A bigger, redesigned version of a solar-powered plane that flew from coast-to-coast in the US last year has been unveiled in Switzerland, which its makers say will attempt to fly around the world without fuel next year.

An early version of the Solar Impulse successfully flew from the US west coast to the east coast, marking the first time the journey had been undertaken without fuel.

The new version, Solar Impulse 2, which has a wingspan around eight metres larger than its predecessor, was shown off on Wednesday. The plane's cockpit has also been completely redesigned, built to improve aerodynamics and reduce weight.

The Swiss team behind the plane hope to fly it for five days and five nights in March 2015, solely using electricity generated from the sun hitting the photovoltaic panel across its distinct wing. The power generated during the day will be stored in batteries for the night journeys, when it will fly slower to conserve power.

Bertrand Piccard, one of the plane's pilots and chairman of Solar Impulse, told a press conference: "In the day we can fly much faster then we did with the first prototype."

He also joked that "it's not the easiest way to fly around the world, but probably the most spectacular to attract the awareness ... to show what we can do with renewable energies."

Several test flights will be undertaken in 2014, before the round-the-world attempt next year, which is expected to take several months with around 20 days in flight.