On June 23, a spectacular showcase of clean mobility took place at Swiss Aeropole in Payerne — both on the tarmac and in the skies! An electric semi-truck from our partner Planzer drove alongside our solar-powered aircraft, SolarStratos, piloted by Raphaël Domjan. It was a bold performance challenge, aimed at raising awareness about the importance of solar and sustainable mobility for the planet.We already shared a video from that unforgettable day (watch it here : h ttps://vimeo.com/1097477338).
Now, Planzer has released their own film — incredibly inspiring and guaranteed to give you chills. One thing’s for sure: with Planzer and SolarStratos, the pioneer spirit truly takes flight!
The full report on the our partner’s website.
The Record-Breaking Flight of August 12 is Making Global Headlines
On August 12, 2025, SolarStratos turned a new page in aviation history. Taking off from Sion, Raphaël Domjan and the solar-electric aircraft HB-SXA soared to an altitude of over 9,500 meters, setting a new record for the highest manned solar-powered electric flight ever achieved. This milestone crowns years of preparation and more than a hundred test flights. The achievement has captured international attention—and the impact continues to spread across the globe.
It’s a fitting reward for all the effort, and we are thrilled to share the joy of this moment with our friends, partners, and sponsors—led by our main partner Longines, with Bordier & Cie and Bitcoin Suisse AG. Without them, without you, without Roland Loos, our CTO and tireless supporter, and without the passionate team behind this mission, this feat would never have been possible. Thank you for flying with us. Thank you for helping us promote a solar-electric, decarbonized world—where dreams still take flight, and the vision of Icarus can finally be realized, sustainably.
Timeline of a Triumph—Topped with Raclette
On July 31, the eve of Switzerland’s National Day, SolarStratos climbed to 21,618 feet (6,589 m) above the Swiss Alps and the Matterhorn—a new record for the aircraft. On August 8 and then again on August 10, HB-SXA broke its own record twice, reaching 8,377 meters—flights already picked up by international media, including the front page of the Financial Times Weekend. Then, on Tuesday, August 12, in a historic flight lasting 5 hours and 9 minutes, powered by sunlight and rising thermals, Raphaël Domjan climbed above 9,500 meters, surpassing Solar Impulse’s 9,235-meter milestone.
“We did it!”. The flight is now being submitted for official certification by the Fédération Aéronautique Internationale (FAI), which will validate the final altitude corrected to ISA standard atmosphere. A moment of high emotion for the whole team—celebrated the Swiss way, over a well-deserved raclette!
“I Crossed Paths with a Commercial Airliner”
During the record-breaking flight, Domjan experienced an unforgettable moment: “Up there, I crossed paths with a commercial airliner flying at FL300. When air traffic control informed the crew I was a solar plane, I wish I could have seen their reaction! They didn’t respond… But for me, it was pure magic.” A scene symbolic of SolarStratos’ message: Solar energy can take us as high as airliners— and even higher. Beyond where fossil fuels can burn, solar energy keeps electric motors running.
Jubilation in Motion
To relive and share the jubilation of this flight, filmmaker Stéphane Chopard has created a video montage, released earlier this week—and we’re proud to share it with you here. We hope it sends shivers down your spine, as it did ours.
Teamwork and Team Spirit
This record was the product of extraordinary teamwork. From Cindy da Silva to intern Hugo Peyrot, from General Michaël Stähli to test pilot Gérald Ducoin, everyone played a vital role. Engineer and pilot Jean-Baptiste Loiselet, ever humble, made a crucial contribution: “My modest role was to scout the route with my motorglider just before HB-SXA’s flight, using my experience with the Sol.Ex to help chart an optimal path.” He also salutes his colleagues at the Mission Control Center, who monitored everything in real time—from solar input to energy consumption—as well as local soaring expert Gabriel Cachin and the rest of the team: Roland Loos, Nadia Keller, Stéphane Chopard, Giovanni Sammali, Olivier de Sybourg, Alexis Domjan, our test pilot Gérald Ducoin and many others who supported the pilot, founder, and driving force of this mission—Raphaël Domjan, a man with more than one trip around the world under his belt.
