Changes in the current density-voltage and external quantum efficiency characteristics of n-type single-crystalline silicon photovoltaic modules with a rear-side emitter undergoing potential-induced degradation

This study addresses the potential-induced degradation (PID) of n-type single-crystalline silicon (sc-Si) photovoltaic (PV) modules with a rear-side emitter. The n-type rear-emitter module configurations were fabricated using n-type bifacial sc-Si solar cells by module lamination with the p(+) emitter side down. After the PID tests applying -1000 V, the modules show a rapid decrease in the open-circuit voltage (V-oc), followed by relatively slower reductions in the fill factor and the short-circuit current density (J(sc)). Their dark current density-voltage (J-V) data and external quantum efficiencies (EQEs) indicate that the drop in V-oc is caused by an increase in the saturation current density due to the enhanced surface recombination of minority carriers. In contrast, the modules exhibit slight degradation under +1000 V, which is characterized by only slight decreases in V-oc and J(sc). The EQE measurement reveals that these decreases are also attributed to the enhanced surface recombination of minority carriers. This behavior is almost identical to that of the polarization effect in n-type interdigitated back contact PV modules reported in a previous study. By comparing the PID resistance with that of other types of modules, the n-type rear-emitter PV modules are relatively resistant to PID. This may become an advantage of the n-type rear-emitter PV modules. (C) 2016 Elsevier B.V. All rights reserved.