Investigation of a wedge adhesion test for edge seals

Kempe, Michael; Wohlgemuth, J.; Miller, David C.; Postak, Lori; Booth, Dennis; Phillips, Nancy H.

doi:10.1117/12.2239161

Cited by 5 publications

(7 citation statements)

References 14 publications

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“…5 The adhesion test is intended to be used to say the adhesion is not changing significantly giving reasonable expectation that it can perform its intended function. The adhesion strength of these materials is so small that they should be ignored when considering if the PV package is adhered well enough to stay together, a module level F I G U R E 7 Maximum stress results.…”

Section: Discussionmentioning

confidence: 99%

“…B, Repeatability or within-laboratory consistency test is needed to determine the overall adequacy of a design which includes an edge seal. 5 The adhesion test is intended to be used to say the adhesion is not changing significantly giving reasonable expectation that it can perform its intended function.…”

Section: Discussionmentioning

confidence: 99%

“…In prior work, 5 a Boeing Wedge type of test [6][7][8][9] was evaluated because it caused delamination at a rate and in a method consistent with field failure. Typically, edge seal materials fail cohesively and have a high dependence of the maximum shear stress on the pull rate.…”

Section: Introductionmentioning

confidence: 99%

“…Also, for most PV applications, the failure mode is dominated by tensile forces, not shear, and it is characterized by the propagation of a | 355 KEMPE Et al. crack. In prior work, 5 a Boeing Wedge type of test [6][7][8][9] was evaluated because it caused delamination at a rate and in a method consistent with field failure. However, this method required the use of engineering samples, suffered from significant repeatability and reproducibility issues, and demonstrated that the fracture energy of adhesion of these materials was extremely low (between 1 J/m² and 10 J/m²).…”

Section: Introductionmentioning

confidence: 99%

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Using a butt joint test to evaluate photovoltaic edge seal adhesion

Kempe

Korkmaz

Postak³

et al. 2019

Energy Science & Engineering

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Many photovoltaic (PV) technologies have been found to be sensitive to moisture that diffuses into a PV package. Even with the use of impermeable frontsheets and backsheets, moisture can penetrate from the edges of a module. To limit this moisture ingress pathway from occurring, manufacturers often use a low permeability polyisobutylene (PIB)‐based edge seal filled with desiccant to further restrict moisture ingress. Moisture ingress studies have shown that these materials are capable of blocking moisture for the 25‐year life of a module; but to do so, they must remain well‐adhered and free of cracks. This work investigates the potential use of a butt joint test for evaluating the long‐term durability of adhesion by looking for significant changes in the failure mode or quantitative value of a butt joint test. A round robin experiment was conducted using six different materials and two sample constructions, with and without effort to control edge pinch. Tests were evaluated looking at the strength of the bond, and the type of failure observed in a round robin test involving five laboratories. It was found that both the measured values, and the observed failure modes were repeatable and reproducible within at 95% confidence interval.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Using a butt joint test to evaluate photovoltaic edge seal adhesion

Kempe

Korkmaz

Postak³

et al. 2019

Energy Science & Engineering

Self Cite

View full text Add to dashboard Cite

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“…Another method of testing creep crack resistance is to insert a wedge into the DCB specimen, which is the Boeing wedge test [ 28 , 29 , 30 , 31 ]. In this case, creep-loaded specimens can be exposed to different environmental conditions to investigate their degradation [ 32 , 33 , 34 , 35 ]. Conversely, optical crack measurement is required to calculate the fracture toughness, leading to concerns regarding increased calculation errors.…”

Section: Introductionmentioning

confidence: 99%

Creep Crack Growth Behavior during Hot Water Immersion of an Epoxy Adhesive Using a Spring-Loaded Double Cantilever Beam Test Method

et al. 2023

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Double cantilever beam (DCB) tests were conducted by immersing the specimens in temperature-controlled water while applying a creep load using a spring. By introducing a data reduction scheme to the spring-loaded DCB test method, it was confirmed that only a single parameter measurement was sufficient to calculate the energy release rate (ERR). Aluminum alloy substrates bonded with an epoxy adhesive were used, and DCB tests were performed by changing the initial load values, spring constants, and immersion temperatures for two types of surface treatment. The initial applied load and spring constant had no effect on the ERR threshold. In contrast, the threshold decreased with the increasing immersion temperature, but even in the worst case, it was 15% of the critical ERR in the static tests. Using the creep crack growth relationship, it was revealed that there were three phases of creep immersion crack growth in the adhesive joints, and each phase was affected by the temperature. The spring-loaded DCB test method has great potential for investigating the combined effects of creep, moisture, and temperature, and this study has demonstrated the validity of the test method. The long-term durability of adhesive joints becomes increasingly important, and this test method is expected to become widespread.

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Modeling of the effectiveness of novel edge seal designs for fast, low‐Cap‐Ex manufacturing

Kempe

Watts

Shimpi

et al. 2023

Energy Science & Engineering

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In the manufacturing of photovoltaic (PV) modules, the lamination process can take up to 20 min to complete. In this work, new lamination processes are being developed, and have been prototyped, which hope to be able to cut this time down to as little as 30 s. This could provide significant savings in the cost of lamination equipment, floor space, and energy. PV modules are expected to have a lifespan exceeding 20 to 30 years. For moisture‐sensitive PV technologies, the edge seal between the two layers of glass can be the weakest point of its reliability. There is an inherent challenge when evaluating edge seal materials due to their low permeation rates. As part of Colorado State University's Photovoltaic Research and Development 2, work at the National Renewable Energy Laboratory has developed models to evaluate edge seal configurations in glass‐glass PV modules. Here, this new manufacturing process is evaluated for long‐term moisture durability. Different edge seal design options within glass–glass PV modules are explored. Most of these designs are targeting a superstrate on glass configuration, e.g CdTe, but some designs could be used on conventional crystalline Si cells. Using COMSOL finite element simulation software, we investigated the edge seal and interlayer design configurations containing silicone perimeter edge adhesive, desiccated polyisobutylene‐based edge seal, air, and polyolefin while integrating climate conditions equivalent to a hot and humid environment such as Miami, Florida. We found optimized configurations that will allow the module to prevent moisture ingress over 50 years minimizing the amount of time and material used while utilizing polymers that are easily dispensed.

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Investigation of a wedge adhesion test for edge seals

Cited by 5 publications

References 14 publications

Using a butt joint test to evaluate photovoltaic edge seal adhesion

Using a butt joint test to evaluate photovoltaic edge seal adhesion

Creep Crack Growth Behavior during Hot Water Immersion of an Epoxy Adhesive Using a Spring-Loaded Double Cantilever Beam Test Method

Modeling of the effectiveness of novel edge seal designs for fast, low‐Cap‐Ex manufacturing

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