EPJ Photovoltaics最新文献

{"title":"Model for contact formation of novel TeO2 containing Pb-free silver paste on n+ and p+ doped crystalline silicon","authors":"F. Geml, Benjamin Gapp, Simon R. Johnson, P. Sutton, A. Goode, Jonathan Booth, H. Plagwitz, G. Hahn","doi":"10.1051/epjpv/2022034","DOIUrl":"https://doi.org/10.1051/epjpv/2022034","url":null,"abstract":"Silver (Ag) pastes are widely used in the global market for most solar cell architectures. Thereby, lead (Pb) is no longer wanted in productions for environmental reasons. In this work, a model for the contact formation between Pb-free, tellurium oxide (TeO2) containing screen-printable Ag pastes and silicon is presented. It is shown that Te plays a key role in this model. Te is not only an important part in etching the surface passivation layers with TeO2 dissolving the dielectric layer but also for a formation of the contacts with Te forming a compound consisting of Ag2Te. Using EDX mapping, local contact regions can be examined and interpreted for contact formation. The used paste system enables far more flexible paste mixturing leading to a novel developed commercial paste which is on a par with other pastes used in industry concerning the resulting contact properties. This is also demonstrated in this work by the very low contact resistivity of less than 1 mΩcm2 over a wide range of firing peak temperatures. It is additionally shown that good resistivities can be achieved on both n+- and p+-doped regions.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating","authors":"S. Heise, A. Komilov, M. Richter, B. Pieters, A. Gerber, Janet Neerken","doi":"10.1051/epjpv/2023008","DOIUrl":"https://doi.org/10.1051/epjpv/2023008","url":null,"abstract":"When a solar cell is subjected to a negative voltage bias, it locally heats up due to the deposited electrical power. Therefore, every investigation of cell characteristics in the negative voltage regime faces the challenge that the measurement itself changes the state of the cell in a way that is difficult to quantify: On the one hand, the reverse breakdown is known to be strongly temperature dependent. On the other hand, negative voltages lead to metastable device changes which are also very sensitive to temperature. In the current study, we introduce a new approach to suppress this measurement-induced heating by inserting time delays between individual voltage pulses when measuring. As a sample system we use thin-film solar cells based on Cu(In,Ga)Se2 (CIGS) absorber layers. First we verify that with this approach the measurement-induced heating is largely reduced. This allows us to then analyse the impact of the heating on two characteristics of the cells: (i) the reverse breakdown behaviour and (ii) reverse-bias-induced metastable device changes. The results show that minimising the measurement-induced heating leads to a significant increase of the breakdown voltage and effectively slows down the metastable dynamics. Regarding the reverse breakdown, the fundamental tunneling mechanisms that are believed to drive the breakdown remain qualitatively unchanged, but the heating affects the quantitative values extracted for the associated energy barriers. Regarding the reverse-bias metastability, the experimental data reveal that there are two responsible mechanisms that react differently to the heating: Apart from a charge redistribution at the front interface due to the amphoteric (VSe–VCu) divacancy complex, the modification of a transport barrier is observed which might be caused by ion migration towards the back interface. The findings in this study demonstrate that local sample heating due to reverse-bias measurements can have a notable impact on device behaviour which needs to be kept in mind when developing models of the underlying physical processes.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of PV array configurations under dynamic partial shadings","authors":"Chuanyong Shao, A. Migan-Dubois, D. Diallo","doi":"10.1051/epjpv/2023012","DOIUrl":"https://doi.org/10.1051/epjpv/2023012","url":null,"abstract":"The partial shading effect (PSE) is responsible for most power losses in a photovoltaic (PV) system. By modifying the interconnections between PV modules, called PV array reconfiguration, it is possible to improve the power output under partial shading conditions (PSCs). Compared to research on static PSCs, the impact of dynamic PSCs on PV arrays is rarely mentioned, although it deserves to be studied. This paper studies the dynamic PSE on four traditional PV configurations and two