Construction began last Friday on a 15 MW solar farm on the eastern slopes of the Cascade Mountains in central Washington, the third utility-scale project in a state on the verge of a solar boom.

Gov. Jay Inslee greenlit the $25 million Columbia Solar project in 2018, but the developer, Seattle-based TUUSSO Energy, has taken nearly three years to begin building the solar farm, which will spread across three 5-megawatt sites in the Kittitas Valley.

The valley is one of the sunniest areas in the state, the Washington Energy Facility Site Evaluation Council (EFSEC) said.

TUUSSO has begun work on a 5-megawatt site near Ellensburg and will follow up in a few weeks with two similar sites in the same vicinity. All the land is agricultural or pastureland.

The three sites will be completed by the end of the year or early 2022, TUUSSO CEO Owen Hurd told NetZero Insider. TUUSSO will also operate the sites, which will deliver power to Puget Sound Energy.

Founded in 2008, TUUSSO Energy has developed five solar farms totaling 145 MW in California, Arizona, Georgia and Maryland

On June 15, the EFSEC approved the Initial Site Restoration Plan for the project. That plan requires the developer to return the sites to their original conditions if and when the solar panel farms are closed and removed.

In 2017, TUUSSO Energy applied for a site certification agreement from EFSEC to build and operate the facility. EFSEC determined the project would have limited impacts on the environment with mitigation measures. Gov. Inslee, based on EFSEC’s recommendation, approved construction in October 2018.

However, EFSEC withdrew that approval because TUUSSO had not paid all of the permitting fees due to the state. EFSEC reviewed its permission in November 2019 when TUUSSO paid what it owed the state plus an extra $50,000 — an amount totaling $273,378. At that time, construction was supposed to begin in early 2020.

The project was originally designed to consist of five 5 MW solar farms scattered around Ellensburg. But power lines in the area did not have the capacity to handle more than 15 extra megawatts, so the five sites were trimmed to three, Hurd said.

The project was supposed to be finished in 2018, but was then delayed to 2020 because of financing problems, Hurd said, declining to elaborate. Those same financing problems led to TUUSSO owing more than $200,000 in permitting fees to EFSEC.

“We’re very excited to get this built out,” Hurd said.

More than 20 solar projects have been proposed for Washington, nearly all of which would be located east of the Cascades.