2003: Solar Impulse

Solar Impulse is a Swiss long-range experimental solar-powered aircraft project, and also the name of the project’s two operational aircraft. The privately financed project was led by Swiss engineer and businessman André Borschberg and Swiss psychiatrist and balloonist Bertrand Piccard. The Solar Impulse project’s goals were to make the first circumnavigation of the Earth by a piloted fixed-wing aircraft using only solar power and to bring attention to clean technologies.

The adventure began with Bertrand Piccard’s vision that clean technologies and energy efficiency can reduce our emissions and improve our quality of life. It led up to the attempt of the First Round-The-World Solar Flights.

The prototype, often referred to as Solar Impulse 1, was designed to remain airborne up to 36 hours. It conducted its first test flight in December 2009. In July 2010, it flew an entire diurnal solar cycle, including nearly nine hours of night flying, in a 26-hour flight. Piccard and Borschberg completed successful solar-powered flights from Switzerland to Spain and then Morocco in 2012, and conducted a multi-stage flight across the US in 2013.

A second aircraft, completed in 2014 and named Solar Impulse 2, carries more solar cells and more powerful motors, among other improvements. On 9 March 2015, Piccard and Borschberg began to circumnavigate the globe with Solar Impulse 2, departing from Abu Dhabi in the United Arab Emirates. The aircraft was scheduled to return to Abu Dhabi in August 2015 after a multi-stage journey around the world. By June 2015, the plane had traversed Asia, and in July 2015, it completed the longest leg of its journey, from Japan to Hawaii. During that leg, the aircraft’s batteries sustained thermal damage that took months to repair. Solar Impulse 2 resumed the circumnavigation in April 2016, when it flew to California. It continued across the US until it reached New York City in June 2016. Later that month, the aircraft crossed the Atlantic Ocean to Spain. It stopped in Egypt before returning to Abu Dhabi on 26 July 2016, more than 16 months after it had left, completing the approximately 42,000-kilometre first circumnavigation of the Earth by a piloted fixed-wing aircraft using only solar power.

One of the goals of the project was to spread the message that everybody could use the plane’s technologies on the ground to halve our world’s energy consumption, save natural resources and improve our quality of life.

Project timeline

  • 2003: Feasibility study at the École Polytechnique Fédérale de Lausanne
  • 2004–2005: Development of the concept
  • 2006: Simulation of long-haul flights
  • 2006–09: Construction of first prototype (HB-SIA; Solar Impulse 1)
  • 2009: First flight of Solar Impulse 1
  • 2009–11: Manned test flights
  • 2011–12: Further test flights through Europe and North Africa
  • 2011–13: Construction of second prototype (HB-SIB; Solar Impulse 2)
  • 2013: Continental flight across the US by Solar Impulse 1
  • 2014: First flight of Solar Impulse 2
  • 2015–2016: Circumnavigation of the Earth by Solar Impulse 2, conducted in seventeen stages over 16-1/2 months

Solar Impulse 2, general characteristics

  • Crew: 1
  • Length: 22.4 m
  • Wingspan: 71.9 m
  • Height: 6.37 m
  • Wing area: 17,248 photovoltaic solar cells cover the top of the wings, fuselage and tailplane for a total area of 269.5 m2  (rated at 66 kW peak)
  • Take-off speed: 36 km/h
  • Powerplant: 4 × electric motors, 4 x 41 kWh lithium-ion batteries (633 kg), providing 13 kW (17.4 hp) each
  • Propeller diameter: 4 m


  • Maximum speed: 140 km/h
  • Cruise speed: 90 km/h 60 km/hat night to save power
  • Service ceiling: 8,500 m with a maximum altitude of 12,000 metres

About André Borschberg

André Borschberg (born 13 December 1952 ) is a Swiss entrepreneur, explorer, pilot and speaker. During the Japan-to-Hawaii leg, he broke the world record for longest solo flight in an airplane of any kind: 117 hours and 52 minutes

About Bertrand Piccard

Bertrand Piccard (born 1 March 1958 in Lausanne, Switzerland) is a Swiss psychiatrist and balloonist. His grandfather Auguste Piccard was a balloonist and his father Jacques Piccard was an undersea explorer.


Leave a comment

1 × two =

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Please Note:
You may use one of these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>