Hawaii Clean Energy Guide

Hawaii is the most unusual clean-energy market in the country: six islanded grids with no RTO or ISO, the highest retail electricity prices in the United States, and — historically — the most petroleum-dependent power system in the nation. It was also the first state to legislate a 100% renewable portfolio standard. This guide covers how those extremes shape a transition that runs less on giant projects than on island-scale solar-plus-storage and the highest rooftop-solar penetration in the country.

The Oil-and-Islands Problem That Drives Everything

To understand Hawaii's clean-energy market you have to start with the structural facts, not the ambition. Petroleum is still the primary energy source for electricity here — Hawaii is the most oil-dependent state in the country for power generation. Total net generation was about 9.16 TWh in 2024, ranking Hawaii 47th nationally in generation and 46th in net summer capacity (3,369 MW). Burning imported oil on six separate grids with no economies of scale produces the inevitable result: an average retail price of about 38 cents/kWh in 2024, the highest in the United States.

That price is the engine behind everything else. When power costs two to three times the mainland average, rooftop solar pays for itself fast, and Hawaiians have adopted it at a rate no other state approaches — roughly 45% of single-family homes now have panels, across 120,570 rooftop systems as of 2025. The clean-energy story in Hawaii is therefore inverted from the mainland: distributed solar leads, and utility-scale capacity, while growing, remains modest by continental standards.

First-in-the-Nation Mandate, Real-World Constraints

Hawaii legislated the country's first binding 100% Renewable Portfolio Standard. The framework began with S.B. 2474 in 2004 (20% by 2020) and was rewritten by H.B. 623 in 2015 (Act 97), which set the goal that made Hawaii famous: 100% of net electricity sales from renewables by December 31, 2045, with interim milestones of 40% by 2030 and 70% by 2040. A 2022 revision changed how private rooftop solar is counted, shifting the RPS to a percent-of-net-generation basis.

The trajectory is real but the back half is hard. In 2025, Hawaiian Electric hit a consolidated RPS of 37% (3,928 GWh, or 36.8% of net generation) — its highest ever and up a point from 35.8% in 2024, with solar alone supplying more than 22% of generation. That puts the 40%-by-2030 milestone within reach. Hawaii's own 2022 independent evaluation (HNEI), however, judged both utilities likely to meet 2030 while flagging genuine concern about the 70% (2040) and 100% (2045) mandates. Governor's Executive Order 25-01 (January 2025) pushes harder still, targeting 100% renewable a decade early — by 2035 — for neighbor-island communities and 50,000 distributed renewable installations statewide by 2030.

Rooftop Rules and the End of Net Metering

Hawaii was one of the first states to end traditional net energy metering, closing it to new applicants back in 2015 as rooftop penetration overwhelmed the old compensation model. New solar customers now use successor tariffs — Customer Grid Supply Plus, Smart Export (for solar-plus-storage), and Battery Bonus grid-service programs. The 2025 session added muscle: SB 589 directs the PUC to set a goal of 50,000 new customer-sited DER installs before 2031 and to provide fair compensation, up to full retail rate, for exported solar-plus-storage energy under grid-service programs. It passed unanimously.

Incentives Tilted Toward Storage

• State solar tax credit (RETITC): The Renewable Energy Technologies Income Tax Credit (HRS §235-12.5) covers up to 35% of a solar PV or thermal system's cost, capped at $5,000 per residential PV system, with no expiration date.
• Battery retrofit expansion: HB 513 (2025) expands the RETITC so owners of existing solar systems can claim a 35% credit — up to $500,000 per system — when retrofitting with battery storage after December 31, 2025.
• Grid-service programs: Battery Bonus and Smart Export reward customers for pairing solar with storage and exporting during evening peak, when the islanded grids need it most.

The Projects Carrying the Transition

Because each island is its own grid, the utility-scale buildout is a portfolio of relatively small solar-plus-storage plants plus a handful of firm resources — not a few giant farms. The flagships tell the story:

• Kuihelani Solar-plus-Storage (Central Maui): 60 MW solar + 240 MWh battery from AES Hawaii — Hawaii's largest solar facility. Online since June 2024 under a 25-year PPA with Hawaiian Electric at 8 cents/kWh, the lowest renewable cost in the state; it supplies roughly 15% of Maui's energy, about 27,000 homes.
• Kapolei Energy Storage (Oahu): 185 MW / 565 MWh standalone battery from Plus Power, built with 158 Tesla Megapack 2 XL units. Online December 2023, it is Oahu's largest storage project and replaced firming capacity from a retired AES coal plant.
• Puna Geothermal Venture (Big Island): Ormat's roughly 41 MW plant is the state's only geothermal facility and its rare source of firm, non-intermittent baseload. A 46 MW PPA landed in February 2024, and a repower to swap 12 units for 3 more-efficient ones drew a Department of Health permit hearing in December 2025.
• Hoohana Solar 1 (Oahu): 52 MW solar + 208 MWh battery, online July 2025.
• Waiawa Phase 2 (Oahu): 30 MW solar + 240 MWh battery, online November 2025.
• Kawailoa Wind (Oahu, North Shore): 69 MW across 30 turbines — Hawaii's largest wind farm, operating since around 2012.

