Solar Roads Being Implemented in the U.S.

A new solar roadway the Federal Highway Administration is testing that could provide power for everything from traffic signs to heaters.

📅 Mon September 29, 2014 - National Edition
Lori Tobias - CEG CORRESPONDENT


The demonstration project's completed foundation. Next step, erecting the solar array.
The demonstration project's completed foundation. Next step, erecting the solar array.

There’s been much talk lately about a new solar roadway the Federal Highway Administration is testing that could provide power for everything from traffic signs to heaters – even sensors warning drivers of animals on the roads. If the concept dreamed up by an Idaho couple to put solar panels directly onto the roadway pans out, it could change the world of transportation dramatically.

But meanwhile in Oregon — albeit not quite so dramatic — the Department of Transportation is making good use of the solar technology already existing. ODOT has already built two solar stations and is looking into a third. And ODOT is doing it without state money and on property — highway right-of-way — already owned by the state and cleared for development.

The idea for the solar stations came to Allison Hamilton, manager of the ODOT Solar Highway Program, after she saw a PBS program on the solar panels along the Autobahn in Germany.

“I thought if they can do that in Europe, why can’t we do that at ODOT?” said Hamilton. “Everything just fell into place.” Her bosses gave her the go-ahead to develop the concept and figure out what it would take.

“But I couldn’t use ODOT money,” she said. “This fell under that umbrella of public/private partnerships.”

She was able, however, to hire a consultant, whose partner, as it turned out, was a former vice president at Portland General Electric. Between the two of them, they knew just about everything there was to know about the utility business. And it didn’t hurt that the site was shovel ready.

“That’s not any extra work on our part because this is on public right of way,” Hamilton said. “All the inspections required before you the put project in place were already done as part of the transportation improvement process. We are able to offer it up in risk-free condition to a developer. That means a lot.”

PGE signed on as the partner with ODOT and on December 19, 2008, just one year after Hamilton conceived the idea, the solar station at the interchange of I-5 and I-205 became the first solar highway project not only in the U.S. but in all of the Americas.

The 104 kilowatt DC ground-mounted solar array features 594 solar panels and offsets more than one-third of the energy needed to light the freeway at that site.

Four years later, ODOT and PGE debuted a second solar station, this one ten times the size of the first, at the French Prairie Safety Rest Area (formerly the Baldock Rest Area) on I-5 just south of Wilsonville.

Known as the Baldock Solar Station, the project features 7,000 solar panels set on seven acres behind the main rest area.

“We learned a lot after doing the pilot project,” said Mark Osborn, who was the smart grid manager of PGE when the two projects were built and is now senior vice-president with consulting firm Five Stars International, Ltd. “We used recycled steel on that one and that structure was very solid, but heavy and kind of expensive. For the Baldock, project, we went with a locally extruded aluminum. It made it a beautiful installation and it was a lot less expensive and it was easier to install. It really helped to have that speed of the installation in there.”

The solar station functions like a regular power plant feeding into the grid, he said. “The solar panels, which are DC power, are grouped together in strings so that they make a nice transition into the 480 volt inverter. The inverter converts the DC power from the solar panels into AC power at 480 volts. That all feeds into a single set of switch gear that is connected to the transformer. The transformer will step up the voltage from 480 volts to 13,000 volts. The power that flows from the solar array into the inverter goes into the transformer and into the PGE system.”

The stations produce not only green power, but Renewable Energy Certificates (RECs), which according to the EPA, “… represents the property rights to the environmental, social, and other nonpower qualities of renewable electricity generation. A REC, and its associated attributes and benefits, can be sold separately from the underlying physical electricity associated with a renewable-based generation source.”

ODOT gets some of the RECs, with the rest going to PGE and the Energy Trust of Oregon. ODOT also gets a small site fee.

“As solar costs continue to drop we’ll be able to charge more and still have sites feasible,” Hamilton said. “We also no longer have to maintain that piece of land. That now becomes the utility’s responsibility. It takes expenses off our back.”

The Baldock Solar Station is an all-Oregon project, with state vendors designing and constructing the station. Panels were built by an Oregon designer and even the master gardeners who landscaped the project were Oregonians.

Up next is a third station still in negotiation.

“We’re hoping to partner with PGE again, but they cannot commit at this time,” Hamilton said. “So we’re talking with some private entities. The Oregon Military Department located at Camp Withycomb in rural Clackamas County is very interested in powering their facility with 100 percent green energy. They don’t know how they might partner on the project, but they are interested and investigating internally. They want to become zero net energy. Everything is still probably a year out.”