA-reported operating capacity and 676 MWh of reported energy capacity in Kern County, California, registered as EIA Plant ID 65672. Terra-Gen Operating Co-BESS owns and operates the plant. The facility interconnects at Windhub Substation at 220 kV. Its grid role is battery storage supporting cleaner, more reliable and resilient power delivery to the CAISO grid.

## Key facts

- Technology: Batteries
- Power capacity: 169 MW
- Energy capacity: 676 MWh
- Operating status: operating

## Grid and market context

- ISO/RTO: CAISO
- Balancing authority: CISO
- Substation: Windhub Substation
- Point of interconnection: Windhub Substation
- Transmission owner: Southern California Edison Company
- Interconnection voltage: 220 kV

## Source-backed facts

- Owner logo domain: terra-gen.com — Terra-Gen: Home · confidence: medium
- Identifiers: [{"value":"65672","system":"EIA plant ID"},{"value":"BESS","system":"EIA generator ID"},{"value":"CISO","system":"EIA balancing authority"},{"value":"CAISO","system":"ISO/RTO"},{"value":"Sanborn 3","system":"CAISO participating-resource ID"},{"value":"52228","system":"FERC MBR EIA-index record"}] — Resource category and phase · confidence: medium
- Official project url: https://terra-gen.com/edwards-sanborn/ — Edwards Sanborn (Edsan) Solar Storage Phase 1A & 1B - Terra-Gen · confidence: medium
- Parties: [{"relationship":"Operator","name":"Terra-Gen Operating Co-BESS","official_url":"https://terra-gen.com/"}] — Terra-Gen: Home · confidence: medium
- Identifiers.4: {"value":"Sanborn 3","system":"CAISO participating-resource ID"} — Resource category and phase · confidence: medium
- Site acres: 4600 — Edwards Sanborn (Edsan) Solar Storage Phase 1A & 1B - Terra-Gen · confidence: medium
- Manufacturer name: LG Chem, Samsung, and BYD (identified for the broader Edwards Sanborn project; allocation to Sanborn BESS 3 is not specified) — Mortenson Announces Completion of Edwards & Sanborn Solar + Storage Project | Mortenson · confidence: low
- Equipment models: [] — California project with world's biggest battery at 3,287MWh online · confidence: medium
- Manufacturer name: LG Chem, Samsung, and BYD (identified for the broader Edwards Sanborn project; allocation to Sanborn BESS 3 is not specified) — California project with world's biggest battery at 3,287MWh online · confidence: medium
- Manufacturer name: LG Chem, Samsung, and BYD (identified for the broader Edwards Sanborn project; allocation to Sanborn BESS 3 is not specified) — Mortenson Announces Completion of Edwards & Sanborn Solar + Storage Project | Mortenson · confidence: medium
- Description: Sanborn BESS 3 is an operational battery power plant in Kern County, California, with one generating unit rated at 169 MW. It is operated by Terra-Gen Operating Co-BESS and participates in the CISO balancing authority and CAISO market. The facility corresponds to the 169 MW/676 MWh Edwards Sanborn Energy Storage resource identified in PG&E procurement materials. The unit entered operation on October 1, 2023, during the broader Edwards Sanborn solar-and-storage build-out. — PG&E plans 1.6GW/6.4GWh battery storage portfolio through 2024 - pv magazine USA · confidence: medium
- Description: Sanborn BESS 3 is an operational battery power plant in Kern County, California, with one generating unit rated at 169 MW. It is operated by Terra-Gen Operating Co-BESS and participates in the CISO balancing authority and CAISO market. The facility corresponds to the 169 MW/676 MWh Edwards Sanborn Energy Storage resource identified in PG&E procurement materials. The unit entered operation on October 1, 2023, during the broader Edwards Sanborn solar-and-storage build-out. — Terra-Gen closes $1billion loans for phase two of Edwards Sanborn · confidence: medium
- Quality notes: ["The $959 million financing was for the broader second phase of Edwards Sanborn and was not disclosed as an amount allocated specifically to EIA plant 65672; it should not be treated as sale consideration.","The EIA-based record reports 169 MW, while a FERC index record reports 175.5 MW for the same EIA plant ID; the EIA operational capacity is used here because it identifies the plant’s current generator record.","An Axium Infrastructure acquisition of an 80% interest in Edwards Sanborn 1A is documented separately and is not identified as a transaction involving Sanborn BESS 3. No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering event was identified for the exact asset."] — Axium Infrastructure Invests In Phase 1 Of Edwards... · confidence: medium
- Financing summary: In September 2022, Terra-Gen closed $959 million of senior secured project financing for the second phase of the broader Edwards Sanborn Solar Storage facility. The package comprised a $460 million construction and term loan, a $403 million tax-equity bridge facility provided by U.S. Bank, and a $96 million construction and revolving letter-of-credit facility. BNP Paribas, CoBank, ING, and Nomura Securities led the construction and term financing. The financing covered a broader phase containing 1,786 MWh of battery storage; no separate financing amount for Sanborn BESS 3 and no sale price were disclosed. — Media Room - Page 2 of 3 · confidence: medium
