Postmetallization “Passivated Edge Technology” for Separated Silicon Solar Cells

Abstract

This article introduces a postmetallization "passivated edge technology" (PET) treatment for separated silicon solar cells consisting of aluminum oxide deposition with subsequent annealing. We present our work on bifacial shingle solar cells that are based on the passivated emitter and rear cell concept. To separate the shingle devices after metallization and firing, we use either a conventional laser scribing mechanical cleaving (LSMC) process or a thermal laser separation (TLS) process. Both separation processes show similar pseudo fill factor (pFF) drops of − 1.2% abs from the host wafer to the separated state. The pFF of the TLSseparated cells increases by up to +0.7% abs from the as-separated state after PET treatment due to edge passivation, while the pFF of LSMC-separated cells increases by up to +0.3% abs. On cell level, the combination of TLS and PET allows for a designated area output power density of p out = 23.5 mW/cm², taking into account an additional 10% rear side irradiance.

Mitigating Cut Losses in Interdigitated Back Contact Solar Cells

“…3) Different strategies for mitigating cut losses have also been extensively investigated. It is possible to repassivate the cut edges by adding an additional layer of passivation [14], [15], [16]. Another promising approach is to introduce a specific pattern at the cell edge by using emitter windows or similar [17], [18], [19] or using laser doping [20].…”

Compensating Cutting Losses by Passivation Solution for Industry Upgradation of TOPCon and SHJ Solar Cells

“…However, the unpassivated silicon on the new cross sections created by cutting is still a problem that needs to be solved. Puzant Baliozian et al [34,36] solved this problem by depositing a AlO X layer using atomic layer deposition (ALD) along with a light soaking process. However, ALD technology is expensive and complicated, and more importantly ALD-deposited AlO X is incompatible with the thermal laser separation process (cutting water) used in production lines.…”

“…For the integration of stripes into shingle solar panel modules, it is necessary to cut the host/complete silicon cells into 1/2, 1/3, 1/4 or even more sub‐cells through a laser scribing process, [ 34 ] which will inevitably cause cutting damage and form new unpassivated edge surfaces, leading to a large decrease of PCE due to recombination. [ 35,36 ] The combination of water and thermal laser separation is currently used to solve the problem of cutting damage from the conventional laser scribing and mechanical cleaving process. However, the unpassivated silicon on the new cross sections created by cutting is still a problem that needs to be solved.…”

FoilMet®‐Interconnect: Busbarless, electrically conductive adhesive‐free, and solder‐free aluminum interconnection for modules with shingled solar cells

“…This, however, leads to higher consumption of precious resources as silver (Ag) or copper and magnifies shadowing effects. Another way to reduce the cell interconnection losses is the reduction of string currents by interconnecting separated, that is, smaller, solar cells such as half cells 2–10 and shingle cells 3,11–19 . Conventional shingling also increases the consumption of Ag 20 due to the necessity of Busbar and Ag containing electrically conductive adhesives (ECAs), however, reduces shadowing effects.…”

“…Another way to reduce the cell interconnection losses is the reduction of string currents by interconnecting separated, that is, smaller, solar cells such as half cells [2][3][4][5][6][7][8][9][10] and shingle cells. 3,[11][12][13][14][15][16][17][18][19] Conventional shingling also increases the consumption of Ag 20 due to the necessity of Busbar and Ag containing electrically conductive adhesives (ECAs), however, reduces shadowing effects. Since increased recombination occurs at postfiring separated edges, the cell pieces cannot be chosen arbitrarily small and a compromise between the reduction of series resistance and increase of edge recombination must be found.…”