Towards a Kinetic Model of Potential-Induced Shunting

Abstract

Potential-induced shunting (PIS) of wafer-based silicon solar cells is one of the most severe types of potential-induced degradation (PID). The correlation between laboratory PIS test results and the PIS behavior of PV modules in the field is still an open question. One reason for this is the fact that, due to intermittent stress, PIS is competing with regeneration episodes in the field unlike in most laboratory PIS setups. Since there is no detailed study of the regeneration from PIS available in literature, in this work, the overall kinetics of PIS is investigated. PIS is generated in the lab by applying a voltage bias to the cells of single-cell modules covered with grounded aluminum foil. Regeneration is enabled by eliminating voltage bias. The degradation and regeneration behavior is analyzed by shunt resistance (Rsh) measurements and performance measurements. It is found that in case of single-cell modules Rsh measurements are a suitable way to monitor the progress of PIS in terms of power degradation. The measurements reveal that the temperature dependences of both the shunting as well as the regeneration phase are Arrhenius like.