Measurement and simulation of vibrations of PV‐modules induced by dynamic mechanical loads

Aßmus, Marcus; Jack, Steffen; Weiß, Karl-Anders; Koehl, Michael

doi:10.1002/pip.1087

Cited by 47 publications

(22 citation statements)

References 4 publications

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“…) confirmed the laboratory investigations. A fundamental vibration at a frequency of about 11 Hz could be found, but the module deflection did not exceed 4 mm at a wind speed above 20 m/s (70 km/h), which corresponds well to the wind‐tunnel results .…”

Section: Micro‐climate and Combined Stressessupporting

confidence: 86%

Categorization of weathering stresses for photovoltaic modules

Koehl

Heck

Wiesmeier

2018

Energy Science & Engineering

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Solar energy conversion requires permanent outdoor operation of essential components such as photovoltaic modules, solar collectors, or reflectors. They are exposed to weathering stresses. The stress levels depend on the local climates. Monitoring of climatic properties and sample properties in different climatic zones (alpine, arid, maritime, moderate, and tropical) during several years provided the base for categorization of these climates. The local climate does not differ very much from year to year in terms of frequency distributions, but big differences are found for different regions or climatic zones. Especially, the solar irradiation is very location‐dependent. The alpine location shows the highest UV irradiation. The UV fraction of the solar irradiation is varying between 2.2% (tropics) and 4.7% (alps). The temperature histograms can be modeled by Gaussian distribution functions. The maritime histogram is very slim and high, showing the cooling by the sea and the wind. Several approaches for a categorization of these local climates can be applied: Mean temperatures, effective temperatures, or the corresponding constant testing time for fictive degradation processes with arbitrary activation energy. The categorization of the relative humidity revealed humid climates in the alpine and the tropical test site, when considering the time of wetness (rh > 80%). Obviously, the humidity stress or the corrosivity would be very different at those sites. Therefore, a more holistic approach considering more stress factors simultaneously would be more appropriate for the categorization. The interaction between the samples and the climate creates the so‐called micro‐climate which is the real stress on the samples, such as surface temperature, daily temperature cycles, surface humidity, or temperature‐enhanced photo‐degradation. The conditions for accelerated life testing (ALT) modeled on the base of monitored climatic data and sample temperatures are different for the different locations. They offer another possibility for categorization of the climatic stresses and the option for designing climate‐adapted components.

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Section: Micro‐climate and Combined Stressessupporting

confidence: 86%

Categorization of weathering stresses for photovoltaic modules

Koehl

Heck

Wiesmeier

2018

Energy Science & Engineering

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“…Assmus et al [2] have monitored the dynamic stresses on outdoor exposed PV modules under real wind conditions. They show that the observed pressure (+230 Pa) is smaller than the test pressure of 2400 Pa defined by the IEC standard for wind loads and that typical oscillation frequencies are found in the range of 17-35 Hz.…”

Section: New Test Requirements Equipment and New Approachesmentioning

confidence: 99%

PV Module Technology and Reliability – Status and Perspectives

Wirth¹,

Ferrara²

2012

Green

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Solar cell processing into modules is mostly responsible for the product's reliability, has a severe impact on product costs and controls 10 -15% of its efficiency. This article gives an overview on current module technology and highlights innovative approaches to reduce material cost and increase module efficiency. High potential approaches like back contact technology are those that simultaneously address cell and module technology to offer efficiency gains in the range of 10%.Module reliability expectations of 25 years or more require quality assurance beyond the common type approval standards. In its second part, the article addresses stress factors for PV modules. To ensure fast innovation cycles, accelerated aging tests are used to reproduce these stress factors in the laboratory. Results from certification testing are discussed as well as new approaches for improved testing. More realistic test results can be obtained by simulating combinations of stress factors.

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“…It is important to understand the frequency response of the droplet and to match it with the dynamic behavior of the PV modules 29 . The water droplet exhibits different resonance modes depending on mass and surface tension.…”

Section: The Frequency Response Of the Droplet Transportmentioning

confidence: 99%

An active self-cleaning surface system for photovoltaic modules using anisotropic ratchet conveyors and mechanical vibration

Sun

Böhringer

2020

Microsyst Nanoeng

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The purpose of this work is to develop an active self-cleaning system that removes contaminants from a solar module surface by means of an automatic, water-saving, and labor-free process. The output efficiency of a solar module can be degraded over time by dust accumulation on top of the cover glass, which is often referred to as “soiling”. This paper focuses on creating an active self-cleaning surface system using a combination of microsized features and mechanical vibration. The features, which are termed anisotropic ratchet conveyors (ARCs), consist of hydrophilic curved rungs on a hydrophobic background. Two different ARC systems have been designed and fabricated with self-assembled monolayer (SAM) silane and fluoropolymer thin film (Cytop). Fabrication processes were established to fabricate these two systems, including patterning Cytop without degrading the original Cytop hydrophobicity. Water droplet transport characteristics, including anisotropic driving force, droplet resonance mode, cleaning mechanisms, and system power consumption, were studied with the help of a high-speed camera and custom-made test benches. The droplet can be transported on the ARC surface at a speed of 27 mm/s and can clean a variety of dust particles, either water-soluble or insoluble. Optical transmission was measured to show that Cytop can improve transmittance by 2.5~3.5% across the entire visible wavelength range. Real-time demonstrations of droplet transport and surface cleaning were performed, in which the solar modules achieved a 23 percentage-point gain after cleaning.

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Measurement and simulation of vibrations of PV‐modules induced by dynamic mechanical loads

Cited by 47 publications

References 4 publications

Categorization of weathering stresses for photovoltaic modules

Categorization of weathering stresses for photovoltaic modules

PV Module Technology and Reliability – Status and Perspectives

An active self-cleaning surface system for photovoltaic modules using anisotropic ratchet conveyors and mechanical vibration

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