Thermomechanical stress in solar cells: Contact pad modeling and reliability analysis

Rendler, L.C.; Romer, Pascal; Beinert, Andreas J.; Walter, Johann; Stecklum, S.; Kraft, Achim; Eitner, Ulrich; Wiese, S.

doi:10.1016/j.solmat.2019.03.041

Cited by 24 publications

(11 citation statements)

References 28 publications

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“…For distances to This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see http://creativecommons.org/licenses/by/4.0/ the cell edge larger than about 8 mm, the maximum tensile stress is independent of the solder joint length [18]. This implies that for the performed variations-assuming the same metallization layout for all variations-the contribution of the solder joint to the total stress is approximately constant.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Cell and Module Dimensions on Thermomechanical Stress in PV Modules

Beinert

Romer

Heinrich

et al. 2020

IEEE J. Photovoltaics

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We present an evaluation of the silicon solar cell as well as the photovoltaic (PV) module size and its effect on thermomechanical stress. The evaluation is based on finite-element method (FEM) simulations. Within these simulations, we perform parameter variations of the number of solar cells within a PV module from 60-140 cells, of the cell size from 156.0-161.75 mm, and the cell format from full cells down to quarter cells. The FEM simulations cover the lamination process, mechanical load, and thermal cycling for glass-foil as well as glass-glass modules. The presented results reveal correlations between the solar cell and module size with the stress in the solar cells. We also find that the interaction of the laminate with the module frame plays a significant role in thermal cycling. Of the varitations under investigation, the increase in cell size has the largest effect on the stress. However, at a mechanical load of 2400 Pa, glass-foil modules with less than 96 solar cells have a negligible failure probability. The advantage of placing the solar cells in the neutral axis of the laminate is proven by the negligible tensile stress values for all variations of the glass-glass modules.

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Section: Methodsmentioning

confidence: 99%

The Effect of Cell and Module Dimensions on Thermomechanical Stress in PV Modules

Beinert

Romer

Heinrich

et al. 2020

IEEE J. Photovoltaics

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“…The manufacturing process of PV modules from silicon solar cells is conventionally performed by soldering copper strips to the solder and metallizing the contact area. Contact shooting and screen printing are used for this purpose [4].…”

Section: Introductionmentioning

confidence: 99%

“…Since PV modules are installed outdoors, thermo-hygrometric cycles, wind gusts, snow, and hail are the main sources of damage and degradation over the estimated 25 years of operation. To determine whether the solar cell and mechanical stresses exceed the permissible stress levels, several studies used the Finite Element Method (FEM) [4]. Beinert et al analyzed mechanical stresses in frame-based and non-composite PV modules, where mechanical stresses were induced [6].…”

Section: Introductionmentioning

confidence: 99%

“…Beinert et al analyzed mechanical stresses in frame-based and non-composite PV modules, where mechanical stresses were induced [6]. Other studies focused on determining the influence of joints [7] and their coating, mechanical properties [8], and geometry [4] on the mechanical stresses of PV modules. Mechanical impacts are among the factors most affecting the reliability and rigidity of PV modules [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…The newly-developed testbed allows achieving the parameters used in similar research (ball speed and the impact force) [11]. Most studies simulate the effects of hail using pneumatic equipment that provides the energy needed to move a piece of ice [2,4,[32][33][34][35][36]. The hail test requires expensive, time-consuming equipment.…”

Section: Introductionmentioning

confidence: 99%

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Research of the Energy Losses of Photovoltaic (PV) Modules after Hail Simulation Using a Newly-Created Testbed

et al. 2019

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The impact of hail ice cubes on composite structures (such as solar cells) causes actual defects. This article presents a series of tests, in which solar cell modules were exposed to hail simulation testbed balls, allowing to assess the following: the impact energy, which causes the major defects in solar cells; the formed micro-cracks in the structure of solar cells, resulting in the loss of power generated by a solar cell; and the solar cell parameters necessary for modelling. In addition, this article presents a digital analysis of hail simulation. Information received from the digital analysis was used to optimize the structure of solar cells in order to improve its resistance properties. The aim of this study was to present a simple method for experimental hail simulation. The proposed hail impact estimation method can be successfully applied to study the influence of the mechanical–dynamic impact of photovoltaic (PV) modules of different structures on the technical characteristics of these modules (structural stability, power generation, etc.). The study showed that PV modules are subjected to an irreversible effect of the excitation force (i.e., micro-cracking) and it can reduce the generated power by 2.33% to 4.83%.

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Drivers for the cracking of multilayer polyamide‐based backsheets in field photovoltaic modules: In‐depth degradation mapping analysis

Fairbrother

Gong

et al. 2020

Progress in Photovoltaics

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There's a lack of understanding on the root cause of cracking of photovoltaic (PV) backsheets due to the challenge of multilayer characterization and the complicated failure modes at the sub-module level. In this work, in-depth degradation mapping of field-exposed polyamide-based (PA-based) PV module backsheets was studied, with the major focus on the identification of underlying drivers for the through cracking (in between the solar cells). PV modules were retrieved from five different locations, comprising a variety of climates, including humid subtropical, hot-summer Mediterranean, tropical savanna climate and hot arid. A suite of microscale cross-sectional characterizations, including chemical changes, fluorescence intensity, and modulus as a function of distance from the air surface of the backsheet, were performed. Results showed more advanced signs of degradation of the inner layer than the outer layer in the cracking region. Increases in the modulus was identified as the major indicator for the cracking. Moreover, a rudimentary test by immersion in acetic acid, which forms during photodegradation of the ethylene-vinyl acetate copolymer (EVA) encapsulant, showed the first-time direct evidence that acetic acid can largely accelerate the chemical degradation and facilitate the cracking of PA inner layer. This study suggests that the field cracking of PA-based backsheet can be attributed to the combined effects of chemical degradation and physical reorganization (chemi-crystallization) under cyclic thermomechanical stresses. Therefore, it is important to consider effects of local

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Thermomechanical stress in solar cells: Contact pad modeling and reliability analysis

Cited by 24 publications

References 28 publications

The Effect of Cell and Module Dimensions on Thermomechanical Stress in PV Modules

The Effect of Cell and Module Dimensions on Thermomechanical Stress in PV Modules

Research of the Energy Losses of Photovoltaic (PV) Modules after Hail Simulation Using a Newly-Created Testbed

Drivers for the cracking of multilayer polyamide‐based backsheets in field photovoltaic modules: In‐depth degradation mapping analysis

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