Abstract: A solar tracker includes a main frame, pivotal first and second frames to both sides of the main frame respectively, solar panels on the frames, a vertical axle under the main frame, two hydraulic cylinders each having one end pivotably secured to the vertical axle and the other end secured to the bottom of the first or second frame, a support comprising two spaced inclined members pivotably secured to the bottom of the main frame, an extension board on an intermediate portion of the vertical axle, the bottom of the support being pivotably connected to the vertical axle, a telescopic actuating member secured to the extension board and engaged with the bottom of the main frame proximate to an edge of the main frame, a rotational seat rotatably secured to the vertical axle, and a vertical moving device comprising a platform for supporting the rotational seat.