Raphaël Domjan already made history once, as the initiator of PlanetSolar, the first boat to circle the world on solar power. His next goal was even more ambitious: fly a solar plane with a pilot into the stratosphere, above 20,000 m, where the sky turns dark blue and you can see the curve of the Earth.
The aircraft, SolarStratos (registration HB-SXA), was designed and built by Calin Gologan of Elektra-Solar in Germany. It is a two-seater with a 24.8 m wingspan carrying 22 m² of high-efficiency solar cells. The whole plane weighs about 450 kg. A 32 kW electric motor turns a 2.2 m propeller, and a 20 kWh lithium-ion battery stores energy for the climb.
On 12 August 2025 Domjan took off from Sion airport in the Swiss Valais and, in a 5-hour 9-minute flight on solar power helped by thermals, climbed to 9,521 m above the Alps. That beat the 9,235 m set by Solar Impulse pilot André Borschberg in 2010, and made it the highest flight ever by a crewed solar-electric aircraft (FAI validation was pending at the time).
Next on the list: going above 10,000 m, and eventually reaching the stratosphere wearing a pressure suit.
Technical data
| Designer / builder | Calin Gologan, Elektra-Solar GmbH (Germany) |
|---|---|
| Mission / pilot | Raphaël Domjan (Switzerland) |
| Seats | 2 |
| Wingspan | 24.8 m |
| Solar | 22 m² of solar cells |
| Weight | ~450 kg |
| Motor / battery | 32 kW electric, 2.2 m propeller / 20 kWh Li-ion |
| Record flight | 12 August 2025, Sion: 9,521 m, 5 h 09 min |
Photo (Payerne hangar): FNansen1921 / Wikimedia Commons, CC BY-SA 4.0
Sources: SolarStratos (2025) · Wikipedia: SolarStratos · CleanTechnica