The $19 million, 1.2-megawatt La Ola Solar Farm is expected to supply up to 30 percent of Lanai's electricity.
Maui Electric Co. plans to buy the farm's power and transmit it to Lanai homes through its electric power grid. It's part of a Castle & Cooke plan to powered the island entirely with renewable energy by 2020.
Gov. Linda Lingle and Maui Mayor Charmaine Tavares attended a blessing ceremony for the farm.
Castle & Cooke Chairman and Chief Executive David Murdock stressed the need for the state to ease its dependence on imported oil. Hawaii spends $7 billion a year on foreign oil.
Castle & Cooke owns 98 percent of Lanai and employs 85 percent of its nearly 3,200 residents.
The array of 7,400 tilting photovoltaic panels now cuts across 10 acres of the former agricultural land.
The company hired 24 workers from Keo Construction and Hawaii Island Diggers to build the farm starting in November 2007.
Completion was delayed by eight months to work out permitting problems with the land's agricultural designation, which prohibited the construction of a solar farm.
The farm was built with panels from California-based SunPower Corp. It currently produces up to 500 kilowatts of energy, and is expected to produce up to 1.2 megawatts upon completion by June.
That will be enough to provide up to 30 percent of the island's daily peak electrical needs, which occurs between 5:30 p.m. and 7:30 p.m.
"This is state-of-the-art in the world," said Harry Saunders, president of Castle & Cooke. The panels can be remotely controlled by Maui Electric and tilt with the sun for 25 percent more efficiency than if they were fixed.
Lanai is also the site of a proposed wind farm that would transfer up to 400 megawatts of wind power via underwater cable to Oahu.
Ed Reinhardt, president of Maui Electric, said he was unsure how much relief the solar farm will provide Lanai residents, who currently pay the highest electric rates in the state.
Retired airport maintenance worker Ron McOmber, who attended the blessing and has voiced concerns about other Castle & Cooke projects in his 30 years on Lanai, said he pays more than $300 a month to power his single-family home.
"It doesn't make me feel any better unless I see it financially," he said.