reconfiguration techniques based on a 5 × 5 PV array. The four traditional PV configurations are Series-Parallel (SP), Bridge-Link, Honey-Comb, and Total-Cross-Tied (TCT). The two reconfiguration techniques are SuDoKu (SDK) representing Physical Array Reconfiguration (PAR) and Electrical Array Reconfiguration (EAR). The dynamic PSCs are simplified to three types based on the varying orientation: horizontal, vertical, and diagonal. Simulations are carried out with Matlab & Simulink. The performance comparison for the four traditional PV array and two reconfiguration techniques is based on daily energy losses. The results show that four traditional PV configurations techniques, in all PSCs' scenarios, EAR has the most stable performance and the lowest energy losses. The energy losses of SP connection are the largest in all PSCs cases. Although their performance varies depending on the partial shading case, Total-Cross-Tied and SudoDKu lead to the lowest energy losses.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the cooling rate on encapsulant's crystallinity and optical properties, and photovoltaic modules' lifetime","authors":"Vincent Meslier, B. Chambion, Amandine Boulanger, Ichrak Rahmoun, F. Chabuel, T. Béjat","doi":"10.1051/epjpv/2022028","DOIUrl":"https://doi.org/10.1051/epjpv/2022028","url":null,"abstract":"Since the renewable energy thrive, performances and lifetime of photovoltaic (PV) modules have been one of the big international concern. The mechanical bonding between the different components and the materials' choice can significantly improve both performances and lifetime of PV modules. The manufacturing process plays also a significant part in the modules lifetime [G. Oreski, B. Ottersböck, A. Omazic, Degradation Processes and Mechanisms of Encapsulants, in Durability and Reliability of Polymers and Other Materials in Photovoltaic Modules (Elsevier, 2019), pp. 135–152]. This work deals with the controlled cooling part of the manufacturing process. The aim is to characterize its influence on an encapsulant properties, and its influences on modules degradation. This work is a part of improving both performances and lifetime of PV modules. First, the work focuses on describing the real temperature seen by a thermoplastic polyolefin encapsulant during the lamination process. A multi-chamber R&D laminator is used and studied in order to better know the industrial equipment. Results show that the cooling process reduces the time to cool down by a factor of ∼5 compared to natural air convection. Secondly, the material's micro-structure is analysed by Differential Scanning Calorimetry (DSC). The impact of the process is quantified. It does have an influence on the encapsulant crystallites' size distribution without modifying the total crystallinity. Thirdly, the impact of the cooling process on optical properties is investigated. Using spectrophotometry and haze-metry optical characterization, coupled with a known light spectrum, the light intensity coming out from the material is analysed. Results show that the cooling process does not have any influence on transmittance nor reflectance. However, a 34% reduction in the haze factor is recorded when using the industrial laminator cooling process. Fourthly, mechanical bond strength between glass and encapsulant is characterized over ageing. Normalized 10 mm width strips are used to estimate the bond strength. It demonstrates that applying pressure during cooling does not influence the bond strength between glass and encapsulant after 1000 h of damp heat ageing. Finally, impact of the cooling process over ageing on PV modules is discussed. Two accelerating ageing methods, 300 Thermal Cycles and 1000 h damp heat, are used to speed up ageing processes. The electrical components of the PV modules are analysed and used to assess the modules' degradation. Modules manufactured with the cooling process are more sensitive to damp heat after 500 h than modules cooled by natural convection. No significant differences were found in thermal cycling ageing.