From Montréal to Tahiti – Via the Financial Times
Immersed in the project, focused on success, and confident in its impact, we were still taken aback by the scale of the reaction. Stunned, even. Media from across the world picked up the story. As we had hoped, HB-SXA becoming the highest-flying electric solar aircraft in history left a powerful impression. The earlier record attempts had already paved the way—especially with the iconic photo of HB-SXA flying in front of the Matterhorn, featured on the cover of the Financial Times Weekend. Never before have so many TV stations covered SolarStratos: BFM-TV, France24, GB News, and of course RTS—with RAI soon to follow after filming a segment in Sion. Thank you to all the media outlets for your support and interest.
THANK YOU!
To the friends and members of the SolarStratos Club, to our partners and sponsors for their unwavering support, to our families—and of course to:
The Swiss Federal Office of Civil Aviation for their trust,
Calin Gologan of Elektra Solar, the visionary designer of this unique aircraft,
Skyguide and the Swiss Air Force for opening the skies,
The Sion Airport, Alpark, and Swiss Aeropole in Payerne,
And to all those who support and carry our message of hope forward…
Raphaël Domjan and the entire SolarStratos team send you the sunniest of THANK YOUs!
On Tuesday, August 12, 2025, from Sion Airport in Switzerland, eco-explorer Raphaël Domjan piloted the HB-SXA aircraft to an altitude of 9,521 meters above the Valais Alps — the highest flight ever achieved by a manned electric and solar-powered plane. It’s higher than Solar Impulse record (9235 m).
This historic 5-hour-and-9-minute flight, powered entirely by solar energy and supported by thermal updrafts, marks a major step forward toward a more sustainable future. At cruising altitude, Domjan even crossed paths with a commercial airliner — a powerful symbol of what the decarbonised aviation of tomorrow might look like.
The official validation of the altitude is currently under review by the FAI (Fédération Aéronautique Internationale), in accordance with its altitude standards.
A moment of great pride and emotion for the entire SolarStratos team — fittingly celebrated with a well-deserved raclette!
On the eve of August 1st, the SolarStratos mission achieved a highly successful preparatory flight. Despite less-than-ideal conditions on Thursday, July 31, 2025—particularly in terms of thermal updrafts—Raphaël Domjan completed a 2-hour and 31-minute flight from Sion over the Alps, reaching an altitude of 6,589 meters, the highest ever attained by HB-SXA. This performance surpasses that of Klaus Ohlmann (6,376 m), making SolarStratos now the second-highest manned solar-powered aircraft in history. The entire team, with the necessary authorization in hand, is now ready and waiting for a favorable weather window to attempt the 10,000-meter altitude record over the Swiss Alps, which would surpass SolarImpulse (9,235 m). It’s also worth noting that HB-SXA crossed the 100-flight-hour mark on July 31.
Electric Cars on the Tarmac
After the “Planzer electric truck vs. solar-electric plane” challenge at the end of June, it was Genesis, another official partner of the SolarStratos mission, that took to the tarmac at Payerne Airport on July 5. The day featured breathtaking acceleration runs, all under the banner of electric mobility for a more sustainable world. Meanwhile, our aircraft HB-SXA had a busy July marked by notable flights — first a transfer to Sion, then a spectacular flight over the Matterhorn — all in preparation for the altitude record attempt with a manned solar-electric aircraft. Although the attempt couldn’t be made this summer, The Financial Times already featured it on the front page! Ready for a suspenseful August?
Perfect Transfer Flight
The transfer flight from Payerne to Sion, via the Sanetsch Pass, went flawlessly on July 10. Social media lit up with beautiful photos by Fred Fritzy, notably showing HB-SXA with the Château de Tourbillon in the background. The media coverage was also impressive, including features in Le Nouvelliste and on Canal9 | Kanal9 TV.
