The lightweight plane, which has a wingspan of 208 feet, will be about 3,000 feet in the air as it flies above the bridge sometime between 2 p.m. and 3 p.m., said Alexandra Gindroz, spokeswoman for the Swiss firm Solar Impulse, which owns the plane.
"It's quite high but you should be able to see something up there," Gindroz said. "We'll pass by the Bay Bridge between 7 and 8 p.m."
The plane, which weighs only about 3,500 pounds, runs completely on power from the sun drawn from 12,000 solar cells on the craft that send energy into batteries that power propellers running on four electric motors, Gindroz said.
Today's flight is a technical test run to prepare for a planned cross-country trip beginning in early May. On the first leg of the trip, the plane will depart from the Bay Area and head to Phoenix, Gindroz said.
But the test run is also about something more, Gindroz said.
"For us, it's really a message to fly over the Golden Gate Bridge and the Bay Area," she said. "It means that we are here and it's a landmark."
The plane was created by pilot Andre Borschberg in Payerne, Switzerland, and the flight path will take it to Dallas, Atlanta and finally to New York in early July.
The company said on its website that the plane is intended in part to provoke conversations about renewable energy and to show that the technology exists to explore alternatives to traditional fuel.
The Solar Impulse HB-SIA, which is light and sensitive to the winds, will land late tonight at Moffett during a time when only light winds are in the forecast, Gindroz said.
The plane reaches a top speed of 43 mph and holds the record for altitude for solar-powered planes at 30,300 feet, according to the company's website.
Solar Impulse is planning an even longer around-the-globe flight in 2015, according to the website.
Real-time updates on the plane's flight today can be found on the site at www.solarimpulse.com.