Mechanical Reliability of Photovoltaic Cells under Cyclic Thermal Loading

Sonawane, D and Ramamurthy, PC and Kumar, P (2020) Mechanical Reliability of Photovoltaic Cells under Cyclic Thermal Loading. In: Journal of Electronic Materials, 49 (1). pp. 59-71.

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Abstract

Metallic coatings placed on solar cell should retain their structural integrity over the life-span of the devices in order to ensure their reliable functioning. One critical component of such a life-assessment exercise is based on their response to the cyclic thermal stresses generated due to the temperature fluctuation, which is inevitable during regular operation of a solar cell and the difference in the thermal expansion coefficients of metal coatings and Si. Here, we have studied the impact of accelerated thermal cycling on the integrity of the semiconductor–metal layer in a commercial monocrystalline Si based photovoltaic solar cell comprising Ag finger-lining and Al backside coating. We observed that, compared to Si-Ag interface, the Al-Si interface was significantly weaker, wherein cracks easily nucleated and grew during thermal cycling between − 40°C and 90°C. The experimental results were augmented with finite element method (FEM), including extended-FEM (XFEM), simulations using geometry based on the actual microstructure of various metal-Si interfaces in the solar cell module. FEM-based simulations suggest excessive stress concentration at the interface of Al-Si eutectic-Al layers due to the irregular wavy nature of this interface. XFEM results indicate the critical role of the interfacial adhesion strength and roughness of the eutectic-Al interface on the crack growth and its propagation path. Based on the obtained results, a discussion on the fabrication of solar cell modules resistant to thermal stress induced structural damage is presented.

Item Type:	Journal Article
Publication:	Journal of Electronic Materials
Publisher:	Springer
Additional Information:	The copyright for this article belongs to Springer.
Keywords:	Aluminum coatings; Aluminum compounds; Artificial life; Crack propagation; Cracks; Eutectics; Fracture; Metals; Photoelectrochemical cells; Photovoltaic cells; Silicon solar cells; Silver compounds; Solar power generation; Structural analysis; Thermal cycling; Thermal expansion; Thermal stress, Accelerated thermal cycling; Interfacial adhesion strength; Mechanical reliability; Photovoltaic solar cells; Si-based solar cells; Temperature fluctuation; Thermal expansion coefficients; XFEM, Silicon compounds
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	08 Feb 2023 09:22
Last Modified:	08 Feb 2023 09:22
URI:	https://eprints.iisc.ac.in/id/eprint/80077

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