Image: SolarStratos

The SolarStratos, a Swiss-built stratospheric solar aircraft, has reached a personal best altitude of 8,224 meters, falling short of the current world record for a solar-powered flight but marking another step toward its ambitious goals.

The project team, which has been developing the aircraft since 2014, had planned an official attempt on August 8, 2025, to surpass the 10,000-meter mark as part of its long-term mission to reach 25,000 meters. While weather conditions were generally favorable, the lack of warm air updrafts—crucial for the final climb—prompted pilot Raphaël Domjan to postpone the record attempt to conserve battery power.

During this week’s four-and-a-half-hour flight, Domjan reached 8,224 meters—still below the team’s 10,000-meter target and the standing world record of 9,235 meters, set by Solar Impulse pilot André Borschberg. The team announced on social media that they will make another attempt in the coming days. The aircraft remains positioned in sunlight to recharge its lithium-ion batteries exclusively via its 22 m² solar panels, under official notarial supervision.

The two-seat SolarStratos measures 8.5 meters in length, with a wingspan of 24.8 meters and a weight of 450 kilograms. Its solar array, boasting 25% efficiency and an output of about 5 kWp, powers an electric motor designed for high-altitude, low-emission flight.

“Being a pioneer, an adventurer, is trying something you’re not sure will succeed,” Domjan told AFP. “We’re going to try again and again until we reach 10,000 meters. It’s important to demonstrate what we can achieve with solar energy and electricity.”