78 MW Batteries (39 MW) + Solar Photovoltaic (39 MW) operating in Honolulu, HI
78 MW
Nameplate Capacity
2
Generators
units
Hybrid (2)
Technology
Batteries + Solar Photovoltaic
2022
Operating Since
Coordinates
21.4279, -158.0199
County
Honolulu, HI
Nearby Plants
Owner data does not fully agree across sources.
EIA typically reports the operating utility, while GEM resolves to the financial owner or parent corporation. Both can be correct.
| Field | EIA | GEM | Wikidata |
|---|---|---|---|
| Operator | Mililani I Solar LLC | Clearway Energy Group | — |
| Owner(s) | Mililani I Solar LLC | Clearway Energy | — |
| Status | Operating | operating | — |
Mililani South Solar Farm is a 78 MW hybrid solar and battery storage facility located in Honolulu County, Hawaii. The plant, which began operating in 2022, is owned by Clearway Energy and operated by Mililani I Solar LLC. It ranks as the fourth-largest solar facility in Hawaii out of 20, and 548th nationally out of 1205. The facility utilizes both solar photovoltaic technology with single-axis tracking and battery energy storage.
The plant's battery energy storage system (BESS) has a capacity of 156 MWh and a duration of 4 hours, employing lithium-ion battery chemistry. In its most recent year of operation, Mililani South Solar Farm generated 62,582 MWh of electricity, achieving a capacity factor of 9.2%. Financial data is available for the plant, sourced from LBNL Solar. The plant's primary fuel is listed as "MWH" in the provided data.
Generated from EIA, GEM, and public data sources
NERC Region
—
Balancing Authority
—
Grid Voltage
138 kV
Regulatory Status
NR
Entity Type
Independent Power Producer
Sector
IPP Non-CHP
3.2K MWh
Net Discharge
62.6K MWh
Annual Net Energy
9.2%
Capacity Factor
Positive values indicate net discharge (generation exceeds station load). Negative values indicate net charging. Pure battery storage plants are typically net negative due to round-trip efficiency losses.
$172.0/MWh
Energy Value
This plant is outside organized wholesale electricity markets (ISOs/RTOs). Nodal pricing data is not available.
Flash Flood Warning: Oahu in Honolulu, HI
Flash Flood Warning issued March 21 at 8:40AM HST until March 21 at 11:00AM HST by NWS Honolulu HI
Flood Watch: Waianae Coast; Oahu North Shore; Olomana; Central Oahu; Waianae Mountains; Lanai Mauka; Kahoolawe; M
Flood Watch issued March 21 at 3:53AM HST until March 22 at 6:00PM HST by NWS Honolulu HI
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Last updated 2026-03-21
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