TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The chemical bath deposition system further comprises an analyzing device for analyzing the purified solution to generate the component ratio. The analyzing device is at least one of a classic titration device, an automatic titration device, an oxidation-reduction titration device, an acid-base titration device, a column-chromatography titration device, an atomic-absorption-spectrometry analyzing device, and an UV-visible-spectrometry analyzing device, and used for analyzing the purified solution by an online analyzing method or an off-line sampling method. The cation is at least one of a zinc ion, a cadmium ion, a mercury ion, an aluminum ion, a gallium ion, and an indium ion. The anion is at least one of an oxygen ion, a sulfur ion, a selenium ion, and a hydroxide ion. The chemical-solution purification device is at least one of a thermal processing device, an acid-base processing device, and an oxidation-reduction processing device. The chemical bath deposition system further comprises: a pre-cleaning device for cleaning the back electrode substrate before the back electrode substrate is placed in the chemical bath tank; a post-cleaning device for cleaning the back electrode substrate after the back electrode substrate is displaced from the chemical bath tank; and a cleaning-solution purification device communicated with the pre-cleaning device and the post-cleaning device, for purifying a cleaning solution generated by the pre-cleaning device and the post-cleaning device after the pre-cleaning device and the post-cleaning device clean the back electrode substrate and for guiding the cleaning solution back into the pre-cleaning device and the post-cleaning device. The cleaning-solution purification device is at least one of an ion-exchange resin purification device, a reverse-osmosis membrane dialysis device, an electrolytic purification device, and an oxidation-reduction processing device. The dosing device is used for performing compensation of the cation after the purified solution is directly guided back into the chemical bath tank.