Add the Temperature Controller
If adding a thermal switch/temperature controller, add a standard plastic electrical box to an area near the fan. After securing it into place, feed the cable into the box (which will house the controller) from the solar panel.
Connect one wire from the controller to the panel wiring, and connect the other wire to the fan wiring (Image 2). Use a wire nut to secure all together.
Secure the temperature controller within the electrical box and set a temperature that will activate the fan.