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The Influence of the EVA Film Aging on the Degradation Behavior of PV Modules Under High Voltage Bias in Wet Conditions Followed by Electroluminescence
摘要： The influence of the ethylene-vinyl acetate (EVA) film quality on potential induced degradation was studied on in-house developed mini modules with p-type monocrystalline silicon solar cells. The modules were assembled with EVA films of equivalent qualities, but different ages and exposed to an accelerated test (relative humidity = 85%, T = 60 °C, Vbias = +1000 V). The age of the EVA film was determined from the time we received the EVA film, and opened the sealed enclosure and the time of lamination. After the EVA film was removed from the sealed enclosure, it was kept in a dark place at room temperature. The storage times of the “fresh,” “aged,” and “expired” films were: less than 14 d, around 5 mo, and more than 5 years, respectively. While modules with a “fresh” EVA film exhibit almost no degradation, the modules with the “aged” EVA film degrade very rapidly and severely. Their degradation rate was around 0.2%/d during the 2000 h of damp heat test. We also observed a strong silver line corrosion, which occurs because of the peroxide leftovers in the “aged” EVA films.
关键词： photovoltaic (PV) modules,high voltage stress,EVA film,Degradation,potential induced degradation (PID),leakage current
更新于2025-09-23 15:21:01
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Enhancement for Potential-Induced Degradation Resistance of Crystalline Silicon Solar Cells via Anti-Reflection Coating by Industrial PECVD Methods
摘要： The issue of potential-induced degradation (PID) has gained more concerns due to causing the catastrophic failures in photovoltaic (PV) modules. One of the approaches to diminish PID is to modify the anti-re?ection coating (ARC) layer upon the front surface of crystalline silicon solar cells. Here, we focus on the modi?cation of ARC ?lms to realize PID-free step-by-step through three delicate experiments. Firstly, the ARC ?lms deposited by direct plasma enhanced chemical vapor deposition (PECVD) and by indirect PECVD were investigated. The results showed that the ef?ciency degradation of solar cells by indirect PECVD method is up to ?33.82%, which is out of the IEC 62804 standard and is signi?cantly more severe than by the direct PECVD method (?0.82%). Next, the performance of PID-resist for the solar cell via indirect PECVD was improved signi?cantly (PID reduced from ?31.82% to ?2.79%) by a pre-oxidation step, which not only meets the standard but also has higher throughput than direct PECVD. Lastly, we applied a novel PECVD technology, called the pulsed-plasma (PP) PECVD method, to deal with the PID issue. The results of the HF-etching rate test and FTIR measurement indicated the ?lms deposited by PP PECVD have higher potential against PID in consideration of less oxygen content in this ?lm. That demonstrated the ?lm properties were changed by applied a new control of freedom, i.e., PP method. In addition, the 96 h PID result of the integrated PP method was only ?2.07%, which was comparable to that of the integrated traditional CP method. In summary, we proposed three effective or potential approaches to eliminate the PID issue, and all approaches satis?ed the IEC 62804 standard of less than 5% power loss in PV modules.
关键词： solar cell,potential-induced degradation,anti-re?ection coating,plasma enhanced chemical vapor deposition
更新于2025-09-23 15:21:01
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Influence of shadow on shunt-type potential-induced degradation for crystalline Si photovoltaic modules exposed outdoors
摘要： Potential-induced degradation (PID) was observed for crystalline Si photovoltaic (PV) modules set at a PID test system constructed outdoors. It was clearly shown that partial shadow and periodical water spray during daytime accelerate PID generation. PID easily occurred just underneath the shielding plate. It was also found that when a large part of one cell in the PV module was shadowed, PID is accelerated; however, when a small part of one cell in the PV module was shadowed or when the weak light is uniformly irradiated, less PID acceleration is observed. Simulation was also carried out for discussing the influence of light irradiation. These findings suggest that UV irradiation during the PID indoor test is essential for the exact estimation of the acceleration factor of the indoor PID test.
