&lt;italic&gt;In-Situ&lt;/italic&gt; Monitoring of Moisture Ingress in PV Modules Using Digital Humidity Sensors

Jankovec, Marko; Galliano, F.; Annigoni, Eleonora; Li, Heng Yu; Sculati‐Meillaud, Fanny; Perret-Aebi, Laure-Emmanuelle; Ballif, Christophe; Topič, Marko

doi:10.1109/jphotov.2016.2583779

Cited by 38 publications

(19 citation statements)

References 18 publications

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“…In our humidity sensor experiments, and in similar experiments from the literature, it was seen that a nonzero initial concentration is present in EVA originating from diffusion from the atmosphere during warehouse storage prior to fabrication of the solar modules. For Fickian diffusion, the EVA properties are not affected by a nonzero C 0 , however the time required to reach saturation decreases with increasing C 0 .…”

Section: Finite Element Modelsupporting

confidence: 79%

Measurement and modelling of water ingress into double‐glass photovoltaic modules

Wisniewski

Lv²,

Nair

et al. 2018

Progress in Photovoltaics

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Polymer encapsulants are an essential component in photovoltaic (PV) devices, providing mechanical support, optical coupling, and electrical and physical isolation. However, moisture ingress into the module can degrade these polymers and subsequently the performance of the device. In this paper, we report experimental measurements of the temporal evolution of moisture content in ethylene‐vinyl acetate (EVA) encapsulant in a double‐glass PV module. Using physical properties of EVA as determined by water vapour transmission rate measurements, we simulate diffusion of water into the module using a finite element model. The model accounts for realistic geometry of our module and is used to simulate accelerated test conditions and outdoor operation in geographic locations. Using the calculated results, we propose two schemes using the accelerated test results to understand the behaviour of modules operating in humid climates. Finally, we show that the time needed to reach the saturation water concentration can be increased by as much as a factor of two by reducing the initial water content in EVA films.

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Section: Finite Element Modelsupporting

confidence: 79%

Measurement and modelling of water ingress into double‐glass photovoltaic modules

Wisniewski

Lv²,

Nair

et al. 2018

Progress in Photovoltaics

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“…In a G/G module, water is able to penetrate from the edges into the unprotected encapsulant. We solve the diffusion equation in a 2D domain of length L x and width L y equal to 0.2 m (ie, the size of a one‐cell mini‐module) using the Fourier series shown in Equation , an approach previously used by Kempe et al and Jankovec et al In the equation, c init and c surf are, respectively, the initial and the surface concentration of the encapsulant (g/m 3 ), and D its diffusion coefficient (m 2 /s).

c ((),,, x, y, t) = c_{surf} + ((), c_{init} - c_{surf}) \cdot \frac{16}{π^{2}} \cdot \sum_{n = 0}^{\infty} \frac{1}{2 n + 1} sin ((), \frac{(2 n + 1) πx}{L_{x}}) e^{- \frac{{(2 n + 1)}^{2} π^{2}}{L_{x}^{2}} italicDt} \cdot \cdot \sum_{m = 0}^{\infty} \frac{1}{2 m + 1} sin ((), \frac{(2 m + 1) π y}{L_{y}}) e^{- \frac{{(2 m + 1)}^{2} π^{2}}{L_{y}^{2}} italicDt}

…”

Section: Experimental Work and Modellingmentioning

confidence: 99%

One‐type‐fits‐all‐systems: Strategies for preventing potential‐induced degradation in crystalline silicon solar photovoltaic modules

Virtuani

Annigoni

Ballif

2018

Progress in Photovoltaics

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In this work, we investigate the relationship between potential‐induced degradation (PID) and the bill of material used in module manufacturing. We manufacture samples with different combination of materials, using two types of solar cells (conventional vs PID‐free c‐Si cells), two types of ethylene‐vinyl acetate (EVA) films with low/high resistivity, and two types of backsheets with, respectively, low/high breathability properties, and subject the mini‐modules to extended PID testing. Our results clearly indicate that, when using a breathable polymeric backsheet, to have a “PID‐free” module the combination of PID‐free cells and high‐resistive EVA encapsulants is recommendable. The use of a conventional c‐Si cell in combination with a high‐resistive EVA encapsulant is still more effective than the use of PID‐free cells in combination with low‐quality EVA. Further, our results initially show that the breathability properties of the backsheet have apparently no influence on PID degradation. A second set of experiments using sandwich structures with increased resistance properties to water ingress (ie, glass and backsheets with barrier layers as rear covers and an edge sealant), however, indicates that preventing or reducing the diffusion of moisture in the encapsulant layer plays a role in further mitigating the impact of PID. This finding is supported by simulations of moisture ingress in the sandwich structures. Finally, we show that the use of a glass rear cover—compared with a polymeric backsheet—does not contribute in worsening the PID effect. On the contrary, by reducing moisture ingress in the front encapsulant layer, it delays the occurrence of PID.

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“…The leakage current at negative biased modules was decreasing (exponential decay) over time to a more or less stable value. The current stabilizes when the EVA in the front and at the back of the cell is completely water soaked [16]. The leakage current of all four modules is presented in Figure 2.…”

Section: Leakage Currentmentioning

confidence: 98%

Examination of Photovoltaic Silicon Module Degradation Under High-Voltage Bias and Damp Heat by Electroluminescence

Brecl

Bokalič

Topič

2017

Journal of Solar Energy Engineering

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The photovoltaic (PV) modules are in PV arrays normally connected in series and thus some of them exposed to high system voltages since frames of the PV modules are grounded. To predict the long-term PV system energy output and PV module lifetime, it is very important to understand and take into account the degradation process of PV modules under high voltage stress. Accelerated tests under damp heat (over 1300 hours of DH85/60; RH = 85 %, T = 60 °C) of in-house developed monocrystalline silicon PV modules were preformed while connected to a positive or negative voltage bias of 1000 V. The negative biased modules exhibited just a little degradation, while the positive biased modules degraded rapidly. We identified three degradation mechanisms: ion migration, silver corrosion and EVA evaporation. The degradation mechanisms contribute to almost 15 % of the performance loss of the 1000 V positive biased modules after more than 1300 h of DH85/60 testing, while the power degradation of the negative biased modules remains below 3 %.

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<italic>In-Situ</italic> Monitoring of Moisture Ingress in PV Modules Using Digital Humidity Sensors

Cited by 38 publications

References 18 publications

Measurement and modelling of water ingress into double‐glass photovoltaic modules

Measurement and modelling of water ingress into double‐glass photovoltaic modules

One‐type‐fits‐all‐systems: Strategies for preventing potential‐induced degradation in crystalline silicon solar photovoltaic modules

Examination of Photovoltaic Silicon Module Degradation Under High-Voltage Bias and Damp Heat by Electroluminescence

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