ABSTRACT
With the recent expansion of the photovoltaic market, the reliability of crystalline Si cells, modules and materials has become a great concern for customers. The reliability has been investigated worldwide since the Flat-Plate Solar Array Project of USA in early 1980’s. In this paper, the issue is discussed from long- and short-term points of view. The long-term reliability includes more engineering matters, i.e. solarization of glass sheet materials, delamination, and discoloration of encapsulation materials. The short term relates to relative new phenomena regarding initial light-induced degradation of cell and module efficiencies due to minority-carrier lifetime degradation of crystalline Si materials. Forming a boron-oxygen complex or creating interstitial iron from iron-boron pairs is considered to generate the light-induced degradation of minority-carrier lifetimes. Two kinds of practical solutions to suppress light degradation are the usage of gallium dopant instead of boron and the reduction of interstitial oxygen and iron impurity.
