The utility model discloses a novel wall-hanging solar energy heat storage water tank, including water tank shell, inner water tank and heat transfer jacket, the heat transfer jacket is equipped with the notes liquid mouth that feeds through mutually with it, should annotate the liquid mouth and project to water tank shell outside, also includes the liquid level display that feeds through mutually with the heat transfer jacket, and the liquid level display includes that the medium flows into the pipeline, installs the transparency cover that flows into pipeline one end at the medium, and the other end that the medium flowed into the pipeline feeds through with the heat transfer jacket mutually, is equipped with the observation window corresponding with the transparency cover on the water tank shell. Also be equipped with in the transparency cover and be used for observing the floater that the interior liquid level of liquid level display changes. Can in time add the heat transferring medium when the floater is located or be less than the minimum scale mark of liquid level display, ensures the normal guarantee of work heat exchange efficiency of solar water heater. Whether the heat transferring medium of seeing that can be clear through observation window has rotten phenomenon, can in time change the medium, ensures that water tank, heat collector will not lead to the destructive damage of system because the medium deterioratees.