Pilots Bertrand Piccard and Andre Borschberg said the Solar Impulse 2 improves dramatically upon the single-seater prototype that first took flight five years ago.
They say the technology has advanced so much the new design could remain in the air indefinitely.
The updated plane presented to the world at the Payerne Air Force Base in Switzerland has better batteries for storing energy soaked up from the sun by the 7,200 solar cells that cover its massive wings.
The Swiss team planning to complete the first round-the-world solar flight next year have already demonstrated that a solar-powered plane can fly through the night, between two continents and across the United States.
At 72 meters (236 feets) its wingspan is eight meters longer than the first prototype – longer even than the wings of a Boeing 747 jumbo jet – but still only weights 2.3 metric tons (2.54 tons), about as much as a large car.
The materials in the updated plane are also lighter than before, it has more efficient electric motors, and a ‘good business class seat,’ Borschberg said