It is critically important that solar-car teams clock up test kilometres before the big race. This is partly because of what engineers call the “bathtub curve.” Failures in any piece of technology are common at the start, but then level out to a low constant failure rate during the object’s lifetime (and of course, once the object starts to wear out, failures increase again).
In the business world, short warranties are used to cover that early failure-prone period. In racing, it’s essential to make sure that the car is out of that early period before the race begins. Therefore, the top teams test, test, and test some more!
Here is a montage of recent solar-car testing, which I have already posted to Twitter: