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Title: From cells to laminate: probing and modeling residual stress evolution in thin silicon photovoltaic modules using synchrotron X-ray micro-diffraction experiments and finite element simulations

Fracture of silicon crystalline solar cells has recently been observed in increasing percentages especially in solar photovoltaic (PV) modules involving thinner silicon solar cells (<200 μm). Many failures due to fracture have been reported from the field because of environmental loading (snow, wind, etc.) as well as mishandling of the solar PV modules (during installation, maintenance, etc.). However, a significantly higher number of failures have also been reported during module encapsulation (lamination) indicating high residual stress in the modules and thus more prone to cell cracking. Here in this paper we report through the use of synchrotron X-ray submicron diffraction coupled with physics-based finite element modeling, the complete residual stress evolution in mono-crystalline silicon solar cells during PV module integration process. For the first time, we unravel the reason for the high stress and cracking of silicon cells near soldered inter-connects. Our experiments revealed a significant increase of residual stress in the silicon cell near the solder joint after lamination. Moreover, our finite element simulations show that this increase of stress during lamination is a result of highly localized bending of the cell near the soldered inter-connects. Further, the synchrotron X-ray submicron diffraction has proven to be a very effectivemore » way to quantitatively probe mechanical stress in encapsulated silicon solar cells. Thus, this technique has ultimately enabled these findings leading to the enlightening of the role of soldering and encapsulation processes on the cell residual stress. This model can be further used to suggest methodologies that could lead to lower stress in encapsulated silicon solar cells, which are the subjects of our continued investigations.« less
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  1. Singapore Univ. of Technology and Design (Singapore). Xtreme Photovoltaics Lab.
  2. Singapore Univ. of Technology and Design (Singapore). Xtreme Photovoltaics Lab.; National Univ. of Singapore (Singapore)
  3. Surya Univ., Tangerang (Indonesia). Center for Solar Photovoltaics Materials and Technology (CPV)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; 0416243; NRF2013EWT-EIRP002-017
Accepted Manuscript
Journal Name:
Progress in Photovoltaics
Additional Journal Information:
Journal Volume: 25; Journal Issue: 9; Journal ID: ISSN 1062-7995
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Research Foundation (NRF)/Economic Development Board (EDB) of Singapore
Country of Publication:
United States
14 SOLAR ENERGY; solar PV; crystalline silicon cell; synchrotron X-ray microdiffraction; finite element analysis; thermo-mechanical residual stress; encapsulation stress; soldering stress; CTE mismatch
OSTI Identifier: