Solar Plane Makes Last Test Flight Before 'Across America' Trip

Image credit: Jean Revillard/Solar Impulse

The Solar Impulse solar-powered airplane made history in 2010 when it embarked on the first-ever solar-powered night flight, and again in 2012 when it made the first intercontinental solar-powered flight (Europe to North Africa).

Now the co-founders and pilots of Solar Impulse have announced plans to conduct the first solar-powered coast-to-coast United States flight - Solar Impulse Across America - kicking off early next month.

Tuesday, Solar Impulse flew over the San Francisco Bay area, its final pre-cross-country test flight. The Across America trip will take off from San Francisco and reach its final destination in New York by early July, making stops in Phoenix, Dallas and Washington, D.C., along the way.

The wingspan of the plane is 208 feet, about the same as a jumbo jet, but it weighs no more than a car and has a cockpit just large enough to host a single pilot. Because of its light weight, the plane can collect sufficient energy solely from solar cells, and it even stores power, making night flights possible.

Swiss co-founders Bertrand Piccard and André Borschberg began working on Solar Impulse in 2003 as an aviation and energy project.

"We want to show that with clean technologies, a passionate team and a far-reaching pioneering vision one can achieve the impossible," said Piccard at last month's announcement of the Solar Impulse Across America trip. "If we all challenge certitudes by driving change and being pioneers in our everyday lives, we can create innovative solutions for society's biggest challenges."

Ross Aimer, CEO of Aero Consulting Experts, told ABC News that he believes Solar Impulse's Across America flight is "a big step, but also a baby step."

"When it comes to a commercial craft, you would need more power. … You'd probably need something like two football fields of solar panels," said Aimer, a retired United Airlines captain.

But the flight expert is confident. Seeing advances in solar flights and some new airplanes using biofuel encourages Aimer. "Anything to get us away from burning kerosene," he said.

Some commercial planes are already using electric battery backup systems, although that technology is still in its early stages, Aimer said.

The Across America flight will be live streamed and chronicled at the Solar Impulse website beginning next week.

"Hopefully, the [Across America] flight will get some people's attention. I'm optimistic that the future can be solar and electric," said Aimer.