Continuing the analysis of my Solar Racing Basics Poster (see this tag), it’s important to remember that the “best” car doesn’t always win the race. The work of the strategy subteam in the “chase vehicle” is also critically important. During the race, this subteam constantly calculates the best speed for the conditions, taking into account weather, road conditions, and existing battery charge. This includes deciding where it is worth speeding up to avoid upcoming bad weather. Making the right decision can be critical – the chart below (click to zoom) summarises the Challenger Class of the 2017 World Solar Challenge:
Road distance in this chart is from left to right, and the vertical axis shows how fast teams are (higher is slower, and the faint dashed lines show specific speeds). Teams 15 (Western Sydney University) and 88 (Kogakuin) were keeping up with the leaders, but made what in hindsight was the wrong decision when bad weather loomed, losing 6 or 7 hours as a result. Making the right decision under these circumstances is very difficult, however, and relies on good weather prediction services (or, as some teams have done in the past, on taking a meteorologist along).
Click to zoom / Image credits: NASA (unsettled weather across central Australia, 2013) and Vattenfall/Nuon/Delft Solar Team (interior of their chase vehicle for the 2011 World Solar Challenge)
In the Cruiser class, race strategy also includes deciding how many passengers to carry (more points, but more weight), and how much to recharge from the grid at stage stops (more energy, but fewer points). That makes Cruiser strategy an even more difficult problem.
To read more, see this post on Challenger strategy which I wrote in 2018.