Increased silicon ingot diameter and enhanced energy efficiency through numerical simulations

Solar cell (photovoltaics, PV) is the largest contributor to the world’s new renewable electricity production capacity. Nearly all PV is based on monocrystalline silicon wafers grown by the Czochralski method as large single-crystal ingots before being cut into thin wafers. NorSun has long been in the forefront of developing high quality monocrystalline n-type silicon. Today, NorSun is one of the few remaining European producers of monocrystalline silicon ingots and wafers. The global PV market is moving towards larger wafers and ingots. In DIAMANT, we will use detailed numerical models of the whole ingot pulling process, including physical properties and chemical reactions occurring throughout the duration of the many hours long pull. This will guide the understanding of crystal growth and growth parameters, in addition to the puller design. The location of NorSuns factory in Årdal secures a steady supply of green and low-CO2 electricity and cooling water. Throughout the project, resulting wafers will be processed and characterized to verify the numerical models and properties of the final products. The result will be world-leading sustainability and energy efficiency of PV wafer production.

NorSun is one of the few remaining European producers of monocrystalline ingots and wafers, with production facilities in Norway. The silicon PV market is trending towards larger wafers sizes where M10 and G12 format wafers from ingots produced in 36-40” hot zones are increasing most rapidly. Guided by detailed numerical modelling, DIAMANT will bring together state-of-the-art ingot and crucible dimensions, understanding of growth kinetics and puller design to obtain world-leading sustainability and energy efficiency. Detailed FEM models of the large diameter pullers will be established, and the physical properties and chemical reactions during the pulling process will be simulated. The models will be verified towards processing parameters as well as material characterization of the final product. The increased production volume and the increased yield will improve the overall energy efficiency of the monocrystalline silicon ingot production.