MELBOURNE : More than 40 racing teams from 21 countries left Darwin on Sunday to race across Australia to the southern city of Adelaide is the world’s fastest solar-powered cars.The 3,000 kilometers (1,864 miles) Bridgestone World Solar Challenge is one of the most prestigious solar car races. The biennial event first began in 1987 and is based on a notion that a 1000 watt car would complete the trip from Darwin to Adelaide in 50 hours. The teams are expected to complete the race by Thursday, with speeds of 90-100 km (55-62 mph) powered only by the sun. In the week preceding the event, teams had to pass a series of practical safety and compliance tests to qualify for the start line.Top Dutch Solar Racing team car ‘Green Lightning’ led off the competitors from Darwin’s State Square after earning pole position with the fastest lap at Hidden Valley Raceway on Saturday. The teams, comprising of secondary and tertiary students from countries ranging from Australia through Sweden, Netherlands, and Japan to the United States, must be self-sufficient, traveling each day as far as they can until 5 p.m. and making camps to stay overnight along the route through the desert. The solar vehicles are categorized to compete in three different classes: challenger, cruiser, and adventure.