The high-tech aircraft was greeted by an enthusiastic crowd of supporters at Payerne airport in western Switzerland two months after it took off from there on May 24 on a journey that took it from Europe to North Africa and back.
"This was an extraordinary adventure, not only because of what was achieved with this plane... but also because of the solid team," Andre Borschberg, one of the co-founders of the project, said in a statement.
Earlier on Tuesday pilot Bertrand Piccard took the plane up into a cloudless sky from an airfield near Toulouse, southern France, where it had waited for a week for the right weather conditions to complete a journey which took it to Spain, Morocco and back again to Switzerland.
The high-tech aircraft, which has the wingspan of a large airliner but weighs no more than a saloon car, is fitted with 12,000 solar cells feeding four electric engines.
With the final stage completed, the 6,000-kilometre (3,700-mile) journey became the longest to date for the aircraft after an inaugural flight to Paris and Brussels last year.
The flight was transmitted live on www.solarimpulse.com, the website of the project run by Piccard, an explorer who has travelled around the world in a hot-air balloon, and fellow pilot Borschberg, who took turns to fly the plane on its latest journey.
The trip was intended as a rehearsal for a round-the-world flight planned for 2014 in an updated version of the plane.
The organizers said in a statement that Solar Impulse had now demonstrated the reliability of the technology it uses as well as its energy efficiency.
Solar Impulse made history in July 2010 when it became the first manned plane to fly around the clock on the sun's energy.
It holds the record for the longest flight by a manned solar-powered aeroplane after staying aloft for 26 hours, 10 minutes and 19 seconds above Switzerland, also setting a record for altitude by flying at 9,235 metres (30,298 feet).