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A direct measure of positive feedback loop-gain due to reverse bias damage in thin-film solar cells using lock-in thermography","authors":"Suheir Nofal, B. Pieters, M. Hülsbeck, C. Zahren, A. Gerber, U. Rau","doi":"10.1051/epjpv/2022030","DOIUrl":"https://doi.org/10.1051/epjpv/2022030","url":null,"abstract":"In this work, we present a method to study thermal runaway effects in thin-film solar cells. Partial shading of solar cells often leads to permanent damage to shaded cells and degrades the performance of solar modules over time. Under partial shading, the shaded cells may experience a reverse bias junction breakdown. In large-area devices such as solar cells, this junction breakdown tends to take place very locally, thus leading to very local heating and so-called “hot-spots”. Previously, it was shown that a positive feedback effect exists in Cu(In,Ga)Se2 (CIGS) thin-film solar cells, where a highly localized power dissipation is amplified, which may lead to an unstable thermal runaway process. Furthermore, we introduced a novel characterization technique, laser induced Hot-Spot Lock-In Thermography (HS-LIT), which visualizes the positive feedback effect. In this paper, we present a modified HS-LIT technique that allows us to quantify directly a loop-gain for hot-spot formation. By quantifying the loop-gain we obtain a direct measure of how unstable a local hot-spot is, which allows the non-destructive study of hot-spot formation under various conditions and in various cells and cell types. We discuss the modified HS-LIT setup for the direct measurement of the loop-gain. Furthermore, we demonstrate the new method by measuring the loop-gain of the thermal runaway effect in a CIGS solar cell as a function of reverse bias voltage.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy performance of commercial c-Si PV modules in accordance with IEC 61853-1, -2 and impact on the annual specific yield","authors":"C. Monokroussos, Yating Zhang, Eleanor W. Lee, Frank Xu, Allen Zhou, Yichi Zhang, W. Herrmann","doi":"10.1051/epjpv/2022032","DOIUrl":"https://doi.org/10.1051/epjpv/2022032","url":null,"abstract":"As energy yields of photovoltaic modules are highly related to local climate and ambient conditions, it is necessary to assess the energy-yield performance of PV modules under various operating conditions. This work compares commercial crystalline silicon (c-Si) based PV modules (including mono c-Si Al BSF, mono c-Si PERC, multi-crystalline (mc-Si) Al BSF, and n-type c-Si solar cells) sampled from 27 PV module manufacturers located in the Asia-Pacific region between 2016 and 2022. Several test items were compared including: (i) light-induced degradation (LID), (ii) irradiance-temperature-efficiency (GTE) matrix, (iii) angular response and (iv) temperature coefficients, which are correspondingly performed according to IEC 61215-1, -1-1, -2 and IEC 61853-1, -2. The coefficient of variation (CoV) was calculated to express the module-to-module differences within similar technology types. Benefiting from the technological innovation of c-Si based PV modules, emerging PV modules feature better performance in some extreme ambient conditions, such as low irradiance, high ambient temperature, and high ratio of diffuse irradiance. The analysis of CoV indicates that the difference of irradiance-dependent and thermal behavior between modules within the same technology may exceed the differences between different technologies. Using synthetic hourly meteorological data of 5 sites from MeteoNorm in PVsyst, the annual specific yield of four technology groups of PV modules were simulated and compared. Overall, it is shown that the maximum differences as large as 7.34% in terms of PV module's specific yield are expected within same PV technology, which exceeds the maximum difference of 2.16% obtained for specific yields of different PV technologies.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advanced UV-fluorescence image analysis for early detection of PV-power degradation","authors":"L. Neumaier, G. Eder, Yuliya Voronko, K. Berger, G. Ujvari, K. Knöbl","doi":"10.1051/epjpv/2023001","DOIUrl":"https://doi.org/10.1051/epjpv/2023001","url":null,"abstract":"Reliability and durability of photovoltaic modules are a key factor for the development of emerging PV markets worldwide. Reliability is directly dependent on the chemical and physical stability of the polymeric encapsulation materials. One method capable of detecting ageing effects of the polymeric encapsulant directly on-site is UltraViolet Fluorescence (UVF) imaging. This work deals with advanced imaging analysis of UVF images and the subsequent correlation to electrical parameters of PV modules, which were exposed to climate-specific, long-term, accelerated aging procedures. For establishing a correlation, a so called UVF area ratio was established, resulting from the typical fluorescence patterns of the encapsulant material, which arise due to stress impact (e.g., water vapor ingress, elevated temperature, irradiation) and aging/degradation processes. Results of the data analysis show a clear correlation of the UVF area ratios and the electrical parameters with increasing aging time. In particular, the relationship between power and series resistance could be confirmed by extensive long-term test series with different climate-specific aging processes. Assuming the same type of polymeric encapsulation and backsheet and a comparable climate, determining the UVF area ratio can be used to estimate the service life and electrical power dissipation of each module installed in a PV array.