Integrating the Value Chain: The Impact of Silicon Quality on Cell Performance

In the current market, about 90% of the PV systems are based on silicon solar cells. Despite several predictions that thin-film solar cells would take over the market, silicon has remained the dominant technology. One of the main reasons is that the prices of silicon photovoltaic modules have come down dramatically over the last two years. This is for a large part due to the strongly increased manufacturing capacity, especially in Asia, and the reduction in European subsidy levels. Also, the wealth of knowledge on silicon processing from the semiconductor industry and the supplier industry combined with the results from the solar research institutes in Europe, has improved both the cell performance and the quality of manufacturing. In order to cope with the strong decline in module prices, there is a need to establish more and more aggressive cost roadmaps for manufacturing. These cost roadmaps are driven by: (1) the costs of silicon feedstock, (2) the conversion costs to convert silicon into PV modules, and (3) the conversion efficiency of the cells, driving module power. Vertically integrated companies have the advantage that they can work on all aspects of the cost roadmap, and that they have the ability to evaluate changes throughout the full value chain. In this paper, the advantages of vertical integration over the value chain will be discussed for 3 specific cases: the introduction of FBR feedstock material, the evaluation of furnace performance on cell efficiency and the impact of thinner wafers on cell efficiency and mechanical yield.