# Elliott Energy Storage

CAISO asset profile · https://askthegrid.com/assets/facilities/elliott-energy-storage

## Current generation inventory

EIA plant 66278 · Inventory reporting month: 2026-08.

- batteries: 10 MW operating nameplate
- Capacity basis: operating_generator_nameplate_mw
- Source inventory: [EIA-860M workbook (preliminary)](https://www.eia.gov/electricity/data/eia860m/xls/august_generator2026.xlsx)
- Inventory retrieved: 2026-10-10T22:49:53.020309+00:00
- Filed coordinate (longitude, latitude): -117.0889, 32.81638
- OSM extract: 2026-10-09T20:21:04Z
- OSM mapped edit: 2026-01-05 14:44:54+00:00
- Map prepared: 2026-10-10T23:05:21.219412+00:00

Battery power (MW) and stored energy (MWh) are separate measures. Shared physical-site membership does not establish electrical connectivity, settlement or a common export limit.

## Reviewed overview

Elliott Energy Storage is SDG&E’s battery microgrid at Elliott Substation in Tierrasanta, San Diego. EIA’s August 2026 inventory lists 10 MW / 10 MWh and operating month March 2024. Separately, SDG&E’s August 2024 financing report describes a 10 MW / 40 MWh microgrid completed that March. The original procurement specified 50.5 MWh at beginning of life, including a microgrid reserve; these are distinct source-specific ratings.

## Profile

- **SDG&E role:** Utility owner and operator of the battery plant.

## Reviewed metrics

- **EIA nameplate power / energy:** 10 MW / 10 MWh — August 2026 preliminary generator inventory; current operating generators only.
- **Utility project rating:** 10 MW / 40 MWh — SDG&E August 2024 financing report; separate from the later EIA inventory energy value.
- **Nameplate capacity:** 10 MW — Canonical EIA plant baseline.
- **Registry anchor:** Plant 66278 — plant-66278

## Facts

- **Technology:** Batteries
- **Operator:** San Diego Gas & Electric Company (SDG&E)
- **Operating status:** Operating

## Related parties

- **Owner / operator:** San Diego Gas & Electric Company (SDG&E) — Project owner and operator ([source](https://www.sdge.com/))
- **O&M provider / equipment supplier:** Mitsubishi Power America, Inc. — Equipment supplier and long-term services provider; Emerald storage solutions ([source](https://power.mhi.com/regions/amer/news/20220811.html))
- **Construction contractor:** Morrow Meadows Corporation — Balance-of-plant contractor ([source](https://www.morrow-meadows.com/))
- **Parent company:** Sempra — Parent company of SDG&E; not identified as a project contractor ([source](https://www.sempra.com/))

## Sources

- [docs.cpuc.ca.gov](https://docs.cpuc.ca.gov/PublishedDocs/Published/G000/M490/K125/490125839.PDF) — docs.cpuc.ca.gov · authoritative — Source retained for exact-record publication review.
- [docs.cpuc.ca.gov](https://docs.cpuc.ca.gov/PublishedDocs/Published/G000/M496/K335/496335922.pdf) — docs.cpuc.ca.gov · authoritative — Source retained for exact-record publication review.
- [mbrweb.ferc.gov](https://mbrweb.ferc.gov/SearchlkpEIA/Index?page=757) — mbrweb.ferc.gov · authoritative — Source retained for exact-record publication review.
- [power.mhi.com](https://power.mhi.com/regions/amer/news/20220811.html) — power.mhi.com · public_source — Source retained for exact-record publication review.
- [sdge.com](https://www.sdge.com/sites/default/files/SDGE%20WDAT%20Generation%20Interconnection%20Queue%202-6-2026.pdf) — sdge.com · public_source — Source retained for exact-record publication review.

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Canonical page: https://askthegrid.com/assets/facilities/elliott-energy-storage
Website: [San Diego Gas & Electric Company (SDG&E)](https://www.sdge.com/)

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