Effects of impurities concentration on the efficiency of solar cells manufactured with upgrade metallurgical silicon

In this work we reported the production of upgraded metallurgical grade silicon using a combination of different purification techniques, i.e., vacuum degassing, directional solidification and Czochralski growth. Chemical composition, resistivity and efficiency of silicon solar cells are presented. It was observed that those methods have different purification efficiency for different elements. The use of vacuum degassing is demonstrated to be a potential procedure to be used in a combination with other techniques to reduce impurities in metallurgical silicon as well as reduce the final price of the silicon wafers. The combination of vacuum degassing and Czochralski method provided upgraded metallurgical grade silicon. Solar cells efficiency approaching 10% was obtained using this material.