Slashdot Mirror

← Back to Stories (view on slashdot.org)

World Solar Challenge Beginning

Posted by michael on from the spin-long-light-from-the-glory-of-the-sun dept.

Stuart Bowden writes: "Today (Sunday at 8:00am Central Australian time) is the start of the 2001 World solar Challenge, a sort of alternative Cannonball Run in which the solar cars cost up to $10 million. Over the next five days or so thirty three solar powered cars will race 3000km across the Australia desert powered only by sunlight. The official site is at WSC and there is extra gossip, pictures and information at our site at the University of NSW. We'll be doing the web upgrades on the road by begging connections at roadside diners and the occasional satellite phone. The big problem is keeping up with solar cars that don't stop for fuel." Our previous story had more links.

1 of 102 comments (clear)

  1. Making Solar Cells a misallocation of resources. by agotterba · · Score: 4, Interesting
    I've learned a lot about solar cells with the team at my school, including why development of new cells can be a poor investment of resources.

    Solar cells have a theoretical maximum efficency of not more than 50%. Currently, triple junction GaAs cells will get you about 35% (pretty close to the limit). Such an array for a solar car (5m by 1.8 m) can cost in the neighborhood of 500,000 USD. Meanwhile, a 19% Si array can be had for 70,000, and a 13 - 14% array for 10,000. As you can see, the price of an array has something of an exponential relationship to the efficency. To inprove the maximum efficency, you have to have the money to play with some very expensive toys. Only a few companies can afford such equipment (such as Honda and Aurora) and no school that I know of has a suffcient budget. We can (and do) play with making cells, but to commit to designing them and trying various chemistries and encapsulations requires more money than we have. Our object is to make cells that at a given efficency are cheaper than the ones on the market.

    Meanwhile, the only things that slow you down are rolling resistance and aerodynamic drag. Cutting weight usually requires nothing more than a lot of thought into material selection and structural design (not hundreds of thousands of dollars).

    Aero is a little more interesting, as there are tradeoffs betweeen the effective efficency of your array and your aerdynamic drag (for example, a taller car can catch more sun in the mornings and evenings, but will have more drag). These tradeoffs are related to how fast you want to go, and the conditions of the specific race you are designing for (whether it is primarily from north to south or east to west effects how you handle these tradeoffs; a car sloped to a particular side doesn't help if that side never faces the sun).

    Also worth mentioning is that all the American college teams that I know are in the WSC just came off competing in the American Solar Challenge. Teams that did not have large budgets in that race competed in stock class, where they were only allowed to spend $10 per watt that they expected out of their array (limiting them to silicon cells) and lead acid batteries. I do not know if any of those teams went to WSC, but that would explain their use of lower power cells.

    Photovoltaic cell research is one of the mose exciting fields of renewable energy, but when it comes to racing cars, you're more likly to win by buying the best array you can afford, and improving the other aspects of your car.