Swiss pilot Raphael Domjan got within around a thousand metres of setting a new altitude record in a solar-powered plane Sunday as he chases the goal of breaking the 10,000m barrier.

Self-described eco-explorer Domjan, 53, flew the SolarStratos electric plane to an altitude of 8,224m in a flight lasting around four and a half hours, his team told reporters, after he landed back at Sion airport in southwestern Switzerland.

The current altitude record for a solar plane stands at 9,235m, set in 2010 by the Solar Impulse experimental aeroplane, flown by Swiss pilot Andre Borschberg.

Domjan is aiming to get to 10,000m or beyond – flying at the same altitude as airliners.

A warm-up flight on July 31 got to 6,589m – the highest-ever for SolarStratos.

And an attempt on Friday was cut short when the rising warm air thermals needed to boost the ascent failed to materialise, with Domjan turning back to preserve the charge in the batteries.

Sunday's second attempt of the season set a new high altitude best for the two-seater SolarStratos, which has high-spec solar panels covering its huge 24.8m wingspan.

The slow-charging plane will be left out in the sun to get the batteries back up to 100% for the next attempt.

"To be a pioneer, an adventurer, it means trying something you are not sure will succeed," Domjan told AFP on Friday. "We'll try and try until we go to 10,000m."