A method for fabricating a thin film solar cell includes providing a soda lime glass substrate comprising a surface region, treating the surface region with one or more cleaning process including an aqueous solution to remove one or more contaminants and/or particulates, and forming a lower electrode layer overlying the surface region. The method also includes performing a thermal treatment process to remove any residual water species to substantially less than a monolayer of water species from the lower electrode layer and soda lime glass substrate. The thermal treatment process changes a temperature of the soda lime glass substrate from a first temperature to a second temperature to pre-heat the soda lime glass substrate. Additionally, the method includes transferring the soda lime glass substrate, which has been preheated, to a deposition chamber and forming a layer of photovoltaic material overlying the lower electrode layer within the deposition chamber.