Detroit Auto Show: Michigan solar team building new car under slower rules

click on the above image to view the photo gallery of the team exhibit

Solar cars are going too fast!

I stopped by the University of Michigan solar racer exhibit at the Detroit Auto Show and discovered that race organizers are slowing down the cars for upcoming major races. Even though the cars must compete on public roads and go no more than 65 mph, too many of them are running right on the edge. Top speed for some of the racers is over 85 mph. I talked with a few of the student engineers who said the latest rule book for the 20th running of the World Solar Challenge, which will be staged in Australia later this year, calls for changes that affect the aerodynamics and available power to slow down the vehicles.

The first significant ruling forces drivers to sit upright. Previous vehicles had the drivers lying in the prone position but now the seat-back angle is regulated. The new body design won't be as slippery with a bigger cockpit.

The other major change limits the area used for solar cells. In previous years the teams could put solar cells anywhere on the body, although there were dimension limits for the body. Now they're limited to about six square meters, robbing the teams up to 40 percent of their power generation. However, with a smaller solar array, there may be options to decrease the size of the body and possibly improve aerodynamics or reduce weight. The new restriction will also help teams with cost. Each gallium arsenide solar cell, which is about the size of a business card, costs $200 to $300.

The University of Michigan is the defending North American Solar Challenge champion. On display were the 2005 champion named Momentum and the 2001 champ named M-Pulse. Both vehicles also placed third in the World Solar Challenge, a 1,800-mile run down the middle of Australia. The team needs to raise more than $2 million to build the car (the solar array runs nearly $500,000) and for team support.

Click on the images above or below to see a high-resolution (1,280 pixel wide) image gallery of U of M's solar car display .