The power of a vision: technological innovation tackling the environmental challenges of our times

In a society that depends on fossil fuels, Solar Impulse is a paradox, almost a provocation, aiming to fly without fuel or pollution, opening up a new way forward. By completing the first global circumnavigation in a solar-powered electric airplane on 26th July 2016 – a flight of 43,000 kilometers - Bertrand Piccard achieved much more than a major human and technological feat. Together with his partner André Borschberg, the Swiss psychiatrist and explorer proved that new clean technologies were efficient in saving the planet's natural resources. This makes him a pioneer of the ecological transition.

The around-the-world balloon flight was the fulfilment of Bertrand’s dreams of adventure, but Solar Impulse is his life’s project. It’s more than just a solar airplane capable of flying through day and night without fuel, it’s a powerful demonstration of how clean technologies can give our planet a more sustainable future. It offered him everything his family had bequeathed - the pioneering spirit; curiosity; perseverance; scientific exploration; airborne adventure; high technology; teamwork; calling into question what’s considered “impossible”…and of course environmental protection.

« Solar Impulse was built not to transport passengers but to carry a message. We want to demonstrate the importance of the pioneering spirit, to encourage people to question their certainties. Our world needs new solutions to improve the quality of human life. Clean technologies and renewable energies are among them.»
Bertrand Piccard
  • 1999

    A vision in the desert

    The vision of a solar airplane, flying day and night without fuel, occurred spontaneously to Bertrand after his around-the-world balloon flight. Having lifted off with 3.7 tonnes of liquid propane, he was left with only 40 kg on landing. His success had depended entirely on how much fuel the burners consumed. So, our explorer vowed to himself that he would go around the world once more, but this time without any fossil fuel on board.

    The road is sometimes long from dream to reality. The question was whether all this was achievable with current levels of knowledge and technological development…

  • 2002

    Taking stock

    Bertrand asked the Geneva Industrial Services Department for an initial analysis; traveled right across the United States to take stock of current research; and made contact with several solar aviation specialists, including Paul McCready. Solar airplanes had already flown, but only in the middle of the day and without being able to store energy.

  • 2003

    The challenge is launched

    Bertrand then turned to the prestigious technical university in Lausanne (EPFL) whose research director, Stefan Catsicas, was enthusiastic about the project. He recognized the solar airplane’ formidable potential as a flying laboratory. A feasibility study, led by engineer André Borschberg, had mixed conclusions: the outcome was uncertain, it would not be easy, but was feasible if daunting technical advances could be made.

    None of the aviation specialists he met believed in the project. So, he had to assemble a team to build the airplane himself. Bertrand invited André Borschberg to join him in confronting this challenge. This was the start of a long collaboration between the two men. The project was officially announced to the public on 23 November 2003.

  • 2004-2007

    Betting on innovation

    The vision was there, and the structure in place. But support was still needed to transform these into reality. Bertrand went about approaching partners for funding and technology support, while André put together and led the technical team. The first prototype they designed had an unpressurized cabin, a wingspan of 63 meters and a mass of 1,600 kg. This aircraft was registered as HB-SIA.

  • A revolutionary prototype

    To permit the first Solar Impulse prototype to fly through day and night without any fuel, highly sophisticated methods had to be used to minimize weight and optimize energy consumption, performance and maneuverability. Photovoltaic cells - 11,628 of them - captured the solar energy. This was then was transmitted in the form of electricity to the four motors and to lithium-polymer batteries that stored it for later use at night. The carbon-fiber structure, proportionally 10 times lighter than that of the best competition glider, was manufactured by a boat-builder.

  • 2008

    Aircraft construction: high technology, high demands

    The combined talents of more than fifty employees, and the support of around a hundred experts and advisers allowed boundaries to be pushed back and impressive technological progress made. An empirical approach was not an option for this cutting-edge, futuristic project. Every concept and component part of the solar airplane had to pass several tests to be certified «fit to fly».

  • Simulations and virtual training sessions

    Virtual flights and strategy simulations in authentic weather conditions allowed a wealth of lessons to be learned. The flight simulator, consisting of five screens arranged around the cockpit, placed the two aviators in position for a 25-hour flight, fully equipped and strapped in as they would be in reality.

  • 2009

    First flights

    Four years of research, complex calculations and simulations, had been followed by 2 years of construction. HB-SIA now made its first test flights. With the wingspan of an Airbus 340 but the weight of a small car, nothing was easy: 106 years after the Wright Brothers, history had begun again, but this time without fuel!

« The Wright brothers demonstrated that it was possible for a heavier-than-air airplane to fly. As for the Solar Impulse engineers, they demonstrated that clean technologies can enable an aircraft to be made so much lighter and more efficient that it can fly through day and night using only solar cells. »
Bertrand Piccard


Night flight

The first all-day-and-night flight on solar energy

  • In July 2010, with André at the controls, Solar Impulse flew through the night… on solar energy! This was an historic success, a great human and technological achievement, presented by the world’s media as a decisive step forward. The flight lasted 26 hours and established the credibility of Bertrand's vision.

