André Borschberg, 61, escaped from the accident with minor injuries, Le Nouvelliste said in a report confirmed by the Solar Impulse team.
The accident occurred on the Brenay glacier near Arolla at an altitude of 3,500 metres, according to reports.
The cause and circumstances of the incident were not immediately known.
Borschberg was rescued by crew from a Swiss Air Force helicopter after he activated a distress signal at around 6pm, the ATS news agency said.
He was taken to hospital in Sion for treatment.
The pilot was making a training flight when the accident occurred, a spokeswoman from Solar Impulse told the news agency.
The Swiss accident investigation service has launched an inquiry.
Borschberg and adventurer Bertrand Piccard, who co-piloted the first balloon to circle the world non-stop, are leading the Solar Impulse project.
The project, involving technology developed at Lausanne’s Federal Institute of Technology (EPFL), aims to fly a solar-powered experimental plane around the world in 2015.
Borschberg and Piccard have already conducted test flights with a prototype aircraft powered by solar cells in Switzerland, from Spain to Morocco, and earlier this year, across the US.