Sometimes big ideas come from unexpected places. A proposal to power the entire United States with solar energy, without wires or solar farms, by using solar cells to pave roads and parking lots, is certainly a big idea. It comes from the Idaho couple, Scott and Julie Brusaw, yet it’s promising enough to have received finding from the U.S. Federal Highway Administration.

The Brusaws began by simply wanting to create a grid that would make electric vehicles, but quickly began to see other uses for the hexagonal paving squares. Their company, Solar Roadways, will see its FHA contract expire in July and they’re looking for another $1 million in funding on Indiegogo to manufacture the product commercially.

Even when roads are congested and parking lots are full, there’s still enough exposed pavement to produce energy.

In the latest prototype, a tempered glass shell allows light to hit solar panels inside a hexagonal tire-sized panel. But, withstanding up to 250,000 pounds, the glass protects the panels and, beneath them, a circuit board. Multicolored LED lights allow transportation authorities to display various traffic lines or text.

The glass is textured with additional hexagonal bumps that provide more traction than asphalt. They also help the solar pavers perform their core functions.

“Those little hexagons have six sides and they’re angled at a 45-degree angle, so it becomes a prism. No matter where the sun is in the sky, it bends that light down on the solar cells. And our LEDs are underneath those hexagons, so the LED lights emanate out six different directions so you can’t miss them,” said Scott, an electrical engineer, in a Solve for X talk.

As shown off in a demonstration parking lot (above), a trough would run alongside the pavement, housing cables that send back the energy generated by the panels and any data. The empty demonstration lot, located in chilly Northern Idaho, manages to pump out 3,600 watts.

Alongside the trough for wires is a separate trough that collects storm water, a major source of water pollution, and purifies it and/or transports it to a water treatment facility. This water technology appears to be very much in the idea phase, though.

As for charging those EVs, that can be done through wireless induction or through a charging station at the side of the solar road.

The Brusaws have seen more and more uses for the solar roadways as they’ve pushed forward after first receiving FHA funding in 2009. The tiles wouldn’t just juice vehicles; they could supply the entire nation with electricity even though the solar technology in the latest prototype is just 18 percent effective. There are, after all, 31,251 square miles of roads and sidewalks to work with.

The panels would also make transportation authorities’ jobs easier in a couple of ways. The LED lights would make re-painting a thing of the past. And because the tiles are warm, they stay clear of snow and ice: A winter-long test was run in northern Idaho.

The circuit boards offer the biggest benefits: The pavers can communicate directly with road crews and, potentially, drivers. The tiles check in with transportation officials as part of their normal operations, so if one stops responding road crews can be notified immediately and provided with the exact location of the trouble spot. The tiles are also equipped to communicate with vehicles, folding in nicely with the governments’ plans to link roads and vehicles together with internet communications.

All told, the tiles present the prospect of a paving material that pays for itself, the company says. And even if the tiles don’t get widespread adoption, smaller implementations can power crosswalk signs and streetlights.

Solar Roadways is, quite literally, a mom-and-pop operation, which leaves some doubt about whether the company can execute on its big ideas. The Brusaws say they have so far turned away major investors because they want to retain control of the company and are committed to doing the manufacturing in the United States, even if it would be cheaper to do it overseas. The technology has earned kudos not just from Google but also from GE, the IEEE and NASA.