Predicting Photovoltaic Module Series Resistance based on Indoor-Aging Tests and Thermal Cycling Cumulative Exposure Estimates

Jones, C. Birk; Hobbs, William B.; Libby, Cara; Gunda, Thushara; Hamzavy, Babak

doi:10.1109/pvsc40753.2019.8981189

Cited by 2 publications

(5 citation statements)

References 12 publications

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“…As disclosed in this project, cells with extensive EVA browning cause permanent current mismatch, leading to high T c , or hot cells, which degrade or age the physicochemical status of the cells at a fast rate. These may trigger a cascade of ageing factors, bringing the cells into an irreversible state and causing, in turn, further permanent physicochemical changes and high permanent T c patterns, as also reported in other studies [ 7 , 11 , 48 ]. EVA degradation is usually linked to exposure to high SRD, whereas negligible EVA degradation is expected in cells exposed to low SRD.…”

Section: Identification Of Defects Cause and Effect And The Need For ...supporting

confidence: 60%

“…The photovoltaic (PV)-ageing and performance-degradation modes have been extensively studied as far as they concern weathering due to outdoor conditions [ 1 , 2 , 3 ], early ageing [ 4 ] and long-term operational degradation [ 5 , 6 ]. Indoor ageing and thermal-cycling cumulative exposure were previously studied to predict degradation in the series resistance R s [ 7 ] and optical degradation [ 8 ]. Reports on sensors, non-destructive testing (NDT), and methodologies focus on the diagnosis of ageing factors and their effects [ 9 , 10 , 11 , 12 , 13 ], whereas analysis of faults linked to degradation factors and defects and their implications are provided in [ 14 , 15 , 16 , 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…External factors, such as solar radiation, shading, wind, and other environmental parameters, as well as internal factors, along with the conditions that trigger degradation processes, have been investigated in depth. Strong PV-cell temperature T c , fluctuations, or cycles may cause thermal shocks that trigger ageing processes and/or structural deformation [ 1 , 2 , 6 , 7 , 9 , 13 ]. Ambient temperature T a cycles in cold sites or in deserts cause module thermal fatigue and damage the frame, similarly to the strong wind effect, resulting in cracks, frame deformation, and enhancement of humidity ingress [ 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

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PV Defects Identification through a Synergistic Set of Non-Destructive Testing (NDT) Techniques

Kaplanis

Kaplani

Borza

2023

Sensors

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A synergistic set of NDT techniques, including I–V analysis, UVF imaging, IR thermography, and EL imaging, supports a diagnostics methodology developed in this work to qualitatively and quantitatively identify a wide range of PV defects. The methodology is based on (a) the deviation of the module electrical parameters at STC from their nominal values, for which a set of mathematical expressions was developed that provide an insight into potential defects and their quantitative impact on the module electrical parameters, and (b) the variation analysis of EL images captured at a sequence of bias voltages for a qualitative investigation on the spatial distribution and strength of the defects. The synergy of these two pillars, supported by UVF imaging, IR thermography, and I–V analysis cross-correlating their findings, makes the diagnostics methodology effective and reliable. It was applied on c-Si and pc-Si modules operating from 0–24 years, exhibiting a diversity of defects of varying severity, either pre-existing or formed by natural ageing or externally induced degradation. Defects such as EVA degradation, browning, corrosion in the busbar/interconnect ribbons, EVA/cell-interface delamination, pn-junction damage, e−+hole recombination regions, breaks, microcracks, finger interruptions, and passivation issues are detected. Degradation factors triggering a cascade of internal degradation processes through cause and effect are analysed and additional models are proposed for the temperature pattern under current mismatch and corrosion along the busbar, further empowering the cross-correlation of NDT results. Power degradation was determined from 1.2% in 2 years of operation to more than 50% in modules with film deposition.

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Section: Identification Of Defects Cause and Effect And The Need For ...supporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

PV Defects Identification through a Synergistic Set of Non-Destructive Testing (NDT) Techniques

Kaplanis

Kaplani

Borza

2023

Sensors

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“…1) Thermal cycling. A linear relationship between thermal cycling and Rs for indoor tests with TC200 and TC500 was extrapolated to accurately predict Rs in fielded modules after about 6 years of exposure [6], [12], [13]. TC200 and TC500 exposures were equivalent to about 2 years and almost 5 years, respectively, in the outdoor environment at the U.S. Southwest plant location.…”

Section: F Insights On Accelerated Aging Protocolsmentioning

confidence: 99%

“…Solder bond interconnection damage because of thermal cycling was determined to be the dominant degradation mechanism in PREDICTS2 test modules and fielded modules that were aged in the natural environment for approximately 6 years at the commercial plant in the U.S. Southwest [6]. EL imaging revealed that busbar defects -lower carrier concentration along the length of cell busbars -was the only type of defect with a notable correlation with series resistance (Rs) [6], and the condition was more prevalent in modules with higher TC exposure. Neither IEC 61215 nor Qual Plus capture backsheet failures or inner layer cracks that lead to solder joint corrosion and submodule faults.…”

Section: Introductionmentioning

confidence: 99%

Analysis of PV Module Power Loss and Cell Crack Effects Due to Accelerated Aging Tests and Field Exposure

Libby

Paudyal

Chen

et al. 2023

IEEE J. Photovoltaics

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This study compared module power loss for 36 modules that endured various accelerated aging test sequences before installation outdoors on a 10-kWp array in Birmingham, AL, USA for 1.72 to 2.72 years. Twelve modules endured standard IEC 61215 aging tests and 24 endured Qualification Plus (Qual Plus). Modules in each group were further split into two test sequences with different exposures. Electrical parameter variations were analyzed as a function of aging test and field exposure history. Fill factor loss was determined to be the cause of observed decreases in power output during accelerated aging tests, while decreases in both open circuit voltage and fill factor dominated the power loss during subsequent on-sun testing. Quantified cell crack features were extracted via computer vision tools from electroluminescence images and correlated with power loss. Results illustrate that standard aging tests led to negligible cracks, while Qual Plus test sequences yielded more severe cracks. While correlating results from qualification tests with in-field performance degradation parameters remains a challenge, this study provides new insights on specific environmental stressors and crack features that may play a role in power loss. Insights on accelerated aging protocols are discussed.

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Predicting Photovoltaic Module Series Resistance based on Indoor-Aging Tests and Thermal Cycling Cumulative Exposure Estimates

Cited by 2 publications

References 12 publications

PV Defects Identification through a Synergistic Set of Non-Destructive Testing (NDT) Techniques

PV Defects Identification through a Synergistic Set of Non-Destructive Testing (NDT) Techniques

Analysis of PV Module Power Loss and Cell Crack Effects Due to Accelerated Aging Tests and Field Exposure

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