The Matterhorn Steals the Show
The power of imagery, the impact of the message! On Friday, July 18, Raphaël Domjan flew around the Matterhorn at the controls of HB-SXA. This preparatory flight yielded iconic images of the SolarStratos aircraft soaring on solar power in front of the legendary mountain. The flight made a strong impression far and wide: the photo of the day, picked up by major Swiss media outlets, was even published on the front page of The Financial Times Weekend! When it comes to showcasing the potential of solar energy, it doesn’t get much better than that.
When the Weather Says No…
The July 18 flight over the Matterhorn lifted spirits and gave the team a boost. Everyone was ready to continue with the final calibration flights at FL 250 (just over 7,600 meters), ahead of the attempt at 10,000 meters. But then… Except that Mother Nature threw us a curveball… : rain and wind grounded Raphaël Domjan and HB-SXA in the following days. Just take a look at the MeteoSwiss forecast for Saturday, July 27 — it’s almost unbelievable: nothing but gray skies. But hang in there — August will shine even brighter. And the record? Still within reach!
“Thank You, Sun!”
This brief setback with the weather hasn’t stopped solar energy from… skyrocketing! Raphaël Domjan shared the good news: in June 2025, for the first time ever on the European continent, solar power generated more electricity than nuclear, wind, or gas! A historic milestone. “A shift is underway: solar, once marginal, is now forcing a full-on paradigm change. We’re no longer burning raw materials to produce energy. We’re entering a world where energy is transformed — with nothing burned — at unprecedented efficiency,” said the pilot and founder of SolarStratos, concluding with a heartfelt, “Thank you, my sun.” Trying to fly up to 10,000 meters powered solely by sunlight gives the message even more weight.
Flying towards 10,000 m… and beyond
You might think solar energy with its infinite potential has become second nature, woven seamlessly into our habits, political decisions and new developments. Yet the reactions and comments on our social media remind us there is still work to be done! There are still sceptics who question the purpose of the challenges our electric solar aircraft takes on. This is exactly why our mission remains so important. Each flight by HB-SXA – like those in June preparing for this summer’s 10,000m flight over the Swiss Alps – is another symbolic step forward. Fulfilling the dream of Icarus: flying ever higher, without burning fossil fuels – or our wings. A powerful statement that a decarbonised future is already in motion. We invite you to join us for what promises to be an exhilarating summer!
Performance flights
Around 10 flights this month enabled us to perfect the variable-pitch settings of our new propeller and confirm the performance gains. The news is promising as we prepare to reach FL330 this summer: HB-SXA is climbing faster than ever. The test campaign ended with a performance flight on 25 June, when our test pilot reached FL170 – over 5,000 metres. This was also a chance to test the automatic power cut-off protection system – vital for optimising battery use and solar energy at high altitude. Now we head to Sion Airport, where the team will settle in to prepare for the 10,000 m attempt!
Truck vs. plane
It was like a scene from an action film on 23 June at Payerne Airport. An electric articulated lorry, the Volvo FH Electric T from our partner Planzer, sped along at 80km/h as our aircraft flew overhead and accelerated to 120km/h to win this ‘electric race’! The high-speed choreography was captured by helicopter. The goal – to raise awareness about switching to clean mobility to protect the planet – was achieved in full: numerous media outlets picked up the Keystone-ATS photo of the SolarStratos-liveried lorry, capable of carrying up to 20 tonnes of cargo with minimal CO2 emissions, being buzzed by our featherweight solar-powered aircraft.
Read the full story on Watson.ch.
Special Stratostime
To (re)experience the challenge with the Planzer electric truck, take a look at the special Stratostime edited by Stéphane Chopard, in charge of the videos and films documenting the SolarStratos mission. In one minute, this clip captures the intensity of the moment and the power of the image in promoting low-carbon transport for a more sustainable world
Flying with Fred To
A wonderful return to the future. In early June Raphaël Domjan and Fred To shared a flight rich in symbolism. To, a pioneer of the first solar adventure in 1978, took to the skies once more with today’s pioneer Domjan for an electric flight over Switzerland. A few days earlier, To – the co-designer of the world’s first solar aircraft – had also joined remotely from England for the opening of the PlanetSolar Foundation exhibition, which runs until 23 October at the Kosmos space of Primeo Energie in Münchenstein (BL).