- Timeline: [{"event":"Broader-project construction commenced","date":"2020","detail":"Terra-Gen states that construction of the Edwards Sanborn Phase 1A/1B project began in 2020. A separate Sanborn BESS 3 construction-start date was not identified."},{"event":"Second-phase project financing closed","date":"2022-09-15","detail":"Terra-Gen announced the close of $959 million in senior secured financing for the second Edwards Sanborn phase, which included battery storage scheduled to be fully operational in the third quarter of 2023."},{"event":"Planned PG&E initial delivery","date":"2023-08","detail":"PG&E procurement materials identified a Terra-Gen Edwards Sanborn Energy Storage resource rated at 169 MW/676 MWh and listed August 2023 as its planned delivery date."},{"event":"Commercial operation","date":"2023-10-01","detail":"The EIA-based plant record reports Sanborn BESS 3’s first unit online on October 1, 2023; the plant has one operational battery generating unit rated at 169 MW."},{"event":"Acquisition, sale, predecessor-owner transfer, retirement, or repowering","date":null,"detail":"No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering milestone was identified for the exact Sanborn BESS 3 plant. The documented transaction record identifies project financing, while the separately reported Axium acquisition concerns Edwards Sanborn 1A."}] — Edwards Sanborn (Edsan) Solar Storage Phase 1A & 1B - Terra-Gen · confidence: medium
- Timeline: [{"event":"Broader-project construction commenced","date":"2020","detail":"Terra-Gen states that construction of the Edwards Sanborn Phase 1A/1B project began in 2020. A separate Sanborn BESS 3 construction-start date was not identified."},{"event":"Second-phase project financing closed","date":"2022-09-15","detail":"Terra-Gen announced the close of $959 million in senior secured financing for the second Edwards Sanborn phase, which included battery storage scheduled to be fully operational in the third quarter of 2023."},{"event":"Planned PG&E initial delivery","date":"2023-08","detail":"PG&E procurement materials identified a Terra-Gen Edwards Sanborn Energy Storage resource rated at 169 MW/676 MWh and listed August 2023 as its planned delivery date."},{"event":"Commercial operation","date":"2023-10-01","detail":"The EIA-based plant record reports Sanborn BESS 3’s first unit online on October 1, 2023; the plant has one operational battery generating unit rated at 169 MW."},{"event":"Acquisition, sale, predecessor-owner transfer, retirement, or repowering","date":null,"detail":"No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering milestone was identified for the exact Sanborn BESS 3 plant. The documented transaction record identifies project financing, while the separately reported Axium acquisition concerns Edwards Sanborn 1A."}] — Media Room - Page 2 of 3 · confidence: medium
- Timeline: [{"event":"Broader-project construction commenced","date":"2020","detail":"Terra-Gen states that construction of the Edwards Sanborn Phase 1A/1B project began in 2020. A separate Sanborn BESS 3 construction-start date was not identified."},{"event":"Second-phase project financing closed","date":"2022-09-15","detail":"Terra-Gen announced the close of $959 million in senior secured financing for the second Edwards Sanborn phase, which included battery storage scheduled to be fully operational in the third quarter of 2023."},{"event":"Planned PG&E initial delivery","date":"2023-08","detail":"PG&E procurement materials identified a Terra-Gen Edwards Sanborn Energy Storage resource rated at 169 MW/676 MWh and listed August 2023 as its planned delivery date."},{"event":"Commercial operation","date":"2023-10-01","detail":"The EIA-based plant record reports Sanborn BESS 3’s first unit online on October 1, 2023; the plant has one operational battery generating unit rated at 169 MW."},{"event":"Acquisition, sale, predecessor-owner transfer, retirement, or repowering","date":null,"detail":"No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering milestone was identified for the exact Sanborn BESS 3 plant. The documented transaction record identifies project financing, while the separately reported Axium acquisition concerns Edwards Sanborn 1A."}] — PG&E plans 1.6GW/6.4GWh battery storage portfolio through 2024 - pv magazine USA · confidence: medium
