Potential‐Induced Degradation in High‐Efficiency n‐Type Crystalline‐Silicon Photovoltaic Modules: A Literature Review

Abstract

n‐Type crystalline‐silicon (c‐Si) photovoltaic (PV) cell modules attract attention because of their potential for achieving high efficiencies. The market share of n‐type c‐Si PV modules is expected to increase considerably, with wide use in PV systems, including large‐scale PV systems, for which the system bias is set as markedly high. Such a high system bias leads to performance losses known as potential‐induced degradation (PID). By virtue of many researchers’ efforts, the PID behaviors, mechanisms, and preventive measures against PID have been well documented in conventional p‐type c‐Si modules. Researchers recently started to investigate PID in high‐efficiency c‐Si solar cells including n‐type c‐Si PV modules. Yet, the understanding of PID phenomena remains incomplete. Herein, a literature review of PID in high‐efficiency n‐type c‐Si PV modules is provided as a resource elucidating the current status of related research and remaining unresolved issues. This report mainly presents discussion of PID in several kinds of n‐type c‐Si PV modules in terms of materials science. PID phenomena are described as divided into some degradation modes. Details present a review of their respective degradation modes, degradation behaviors, proposed mechanisms, and potential measures against degradation. Remaining open issues and anticipated future studies are also summarized.

Polarization-Type Potential-Induced Degradation in Front-Emitter p-Type and n-Type Crystalline Silicon Solar Cells

“…Recently, potential-induced degradation (PID) has been identified as a central reliability issue of photovoltaic (PV) cell modules. − Causing marked degradation in a short time, such as several months, PID is triggered by potential differences between grounded frames and the active circuit of cells in modules in the field. The PID behavior varies to a considerable degree depending on PV cell material, structure, and PID-stress intensity. , For instance, sodium-penetration-type PID (including shunting-type PID), − polarization-type PID, − and corrosion-type PID ,− are known to occur depending on these factors.…”

Effects of SiNx refractive index and SiO2 thickness on polarization‐type potential‐induced degradation in front‐emitter n‐type crystalline‐silicon photovoltaic cell modules

“…Particularly, polarization-type PID is the fastest degradation mode among all of the PID modes. 11 It has been observed for c-Si cells of several types, including n-type passivated emitter and rear totally diffused (n-PERT) cells, [12][13][14][15][16][17][18][19][20][21] n-type interdigitated back-contact cells with front surface field 22,23 or with front floating emitters, 24 p-type passivated emitter and rear cells, 19,25 and p-type conventional c-Si cells. 26 Polarization-type PID is characterized by reduced short-circuit current density J SC and open-circuit voltage V OC .…”

“…The application of PV cells in large‐scale PV systems requires knowledge of the behaviors and mechanisms of their potential‐induced degradation (PID) 5–11 . Actually, PID is triggered by potential differences between grounded frames and the active circuit of cells in modules.…”

“…Therefore, such PID can occur even in small‐scale PV systems with low system voltages. Additionally, some of the preventive measures that have been developed for PID in conventional p‐type c‐Si PV modules are known not to be consistently effective for polarization‐type PID 11,18 . These features make polarization‐type PID a more severe problem.…”

“…The application of PV cells in large-scale PV systems requires knowledge of the behaviors and mechanisms of their potential-induced degradation (PID). [5][6][7][8][9][10][11] Actually, PID is triggered by potential differences between grounded frames and the active circuit of cells in modules. One feature is that a marked degree of degradation appears quickly, such as within several months, in the field.…”