The winner’s flight
Our online game – where you collect suns while avoiding clouds – culminates each year in a contest. This month the 2024 winner enjoyed his prize: an electric flight in a Pipistrel with Raphaël Domjan. Congratulations to Daryl, who achieved several top-10 finishes, including the current record of 17,900 points. For his flight from Ecuvillens he was joined by his sister Chloé, who also excelled in the game. Now it’s your turn! Enter the 2025 edition – it’s an unforgettable thrill to chase the sun across the sky.
Join the fun here: www.solarstratos.com/aventure/game.html
Worthy of an action film! On Tuesday 23 June, a spectacular demonstration took place at Payerne airport: an ultra-modern Planzer electric semi-trailer (the Volvo FH Electric T) rolled along the taxi-way, while the experimental electric and solar-powered SolarStratos aircraft flew alongside at 80 km/h, before accelerating to 120 km/h. A feat of synchronisation with a clear objective: to raise public awareness of the need to move towards clean mobility that preserves our planet, its climate and its biosphere.
There’s no better way to get the message across than this duo show of electric vehicles – one capable of carrying up to 20 tonnes of freight with very low CO2 emissions, the other flying on solar power, and this summer aiming for the highest flight ever made by a manned electric aircraft over the Alps. Then the ultimate flight to the stratosphere!
The media have covered this challenge for the future: https://www.swissinfo.ch/fre/payerne%3A-duel-in%C3%A9dit-entre-un-avion-solaire-et-un-camion-%C3%A9lectrique/89572474
HB-SXA finds its voice again
Latest news: Like the rest of the SolarStratos team, HB-SXA had been eager to return to the skies. Since 19 May, the aircraft has been flight-ready — and keen to make itself heard, its new variable-pitch propeller bringing a noticeable change in tone, with a deeper, more resonant sound! With the official Permit to Fly from the Federal Office of Civil Aviation in hand, Raphaël Domjan and our test pilot remained on standby, awaiting the first favourable weather window.
That window finally opened on Friday 23 May, when the first flight of the year was successfully completed — just ahead of an approaching thunderstorm. This 107th flight took place under the attentive gaze of a special guest: Mark Rocket, space enthusiast and CEO of Kea Aerospace, who is soon to become the first New Zealander in space as part of Blue Origin’s next mission. The result of this inaugural flight of 2025? Several performance enhancements — a promising beginning as the team looks ahead to the planned 10,000-metre flight this summer.
Ground thrust tests: a propeller that packs a punch!
Optimisation. Since 13 May, our home base in Payerne has been alive with activity. One major advantage of ground-based thrust testing? It can continue regardless of the weather — grey skies and rain included. A full sequence of tests was conducted according to a precise protocol, including fine-tuning the pitch of the variable propeller to optimise climb rate in relation to energy consumption.
The outcome confirmed the aircraft’s impressive performance: with HB-SXA securely anchored to the ground, the dynamometer recorded nearly 200 kilograms of thrust. And yes — thrust is the technically correct term, even if, like one of our online followers who raised the question, we tend to picture the propeller as ‘pulling’ the aircraft. Propeller thrust even has its own equation — in newtons, thrust (N) = mass (kg) × acceleration (m/s²).
We can even hear the birds sing!
Almost completely silent. One of the standout benefits of a solar-electric aircraft like SolarStratos — though several of you have rightly noted it isn’t entirely noise free — is just how much quieter it is compared to conventional aircraft (especially when set against the roar of FA/18 jets ripping through the skies above Payerne). While reviewing footage from recent ground tests, we were delighted to hear birdsong in the background — a gentle reminder of the aircraft’s near-silent operation.
Beyond offering a decarbonised way to experience the joy of flight, SolarStratos brings with it the added advantage of remarkably low noise emissions.
A curious new bird aboard: welcome Baptistou!
