This Doctoral Thesis comprises research on the reduction of cost and energy consumption of the production of ultrapurified silicon, so-called polysilicon. These respective reductions are essential to achieving two wider objectives for silicon based photovoltaic technology: low production cost and low energy payback time.A crystalline silicon photovoltaic module technology is defined and its production costs are presented. This allows cost and energy reduction measures to be compared and valued with regard to their impact on the final product. It further permits a cost-per-kilowatt comparison of the two main polysilicon production routes: the chemical route, with high quality and high cost; and the metallurgical route, with lower quality and lower cost. This costing exercise shows the quality of polysilicon (evaluated as the cell efficiency) to be an important driver for module cost-per-kilowatt reduction. Consequently, the presented research focuses on the high-quality chemical route. The presented theoretical analysis of polysilicon deposition in a CVD reactor consists in: (a) the study of the optimum deposition conditions by means of fluid mechanical theory; (b) the study of the thermal radiation of the hot silicon rods by means of thermal radiation heat transfer theory; and (c) the study of the electric heating of the silicon rod by means of electromagnetic theory. A novel fluid mechanical model is presented that proposes analytical expressions for the growth rate of polysilicon onto the silicon rods and for the energy loss by convection. The optimum deposition conditions, which reduce energy consumption, are derived from the model. The thermal radiation heat transfer within the CVD reactor is studied in detail for three state-of-the-art configurations: 36 rods arranged in 3 rings, 48 rods arranged in 3 rings and 60 rods arranged in 4 rings. Alternatives are presented regarding the reduction of the radiant energy loss during the polysilicon deposition: enlarge the reactor capacities, enhance the wall reflectivity and introduce thermal shields within the reactor vessel.An important factor affecting overall energy consumption is the maximum rod diameter reached at the end of the process. The main limitation for increasing this maximum diameter is the risk of melting the rod core. The temperature profile within the silicon rod resulting from electrical heating is modelled, and the limiting diameter at which the core begins to melt is calculated. Two alternatives are proposed for increasing the maximum Abstract diameter by reducing the non-homogeneous temperature profile: increasing the wall reflectivity/introducing thermal shields, and use of a high-frequency current source to heat the rods.Based on the presented theoretical study, a complete deposition process is proposed that is characterised by low energy consumption. The deposition conditions and the electrical conditions (current and voltage) for heating rods in a 36 rods CVD reactor are detailed.Finally, polysilicon deposition has been studied experimentall...

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