NASC 2008: Principia takes 2nd!
After a grueling ten day endurance race similar to the Tour de France, solar cars rolled into Calgary in Alberta, Canada. The alien cars are hand built by teams of students from around the world. The stark contrast between a solar car and a normal road car highlights the difference in goals. Roads cars possess the comfort and capabilities to transport several people and their cargo; Solar cars are designed with absolute and total efficiency in mind, a reminder that solar panels can only provide so much energy.
It might be hard to imagine just how comprehensively different a solar car is, so here are the biggest differences between a Prius for example and Ra 7, my alma mater's solar car:
- Ra 7 uses the same amount of power as a toaster (30x less than a Prius)
- Prius has four wheels, Ra 7 has three for less rolling resistance
- Prius weighs 2,921 lbs, Ra 7 weighs 375 lbs
- The aerodynamics are almost 90x better on Ra 7
- Tire pressure is 3x higher on Ra 7 (the ride is a bit bumpier)
- There's no A/C on Ra 7
- Prius costs $22,000+, Ra 7 costs around $200,000
- Prius can take 5 passengers, Ra 7 only fits the driver
- Prius can drive without service for years, Ra 7 requires a pit crew
- Both have rear view cameras although only Ra 7 has no mirrors
Clear, sunny skies provide the solar array with enough power to cruise at 55-60 MPH without touching the 5 kilowatt-hour battery pack made from 55 lbs of lithium polymer battery cells (similar to laptop batteries). The pure efficiency of every system in the car makes for one slick, stealth-fighter-looking machine as you can see.
The arrays on these solar cars are very costly, very fragile, and very powerful. The best solar cars use triple-junction gallium arsenide solar cells meant for military satellites and Mars rovers. Even the most expensive of these solar arrays provide limited power for a vehicle to propel itself at speed. This necessitates a slender, aerodynamic shape that with maximum surface area facing toward the sun for the array. To illustrate the extremities these design goals are taken to, I submit this photograph taken from the front of the University of Michigan's solar car.
Not counting the canopy, the car is ten inches thick at its thickest point. Not much space for the driver and the plethora of electronics needed for driving and racing the car. Racing an experimental car requires strategy and safety, two factors contributing toward a series of sensors and computers on the car recording and transmitting temperatures, voltages, amp draws, speed, GPS coordinates, and pressures back to the team racing the car. A battery protection system (BPS) vigilantly watches for electrical problems that could harm the car or its driver. A fraction of a second is all it takes for the BPS to detect problems and take action.
Having raced in the 2005 North American Solar Challenge, I eagerly followed the 2008 North American Solar Challenge. Today concluded 2400 miles of racing between over a dozen teams from around the world. My team, the Principia Solar Car Team, placed second behind the University of Michigan and ahead of FH Bochum University from Germany. By far, this was the best result my team has ever accomplished, and considering Principia is a liberal arts college with 500 students and no engineering department, it's an impressive feat!
Since I no longer build and race solar cars, I am forced to feed my addiction with something else: Formula 1. The technical details satisfy my inner engineer who misses solar car racing.