Statewide, wind is a modest complement at roughly 233 to 236 MW across about 132 turbines, with no major new wind in construction. Utility-scale battery storage totals about 517 MW across 16 projects, two of them built in 2025 — batteries are the connective tissue that lets intermittent solar serve evening peak on grids with no backup.

Siting and Local Opposition

Getting a project built in Hawaii means clearing an unusually layered process. Utility-scale projects reach the grid through competitive RFPs run by Hawaiian Electric and approved by the Hawaii Public Utilities Commission, which signs off on both the RFP and the individual 20-to-30-year PPAs. Land use, zoning, and building permits are handled at the county level, on top of State Land Use Commission classification, State Historic Preservation Division archaeological review, and Chapter 343 environmental review. The governing statutes — HRS Chapter 269 (PUC authority), Chapter 343 (environmental review), and Chapter 205 (State Land Use Law) — combine into a permitting path widely described as long and complex, and openly recognized as a barrier to hitting 2045.

Opposition here is real but targeted, and it is concentrated on wind and geothermal far more than solar — usually framed around Native Hawaiian cultural and land rights, health, viewshed, and safety rather than blanket zoning bans. The defining episode is the Na Pua Makani wind farm in Kahuku, Oahu: in fall 2019 opponents organized as Ku Kia'i Kahuku repeatedly blocked convoys hauling turbine components, and police arrested more than 127 people between October 17 and late October — including 55 in a single October 18 operation. A central grievance was turbine proximity, with the nearest turbines sited about 1,648 feet from homes and roughly 1,750 feet from a school. The 8-turbine, roughly 24-to-27 MW project was finished and began operating in 2020. Geothermal carries its own decades-long friction on cultural (Pele) and safety grounds; Puna Geothermal was shut down by the 2018 Kilauea eruption, and its restart and expansion continue to draw testimony, most recently at that December 2025 permit hearing in Pahoa.

The nuance worth keeping: unlike some mainland states, Hawaii has no widespread county-level moratorium or outright ban on utility-scale renewables. Opposition is project-specific, and solar's main friction is competition with agricultural and culturally significant land rather than organized mass protest. For the live picture of contested projects, see our Hawaii opposition tracker.

Demand, Planning, and What Comes Next

Demand is finally moving after years of flatness. Electricity use rose 2.5% in 2025, the fastest growth in more than 20 years, which Hawaiian Electric attributes to warmer weather and continued economic recovery since the 2023 Maui windstorm and Lahaina wildfire. Notably — and unlike the mainland narrative — data centers are not cited by the utility as a primary current driver; there is no Hawaii-specific data-center load figure to point to. The growth is broad-based, not hyperscale-led.

The planning vehicle to watch is Hawaiian Electric's Integrated Grid Planning process, now entering its second cycle (2026-2030), which maps the resource pathway to 100% renewable — large amounts of new solar-plus-storage plus firm, dispatchable capacity. The uncomfortable counterpoint is cost on the fossil side: the Hawaii State Energy Office estimates roughly $2 billion is needed just to upgrade the state's thermal generation infrastructure during the transition, a reminder that firm capacity remains a near-term necessity even as renewables climb. On the distributed side, EO 25-01 and SB 589 keep pushing the 50,000-DER target that sustains rooftop solar-plus-storage demand.

Frequently Asked Questions

The Bottom Line

Hawaii is not a mainland-style utility-scale market, and pretending otherwise misreads it. Its edge is structural desperation turned into policy leadership: the highest power prices in the country and the most oil-dependent grid made the first 100% RPS both necessary and popular, and made rooftop solar-plus-storage the default rather than a niche. Hawaiian Electric's 37% in 2025 and a comfortable line of sight to 40% by 2030 show the near term is on track. The open question is the back half — the 70% and 100% mandates that the state's own evaluators flagged, on six small grids where every megawatt of firm capacity, every permit, and every culturally sensitive parcel is contested individually. For utility-scale developers, the opportunity is real but bounded: think island-sized solar-plus-storage and firm resources, not the sprawling projects that define Texas or the Midwest.