Umatilla Electric Cooperative has tapped a different energy source: the sun.

An electrical inspector conducted his final walk-through Monday of Umatilla Electric Cooperative’s new 330-panel solar array. It’s just east of its headquarters, 750 W. Elm Avenue.

The collection of 175-watt solar panels will provide up to 57.8 kilowatts. That’s enough to provide nearly half of the power needed to operate Umatilla Electric’s east wing headquarters building.

Steve Eldrige, general manager and CEO, said a contractor began installing the solar panels in late August and completed the project in early December.

The grid-tie solar electric system includes two major components. Most visible are the 330 solar panels, which Tanner Creek Energy of Portland installed so the shadow from the front row will not fall on the lowest panels of the back row, even in winter.

Mounted behind each row of panels is a 30-kilowatt inverter. They change the direct current the solar panels produce into alternating current so it can be used on the grid and in the building.

Alan Hickenbottom, founder and president of Tanner Creek Energy, said several other Northwest utilities are producing power with solar arrays, but most of them are municipal utilities.

“As far as Oregon’s co-ops this might be the first,” he said. “We’ve been very pleased to work with them. It’s been a terrific partnership.”

Because it’s a grid-tie system and the headquarters building remains attached to the grid, there are no storage batteries, such as in off-grid systems.

Eldrige estimates the project’s cost at less than $200,000.

“We think we’ll be able to cover about 65 percent of the cost with the (state) Business Energy Tax Credit and federal tax incentives,” he said.

Cooperative managers expect the solar array to have a 30- to 40-year lifespan. The solar panels are warranted for 25 years and the inverters for 20.

And once Eldrige and the co-op’s board of directors determine the outcome of the installation, they might decide to erect more solar panels on the lot bordered by Elm Avenue and First Place.

Just as with any experiment, the solar energy project is intended to be a learning experience for co-op managers.

“We’re trying to educate ourselves and formulate a renewable package for our members,” he said.