Mililani South Solar Farm

OperatingBESSSolarHybrid

Ranked #4 of 14 BESS plants in HI#360 of 837 nationally

78 MW Batteries (39 MW) + Solar Photovoltaic (39 MW) operating in Honolulu, HI

EIAGEMWD

78 MW

Nameplate Capacity

Generators

units

Hybrid (2)

Technology

Batteries + Solar Photovoltaic

2022

Operating Since

Location

Coordinates

21.4279, -158.0199

County

Honolulu, HI

Nearby Plants

Lanikuhana Solar LLC
Solar14.7 MW · 0.4 km
Ho'Ohana Solar 1
BESS104 MW · 1.7 km
AES Waiawa Phase 2 Solar
BESS60 MW · 4.4 km

Ownership & Operator

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	—

Ownership Chain

About

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

EIA Plant Profile Wikidata Global Energy Monitor

Engineering & Generators

Grid Context

NERC Region

—

Balancing Authority

—

Grid Voltage

138 kV

Regulatory Status

Entity Type

Independent Power Producer

Sector

IPP Non-CHP

Generation

3.2K MWh

Net Discharge

62.6K MWh

Annual Net Energy

9.2%

Capacity Factor

Jan 2023 – Dec 2025

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.

Financial DataBeta

Source: LBNL Utility-Scale SolarHIGH

$172.0/MWh

Energy Value

Pricing & Market Data

This plant is outside organized wholesale electricity markets (ISOs/RTOs). Nodal pricing data is not available.

News & Articles (10)Beta

Hazards·flooding

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

Flash Flood Warning (hazard)

NWS Honolulu HI·5 days ago