A solar panel cleaning system comprising: a plurality of solar panels arranged in a row; a pair of rails extending along the direction in which the plurality of solar panels are arranged, and provided on both sides across the solar panels; a double-column structural frame movably supported on the rails on both sides of the solar panels and arranged to surround the upper surfaces of the solar panels; a moving device for moving the structural frame along the rails; a rotating brush provided on the structural frame, having a rotation center extending in a direction intersecting the direction in which the plurality of solar panels are arranged, and arranged to be able to come into contact with the upper surfaces of the solar panels; and a drive device provided on the structural frame to rotate the rotating brush, characterized by comprising a water catching unit provided to spread over the upper surface of the structural frame to collect rainwater at the time of rainfall; a water pouring unit for pouring the rainwater collected by the water catching unit into the rotating brush; and a mount for supporting the solar panels to be capable of tilting in a virtual plane orthogonal to the direction in which the plurality of solar panels are arranged, wherein the mount includes a locking device (821, 822, 86R, 86L) for locking the tilt of the mount at a plurality of locking positions to be able to be engaged and disengaged, and the solar panel cleaning system includes a locking device operation unit provided between the structural frame and the mount, and moving the locking position locked by the locking device (821, 822, 86R, 86L) to the next locking position, which is another locking position, in conjunction with the movement of the structural frame by the moving device. a plurality of solar panels arranged in a row; a pair of rails extending along the direction in which the plurality of solar panels are arranged, and provided on both sides across the solar panels; a double-column structural frame movably supported on the rails on both sides of the solar panels and arranged to surround the upper surfaces of the solar panels; a moving device for moving the structural frame along the rails; a rotating brush provided on the structural frame, having a rotation center extending in a direction intersecting the direction in which the plurality of solar panels are arranged, and arranged to be able to come into contact with the upper surfaces of the solar panels; and a drive device provided on the structural frame to rotate the rotating brush, characterized by comprising a water catching unit provided to spread over the upper surface of the structural frame to collect rainwater at the time of rainfall; a water pouring unit for pouring the rainwater collected by the water catching unit into the rotating brush; and a mount for supporting the solar panels to be capable of tilting in a virtual plane orthogonal to the direction in which the plurality of solar panels are arranged, wherein the mount includes a locking device (821, 822, 86R, 86L) for locking the tilt of the mount at a plurality of locking positions to be able to be engaged and disengaged, and the solar panel cleaning system includes a locking device operation unit provided between the structural frame and the mount, and moving the locking position locked by the locking device (821, 822, 86R, 86L) to the next locking position, which is another locking position, in conjunction with the movement of the structural frame by the moving device.