Solar Impulse 2 resumes around-the-world journey after 9-month pause

The pilot of a solar-powered airplane who has just finished the Hawaii-to-California leg of an around-the-world journey believes his voyage can set an example for the rest of the world to harness the power of solar energy.

"We are like a flying laboratory, showing how the future looks like if we have pioneering spirit and if we have spirit of exploration," Solar Impulse 2 aircraft pilot Bertrand Piccard told CBC News from the cockpit somewhere over the Pacific Ocean.

The plane was grounded in Hawaii last July to repair a battery that kept overheating. After raising $20 million US for repairs and a nine-month delay, the flight resumed two days ago.

• Solar Impulse 2 takes off for historic around-the-world attempt

• Solar Impulse 2 passes point of no return of 120-hour trip to Hawaii

The project's website, which is live tracking the flight, says the aircraft has reached the U.S. after a three-day flight over the Pacific. The pilot performed a fly-by over San Francisco's Golden Gate Bridge on Saturday afternoon and is set to land in Mountain View, Calif., at the southern end of San Francisco Bay, at midnight.

The aircraft's wings are covered with solar cells that harness energy from the sun to power the motors turning its propellers. During darkness it relies on energy stored in batteries.​ The aircraft started its journey in March 2015 from Abu Dhabi, the capital of the United Arab Emirates and has been travelling east on the around-the-world journey.

"[The flight] is beautiful for the scenery, but it is very symbolic because half an hour ago, in the middle of the Pacific, I [saw] the sunrise, and the sunrise is the energy for the next day for the Solar Impulse to continue its flight," said Piccard. "But if humankind was a little bit wiser, it would also be the energy for the world to go into the future."

"We have the technology to harvest [solar energy], to do incredible things like flying day and night a solar-powered airplane with no fuel," he added. "So this is really the message."