An installation method of a solar panel includes: an installation step of installing the solar panel such that a light receiving surface of the solar panel is inclined with respect to the horizontal direction and faces the sun; and an ultrasonic vibrator arrangement step of arranging an ultrasonic vibrator generating ultrasonic vibration to the light receiving surface of the solar panel, before or after the installation step is performed, and snow or dust deposited on the light receiving surface of the solar panel is removed by the ultrasonic vibration.