关键词： shadow,outdoor test,UV irradiation,potential-induced degradation,crystalline Si photovoltaic modules
更新于2025-09-23 15:19:57
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Elucidating the mechanism of potential induced degradation delay effect by ultraviolet light irradiation for p-type crystalline silicon solar cells
摘要： A mechanism of potential induced degradation (PID) delay effect by ultraviolet (UV) light irradiation during PID test for p-type crystalline silicon (c-Si) solar cells was proposed in this work. The degradation rate of the solar cell performances is slowed down by the UV light irradiation in the 300–390 nm wavelength range during PID test. The conductivity increase of the silicon nitride (SiNx) anti-reflection coating (ARC) layer on the solar cell surface under UV light irradiation during PID tests, which relates to the mechanism preventing the penetration of sodium ions into the active cell layer, induces the PID delay effect for the p-type c-Si solar cells. The PID delay effect was also analyzed by a microwave photo-conductance decay (μ-PCD) technique in this work. The reduction behavior of the components in the μ-PCD signal curves including rapid (τ1) and slow (τ2) decay time constants and the effective lifetime (τeff) presents a good correlation with the performance degradation behavior of the solar cells over PID test duration. Moreover, the reduction rate of these components is also slowed down under the UV light irradiation in the 300–390 nm wavelength range during PID tests. Notably, their reduction behavior was compatible with the mechanism of the conductivity increase of the SiNx ARC layer under UV light irradiation.
关键词： Potential induced degradation (PID),Silicon solar cells,UV irradiation,Silicon nitride (SiNx),Microwave photo-conductance decay
更新于2025-09-23 15:19:57
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Temperature dependence of potential-induced degraded p-type mono-crystalline silicon photovoltaic cell characteristics
摘要： In this paper, the temperature dependence of the characteristic parameters for a p-type mono-crystalline silicon photovoltaic cell before and after a potential-induced degradation (PID) stress, is measured and compared. It is demonstrated that a 9 h PID stress causes both a drastic decrease in the value of shunt resistance by ～35 times and a decrease in the open-circuit voltage, Voc by ～34%. Consequently the maximum power density, Pmax is decreased by ～62%. The temperature coefficient (TC) of Pmax increases from ?0.459 to ?0.330 caused by a 0 to 3 h PID stress and then decreases to ?0.471%/°C caused by a 3 to 9 h PID stress. Before PID stress, the TC of Pmax was determined mainly by the TC of Voc. However, after PID stress, the TC of Pmax was determined both by the TCs of Voc as well as by the fill factor. ? 2019 The Japan Society of Applied Physics
关键词： maximum power density,photovoltaic cell,temperature coefficient,open-circuit voltage,potential-induced degradation,shunt resistance,temperature dependence
更新于2025-09-19 17:13:59
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Regular and Irregular Performance Variation of Module String and Occurred Conditions for Potential Induced Degradation-Affected Crystalline Silicon Photovoltaic Power Plants
摘要： Potential induced degradation (PID) leads to power degradation, and reduces durability and reliability of solar modules. However, this problem has not been thoroughly solved so far. The results from interlaboratory and field study show contradictory fault phenomenon for PID. In this paper, PID of crystalline silicon photovoltaic power plants distributed in various climate conditions was investigated. These photovoltaic power plants consist of two types of crystalline silicon solar modules, which cover almost all kinds of front glass, ethyl vinyl acetate (EVA) and backsheet available commercially. It was found that only a few of power plants were affected by PID. By measuring current voltage characteristics of PID-affected solar modules, the real faults phenomenon was uncovered and classified into regular and irregular power degradation in a module string. The results obtained in this work show that the negative potential caused by high system voltage and stacking faults are necessary and sufficient conditions for PID occurrence for the first time. The anomalous power degradation is related to the stacking fault, which appears randomly during the crystal growth.
