The impact of the use of new (solar grade) silicon feedstock materials on the manufacturing Cost of wafer-based crystalline silicon photovoltaic modules is analyzed considering effects of material cost, efficiency of utilisation, and quality. Calculations based on data provided by European industry partners are presented for a baseline Manufacturing technology and for four advanced wafer silicon technologies which may be ready for industrial implementation in the near future. lso-cost curves show the technology parameter combinations that yield a constant total module cost for varying feedstock cost, silicon utilisation, and cell efficiency. A large variation of feedstock cost for different production processes, from near semiconductor grade Si (30 epsilon/kg) to upgraded metallurgical grade Si (10 epsilon/kg), changes the cost of crystalline silicon modules by 11% for present module technologies or by 7% for advanced technologies, if the cell efficiency call be maintained. However, this cost advantage is completely lost if cell efficiency is reduced, due to quality degradation, by ail absolute 1.7% for present module technology or by ail absolute 1.3% for advanced technologies. (C) 2009 Elsevier B.V. All rights reserved.