Each team will be given a starter kit of supplies that includes two solar panels. But as you design your project, you will need to obtain additional supplies. Remy Pangle from KidWind-VA states that she orders electrical supplies from Amazon (tape, bulbs, wire, etc) but depending on your project, you may need some specific things from the KidWind supplier, Vernier. Here is what you may need:

Extra solar panels: https://www.vernier.com/product/kidwind-2v-400ma-solar-panel/

Load Devices: https://www.vernier.com/product/kidwind-power-output-pack/

If you want to add a microcomputer to your project, you may want to buy an Arduino kit: https://store.arduino.cc/usa/