Analysis of shingle interconnections in solar modules by scanning acoustic microscopy

Mesquita, Laila V.; Klasen, Nils; Fokuhl, Esther; Philipp, Daniel; Bauermann, Luciana Pitta

doi:10.1063/1.5123871

Cited by 8 publications

(3 citation statements)

References 5 publications

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“…Modules were also fabricated using ptype multicrystalline Si solar cells with an Al back-surface field of 31 × 30 mm 2 . Shingling connections [28][29][30] of the three cells with a 1 mm overlap width were produced using conducting paste. Module bases were made of polycarbonate or polytetrafluoroethylene because preliminary experiments confirmed that a module base made of vinyl chloride was deformed at 85 °C during acceleration testing.…”

Section: Methodsmentioning

confidence: 99%

Encapsulation-free crystalline silicon photovoltaic modules and their hygrothermal and thermal-cycle tolerance

Imajo

Yamakawa

Takahashi

et al. 2023

Jpn. J. Appl. Phys.

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Novel concept of unencapsulated modules was developed for avoiding many degradation phenomena originating from encapsulants, for reducing material costs, and also for both easy repair of cells and easy recycle of modules. Reliability and durability of the novel concept modules were investigated using damp-heat (DH) test, thermal-cycle (TC) test, and sequential test composed of DH and TC tests. No large reduction in maximum power after DH test for 2700 h or TC test for 1000 cycles was observed for unencapsulated modules regardless of cell-connection methods, cell spacing, and existence of intentional microcracks. However, unstable contact between interconnector ribbons and busbar electrodes was found after TC test due to thermomechanical stress. Superiority of shingling connection was suggested for novel concept of unencapsulated modules.

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Section: Methodsmentioning

confidence: 99%

Encapsulation-free crystalline silicon photovoltaic modules and their hygrothermal and thermal-cycle tolerance

Imajo

Yamakawa

Takahashi

et al. 2023

Jpn. J. Appl. Phys.

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“…Note, however, that all quantities within this equation are difficult to access. In principle, it is possible to determine A contact and t ECA experimentally by, e.g., scanning acoustic microscopy (SAM), 13 X-ray imaging, 13 and metallographic cross sections. 11,14 Yet, in practice, finding reliable values for A contact and t ECA is not trivial since the ECA is not a perfectly uniform cuboid and thus a statistically relevant number of such measurements is required.…”

Section: Introductionmentioning

confidence: 99%

How to assess the electrical quality of solar cell interconnection in shingle solar modules

Weber

Roessler

2023

Progress in Photovoltaics

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This work deals with the resistance induced by interconnecting shingle solar cells by means of an electrically conductive adhesive (ECA), which is labeled Rint throughout the work. A new approach to measure Rint directly from shingle joints of actual strings is presented and evaluated. For non‐laminated strings and two different ECAs that are applied as a continuous line on shingles with an edge length of 158.75 mm, similar interconnection resistance Rint ≈ 2.5 mΩ is found. In a full‐size shingle module, such an interconnection resistance would result in a cell‐to‐module loss of around ΔPMPP = −0.8%. Another aspect of the present work is to increase the awareness that in case Rint is unknown, it is not trivial to assess the electrical interconnection quality (of different ECAs, different amounts of the same ECA, etc.). It is demonstrated experimentally that the string/module fill factor can be highly sensitive to current mismatch and is thus not an ideal representative of Rint. The power at maximum power point PMPP tends to indicate Rint differences even less clearly. By simulating virtual strings from a pool of slightly varying shingle I–V curves, it is shown that a more suitable representative of Rint is a quantity that can be derived from the string's/module's dark I–V curve.

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“…In the field of photovoltaics, acoustic waves particularly at the MHz range have often been applied in the qualitative analysis of PV modules for visualizing and detecting several failures and defects within the internal structure of the modules, such as air gaps, voids within the encapsulant, cell cracks, 2,6,16 and interconnect quality in shingled solar cells. 17 Additionally, acoustic methods have also found applications in the determination of crosslinking degree of the encapsulation foil in PV modules 11,13 and its thickness. 18 Besides, because the acoustic properties of polymers depend on both ultrasound frequency and temperature, 15 a thorough characterization of the temperature-frequency dependence of PV module backsheet and encapsulation foils is needed to determine the measurement error and optimal parameter conditions.…”

mentioning

confidence: 99%

Scanning acoustic microscopy analysis of the mechanical properties of polymeric components in photovoltaic modules

Mesquita

Mansour

Gebhardt

et al. 2020

Engineering Reports

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The characterization of mechanical properties of polymeric backsheet and encapsulation foils of photovoltaic (PV) modules usually involves destructive techniques, such as dynamic mechanical analysis and tensile testing. In this article, we validate the scanning acoustic microscopy (SAM) as a nondestructive characterization method to estimate the mechanical properties of polymeric multi‐layers in PV modules. The acoustic speed inside each individual material is measured and its mechanical properties calculated. For this validation, other techniques are employed to determine the values of density, thickness, and elastic modulus of the foils. The viscoelastic properties of the polymeric foils are temperature dependent. The longitudinal modulus measured acoustically at 15 MHz and the Young's modulus from conventional tensile testing were compared at different temperatures. Both techniques show good agreement regarding the change in mechanical properties caused by temperature variation. The disagreement in the absolute values of these parameters is explained by the different frequency magnitudes at which both measurements are performed. This confirms that SAM is a reliable technique to measure changes in the viscoelastic properties of the foils in PV modules nondestructively, and thus to obtain more information about aging‐induced material changes and degradation.

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Analysis of shingle interconnections in solar modules by scanning acoustic microscopy

Cited by 8 publications

References 5 publications

Encapsulation-free crystalline silicon photovoltaic modules and their hygrothermal and thermal-cycle tolerance

Encapsulation-free crystalline silicon photovoltaic modules and their hygrothermal and thermal-cycle tolerance

How to assess the electrical quality of solar cell interconnection in shingle solar modules

Scanning acoustic microscopy analysis of the mechanical properties of polymeric components in photovoltaic modules

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