Automatic sun tracking solar energy device

An automatic sun tracking solar energy device comprises a drive unit, a solar panel mounted on the drive unit, a detection unit mounted on the solar panel, and a circuit unit electrically connected to the drive unit and the detection unit. The detection unit includes an opaque first substrate disposed on the solar panel substantially vertically, and a first optical sensor and a second light sensor respectively set on opposite sides of the first substrate. By using the first and second optical sensors to determine the relative angle of the sun, and through the circuit unit to control the drive unit to rotate the solar panel, a light receiving surface of the solar panel can be made facing the sun, so that the best power generation efficiency can be obtained with a relatively simple structure.