A solar freshwater self-produced ecological film floating on the sea is proposed in this study. The film consists of a floating transparent material in which multiple cavities with a special interior structure concentrate sunlight and produce fresh water. The film can not only produce fresh water using solar energy but also has enough additional space to grow crops. Hence, the film allows realisation of the concept of floating agriculture on the sea. The operating principle of the film and an energy analysis of the solar desalination process are introduced. An optical simulation of concentrating and computational fluid dynamics computation of the heat and mass transfer in the internal structure of the device are also provided. The parameter ranges and the avenues for improvement of the system's structure and thermal performance were provided. Finally, by testing the performance of an actual device, the relation of changes in operation temperature, water yield and solar-thermal conversion efficiency under various solar irradiance conditions and various times was investigated. The results show that under 1000 W/m(2) irradiation, the fresh water yield of the experimental device was 195.1 g/m(2).h, the effective evaporation efficiency was 45.4%, the solar-thermal conversion efficiency was 16.5%, and the temperature for evaporation was 50.8 degrees C.