Theoretical insight into leakage current of solar module under high system voltage

Jin, Xianxu; Bai, Qiaoqiao; Jin, Yang; Wang, Zhonghe; Ouyang, Linjie; Ma, Jiayi; Wang, He; Yang, Hong

doi:10.1109/pvsc45281.2020.9300364

Cited by 7 publications

(5 citation statements)

References 10 publications

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“…This demonstrates how the surface conductivity 25 represents a large source of variability in the leakage current that is highly susceptible to the effects of water and similarly to dust and other pollutants in the air.…”

Section: Resultsmentioning

confidence: 92%

“…Here, the copper foil is at ground, and the voltage is applied to the cells using the tabs coming out from the backsheet. This demonstrates how the surface conductivity 25 represents a large source of variability in the leakage current that is highly susceptible to the effects of water and similarly to dust and other pollutants in the air.…”

Section: Model Fit Of Conductivity/resistivity Measurementsmentioning

confidence: 92%

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Electrochemical mechanisms of leakage‐current in photovoltaic modules

Kempe

Hacke

Morse

et al. 2023

Progress in Photovoltaics

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This paper analyzes the mechanisms and pathways for leakage current flow observed in Si photovoltaic modules subjected to high temperature and humidity and a large voltage bias with respect to ground. The current inside of the frame is in the form of electron motion, but in the glass and polymer, it is in at least a large part attributable to the movement of ions. When the mode of current flow changes from electronic to ionic conduction, electrochemical reactions will take place at the interface. This can include reactions that produce volatile chemical species like H 2 , CO x , and O 2 , along with ionic species such as OH À and H 3 O + . Here, we see evidence of the importance of different charge carriers with different diffusion rates and the influence of electrochemical processes involved. The application of negative voltage to the cell circuit affects the resistivity of glass producing surfaces with poor conductivity but with some increases in the electrochemical potential producing complicated interactions that are important when the voltage is changed. In the polymer, there is the development of a space charge region and a chemical gradient providing two oppositional forces to current flow, which when released create a complicated discharge process. Here, we give a basic understanding of the charge/discharge of PV cells highlighting how the specific mechanisms are important in understanding some of the degradation processes in PV modules. We find that there is evidence of multiple significant charge carrier species with different diffusion time scales. The glass/ polymer interface forms a depleted region of higher resistance after prolonged exposure to current. Charge also builds up at the polymer to cell antireflective coating interface and mostly flows to the gridlines to experience electrochemical reactions.These complexities result in non-linear behavior where the apparent resistivities of the different layers change during charge/discharging processes, making the modeling of the current flow extremely difficult.

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Section: Resultsmentioning

confidence: 92%

Section: Model Fit Of Conductivity/resistivity Measurementsmentioning

confidence: 92%

Electrochemical mechanisms of leakage‐current in photovoltaic modules

Kempe

Hacke

Morse

et al. 2023

Progress in Photovoltaics

View full text Add to dashboard Cite

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“…This demonstrates how the surface conductivity [23] represents a large source of variability in the leakage current that is highly susceptible to the effects of water and similarly to dust and other pollutants in the air.…”

Section: -Task 1 (Subtasks 11 and 12) Resultsmentioning

confidence: 92%

“…The extent of the corrosion is dependent on the corrosion resistance in the basic environment. For example, while Ag is stable at high basicity pH [23], Si or SiO2 can dissolve or directly electrochemically decompose to form SiO3 2as described in the following equations [23]:…”

Section: -Task 1 (Subtasks 11 and 12) Resultsmentioning

confidence: 99%

“…The Pourbaix diagram in Figure 4 shows the thermodynamic stability of water and Na + as a function of potential (relative to a standard hydrogen electrode) at different pH. The equilibrium reduction potential of sodium is far below the reduction potential of water by approximately 3 V [21,23]. This means that water is preferentially reduced when both water and dissolved Na + ions are present on the metal surface.…”

Section: Milestone 111mentioning

confidence: 99%

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Predictive Models and Novel Accelerated Tests for the Reliability of Cell Metallization in Photovoltaic Modules (Final Report)

Kempe,

Hacke,

Morse

et al. 2024

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Design test structures and induce metallization corrosion on the test structures. (M 1-M 10) NREL and SunPowerTask Summary: NREL and SunPower together will design coupons and test structures to monitor metallization corrosion which will be induced in damp heat chambers and under an applied bias (either with a foil on the glass or a grounded frame nearby). Extensive analysis of the coupons and test structures will be initiated. Task Details:The risk in this task is the identification of suitable test structures that mimic coupon level corrosion. Risk mitigation is to build test structures with the same type of metallization as in the actual cells. Subtask 1.1: Design coupons and suitable test structures to mimic corrosion in the cell.(M I-MS) NREL and SunPowerA paint corrosion-testing cell was used to conduct electrochemical testing of front-contact cells (FCCs) and back-contact cells (BCCs) in deionized water [6], Figure 1. The FCC cells were typical commercial Al back surface field cells, and the BCC cells were commercial SunPower cells. The total test area was 13.1 cm 2 , with a solution volume of 40 mL. Vacuum grease was applied to the O-ring to prevent water leakage between the corrosion cell and the samples. A graphite rod was used as a counter electrode, while a saturated calomel electrode (SCE) was employed as the reference electrode. The cathodic polarization measurement was initiated from 10 mV vs. open circuit potential after 10 min delay in the deionized water (to obtain steadystate), and the scanning rate was 0.5 mV/s. Si cells were rinsed with ethanol and deionized water to clean the surface and were then dried using compressed air.This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. Table 5. Transient current characteristics of test samples. Data from the first Voltage-On cycle was ignored in these calculations. For most samples, only one measurement was made, but for some duplicate measurements were made and sometimes with different cycle times as indicated.

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