The takeoff followed a delicate operation at the Payerne airfield in the canton of Vaud on Monday to load the components of the spindly plane with a 72-metre wingspan and four engines powered by electricity from more than 17,000 solar cells.
The aircraft, dubbed the SI2, was developed from a prototype by the Solar Impulse team, headed by adventurer Bertrand PIccard and former Swiss Air Force jet pilot André Borschberg.
The prototype flew across the United States in 2013 without using a drop of fuel.
The SI2 has the same wingspan as an Airbus A380 but at just 2,300 kilograms it weighs less than one percent of the jumbo jet.
It will be reassembled in Abu Dhabi, where after tests it is scheduled to begin the planned around the world flight in 53 days, the Solar Impulse website says.
“This a more touching moment than I had expected,” Piccard tweeted after the CargoLux plane left Payerne with its freight.
The plane was set to fly to Basel to pick up equipment before travelling to the Emirates, where the round the world trip is slated to begin at the end of February.
“It’s a great day because we are leaving Switzerland and Payerne where we have received an exceptional welcome,” Piccard earlier told the ATS news agency.
“The aeroplane is leaving the nest.”
Piccard and Briton Brian Jones became the first people to fly around the world non-stop in a hot-air balloon in 1999.
The Lausanne native and Borschberg plan to take turns flying from the Emirates to China and on to the US and Europe.
"We will need at least five days and five nights to fly from China to the US and from the US back to Europe," Borschberg said earlier this year.
The prototype Solar Impulse plane made its first flight in 2009 and progressive tests showed that it and the SI2 can store enough electricity in the day to keep it flying at night.
For more information, check the Solar Impulse website.