[Jeff K.]

Also, one thing that I think that was overlooked is the motor. What type of motor are you using?
From my experience with solar cars (1st place win in a Shell Solar Car Race), the amps do not matter so much with small solar cars. Putting the cells in series(higher voltage) is the best way to get the fastest car if you keep it as light as possible and reduce the friction in the drive as much as possible. If there is friction, then you may need to increase the current by having the cells in parallel.

The best way to do it would probably just be to make a prototype vehicle, and then test it to see what works best. It also depends on your area, how sunny it is because that affects how much sunlight the panels will absorb. We both live in SoCal...so that isn't really all that big of a deal, but we were limited to using the motor they provided us with as well as one of the solar panels they provided us with.

To your question though, having cells of different total volts in parallel isn't a good idea. It'll go slower, but have more current. Is the race uphill? or just a drag race?

Good luck with your car.