  • «Solar Impulse has a rendezvous with destiny. We want to demonstrate that alternative kinds of energy, when allied to new technologies, can enable the impossible to become reality. By flying through a whole day and night without any fuel, Solar Impulse has become the first aircraft to approach perpetual flight.»
    Bertrand Piccard

  • «Just imagine - the energy reserves were increasing during the flight! To meet this challenge successfully, we had to take maximum advantage of all forms of energy efficiency. It was only by comparing each team member’s experience and adding together their collective potential that we found the solutions. Something the major civil and military aircraft manufacturers had thought impossible was achieved by a small team of engineers… »
    André Borschberg

  • The proof was in.

    Solar Impulse was capable of flying for several days running, and so could overfly the oceans. An around-the-world flight was now on the cards.

  • Flying across Switzerland

    Before considering missions abroad, we had to ensure the reliability of the aircraft, and practice integration into air traffic, and landing on the runways of international airports ... Just like a pedestrian strolling on a busy highway!

  • 2011

    Success makes the political world take notice

    The renown and symbolic significance of the project crossed national borders. The European Commission gave its sponsorship. The International Air Transport Association decided to use Solar Impulse as an example to encourage the reduction of commercial aircraft emissions.

    «For Europe, the symbolism of the solar airplane is that it shows what needs to be done in industry and energy policy, in terms of efficiency and clean mobility. »
    Philippe Lamberts, member of the European Parliament

  • One flights follows another, right across Europe

    Solar Impulse landed in Brussels for a presentation of the project to the European Parliament, before heading off to Paris as guest of honor at the Paris Air Show. Slender and lightweight, but with a similar span, the prototype made a surprising neighbor to the kerosene-powered giants on the tarmac. Solar Impulse indicated the way to the future.

  • Patrons of commitment

    Eminent personalities concerned about the future of the planet lent their names to the undertaking. Among them, Prince Albert II of Monaco, Buzz Aldrin, Yann-Arthus Bertrand, Paulo Coelho, Nicolas Hulot, Hubert Reeves, Jean-Louis Etienne, James Cameron, Richard Branson and the Nobel Peace Prize winners Elie Wiesel and Al Gore.

  • « If the around-the-world balloon flight was the last adventure of the 20th century, Solar Impulse is undeniably the first to represent the challenges of the 21st »
    Prince Albert of Monaco

  • « An effective weapon that demonstrates the importance of clean technologies in meeting the planet's energy requirements »
    Sir Richard Branson

  • Educational program

    The Solar Impulse Foundation was created to add an educational angle to the project and to raise public awareness about the importance of clean technologies and renewable energies.

  • 2012

    1st Intercontinental flight

    A return flight of 6,000 km on solar energy from Switzerland to Morocco, where Bertrand and André were invited by King Mohammed VI to support the construction program for the world's largest solar thermal power plant.

    Meanwhile, the technical team was concentrating on building the second aircraft, for the around-the-world flight. This was even more sophisticated and more efficient. It had a more spacious cockpit and was fitted with an autopilot.

  • 2013

    United States crossing

    From San Francisco to New York in 6 stages. A training exercise for the team, and an opportunity to let Solar Impulse’s message echo from the podium at the United Nations, with a presentation of the technological solutions available to achieve CO2 reduction targets.


Goal: to fly around the world

A great leap into the unknown

  • As for all great “firsts”, there was no prior point of reference. Strategies had to be invented from scratch. Each step - from defining the flight envelope to obtaining various kinds of clearance - meant finding out-of-the-box solutions. The challenge was knowing how to manage long-distance flights and predict all conceivable scenarios.

    Solar Impulse 2, the great record-breaker

    To complete the around-the-world flight, Si2 would have to do what no airplane had ever done before: to fly without fuel for several days and nights in a row, so as to cross the oceans from one continent to another.

  • Construction of the new aircraft was completed in February, and its first test flights took place from Payerne. It was the largest plane ever built of such a low weight. This challenge meant working at the outermost boundaries of the possible, and keeping within unprecedented constraints as regards weight, strength and energy. So: using innovative materials to achieve a light but strong structure; highly efficient motors for record energy yield; and solar cells to capture the unlimited energy source and store it in high-capacity batteries.

    • A wingspan of 72 meters, similar to an Airbus A380
    • The weight of a family car: 2,300 kg
    • The power of a scooter: 4 electric motors, each of 13.5 kW
    • 17,248 solar cells, of hair’s breadth gauge, covering 270 m2
    • A speed of between 45 km / h and 90 km / h
    • A 3.8 m3 cockpit
  • Over-trained pilots

    The preparation of the pilots was flawless. When on mission, they would have to demonstrate extraordinary adaptability and mental resilience. They’d be faced with extreme flight conditions, in temperatures ranging from -20°C to +40°C. wearing an oxygen mask several hours a day at 9,000m. They too had to prove that they were "fit to fly" and capable of controlling this aircraft, whose size and light weight made it sensitive to the slightest turbulence.

