The first crossing of the United States by a solar-powered plane is expected to start in just over a month, its creators said, as they make final preparations for an attempt two years from now at the first round-the-world flight without any fuel.

AN experimental solar-powered plane completed its first 24-hour test flight successfully yesterday, proving that the aircraft can collect enough energy from the sun during the day to stay aloft all night.

IT has the wingspan of a jumbo jet but weighs less than a small car – and is powered entirely by the sun.