World Solar combatants rev their engines batteries

WSC The heat is rising here in the capital of Oz's Northern Territory ahead of tomorrow's starting flag of the World Solar Challenge.

El Reg's Special Projects Bureau is here braving improbable humidity, Oz beer and internet connection shenanigans to bring you the very latest on the world's leading heliowheels, but at 8:30am tomorrow we have to head off to the Outback for our own 3000km odyssey to Adelaide. So if this the last you hear of us we've either a) been killed in a collision with a kangaroo, or b) just got pissed off with the interwebs and decided to go Walkabout™.

Before we go, we'd like to bring you a bit more info about just how this thing works.

First up, we'll cover the rule change that has made the World Solar Challenge the most competitive race in years. Also we will cover some more of the contenders. Over the last couple of days, we've hooked up with Durham Uni and their admirably low-budget wheels - but here we'll have a shufti at some of the big swinging dicks.

According to race pundits, nine or ten teams are vying to win the race, including three "superstar" contenders: Nuon from the Netherlands, Tokai of Japan, and the University of Michigan, from, er, Michigan. The other contestants are here for different reasons - for the experience, the adventure. Their biggest challenge is to complete the course under their own steam, and that is a big ask. Event director Chris Selwood expects that just 30 per cent of the 39 contenders will reach the finish line without hitching a ride on a supporting trailer.

In it to win it

Due to race changes implemented this year, the frontrunners have mostly opted to use the same kind of solar array, sourced from one US company.

Until six years ago, teams were allowed to run on 8m sq of gallium arsenide arrays. These are very expensive and in real life are used only in outer space, unlike the silicon solar arrays that you can, say, find on houses.

Trouble is, this race is on the public highway and the cars were in danger of breaking speed limits (introduced at 130 kph a few years ago in NT and a feeble 110 kph in South Australia). On a practical note, the support vehicles mandated by law, one in the front and one behind the solarcar, had trouble keeping up with their charge. So rules were changed in 2009 to reduce solar coverage on the vehicles to 6sq m. The net effect of this was to reduce the energy to the cars by a mere four per cent, thanks to technological advances.

So the race organisers had another rethink and, instead of banning gallium altogether, ordained that such arrays were allowed a maximum of 3m sq. This prompted the most competitive teams to move en masse to silicon arrays - and mostly to silicon arrays supplied by the same company.

All the teams we spoke to have hailed this rule change, which has levelled the playing field. Ok, so it has levelled the playing field for the favourites. The solar arrays du jour remain prohibitively expensive for most of the players.

So let's talk about the superstars.