Our adventure

In 2015 started the attempt of the First Round-The-World Solar Flight, from Abu Dhabi to Hawaii, already achieving the longest solo solar flight ever achieved in aviation history. Across the Round-The-World flight, the team must overcome technical, human and operational challenges that have never been faced before.
Bertrand Piccard and André Borschberg, our two Pilots and Founders, will continue to fly around the world with no fuel in 2016. With their solar aircraft, a flying laboratory full of clean technologies, they will continue to promote the use of renewable energies and energy efficiency on the ground, for a better quality of life.


Around the world in a solar airplane

After the 8 world records set by the Solar Impulse prototype, when it became the first solar airplane ever to fly through the night, between two continents, and across the United States, Bertrand Piccard and André Borschberg are now attempting the ultimate phase of the adventure: the 2015-2016 First Round-The-World Solar Flight.

35,000 km from Abu Dhabi, our departure and arrival Host City, to India, Myanmar, China, Japan, U.S.A and back to Europe and Abu Dhabi. As with all great firsts, there were no benchmarks. Strategies had to be invented from scratch to allow Solar Impulse 2 to fly across the Pacific for 5 consecutive days and nights, and become the first solar airplane to accomplish an oceanic crossing. This historic and record-breaking flight from Japan to Hawaii was achieved by André Borschberg in July 2015, proving that clean technologies can accomplish incredible things.

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Takeoff date
Distance (km)
Energy produced (kWh)
Leg 1: Abu Dhabi - Muscat
André Borschberg
March 9th 2015
Leg 2: Muscat - Ahmedabad
Bertrand Piccard
March 10th 2015
Leg 3: Ahmedabad - Varanasi
André Borschberg
March 18th 2015
Leg 4: Varanasi - Mandalay
Bertrand Piccard
March 18th 2015
Leg 5: Mandalay - Chongqing
Bertrand Piccard
March 29th 2015
Leg 6: Chongqing - Nanjing
Bertrand Piccard
April 20th 2015
Leg 7: Nanjing - Nagoya
André Borschberg
May 30th 2015
Leg 8: Nagoya - Honolulu
André Borschberg
June 28th 2015
Leg 9: Hawaii to San Francisco
Bertrand Piccard
21st April 2016

Zero-fuel aircraft

The airplane of perpetual endurance

Solar Impulse is not the first solar airplane, but it is the first to fly day and night, without any fuel, only using energy stored in its batteries. It is also the first to have achieved an oceanic crossing: 5 days and nights from Nagoya, Japan, to Kalaeloa, Hawaii. Behind Solar Impulse’s achievements, there is always the same goal: show that if an airplane can fly several days and nights in a row with no fuel, then clean technologies can be used on the ground to reduce our energy consumption, and create profit and jobs.

The plane’s unusual look undoubtedly helps the message of the project to be spread worldwide. The wingspan of a Boeing 747 Jumbo Jet, the weight of a family car, the power of a small motorcycle, Solar Impulse 2 is the largest aircraft ever built with such a low weight.

1 pilot
72 m
2.3 tons
Number of solar cells
Number of propellers and batteries
Total energy produced from Abu Dhabi to Hawaii
5644 kWh
Maximum flight time achieved
117 hours 52 minutes (André Borschberg)
Maximum altitude
28,000 feet
Average airspeed
75 km/h
Maximum recorded ground speed
216 km/h
Fuel consumption
0 L

« A giant step forward, sending a strong message to people around the world. »
Ban Ki-moon (UN secretary general)

« To build an airplane of the size of a 747 with the weight of a car, something which was considered impossible by the aviation industry, we had to develop the right mindset in order to push the limits of the technologies. With Partners who believed in the same vision we developed solutions to make our airplanes very energy efficient. All these technologies can be used today in other applications to make our world more energy efficient as well. »
André Borscherg

Function in Si2
Application on the ground
Protective Transparent Resin
Protect cells from harsh weather conditions
Allow the cells to be molded into the wing curvature
Domestic roof solar cells which last longer and are adaptable to more areas
Composite Material with Carbon Fiber + Carbon fiber alone
Solvay, Decision
Lighten many parts of the plane including the fastening, screws, pneumatic cylinders to raise and lower the landing gear, the light fittings on the wings, and the gondolas’ protective hulls
Lightweight cars allowing to save fuel / Material savings for wind turbines
Ultralight Efficient Solar Cells
Convert solar energy into electricity with an efficiency of 22.7%
More efficient solar cells for domestic roofs
Energy-dense batteries
Store more energy with less weight
Efficient electric cars or battery-powered devices
Intense and Lightweight LEDs
Light up the runway for landing at night
Domestic and public lighting to replace traditional inefficient electric bulbs
Ultra-lightweight High-density Thermal Insulation Foam
Solvay, Covestro
Insulate the cockpit and the batteries for extreme cold conditions
Walls, windows and doorways insulation to seal air leaks in buildings
Smart Energy Dispatcher Systems
Optimize the energy use of the plane
Prevent/secure engine failing situations
Smart grid dispatch systems
Energy Efficient Engines
Decrease mechanical loss of energy to 6%, thanks to a lubricant, VS 70% without
Lubricant for any motors could be upgraded

