A fleet of high-tech solar cars has headed off under the Top End sun on a journey across the Australian outback and into the future of clean-energy motoring.
It's not just a race but a test of innovative technology that may drive the solar-powered vehicles of tomorrow.
The Bridgestone World Solar Challenge started in Darwin on Sunday, with 34 race cars from 17 countries silently whizzing off to drive 3000km south to Adelaide.
The event has been held every two years since 1987 and attracts a global audience of millions, watching solar-powered cars designed, engineered and built at universities and schools in Australia and around the world.
Team Sonnenwagen from Aachen University in Germany was the first to be flagged off, having claimed pole position in time trials on Saturday.
Moritz "Mitzi" Mitzel, 23, one of four drivers taking turns at the wheel, told AAP it was exciting to be in the high-tech race, especially innovating in different fields such as solar cells.
The 44-member Aachen team was ready for outback conditions, he said, with more than 3000km already driven around Coober Pedy in South Australia, including testing the car in high side winds and on rough road surfaces.
"It will be very hot, luckily it's winter ... so the most tough section will be here in the Northern Territory, further down south I think we won't have a big deal with the heat.
"The weather plays a huge role so we expect a tight field in the front and we hope to be part of that," Mr Mitzel said.
Isaac Lush, 20, a driver with the Adelaide University team, said they didn't finish the race last time they entered but hope to do so this year.
"If we don't break down at all, we'll be fine, if we do break down it'll be touch and go."
The team wasn't too concerned about the outback conditions they would face, Mr Lush told AAP.
"Most of us have been camping all our lives, we're obviously from Australia so a fair few people on the team have lived in those conditions."
Once the teams leave Darwin they must travel as far as they can until 5pm each day when they make camp in the desert wherever they happen to be.
Event ambassador Chris Selwood said designing and building a solar car to travel 3000km, qualifying then making it to the start was "an incredible achievement for those with dreams of a more sustainable future".
"Safety for everyone is paramount and that's one area that can't be compromised," he said.
The competition will have teams tackle vast open desert stretches and varied terrain in three classes: Challenger, Cruiser, and Explorer.
The Cruiser Class was created to encourage "green to the mainstream" concept cars kitted out with innovative, sustainable, and potentially practical features that could find their way into real-world design.
Driver-only Challenger class cars must travel 3000km on the power of sunshine, while Cruisers carry a passenger and in addition to solar power are able to charge from external sources after 5pm each day.
The Explorer Class provides an even broader platform to showcase prospective ideas, technology, and renewables.
Overseas entrants this year include teams from Germany, Sweden, Italy, the Netherlands, Estonia, Hong Kong, India, Japan, Taiwan and the US.