关键词： solar module,power degradation,potential induced degradation,crystalline silicon
更新于2025-09-16 10:30:52
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Analysis of Field Degradation Rates Observed in All-India Survey of Photovoltaic Module Reliability 2018
摘要： The analysis of performance degradation in photovoltaic (PV) modules with c-Si technologies as observed in the All-India Survey of PV Module Reliability 2018 is presented in this article. The degradation rates are correlated with the module age, system size, mounting configuration, and climate of deployment. Key failure modes responsible for the higher degradation rates seen in certain sites are identified using visual, infrared, and electroluminescence imaging. Potential-induced degradation is found to be the key mechanism responsible for higher degradation rates seen in Young sites. Also, deployment in hot climates and rooftops is seen to accelerate degradation. Multipoint analysis of degradation rates is presented at sites inspected in prior All-India Surveys.
关键词： potential-induced degradation (PID),All-India Survey,solar photovoltaic (PV),light-induced degradation (LID),field survey,silicon,reliability,degradation
更新于2025-09-12 10:27:22
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Potential-Induced Degradation of Bifacial PERC Solar Cells Under Illumination
摘要： Bifacial passivated emitter and rear cell (PERC) solar cells are promising candidates to reduce levelized cost of electricity since a rear-side power gain can be achieved with minor changes in cell production. However, in addition to the potential-induced degradation of the shunting type (PID-s), some bifacial solar cells may exhibit another degradation related to their rear side. Using three types of purchased industrial bifacial PERC cells encapsulated in our laboratory, we show that a rear-side PID test under simultaneous illumination can cause up to 14% power degradation, which is related to increased carrier recombination at the rear side of the cell. Thus, we ?nd that the degradation under realistic ?eld conditions is strong enough to signi?cantly reduce the bifaciality gains. This is of particular importance as only some of the investigated cells recover under dark conditions. Microstructural analysis of the PID-stressed rear side reveals localized permanent structural damages of the passivation layer leading to an increased rear-side recombination.
关键词： silicon corrosion,Bifacial solar cell,potential-induced degradation,passivated emitter and rear cell (PERC)
更新于2025-09-11 14:15:04
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Effective minority carrier lifetime as an indicator for potential-induced degradation in p-type single-crystalline silicon photovoltaic modules
摘要： In this paper, we report the effective minority carrier lifetime (τeff) in fresh and potential-induced degradation (PID) acceleration tested p-type single-crystalline Si modules. τeff in different regions of solar cells was measured using the microwave photoconductance decay (μPCD) method. Electroluminescence (EL), lock-in-thermography, and dark and light current–voltage (I–V ) measurements were carried out as a complementary analysis of μPCD. In addition, τeff in every stage of Si solar cell fabrication (wafer to solar cell) was measured to investigate the change of carrier dynamics. From the obtained results, a great decrease in τeff was observed in the PID-affected regions, confirming the excess non-radiative recombination centers in that region, suggesting that τeff from the μ-PCD method can be an effective indicator to judge whether PID phenomenon has occurred.
关键词： microwave photoconductance decay,p-type single-crystalline silicon,potential-induced degradation,effective minority carrier lifetime,photovoltaic modules
更新于2025-09-11 14:15:04
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Universal explanation for degradation by charge accumulation in crystalline Si photovoltaic modules with application of high voltage
摘要： It was experimentally found that surface recombination due to charge accumulation, called polarization-type potential-induced degradation (PID), occurs by applying high voltage in n-type crystalline Si photovoltaic (PV) modules. By contrast, polarization-type PID has not been observed yet in p-type crystalline Si PV modules. We investigated the effect of differences in anti-reflection coating (ARC) and the conduction type of the substrate used as a base for PV cells on PID. PID was examined for PV modules using p-type and n-type crystalline Si PV cells with a SiNx or SiNx/SiO2 stacked ARC layer. The results indicate that PID owing to charge accumulation occurs even for p-type crystalline Si PV modules by applying high positive voltage. Furthermore, we found that polarization-type PID due to charge accumulation in ARC, leading to surface recombination, is due not to the conduction type of the substrate but to the ARC structure.
关键词： potential-induced degradation,anti-reflection coating,surface recombination,charge accumulation,photovoltaic modules
更新于2025-09-11 14:15:04