Technical challenges

Engineering a revolutionary airplane

Solar Impulse 2 was built to take up the challenge of achieving the first round-the-world solar flight. This revolutionary airplane has to do what no one has ever done before: fly through 5 consecutive days and nights without using any fuel, so as to cross oceans from one continent to the next. André Borschberg, at the controls, achieved such an oceanic crossing during his record-breaking flight from Nagoya to Hawaii.

Our challenge: to take an airplane to such a high efficiency level of energy efficiency that it can fly day and night relying only on the sun. This required the optimization of new kinds of technology and a drastic reduction in energy consumption. The components normally used in aircraft construction are far too heavy for Solar Impulse.

Solar Impulse’s 80 engineers and technicians, under André Borschberg’s leadership, have had to apply highly innovative solutions. What major civil and military aircraft makers thought impossible has been achieved by the ingenuity of a small team.

« Imagine energy reserves increasing during flight! To make this dream a reality, we had to make maximum use of every single watt supplied by the sun, and store it in our batteries. We tracked down every possible source of energy efficiency. »
André Borschberg


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Human challenges

At the controls for 5 days and 5 nights

The long flights of this adventure represent a challenge of endurance and vigilance for a single-pilot in an unheated and unpressurized 3.8m3 cockpit.

Crossing the Pacific and Atlantic oceans introduces a new kind of difficulty for our pilots Bertrand Piccard and André Borschberg. The #RTW Solar Flight represents approx. a 35,000km journey. Although achieved in several legs, Bertrand Piccard and André Borschberg will cumulate around 500 flight hours in the tiny cockpit.

The pilot must have exceptional stamina to control this plane which is sensitive to turbulence because of its broad wing and light weight.

« What is really special, is that it is the first and only airplane in the world which has unlimited endurance. We have an airplane which is fully sustainable in terms of energy, and our challenge now is to make the pilot sustainable as well. »
André Borschberg

Unpressurized & unheated cockpit

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Endurance & Vigilance

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Piloting performance

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Flight strategies

Guiding Si2 around the world

Even though the pilot is on his own in the plane, he is not alone. He is in contact by satellite with the Monaco Mission Control Center (MCC), where the team monitors the route and manage performance and energy. Weathermen, mathematicians, air traffic controllers, planning engineers, flight director ... all gathered to predict all possible scenarios and prepare a flight strategy.

« The MCC is an essential link for the success of Solar Impulse's round-the-world tour. This is where the decisions are made for the departure and routes of each stage. It is via the MCC that the pilot is in contact with the whole world. »
André Borschberg

« The Mission Control Center is the nerve center of the the project. It is where all the information from the plane, takeoff and landing sites is gathered and shared with the world, to allow everyone to follow our adventure and understand our message about clean technologies. The fact that Monaco has been selected results from a long established friendship with Prince Albert II who, in addition to being a patron of Solar Impulse, is one of the only Heads of State to champion environmental protection at all political discussions. »
Bertrand Piccard

Multi-disciplinary team

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A flight embedded in the MCC

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Operational challenges

Behind the scenes

Landing on the biggest international airports with an experimental aircraft, no hangar big enough to house the aircraft... no problem for the ground crew. The men and women behind the scene make it possible for Si2 and its pilot to go around in a safe and secured way., organizing aircraft safety, movements, and technical tests and check-up in coordination with mission engineers at the MCC.

« The ground crew is a team of about 20 members dealing with a lot of things, mainly the handling on the aircraft from the hangar to takeooff, and at landings until the aircraft is safe into a hangar or its mobile hangar. Add a lot of uncertainties on international airports and you can be sure the team has a lot of challenges! But it is also an immense pleasure to be at the forefront. »
Nils Ryser, Head of Ground Crew

Aircraft Handling

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Aircraft Protection

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Airplane Transportation

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Solar Aviation History

The Solar Impulse is not the first solar airplane ever designed, but it is certainly the most ambitious. None of its predecessors has ever managed to fly right through the night with a pilot on board.

Solar aviation began with model aircrafts in the 1970s, when affordable solar cells appeared on the market. But it was not until 1980 that the first human flights were realized.

« Solar Impulse was not built to carry passengers, but to carry messages. We want to demonstrate the importance of the pioneering spirit, to encourage people to question what they’ve always taken for granted. The world need to find new ways of improving the quality of life. Clean technologies and renewable forms of energy are part of the solution. »
Bertrand Piccard