Siemens Solar has now introduced its next generation of solar modules, the ST5 and ST10 modules based on thin filmCuInSe2-alloys. Experience with volume production of CIS modules is described including production statistics for1×4-foot circuits with an average output of almost 40 watts, or nearly 11&percent; aperture efficiency. Module stability and package development is reviewed together with a survey of future manufacturing challenges. ©1999 American Institute of Physics.