Solar Impulse 2, the
#RTW Solar Airplane

Solar Impulse is the only airplane of perpetual endurance, able to fly day and night on solar power, without a drop of fuel. 

The chances of succeeding at the first attempt to build a solar airplane capable of flying around the world were judged to be slim, so a more rudimentary prototype, HB-SIA, was first constructed. Lessons learned from this prototype are incorporated in Solar Impulse 2, the Round-The-World Solar Airplane.


This revolutionary single-seater aircraft made of carbon fiber has a 72 meter wingspan (larger than that of the Boeing 747-8I) for a weight of just 2,300 Kg, equivalent to that of a car.

The 17,000 solar cells built into the wing supply four electric motors (17.5 CV each) with renewable energy.

During the day, the solar cells recharge lithium batteries weighing 633 Kg (2077 lbs.) which allow the aircraft to fly at night and therefore to have virtually unlimited autonomy.

Learn more about the challenges of building the Round-the-World Solar Airplane.


Solar Impulse by Solar Impulse on Sketchfab


Whereas the prototype uses existing technologies, Solar Impulse HB-SIB requires the development of new materials and new construction methods. Solvay has invented electrolytes that allow the energy density of the batteries to be increased; Bayer MaterialScience is allowing the project to make use of its nanotechnologies; and Décision is using carbon fibers that are lighter in weight than any previously seen.

The first wing spar section was delivered to Dübendorf in March 2012. However, during the final test of this central part, the structure of the wing spar succumbed to the load and broke. The initial shock soon turned out to be an opportunity: the flight around the world had to be postponed which opened the door for going to the United States and completing the epic journey across America.

After the official presentation of Solar Impulse 2 to the public on April 9th, the airplane will be rigorously tested during 2014, and the Round-The-World flight will be attempted between March and July 2015.

Technical Datasheet

Solar Impulse 2's features, in short:

  • Batteries energy density 4 x 260 Wh/kg
  • Airplane Weight 2,3 tons
  • Wingspan 72 meter (236')
  • Solar Cells Thickness 135 micron
  • Solar Cells > 17,000
  • Cockpit Size 3.8 m3

Solar Impulse 2 continues its historic Flight Around the World, bringing a message of clean energy and sustainability to China.

Chongqing (China), March 31, 2015 – Attempting the First Round-The-World Solar Flight to inspire innovation and encourage the use of clean technologies, the solar powered airplane of Bertrand Piccard and André Borschberg successfully landed at the Chongqing Jiangbei International ...

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Chongqing (China), March 31, 2015 – Attempting the First Round-The-World Solar Flight to inspire innovation and encourage the use of clean technologies, the solar powered airplane of Bertrand Piccard and André Borschberg successfully landed at the Chongqing Jiangbei International Airport on Tuesday March 31st.


The airplane departed from Myanmar for the fifth leg of its epic circumnavigation on Monday March 30th at 3:36 am local time (9:06 pm GMT, [March 29]) with Swiss pilot Bertrand Piccard in command. The first ever single-seater solar plane to enter China, Solar Impulse 2 landed in Chongqing 20 hours and 29 minutes later, having covered 1,459 kilometers. Flying above the mountainous Chinese provinces of Yunnan and Sichuan required the pilot to perform a steep climb at the beginning of the journey, and due to continuous flying at high altitude, the pilot had to wear an oxygen mask in the 3.8m3 unpressurized cockpit in which Bertrand Piccard faced temperatures descending to minus 20 degrees celsius. In addition, tackling strong low level winds in Chongqing made this flight one of  the most challenging to date

Jean-Jacques de Dardel, the Swiss Ambassador to the People’s Republic of China, welcomed the Solar Impulse team at the airport alongside Mr. Ai Yang, Deputy Secretary General of Chongqing Municipal Government. During its stay in China, and on the occasion of the 65th anniversary of the establishment of diplomatic relations between China and Switzerland, the Solar Impulse team will honor the strong ties between both countries while organizing a series of events demonstrating that innovation is the key to sustainable development.  “Solar Impulse is an audacious adventure demonstrating typical Swiss innovative teamwork. I am glad it will henceforth  have a Chinese content” said Swiss Ambassador Jean-Jacques de Dardel.


While the Round-The-World is an ambitious scientific project and barrier-breaking adventure, it is also an illustration of the importance of moving the world towards a future centered around clean, renewable energy. A vision which is shared by Solar Impulse Chinese Host Partners, CAST (Chinese Association of Science and Technology) and Sina. Together they will organize visits and conferences for schools and universities to spread the message to the young generation. The key event, involving 1600 students, takes place in Chongqing today at the Bashu Secondary School.


“China has become number one in wind power and in solar panel production, and  if you look at how much efforts the Chinese government is making to increase the use of renewable energy to optimize the energy mix, there is no surprise that Solar Impulse is so well received in the country.” Said the pilots Bertrand Piccard and André Borschberg, co-founders of Solar Impulse.

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