Pilots André Borschberg, right, and Bertrand Piccard with the new model of the Solar Impulse. (Laurent Gillieron/European Pressphoto Agency)

A team from Switzerland that is planning to complete the first round-the-world solar flight next year has unveiled a new version of the plane they say can remain in the air indefinitely.

Pilots Bertrand Piccard and André Borschberg say the Solar Impulse 2 — which uses no fuel — improves upon the prototype that first took to the air five years ago.

The updated plane, presented to the world Wednesday at the Payerne Air Force Base in Switzerland, has better batteries for storing energy soaked up from the sun by the thousands of solar cells that cover its 236-foot wingspan. The plane weighs 2.5 tons and can fly at up to 87 miles per hour.

The single-seater prototype demonstrated that a solar airplane could fly through the night, between two continents and across the United States. The pilots took turns flying it from California to New York last summer. The plane and its crew stopped at Dulles International Airport from June 16 to July 6.

The round-the-world trip is expected to take place next year.

Wire and staff reports