Next time you’re cruising down Interstate-5 and have to take a bathroom break just south of Portland, you might find that the rest stop is powered by a solar array. At least that’s the hope of the Oregon Department of Transportation (ODOT), which received approval from Clackamas County last week for what it said will be a 1.75 megawatt solar array, making it the largest solar highway installation in the world.

Oregon state agencies will soon be required to get all of their energy from renewables under state law, said ODOT spokesperson Shelley Snow. This project and a former solar highway demonstration project will help ODOT meet those goals.

The demonstration project, a 104 kilowatt array located at the interchange of Interstate 5 and Interstate 205, was the first solar highway project in the U.S., according to ODOT. It supplies about one-third of the energy needed for illumination at the site.

The newly proposed solar highway site will produce significantly more power than can be used by the rest area, Snow said. It will also feed excess energy back into the grid. “It allows ODOT to get credit for creating renewable energy,” she said.

The new solar highway site will be built at an existing rest stop, according to Snow. “This rest area’s been there for 30 years. There was a plot of land in back of the area. It had been zoned for farming and was never used. Currently there’s nothing on that piece of land,” she said.

While there are still numerous steps before ODOT can move forward with construction on the solar array, they could start developing the site by the end of 2011. “If everything continues to move forward, we’re looking to build in late 2011 and six months after it’s built we can be online and selling energy into the grid,” Snow said.

When ODOT undertook the first solar highway it ended up using locally produced equipment. “In the end we ended up with an all-Oregon project,” Snow said. The SolarWorld modules were made in Oregon and the array was built by SolarWay, an Oregon-based company. “We’ll be looking for those same kinds of things when we [proceed on this project].…It could be an all-Oregon project again.”

The completed site will include an educational kiosk about the site and about solar energy. “When people are at the safety rest area they can learn about solar energy and how its produced,” Snow said.

Looking forward ODOT will continue to add more solar to its energy supply through its solar highway program. Such steps will include adding 150 kilowatts to the demonstration project site, a 3 megawatt project on I-205 at an ODOT Maintenance storage and developing a project with PacifiCorp near Medford.

Image courtesy of Oregon DOT