August 11, 2022

Clearway Completes O‘ahu’s First Utility-Scale Solar + Storage Power Plant  

Utility-scale solar and storage plant in Mililani Agricultural Park  advances Hawaii’s 100% clean energy goal  

Mililani, Hawai‘i — Clearway Energy Group (Clearway), a national independent power producer and leading solar energy developer in Hawai’i, announced today that it completed construction and reached commercial operations at its Mililani Solar I plant. This is Clearway’s fourth solar plant on O’ahu and the island’s first utility-scale solar and battery storage power plant, which is designed to provide clean energy to the grid even after the sun sets and further advance the state’s goal of 100% renewable energy by 2045.  
The 39-megawatt (MW) Mililani Solar power plant is paired with a 156 MWh battery storage system and includes over 123,000 photovoltaic panels, each measuring 6.5-feet tall and slightly more than three feet wide. The panels are capable of shifting angles throughout the day to maximize generation. The solar power plant, located on 131 acres in Mililani Agricultural Park, will enhance grid reliability and provide grid services at a critical time with the decommissioning of the state’s last coal plant in September.    
“Renewable energy is critical to Hawai‘i to be more affordable and resilient,” said Governor David Ige. “We are a step closer to that goal today because of the Clearway team, which understood the urgency and stepped up to deliver their project ahead of schedule.”

“Hawai’i has long led the nation in the transition to reliable carbon-free power. Today’s celebration of O‘ahu’s first major solar and energy storage plant is evidence that that ambition is well within reach,” said Craig Cornelius, CEO of Clearway. “We’re proud to help Hawai’i achieve its clean energy goals and we are grateful to Hawaiian Electric, whose partnership has been critical in reaching this important milestone.” 

Photo of Mililani Solar I courtesy of Wärtsilä

“Projects like this one help our customers by providing electricity to the grid at one-third the cost of oil and help Hawaiʻi by moving us on the path to a decarbonized energy system,” said Shelee Kimura, president and CEO of Hawaiian Electric. “Working with experienced energy developers like Clearway, we will be bringing eight additional projects online over the next two years on Oʻahu, providing even greater benefits to our communities.” 

The $140 million project broke ground in April 2021 and installation of the panels and battery storage was completed ahead of schedule. Mililani Solar and Clearway’s second solar and storage plant under construction in Waiawa are together expected to contribute $9 million in taxes to the City and County of Honolulu. More than 240 local union jobs were created during construction of both plants and a permanent workforce will support ongoing operations and maintenance.

“Wärtsilä is proud to be leading the clean energy economy in Hawaii and addressing climate change in partnership with Clearway Energy Group and Hawaiian Electric. Power system optimization technology and flexibility solutions such as energy storage play a key role in balancing the state’s renewable energy power systems and ensuring power reliability for island residents,” said Håkan Agnevall, president and CEO, Wärtsilä.  

Clearway has developed and operated renewable power plants in Hawai‘i for the past four years. In 2019, the company completed the construction and commissioning of three utility-scale solar facilities: a 45.9 MW site in Waipi‘o, a 14.7 MW in Mililani, and a 49 MW site in Kawailoa on O‘ahu’s North Shore.  
Construction of Clearway’s second solar and battery storage plant in Waiawa, being built on Kamehameha Schools land, is expected to be complete later this year. Altogether, Clearway’s five solar power plants totaling 185 MW will serve Hawaiian Electric’s grid and generate enough clean electricity to power more than 45,500 O‘ahu homes each year. 
Project construction was led by Moss and the batteries were supplied by Wärtsilä. 

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About Clearway Energy Group
Clearway Energy Group is leading the transition to a world powered by clean energy. Along with our public affiliate Clearway Energy, Inc., we own and operate more than 8 gigawatts of renewable and conventional energy assets across the country. As we develop a nationwide pipeline of new renewable energy projects for the future, Clearway’s 6.9 gigawatts of operating wind, solar, and energy storage assets offset the equivalent of more than 10.5 million metric tons of carbon emissions for our customers today. Clearway Energy Group is headquartered in San Francisco with offices in Carlsbad, Calif.; Scottsdale, Ariz.; Houston; and Princeton, N.J. For more information, visit

About Hawaiian Electric

Since 1891, Hawaiian Electric has powered the islands’ development from a Hawaiian kingdom to a modern American state. Hawaiian Electric and its subsidiaries, Maui Electric and Hawaii Electric Light, serve the islands of O‘ahu, Maui, Lāna‘i, Moloka‘i, and Hawai‘i. In a changing world, Hawaiian Electric is adding renewable energy and developing energy solutions for customers to achieve a clean energy future for Hawai‘i. 

About Moss
Moss is a national privately held construction firm providing innovative solutions resulting in award-winning projects. With regional offices across the United States, Moss focuses on construction management, solar EPC, design-build, and public-private partnerships. The company’s diverse portfolio encompasses a wide range of sectors, including luxury high-rise residential, landmark mixed-use developments, hospitality, K-12 and higher education, justice, solar energy and battery storage, and sports. Moss is ranked by Engineering News-Record as one of the nation’s top 65 general contractors, and the 3rd ranked solar EPC nationwide. Moss prides itself on a strong entrepreneurial culture that honors safety, quality, client engagement and employee development. Its employees consistently rank Moss as one of the best places to work.