Development of Accelerated Test Sequences to Assess Long Term Durability of PV Modules

Gambogi, William J.; Yu, Bao-Ling; Felder, Thomas; MacMaster, Steven; Choudhury, Kaushik Roy; Tracy, Jared; Phillips, Nancy H.; Hu, Hongjie

doi:10.1109/pvsc40753.2019.8981222

Cited by 8 publications

(11 citation statements)

References 6 publications

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“…18 First studies have been reported that bridge the gap between accelerated aging test in the lab and natural degradation in the field. 2,[19][20][21][22][23][24] These studies comprise single observations though and lack the combination and transformation of the individual results to operating conditions in the PV power stations.…”

mentioning

confidence: 99%

Wet leakage resistance development of modules with various backsheet types

Buerhop‐Lutz

Stroyuk

Zöcklein

et al. 2021

Progress in Photovoltaics

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Over the last years, a significant number of inverter shutdowns most likely due to degraded backsheets have been reported by operators, investors, and manufacturers.We investigated water ingress into different backsheets, and the resulting risk for inverter shutdowns. For studying pending insulation issues of inverters, we analyzed exemplarily a 5-MWp photovoltaic (PV) power station with 20,530 PV modules and 314 inverters. For backsheet identification on-site near-infrared absorption spectroscopic measurements of 518 PV modules from 20 inverters were carried out. In the lab, wet leakage tests provide kinetic data of insulation resistances for different backsheet materials. Historic ground impedance data logged by the inverter were evaluated to show the temporal evolution of inverters with different backsheets. We observe different kinetics and drops in leakage resistance for different backsheet types based on polyamide (PA) and air-side fluorinated coating (FC), and distinguish between two types of behavior. "PA-like" is characterized by moderate leakage resistance loss and slower performance reduction with regard to insulation in the field. "FC-like" is characterized by high susceptibility to water and a high leakage resistance loss rate for PV modules after 6-8 years of operation. These characteristics are indicated when measuring inverter GI in dependence of temperature and humidity. For PA-based BSs, the reduction in ground impedance (GI) is steady over 8 years. We observe incidences with GI below the critical value of 400 kΩ on 2.8% of all days. For FC-based BSs, we also observe steady decrease of average GI initially, yet after 6 years in the field, we see a sudden and rapid decline for 20% of those inverters. GI falling below the critical value is observed on up to 5% of all days, with the trend increasing. Therefore we, expect this problem to become even more severe for longer operating times.

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confidence: 99%

Wet leakage resistance development of modules with various backsheet types

Buerhop‐Lutz

Stroyuk

Zöcklein

et al. 2021

Progress in Photovoltaics

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“…While accelerated aging standards for testing PV modules exist, there is significant doubt that these standards will effectively screen new backsheet materials for long‐term performance 10 . Newer accelerated aging protocols, which focus on combined stresses, have been able to replicate field failures in a number of PV backsheet materials 10,11 . However, an understanding of backsheet materials degradation pathways is needed to ensure that newly introduced materials will meet module target service lifetimes.…”

Section: Introductionmentioning

confidence: 99%

“…10 Newer accelerated aging protocols, which focus on combined stresses, have been able to replicate field failures in a number of PV backsheet materials. 10,11 However, an understanding of backsheet materials degradation pathways is needed to ensure that newly introduced materials will meet module target service lifetimes.…”

Section: Introductionmentioning

confidence: 99%

Microstructure changes during failure of PVDF‐based photovoltaic backsheets

Moffitt

Pan

Perry

et al. 2022

Progress in Photovoltaics

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The backsheet layer of a solar module provides a safety and environmental barrier to the high voltages running through the photovoltaic (PV) cells and electrical contacts within the core of the module. However, in the past decade, backsheet cracking has become one of the most observed failure modes in PV module field surveys. In this work, the degradation of polyvinylidene fluoride (PVDF)-based backsheets is explored. Backsheet samples are either exposed to accelerated laboratory aging (UV light, heat, and moisture) or collected from the field. Fourier transform infrared and Raman spectroscopy, fragmentation testing, atomic force and scanning electron microscopy, and small-angle neutron scattering are combined to develop an understanding of how chemistry and microstructure evolve during aging. Chemical degradation, surface pitting, polymer phase changes, and anisotropic polymer domains are all observed in aged backsheet samples. The results provide insight into the degradation mechanisms that lead to cracking and field failure of PVDF-based backsheets. The comparison of aged PVDF-based backsheets helps to lay the groundwork for limiting polymer-based failure modes in PV modules.

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“…Delamination of one or more layers is one of the most critical failure modes of a PV module during its service lifetime [11][12][13], so its root causes have been investigated thoroughly [5,[14][15][16]. Delamination within a backsheet primarily imposes a safety risk due to failing wet leakage insulation [7,17]. Additionally, backsheet delamination may accelerate various other PV module degradation modes such as corrosion, potential induced degradation (PID) or polymer hydrolysis by providing gateways of moisture ingress into the modules [13,18], which could result in a performance loss over time.…”

Section: Introductionmentioning

confidence: 99%

Peeling of Flexible Laminates—Determination of Interlayer Adhesion of Backsheet Laminates Used for Photovoltaic Modules

Pinter

2022

Materials

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Delamination is one of the most critical failure modes of a PV module during service lifetime. Delamination within a backsheet primarily imposes a safety risk, but may also accelerate various other PV module degradation modes. The main aim of this paper is to present a peel test set-up, which is more practical in sample preparation and execution than the width-tapered cantilever beam test and overcomes some issues of standard peel tests like the influence of sample geometry and energy dissipation through deformation on the peel test results. The best results with respect to accuracy and effort were achieved by using a 180° peel geometry where an additional adhesive tape is applied to the peel arm in order to avoid plastic deformation or breakage. The additional support of the adhesive tape leads to comparable peel strength values without any influence of the plastic deformation behavior of the peel arms with different thickness.

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Development of Accelerated Test Sequences to Assess Long Term Durability of PV Modules

Cited by 8 publications

References 6 publications

Wet leakage resistance development of modules with various backsheet types

Wet leakage resistance development of modules with various backsheet types

Microstructure changes during failure of PVDF‐based photovoltaic backsheets

Peeling of Flexible Laminates—Determination of Interlayer Adhesion of Backsheet Laminates Used for Photovoltaic Modules

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