- Timeline: [{"event":"Broader-project construction commenced","date":"2020","detail":"Terra-Gen states that construction of the Edwards Sanborn Phase 1A/1B project began in 2020. A separate Sanborn BESS 3 construction-start date was not identified."},{"event":"Second-phase project financing closed","date":"2022-09-15","detail":"Terra-Gen announced the close of $959 million in senior secured financing for the second Edwards Sanborn phase, which included battery storage scheduled to be fully operational in the third quarter of 2023."},{"event":"Planned PG&E initial delivery","date":"2023-08","detail":"PG&E procurement materials identified a Terra-Gen Edwards Sanborn Energy Storage resource rated at 169 MW/676 MWh and listed August 2023 as its planned delivery date."},{"event":"Commercial operation","date":"2023-10-01","detail":"The EIA-based plant record reports Sanborn BESS 3’s first unit online on October 1, 2023; the plant has one operational battery generating unit rated at 169 MW."},{"event":"Acquisition, sale, predecessor-owner transfer, retirement, or repowering","date":null,"detail":"No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering milestone was identified for the exact Sanborn BESS 3 plant. The documented transaction record identifies project financing, while the separately reported Axium acquisition concerns Edwards Sanborn 1A."}] — Axium Infrastructure Invests In Phase 1 Of Edwards... · confidence: medium
- Commercial parties.2: {"relationship":"Engineering, procurement, and construction contractor","name":"Mortenson","detail":"Mortenson was the full EPC contractor for the solar and energy-storage scopes of the Edwards Sanborn project, including the second phase associated with the 2023 battery build-out.","official_url":"https://www.mortenson.com/"} — Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen · confidence: medium
- Commercial parties.4: {"relationship":"Construction and term-financing lead arranger","name":"BNP Paribas","detail":"BNP Paribas was one of the lead arrangers for the second-phase construction and term financing.","official_url":"https://group.bnpparibas/en/"} — Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen · confidence: medium
- Commercial parties.5: {"relationship":"Construction and term-financing lead arranger","name":"CoBank","detail":"CoBank was one of the lead arrangers for the second-phase construction and term financing.","official_url":"https://www.cobank.com/"} — Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen · confidence: medium
- Commercial parties.6: {"relationship":"Construction and term-financing lead arranger","name":"ING","detail":"ING was one of the lead arrangers for the second-phase construction and term financing.","official_url":"https://www.ing.com/"} — Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen · confidence: medium
- Commercial parties.7: {"relationship":"Construction and term-financing lead arranger","name":"Nomura Securities","detail":"Nomura Securities was one of the lead arrangers for the second-phase construction and term financing.","official_url":"https://www.nomura.com/"} — Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen · confidence: medium
- Commercial parties.8: {"relationship":"Tax-equity provider","name":"U.S. Bank","detail":"U.S. Bank provided the $403 million tax-equity bridge facility in the second-phase financing package.","official_url":"https://www.usbank.com/"} — Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen · confidence: medium
- Timeline.0: {"event":"Broader-project construction commenced","date":"2020","detail":"Terra-Gen states that construction of the Edwards Sanborn Phase 1A/1B project began in 2020. A separate Sanborn BESS 3 construction-start date was not identified."} — Edwards Sanborn (Edsan) Solar Storage Phase 1A & 1B - Terra-Gen · confidence: medium
- Timeline.1: {"event":"Second-phase project financing closed","date":"2022-09-15","detail":"Terra-Gen announced the close of $959 million in senior secured financing for the second Edwards Sanborn phase, which included battery storage scheduled to be fully operational in the third quarter of 2023."} — Media Room - Page 2 of 3 · confidence: high
- Timeline.2: {"event":"Planned PG&E initial delivery","date":"2023-08","detail":"PG&E procurement materials identified a Terra-Gen Edwards Sanborn Energy Storage resource rated at 169 MW/676 MWh and listed August 2023 as its planned delivery date."} — PG&E plans 1.6GW/6.4GWh battery storage portfolio through 2024 - pv magazine USA · confidence: medium
- Timeline.4: {"event":"Acquisition, sale, predecessor-owner transfer, retirement, or repowering","date":null,"detail":"No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering milestone was identified for the exact Sanborn BESS 3 plant. The documented transaction record identifies project financing, while the separately reported Axium acquisition concerns Edwards Sanborn 1A."} — Axium Infrastructure Invests In Phase 1 Of Edwards... · confidence: medium
- Status detail: Operating battery plant with one 169 MW generating unit. CAISO records identify SANBRN_2_SS2BT3 as SANBORN BESS 3 and show the resource in current 2026 network and telemetry records; a telemetry issue was resolved on February 25, 2026. No unit retirement, mothballing, standby conversion, seasonal-operation date, or repowering event was identified. — Telemetry Exemptions 2026 · confidence: high
- Grid role: Battery storage supporting cleaner, more reliable and resilient power delivery to the CAISO grid. — Edwards & Sanborn Solar + Energy Storage | Mortenson · confidence: medium
- Operating status: operating — Telemetry Exemptions 2026 · confidence: high

