Swiss firm Solar Impulse have unveiled a new aeroplane that they hope will be able to circumnavigate the globe using only solar power.

The single seat aircraft weighs 2.3 tonnes, and has with a wingspan of 72m, longer than a Boeing 747 jumbo jet, covered in 17,200 solar cells.

The plane has a top speed of 140km/h, and can theoretically remain airborne indefinitely, with the battery storing enough energy to last the night. However, for the round-the-world trip Solar Impulse plan to make stops at a number of cities en route to change pilots and hold local events.

The Solar Impulse 2 is the second generation solar plane from the firm, with the original Solar Impulse completing a solar-powered flight across the US last year, hopping from city to city.

Test flights for the Solar Impulse 2 begin next month, with the global trip scheduled for March 2015.