  • Air traffic … and sunshine…controllers

    At the mission center in Monaco, the flight director, meteorologists, mathematicians, air traffic controllers and planning engineers were anticipating all possible scenarios and defining flight plans by simulating thousands of trajectories. Through constant satellite contact with the pilot, these guardian angels would keep track of the route and manage the energy needed to get him safely to the next destination.

  • The logistical challenges down route

    The ground crew of more than 60 people were also key participants in the adventure. They would look after the aircraft, perform maintenance and technical checks before and after each flight, and provide shelter for its huge wings. A mobile hangar, designed entirely by Solar Impulse engineers and which could be inflated in less than 5 hours, would protect the aircraft from bad weather. Photographers and cameramen would scramble to immortalize this epic flight, and the communications team would allow millions of people to witness live flyovers of iconic landmarks such as the Statue of Liberty and the Pyramids.

« Imagine an airplane that produces more energy than it consumes ... Just suppose that tomorrow’s world operated according to this model, rather than depleting its natural resources! »
Bertrand Piccard

2015 – 2016

The epic flight around the world

43,000 km without any fuel - a first in the history of energy

  • The final phase of the adventure began in Abu Dhabi on 9th March 2015. Bertrand and André took turns to fly in Si2’s single-seat cockpit, visiting on the way Oman, India, Burma, China, Japan and Hawaii. The first part of the trip around the world ended in July with an historic, record-breaking flight from Nagoya to Honolulu - 5 days and 5 nights flying almost 8,900 kilometers - the longest-ever duration for an airplane flown solo. But the batteries overheated due to an operational error by the safety team, and SI2 remained stranded in Hawaii until the following spring.

  • The mission resumed in April 2016, with the crossing of the second half of the Pacific and then of the USA. Bertrand had met Charles Lindbergh as a child, so crossing the Atlantic from New York had a special symbolic significance for him. Just as the Spirit of St. Louis had pioneered the route for long-haul commercial flights, so, over the same ocean, Solar Impulse 2 opened the way forward to the new, clean technologies.

  • A journey strewn with pitfalls

    Every stage of the flight was a challenge, juggling capricious weather and unforeseen events, some technical, some operational. It was often hard to find the clear skies and light winds needed for take-off and landing. Air traffic controllers - great negotiators of overflight clearances - had to open the routes up and then guide the experimental solar plane along the airways. A slow-moving, noiseless dragonfly in a sky studded with jumbo airliners.

  • A triumphant arrival

    After a really challenging, turbulent flight over the Saudi desert, Bertrand Piccard concluded the epic flight in triumph on 26th July 2016. It took 17 stages and 25 actual flight days spread over 17 months to get back to Abu Dhabi, clocking an average speed of 70 km/h. From the Middle East to the Ganges’ shores, from Mandalay pagodas to Hawaiian volcanoes, from San Francisco’s Golden Gate to the Egyptian pyramids – the 43,000 km of the first no-fuel around-the-world flight were all made possible thanks to 17,248 photovoltaic cells.

  • An airborne messenger

    Solar Impulse hit the headlines, with comments stressing the ground-breaking aspects of the feat. Bertrand's vision was no longer just a crazy dream, but a reality launching the clean technology revolution, a source of economic and social development. Solutions already existed to address environmental problems, as Bertrand pointed out during his live conversation from the cockpit with the Secretary-General of the United Nations, before the representatives of 195 countries that had signed the Paris Agreement.

  • Clean energy can shape the future

    « Even more than a first in the history of aviation, Solar Impulse’s flight around the world is a first in the history of energy. » Politicians started to pass on Bertrand's message, to conceive of solutions that integrate ecology with the economy, something now possible thanks to clean technologies.

    « These technologies could already be installed in our power grids, our homes, cars and industrial processes. Used globally, they would cut polluting emissions in half while creating jobs and profits. »
    Bertrand Piccard

« Imagine an airplane that produces more energy than it consumes ... Just suppose that tomorrow’s world operated according to this model, rather than depleting its natural resources! »« As I flew around the world in my solar airplane, I remember looking at the sun that was powering my four electric motors and their huge propellers. There was no noise, no pollution, no fuel ... and I could fly forever. At that point. I thought to myself, "This is science fiction, I'm in the future." But then I realized, “No, not at all, I'm very much in the present, doing what today's technologies allow me to do.” That’s when I realized how much the rest of the world is stuck in the past, with its old, inefficient and polluting systems. »
Bertrand Piccard
  • 2016 - today

    The 1,000-solution challenge

    During his flight across the Atlantic, Bertrand announced the creation of the Global Alliance for Efficient Solutions to bring together all those involved in these new technologies. Six months later, at the COP 22 in Marrakech, he announced the new challenge launched by the Solar Impulse Foundation: to identify 1000+ solutions capable of protecting the environment in a financially profitable way. The Foundation has become the spearhead organization for reconciling ecology with the economy.

  • A new round-the-world trip

    By April 2021, the first 1,000 solutions had been labelled, and Bertrand was about to set off once again for an around-the-world trip, but this time on the ground. The intention is to present governments and large companies with the tools they need to adopt much more ambitious environmental policies and so achieve their climate goals.

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