## Timeline

- 2020 — Broader-project construction commenced
  Terra-Gen states that construction of the Edwards Sanborn Phase 1A/1B project began in 2020. A separate Sanborn BESS 3 construction-start date was not identified.
  Source: Edwards Sanborn (Edsan) Solar Storage Phase 1A & 1B - Terra-Gen (https://terra-gen.com/edwards-sanborn/)

## Sources

- [Terra-Gen: Home](https://terra-gen.com/) — terra-gen.com · tier other
- [Resource category and phase](https://www.caiso.com/documents/resourcecategoryandphaseallparticipatingresourceids.xlsx) — caiso.com · tier other
- [MBR | Index](https://mbrweb.ferc.gov/SearchlkpEIA/Index?page=716) — mbrweb.ferc.gov · tier regulatory
- [Edwards Sanborn (Edsan) Solar Storage Phase 1A & 1B - Terra-Gen](https://terra-gen.com/edwards-sanborn/) — terra-gen.com · tier other
- [Source](https://sanjosecleanenergy.org/wp-content/uploads/2021/02/Terra-Gen.Edwards.LGIA_.PUBLIC.pdf) — sanjosecleanenergy.org · tier other
- [Edwards & Sanborn Solar + Energy Storage | Mortenson](https://www.mortenson.com/projects/edwards-sanborn-solar-plus-storage) — mortenson.com · tier other
- [HEM](https://power-electronics.com/en/solar/hem) — power-electronics.com · tier other
- [Edwards & Sanborn: US's Largest Solar Storage Project | Coffman Engineers](https://www.coffman.com/news/edwards-sanborn-solar-energy-storage/) — coffman.com · tier other
- [Mortenson Announces Completion of Edwards & Sanborn Solar + Storage Project | Mortenson](https://www.mortenson.com/news-insights/edwards-sanborn-solar-storage-completion) — mortenson.com · tier other
- [California project with world's biggest battery at 3,287MWh online](https://www.energy-storage.news/edwards-sanborn-california-solar-storage-project-world-largest-bess-battery-system-fully-online/) — energy-storage.news · tier other
- [PG&E plans 1.6GW/6.4GWh battery storage portfolio through 2024 - pv magazine USA](https://pv-magazine-usa.com/2022/01/25/pge-plans-1-6gw-6-4gwh-battery-storage-portfolio-through-2024/) — pv-magazine-usa.com · tier other
- [Terra-Gen closes $1billion loans for phase two of Edwards Sanborn](https://www.energy-storage.news/terra-gen-closes-us1-billion-financing-for-second-phase-of-co-located-3-2gwh-battery-storage-in-california-edwards-sanborn/) — energy-storage.news · tier other
- [Terra-Gen Closes Financing for Second Phase of Edwards Sanborn Solar Storage Franchise in California - Terra-Gen](https://terra-gen.com/news-release-1/) — terra-gen.com · tier other
- [Axium Infrastructure Invests In Phase 1 Of Edwards ...](https://terra-gen.com/axium-infrastructure-invests-in-phase-1-of-edwards-sanborn-solar-storage-facility/) — terra-gen.com · tier other
- [Media Room - Page 2 of 3](https://terra-gen.com/media-room/page/2/) — terra-gen.com · tier other
- [JANUARY 11, 2024 - AXIUM INFRASTRUCTURE INVESTS IN PHASE 1B OF THE EDWARDS SANBORN SOLAR STORAGE FACILITY – Axium Infrastructure](https://www.axiuminfra.com/2024/01/12/january-11-2024-axium-infrastructure-invests-in-phase-1b-of-the-edwards-sanborn-solar-storage-facility/?lang=en) — axiuminfra.com · tier other
- [Telemetry Exemptions 2026](https://www.caiso.com/documents/telemetry-exemption-listing-report-2026.pdf) — caiso.com · tier other
- [2026 NQC List](https://www.caiso.com/documents/net-qualifying-capacity-report-for-compliance-year-2026.xlsx) — caiso.com · tier other

## Data quality

- The EIA-based record reports 169 MW, while a FERC index record reports 175.5 MW for the same EIA plant ID; the EIA operational capacity is used here because it identifies the plant’s current generator record. An Axium Infrastructure acquisition of an 80% interest in Edwards Sanborn 1A is documented separately and is not identified as a transaction involving Sanborn BESS 3. No separately disclosed acquisition, sale, predecessor-owner transfer, retirement, or repowering event was identified for the exact asset.

---

Canonical page: https://askthegrid.com/assets/facilities/sanborn-bess-3

Source: Ask the Grid — https://askthegrid.com/