Team update. If you’ve been following us on social media or through our website, you may have spotted a new addition to the SolarStratos team. Jean-Baptiste Loiselet (whose surname translates as ‘little bird’) — better known as Baptistou — has joined us to support the technical operations around this summer’s preparatory flight campaigns, first in Payerne and then in Sion, ahead of our planned attempt to reach 10,000 metres. Armed with the insights gained last year, the team is more determined than ever to achieve this milestone — and Baptistou brings valuable expertise. A seasoned figure in solar aviation, he has spent the past several years developing a remarkable self-launching solar glider capable of autonomous flight. In 2022, he completed a fully solar-powered, solo tour of France in his aircraft, Sol.Ex. Find out more about his pioneering work at https://www.desailespourlaplanete.fr.
The final tests and adjustments are underway this week at the Swiss Aeropole in Payerne to kick off the preparatory flight campaign for the altitude record attempt scheduled this summer in Sion — and which the whole team is convinced will be a success!
The “song” of HB-SXA once again echoed through its home base. On Monday, various thrust tests were carried out with the aircraft secured to the ground, at different engine speeds and with various settings of the new variable-pitch propeller. The results were (very) conclusive: a thrust of around 200 kg was measured.
To the ear, one noticeable difference: the propeller’s sound is now one or two tones lower than before! But what beautiful solar music it is.
Ground tests, including taxiing, are continuing. We can’t wait to hear HB-SXA soaring through the skies again. It’s just around the corner…
When Solar Power Reaches New Heights
In Paris, the Avant-Garde Foundation brought together adventurer-author Sylvain Tesson and solar pioneer Raphaël Domjan for a breakfast event titled Collisions — and the ideas certainly soared. With both speakers deeply committed to sustainability and the future of our planet, the exchange inspired attendees like explorer Gauthier Toulemonde and left a powerful message: when visionaries meet, altitude is more than just physical.
Meanwhile, back on the ground — or rather, back in the air — the HB-SXA solar aircraft has returned from its maintenance in Germany. It’s now back at its home base in Payerne, fully restored and ready for flight. Test flights are scheduled from mid-May, aiming to assess new performance benchmarks — including altitude capabilities. A full weigh-in, à la professional boxing, is also on the schedule.
The sky’s the limit, once again.
Balanced to Perform
The HB-SXA didn’t just come back refurbished — it came back upgraded. A brand-new variable-pitch propeller now allows for more efficient climb performance. Ground tests have confirmed the precision of its balance and function, and early listeners report a subtly different, more electric hum from its engine.
This May’s flight tests will also include assessments of two new half-batteries, integrated to boost the aircraft’s overall energy potential.
Flying with the Sun
PV Magazine Spotlights SolarStratos: SolarStratos earned top billing in PV Magazine this month with an in-depth article by Ann-Marie Corvin, highlighting the project’s commitment to pushing the boundaries of solar-powered aviation. The centerpiece? A bold attempt this summer to reach 10,000 meters over the Swiss Alps — a potential world record in solar flight. A human-scaled mission, with sky-high ambitions. https://www.pv-magazine.com/2025/04/07/flying-with-the-sun/
To the Land of the sun god Inti
PlanetSolar II Reaches Lake Titicaca
While SolarStratos climbs the sky, PlanetSolar II sets sail — this time on Lake Titicaca, the world’s highest navigable lake, and a place deeply rooted in the sun-worshiping traditions of the Inca and their god Inti. The solar-electric boat, operated by the PlanetSolar Foundation, reached the Bolivian shores in late April to begin a scientific and promotional mission focused on solar-powered navigation.
In a touching ceremony in Puno, the Swiss Ambassador to Bolivia officially handed over the vessel to the Binational Authority of Lake Titicaca. Full story and images at www.planetsolar.org.
P.S. Even the trailer got a touch of sunshine! Back from Germany, it was time for a little refresh — and Raphaël Domjan himself took to the task with good humor and a pressure washer in hand. A fresh coat of paint, a bit of elbow grease, and voilà: ready for the next adventure.
