Liquid-based adjusting device (100) for a solar system comprising at least one holding element (1) for attaching at least one solar element, a swivel device (2), designed and intended for swiveling the holding element (1) around at least one swivel axis (S) and/or along a guiding curve (F) of the holding element (1), wherein one floating body (1A) of the holding element (1) is at least partially arranged below a filling level (30A) of the liquid tank (3A) and only by the buoyancy thereof the holding element (1) is swivel-mounted relative to one longitudinal axis (L) of the liquid tank (3A) around the swivel axis (S) and/or along the guiding curve (F) and mounted above the filling level (30A) directly on the rim (31A) of the liquid tank (3A), wherein the filling level (30A) of the liquid tank (3A) can be varied by means of a piping system (4) of the swivel device (1).