Mechanical load testing of solar panels — beyond certification testing

Gabor, Andrew M.; Janoch, Rob; Anselmo, Andrew; Lincoln, Jason; Seigneur, Hubert; Honeker, Christian C.

doi:10.1109/pvsc.2017.8366848

Cited by 4 publications

(8 citation statements)

References 7 publications

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“…The tensile stress is very low with 4 MPa (60 cells) and 13 MPa (140 cells). This corresponds to a negligible probability of failure, as was reported before, e.g., [31], even for the modules with a high number of cells.…”

Section: B Mechanical Loadsupporting

confidence: 75%

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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: B Mechanical Loadsupporting

confidence: 75%

“…Due to the symmetric setup of glass-glass modules, the solar cells are in the neutral zone [31]. Accordingly, the dominating stress is the residual compressive stress from lamination.…”

Section: B Mechanical Loadmentioning

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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“…It is assumed that these cracks were formerly hidden, eg, under or near busbars or at grain boundaries. According to Gabor, new cracks appear at p > 1200 Pa. This corresponds to the presented experimental results.…”

Section: Discussionsupporting

confidence: 89%

“…The test setup will be described in Chapter 3.3. Gabor et al who use a similar load test describe the benefits in comparison with other loading tests, eg, sandbags or indenters. The evaluation will be done by means of EL‐image analysis with respect to the initial status and in correlation to weather data and the loading conditions, respectively.…”

Section: Introductionmentioning

confidence: 99%

Evolution of cell cracks in PV‐modules under field and laboratory conditions

Buerhop‐Lutz

Wirsching

Bemm

et al. 2017

Progress in Photovoltaics

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Damaged modules, especially with cell cracks, can be observed quite often in photovoltaicinstallations. Little knowledge exists about long-term stability of precracked modules at real operating conditions. Previous investigations and existing standards focus on the degradation of new, defect-free modules. This work highlights a twofold approach for life-time study of precracked modules: (1) outdoor exposure of 54 precracked modules for 1 year and (2) artificial stressing of 20 representative precracked modules with a novel load test setup simulating snow and wind loads. The outdoor exposure reveals that at moderate weather conditions, no changes were detectable, neither in electric performance nor in EL-images. However, the accelerated static load tests with stepwise increasing pressures point out that above a certain threshold, cracks grow.Below this threshold, formerly unseen cracks become visible at the loaded stage. In addition, modules with a smaller number of damaged cells have a stronger tendency to degrade further than modules with an already large number of cracked cells. Remarkably, the power output measured with a solar simulator after a stress test up to 2500 Pa (describing conservative proof conditions for severe snow loads according IEC 61215) remains unchanged for almost all modules.

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“…Indeed, as the interconnection can be separated from the encapsulation process, the technology also allows freedom in encapsulation system, with glass–glass encapsulation eliminating humidity ingress through the backsheet which may be beneficial depending on the used encapsulation scheme and environmental conditions during operation . Apart from this, realizing a more symmetrical buildup of the module is beneficial from the perspective of mechanical and thermomechanical stress on the cells inside . Also, considering reliability, the used materials as glass fibre and solder paste have already been previously validated in other PV module concepts and as such lower the unknown factors that are often considered a barrier in PV module technology.…”

Section: Introduction: Woven Multi‐wire Interconnectionmentioning

confidence: 99%

A woven fabric for interconnecting back‐contact solar cells

Borgers

Govaerts

Voroshazi

et al. 2016

Progress in Photovoltaics

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This paper reports on a novel and highly innovative technology to interconnect back‐contact cells. First, a background section explains the currently developed interconnection technologies. Then, our novel concept is introduced: interconnection of the cells is achieved with a woven fabric, combining both conductive wires, needed for the interconnection, and insulating wires, crucial to avoid shunting between both polarities at the backside of the cell. Weaving also allows out‐of‐plane stress relief features. In the third section, we explain that our technology combines the advantages of multi‐wire interconnection such as low‐stress and reduced resistive losses with known and low‐cost materials of traditional module assembly. Additional to previous publications, we demonstrate that the technology can be tuned broadly in terms of costs and resistive losses using an optimized interconnection pattern. These resistive loss simulations are also validated with the measured additional resistance in IBC test samples. We also present a preliminary thermal cycling test with promising results. Finally, first functional demonstrators IBC cells are fabricated, disclosing the process flow and initial technology developments. These results clearly demonstrate the proof‐of‐concept of the woven interconnection fabric, and based on electrical characterization we provide suggestions for improvements. Copyright © 2016 John Wiley & Sons, Ltd.

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Mechanical load testing of solar panels — beyond certification testing

Cited by 4 publications

References 7 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

Evolution of cell cracks in PV‐modules under field and laboratory conditions

A woven fabric for interconnecting back‐contact solar cells

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