A solar still module for use in a solar still arrangement for producing a desired condensate from a feed treatment liquid. The solar still module includes a treatment chamber including a treatment member positioned below an upper solar energy transmission wall to receive, in use, solar energy therethrough. The solar still module includes a treatment liquid supply supplying treatment liquid to an upper end of a first region of the treatment member to flow in a liquid film flow gravitationally downwardly thereover while a component of the treatment liquid is at least partially evaporated and condensed to form a condensate on an inner surface of the upper solar energy transmission wall. The condensate flows gravitationally downwardly on the inner surface of the upper solar energy transmission wall and is collected at a lower location by condensate collection and discharge means. The upper solar energy transmission wall is formed by a clear or highly translucent polymer material with the inner surface being hydrophilic relative to the condensate. The treatment member is formed by a thin metal material as a tray having a tray base forming the first region. A perimeter wall extends upwardly from the tray base along at least side edges and lower edges of the tray base. An outwardly extending flange extends from an upper region of the perimeter wall. The flange is supported on a support frame.