Multiscale thermo-mechanical fracture analysis of polycrystalline silicon shells in photovoltaic modules by a combined phasefield – continuum damage approach.

• Applicants: Professorin Dr. Laura De Lorenzis; Professor Dr.-Ing. Raimund Rolfes
• Subject Area: Mechanics ; Lightweight Construction, Textile Technology
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 400853899

The increasing global energy demand, ecological advantages and the economical benefits are three major points for the application of photovoltaic(PV)-modules. The dominating PV-module technology is based on polycrystalline silicon. Brittle fracture of polycrystalline Siliconwafers (PSWs), making up the PV-module, significantly degrades the electrical efficiency. Design of robust PV-Modules, therefore, inevitably requires a thorough investigation of damage events in PSWs.The objective of the present project is the development of an efficient and accurate model of damage induced by thermal or mechanical loads on the PV-module, both at the local scale of the PSW and the global scale of the PV. For this purpose a combined approach consisting of phasefield models on the local scale and a continuum damage approach on the global scale are persued. Essential aspects of the project are: (i) development of a novel phase-field model for brittle fracture accounting for the anisotropy in PSWs, (ii) developing a computational procedure to investigate the residual stresses in PSWs initiated from the production processes (cofiring, flattening, and soldering), (iii) developing a continuum-shell-element for the anisotropic phase-field model based on the geometrically nonlinear theory, (iv) development of a structural element for a PSW comprising of the PSW and the encapsulant (v) validation of the purely mechanical model by experimental analysis (vi) implementation of the thermo-mechanical coupling in the phasefield and continuum damage models (vii) verification by benchmark problems from the literature.These steps will be conducted within a close collaboration between ISD and IAM based on the expertise and experience of each side for the problem at hand.

• DFG Programme: Research Grants
• International Connection: Switzerland