Crystalline silicon has been the dominant material for the production of solar cells for the past 20 years and this leadership is expected to continue. This is based on the inherent advantages of silicon as a semiconductor and on the major industry that has been built to manufacture silicon devices. A number of trends are becoming clear. Multicrystalline silicon usage is growing more rapidly than monocrystalline. There is a growing emphasis on high-efficiency solar cells and technology is permitting extremely thin wafers to be used. Advances are being made in ribbon silicon, and production of this material is increasing. The prospects are good for steady, continuous growth in photovoltaic solar cells, but establishing a sustainable supply of silicon feedstock remains a key issue as does balancing manufacturing the capacity with demand. (C) 2002 Published by Elsevier Science B.V.