movement). In contrast, an east-west race alignment might reduce the benefit from having cells on the side of the vehicle, and thus might encourage design of a flat array. Because solar cars are often purpose-built, and because arrays do not usually move in relation to the rest of the vehicle (with notable exceptions), this race-route-driven, flat-panel versus convex design compromise is one of the most significant decisions that a solar car designer must make. For example, the 1990 and 1993 Sunrayce USA events were won by vehicles with significantly convex arrays, corresponding to the south-north race alignments; by 1997, however, most cars in that event had flat arrays to match the change to an east-west route. Race strategy Energy consumption Optimizing energy consumption is of prime importance in a solar car race. Therefore, it is useful to be able to continually monitor and optimize the vehicle's energy parameters. Given the variable conditions, most teams have race speed optimization programs that continuously update the team on how fast the vehicle should be traveling. Some teams employ telemetry that relays vehicle performance data to a following support vehicle, which can provide the vehicle's driver with an optimum strategy. Race route The race route itself will affect strategy, because the apparent position of the sun in the sky will vary depending on various factors which are specific to the vehicle's orientation (see "Race Route Considerations," above). In addition, elevation changes over a race route can dramatically change the amount of power needed to travel the route. For example, the 2001 and 2003 North American Solar Challenge route crossed the Rocky Mountains (see graph at right). Weather forecasting A successful solar car racing team will need to have access to reliable weather forecasts in order to predict the power input to the vehicle from the sun during each race day. See also List of solar car teams Race the Sun South African Solar Challenge Tour de Sol Hunt-Winston School Solar Car Challenge The Quiet Achiever, the world's first solar-powered racecar American Solar Challenge References External links Howstuffworks.com: How solar cars work Solar Decathlon website. DOE announced that the third Solar Decathlon competition will be held from 2007-October 12th through the 20th in Washington, D.C. Solar cars in inventors.about.com World Solar Challenge website American Solar Challenge International Solar Car A - Z The Dell-Winston Solar Challenge South African Solar Challenge Carrera Solar Atacama https://web.archive.org/web/20080517201319/http://web.ew.usna.edu/~bruninga/APRS-SPHEV.html National