The top contenders have all covered more than half of the 3000-kilometre race distance as they continue average about 90km/h.

Still holding sway through the Kulgera checkpoint on Wednesday was Dutch Solar Team Twente in their RED E car which had an 11-minute lead over defending champions Vattenfall in NunaX.

Travelling in third place was the Belgian team Agoria with their Bluepoint car about 30 minutes behind the leader.

Germany's Sonnenwagen also continued to impress and was about 25 minutes behind the Belgians in fourth place.

The teams will spend tonight camped in the SA outback ahead of Wednesday's big push across the state in a leg that is likely to decide this year's race.

Changing weather conditions could play a big part with forecast stronger winds in the mid-north likely to pose a challenge.

Rain and cloud could also be a factor as the cars get closer to Adelaide.

Weighing in at just 160 kilos, Twente's RED E car is the smallest in the field and could be hampered by the changing conditions.

The World Solar Challenge for purely solar-powered cars has been held biannually since 1987, promoting sustainability and solar technology.

Australian Associated Press