UV radiation hardness of photovoltaic modules featuring crystalline Si solar cells with AlO_x/p⁺‐type Si and SiN_y/n⁺‐type Si interfaces

Abstract

We report on the UV radiation hardness of photovoltaic modules with bifacial n-type Passivated Emitter and Rear Totally diffused crystalline Si cells that are embedded in an encapsulation polymer with enhanced UV transparency. Modules with front junction cells featuring an AlO x /p þ -type Si passivation interface at the illuminated side are stable for a UV irradiation dose of 598 kWh m À2 . In contrast, irradiating modules with back junction cells featuring an a-SiN y /n þ -type Si passivation interface at the illuminated side reduces the output power by 15%. The quantum efficiency of the a-SiN ypassivated module degrades in the spectral range between 300 and 1000 nm, which we ascribe to a degradation of the surface passivation. Modeling the experimental data shows that photons with an energy above 3.4 eV contribute to the degradation effect and enhance the front surface recombination current density by a factor of 15.

A 22.3% Efficient p‐Type Back Junction Solar Cell with an Al‐Printed Front‐Side Grid and a Passivating n+‐Type Polysilicon on Oxide Contact at the Rear Side

“…Please note that we demonstrated that this surface is UV stable in the laboratory thanks to the Al 2 O 3 /SiN x passivation stack. [ 32 ] We, therefore, consider POLO BJ cells are suitable for modules with UV transparent encapsulation polymers for achieving higher module power output and efficiencies. [ 33 ] We thus conclude that POLO BJ cells are a quite promising option for implementing electron‐collecting passivating contacts into p‐type industrial silicon solar cells.…”

UV‐induced degradation of high‐efficiency silicon PV modules with different cell architectures

“…However, UV exposure can disrupt this surface passivation by damaging the passivation layer itself or the passivation layer/Si cell interface 11–14 as well as causing subsurface damage in the silicon 15,16 . Different research groups have identified distinct wavelengths in the 300–400 nm spectral range as the damaging wavelengths of incident radiation for UV degradation of Si solar cells 13,14,17–24 …”

“…For example, JinkoSolar published an efficiency loss of −4% to −7% in industrial solar cells after exposure to approximately 540 MJ·m −2 (150 kWh·m −2 , i.e., 25 sunny days AM1.5G) of UVA light 25 . In some PERT cells, a UV dose of 1.8 GJ·m −2 at 40°C resulted in 15% power loss 21 . We note that the UVID described here results from the surface region and/or interface effect(s)—distinct from the typical LID (a fast initial power decrease attributed to the evolution of boron‐oxygen and boron‐iron complexes in the bulk of silicon) 26,27 and light and elevated temperature induced degradation (“LETID,” a slow progressing degradation activated during light exposure or via electrical current at temperatures above 60°C) 28,29 …”

Evolution of the external quantum efficiency of Si-based PV minimodules with encapsulated down-shifters and aged under UV radiation

“…3 to show that DS layers on high efficient c-Si and mc-Si solar modules can be detrimental for enhancing the efficiency of such devices, as we have explained elsewhere [25]. However, the high UV transparency of such devices could accelerate the passivation degradation of the solar cell, as it has been described in recent works [43,44]. Then, the DS can be also useful for absorbing UV radiation and, therefore, to slow the passivation degradation reported.…”