Dutch team Nuon on Thursday crossed the finish line in an epic 3,000-kilometre (1,860-mile) solar car race across the Australian outback ahead of Japan's Tokai University, avenging their 2011 defeat.

The World Solar Challenge, first run in 1987 and last held in 2011, set off on Sunday from Darwin in northern Australia with the Dutch team's car Nuna 7 taking 33.05 hours to make the punishing trip to Adelaide.

It was a close battle until the last 50 kilometres when rain and cloud rolled in, forcing Nuon's arch-rival Tokai to stop and recharge, a setback that prevented them from winning a third consecutive title.

A Nuon spokesman said the team carried out precise calculations in advance to ensure they could reach the finish.

"We predict every second of the race. So we know exactly what weather is going to be where, how much is going to be in our battery and how much energy we're going to use with the speed we're driving at," he said.

"We actually calculated everything so that our battery would be fully empty finishing here and so that we could drive at the highest speed possible."

Nuon was narrowly defeated by Team Tokai in the 2011 race, when just 30 kilometres separated the first and second cars in one of the contest's closest finishes in its history.

Another Dutch team, Twente, came third, with Stanford from the United States running fourth as of the end of Thursday's racing and Belgium's Punch Powertrain in fifth place.

Teams from 20 countries were fielding cars in the race, which takes place every two years.

Crews were allowed to store a small amount of energy but most of their power had to come from the sun and their vehicle's kinetic forces.

The cars were allowed to drive between 8am and 5pm each day, and simply set up camp wherever they pulled off the road.

There were seven checkpoints along the route where drivers could get updates on their standings, the weather, and do basic maintenance -- clearing any debris from the car and adjusting tyre pressure.

Teams come from leading international universities and technical institutes and include private entrepreneurs, with the challenge designed to promote alternatives to conventional vehicle engines and showcase advanced automotive technology, according to the organisers.