Continuing the analysis of my Solar Racing Basics Poster (see this tag), solar racing cars are powered by the sun (and, in the Cruiser class, also by some external recharging at Tennant Creek and Coober Pedy). The major components of the electrical system include:
- Silicon solar panels, up to 4 square metres in size for the Challenger class and 5 square metres in size for the Cruiser class. These will convert between about 20% and 25% of the sun’s energy into electricity, giving a maximum power level similar to that of a microwave oven.
- A maximum power point tracker or MPPT (like this one) and other high-voltage electronics which will control the voltage and current of the panels (or of sections of panel individually) in order to give the maximum power output possible under different sunshine conditions.
- A battery pack, made up of lithium-ion, lithium polymer, or lithium iron phosphate cells connected together (the first two kinds can catch fire if charged or discharged incorrectly; the third kind is safer, but twice as heavy). These battery packs are quite complex, including electronics to control charging, sensors to detect problems such as overheating, and cooling fans. Typically the total voltage of the battery pack is around 100–150 volts.
- An electric motor. The most efficient solution is usually to mount a motor in one or both of the back wheels (often using a design developed by the CSIRO). This avoids wasting precious energy in gears or a transmission. The motor will also do “regenerative braking,” sending power to the battery as the car slows down.
- A motor controller which controls the speed of the motor. This is in turn controlled by the throttle or accelerator pedal.
Click to zoom / Image credits: Anthony Dekker (Twente’s RED Shift showing solar panel, 2017), mostdece.blogspot.com (battery from team SunSpec, 2015)
To read more, see see this post about battery packs by Nick Elderfield of the University of Calgary Solar Car Team, this IEF Solar Car Conference presentation on the same subject, and this page on electrical systems in the Solar Car Wiki.