Abstract: A film deposition system for depositing a polycrystalline film on a large area substrate. The system includes a chamber formed of a set of walls, the set of walls defining at least three temperature zones within the chamber. Each of the walls is thermally insulated from the other walls forming the chamber. The system further includes a vacuum source, a set of heat sources, and a plurality of temperature detectors for detecting the temperature of the walls in the set of walls. Temperature control modules monitor and control the temperature in each of the temperature zones. The temperature control modules maintain predetermined temperatures in the walls so that the total mass of film-forming material lost through parasitic losses is less than the film mass deposited on the large area substrate. A method for depositing a polycrystalline film is also described.