Kamehameha Schools wants to use land in Waiawa — long ago approved for development of 7,900 homes — for what would be the biggest solar farm in the state by a long shot, with the capacity to power 22,540 homes.

The trust has arranged for Missouri-based solar industry firm SunEdison Inc. to develop a 115-megawatt facility in two phases on 577 acres that cover much of the site previously intended to become the master-planned Waiawa Ridge community between Pearl City and Waipio.

At 115 megawatts, the project would be nearly 10 times bigger than Hawaii’s largest existing utility-scale photovoltaic power plant — a 12-megawatt facility on Kauai that began operating in July.

"It’s huge,"Jeff Mikulina, CEOof Blue Planet Foundation, said of the Waiawa project.

Mikulina said 115 megawatts represents one-third of all solar power in the state today, and half of all utility-scale renewable energy production proposed for the next two years.

"That’s really exciting,"he said."It makes a lot of sense for Hawaii."

Kamehameha Schools said the solar farm would save Oahu ratepayers $333 million over the envisioned 20- to 25-year life of the project.

The trust, which is the largest private landowner in Hawaii, detailed its plan in a request to the stateLand Use Commission seeking approval for the project on two pieces of a 1,395-acre parcel that represented an initial phase of Waiawa Ridge.

Five years ago, Kamehameha Schools terminated an agreement for local development firm Gentry Cos. to build the residential community after more than 20 years of planning and faulty starts.

Solar power production would be a long-term yet interim use of the site, providing Kamehameha Schools with income to benefit its mission of educating Native Hawaiian children as it re-examines the Waiawa Ridge plan and evaluates other development opportunities for the property, the trust said.

"KS is re-evaluating the Waiawa development that was planned by Gentry,"the trust said in its LUCrequest. "However, mindful of its obligations to its beneficiaries, KSmust always seek to maximize a financial return on the KS property."

Kamehameha Schools did not have an estimated development cost for the project. The 12-megawatt Kauai solar farm cost $40 million.

Mikulina said larger projects benefit from an economy of scale, and that the Waiawa land with a slope to the south is well suited for solar power.

The Waiawa land was once part of a vast area of Central Oahu dedicated to growing sugar cane. Gentry arranged in 1987 to buy about 3,700 acres in the area from the trust, and advanced plans for the community that included up to 12,000 homes, two golf courses, parks, a commercial center and two schools.

Gentry obtained LUCapproval to reclassify an initial 1,395 acres from agricultural to urban use in 1988. The city also approved zoning changes to allow the project. But issues including market timing and financing prevented development from starting.

In 2006 Gentry partnered with local development firm Alexander & Baldwin Inc. to start an initial phase with 5,000 homes, one golf course and parks. Construction was projected to start in 2009. But financing fell apart amid the splintering of financial markets in 2008, and the trust reclaimed control of the property in 2009.

In 2011 Kamehameha Schools solicited proposals for a solar farm on the site and selected SunEdison.

Kamehameha Schools said the project will have a low impact on the land, which has not been farmed since 1983. The panels would not produce glare and otherwise would have little effect on views from surrounding areas, the trust said.

A substation and battery storage facility is proposed close to the western side of the property about 1,000 feet from the H-2 freeway. It would connect to an existing transmission line.

Utility-scale solar power plants are an allowed use on urban land, so the LUCpetition is not expected to be contentious.

The state Office of Planning recommends approving the plan.

Apublic hearing is scheduled for Wednesday in the commission’s meeting room at 235 S. Beretania St. at 9:30 a.m., and the following day if necessary.

Approvals for the project from Hawaiian Electric Co. and the state Public Utilities Commission are pending.

If approvals are obtained, Kamehameha Schools projects that SunEdison can break ground on a 50-megawatt first phase by June 2015 and be generating power by June 2016.

Kamehameha Schools said the solar farm would be removed after about 30 years.

During the period of power production, the trust said it may seek to develop other pieces of the property, perhaps at the southern end that is less than a mile from two planned rail stations near Pearl Highlands and Leeward Community College.

"In light of the proximity of the transit stations, it may ultimately be more desirable for initial development within the KSproperty to be located in the southern portion of the KSproperty rather than the northern portion, as originally proposed by Gentry,"the trust said in its request.

The trust said it envisions strong demand for homes in the area over the long term even with 5,000 homes planned at Koa Ridge, part of which is adjacent to the Waiawa Ridge site, and 11,750 homes at Ho’opili on the Ewa Plain.

"Even with the complete buildout of all planned and entitled projects, there is expected to be a shortfall of some 30,000 housing units by 2030,"the trust said. "As such, it appears that the demand for the 7,906 homes planned for the KSproperty will continue to be strong well into the future."