The invention relates to an automatic
sun tracking method and device, the method adopted is similar to the working principle of a sundial and comprises the following steps of: vertically arranging a pointer in the centre of a disk, using the shadow projected by sun to measure the position of sun, namely, detecting the position and direction of the shadow on the disk, and enabling the disk to rotate towards a direction opposite to the shadow to make the shadow finally disappear on the disk when the pointer points to the sun and the disk faces the sun. By the simple method, the sun can be automatically tracked. Moreover, an automatic
sun tracking device is provided based on the method, wherein an upper, a lower, a left and a right solar panels are arranged at the front face of the disk; since the projected shadow may cause a
voltage difference between two panels in
bilateral symmetry or in longitudinal symmetry, once the state is detected by a
detector, the orientation of a tracker is adjusted to make the shadow on the disk disappear, and at the same time, the symmetrical panels have no
voltage difference, a motor stops rotation, and the disk faces sun; and thus,
sun tracking is realized. The sun tracking device is simple in principle, skillful in structure, completely unmanned, high in tracking precision, and can be widely used in the development and the utilization of
solar energy.