ZURICH, Switzerland — Bertrand Piccard, who along with his co-pilot became the first to fly around the world in a hot-air balloon, won financial support from Germany’s biggest bank to build a solar-powered aircraft that can fly around the globe.

The aircraft, with a wing span of 264 feet, will be able to take off and fly using energy from the sun. Deutsche Bank AG Chief Executive Officer Joseph Ackermann said his bank will contribute $12 million of the project’s estimated $82.5 million cost.

“Energy demand has become a massive challenge,” Mr. Ackermann, who like Mr. Piccard is from Switzerland, said yesterday at a news conference in Zurich. “Every effort to address that must be supported.”

The record-breaking flight is planned for May 2011 along the Tropic of Cancer. Construction of a smaller prototype with a 61-meter wingspan will begin next month. The first test flights are scheduled for next year. The biggest challenge will be to develop an aircraft with batteries capable of storing enough solar energy to fly through the night, Mr. Piccard said.

“We’re going to show that all the beautiful exploration of the last century will go on,” the 49-year-old Mr. Piccard said.

Plans for the project, named Solar Impulse, were first announced at the end of 2003. The wingspan of the aircraft will be about the same as an Airbus A-380 but a fraction of the weight at two tons.

The pressurized cockpit will have room for one pilot who can fly the solar-powered plane at up to 12,000 meters. The wings will be encased in a “skin” made of ultrathin solar cells.

In 1999, Mr. Piccard and co-pilot Brian Jones became the first to fly around Earth in a hot-air balloon. Starting in Chateau d’Oex, Switzerland, they flew west for 45,755 kilometers over 19 days and 21 hours before landing in Egypt.

Solar Impulse has already attracted some 65 million francs in financing, said Andre Borschberg, the project’s chief executive. The other main partners include Swatch Group AG’s Omega brand and Brussels-based Solvay SA.