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the effects of photovoltaic module heating during electroluminescence inspection","authors":"Lukas Koester, Emanuel Vallarella, A. Louwen, S. Lindig, D. Moser","doi":"10.1051/epjpv/2023002","DOIUrl":"https://doi.org/10.1051/epjpv/2023002","url":null,"abstract":"The application of electroluminescence imaging of photovoltaic modules increased in the last years, due to the reliable and detailed identification of degradation and failures. In future plants the time-consuming connection of power supplies could be overcome by use of inverters with bi-directional functionality, allowing backpowering of connected module strings directly. Temperature influences the open-circuit voltage of photovoltaic modules and must therefore be considered during backpowering. This work investigates the heating due to backpowering of photovoltaic modules of different types during electroluminescence inspection. The temperature increase until saturation is estimated by energy balance calculations and experimentally verified to be around 20 °C, with resulting voltage drops of up to 3 V. Further, these changes have an effect on the recorded luminescence intensity: a decrease of the electroluminescence signal intensity between beginning of backpowering and reaching saturation temperature is shown. For application of the results to a real-world scenario, the electroluminescence window of an electroluminescence-ready inverter is introduced, giving the boundaries of current and voltage that can be supplied. Combined with a simulation of the dark current–voltage curves of a connected photovoltaic module string, the electroluminescence inspection possibilities are visualized. Finally, the applicability of this heating phenomenon for snow melting is discussed.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Snapshot of Photovoltaics − May 2023","authors":"A. Jäger-Waldau","doi":"10.1051/epjpv/2023016","DOIUrl":"https://doi.org/10.1051/epjpv/2023016","url":null,"abstract":"In 2022 the cumulative installed photovoltaic electricity generation capacity increased to over 1 TW, 10 years after it reached the 100 GW level in 2012. In 2022, overall investment in renewable energy has increased by 16% to USD 499 billion compared to USD 953 billion for fossil fuels, which saw an increase of 6%. Investments in solar photovoltaics accounted for USD 301.5 billion or 60% of the renewable energy investments. The annual installations of solar photovoltaic electricity generation systems increased by about 40% to over 230 GWp in 2022. Compared to 2021, the number of countries which installed 1 GWp/year or more has increased by almost 80% to 32. Despite the increase in hardware costs for solar photovoltaic systems and battery storage, both markets had a strong growth, driven by the soaring energy prices in 2022. The increase of the levelised costs for solar photovoltaic electricity was well below the increase of electricity generated with fossil fuels. The electrification of heating, transport and industry will create additional demand for renewable electricity, including solar, if we want to stay on track for not more than 1.5 °C global temperature increase.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A self-consistent hybrid model connects empirical and optical models for fast, non-destructive inline characterization of thin, porous silicon layers","authors":"Alexandra Wörnhör, M. Demant, H. Vahlman, S. Rein","doi":"10.1051/epjpv/2022035","DOIUrl":"https://doi.org/10.1051/epjpv/2022035","url":null,"abstract":"Epitaxially-grown wafers on top of sintered porous silicon are a material-efficient wafer production process, that is now being launched into mass production. This production process makes the material-expensive sawing procedure obsolete since the wafer can be easily detached from its seed substrate. With high-throughput inline production processes, fast and reliable evaluation processes are crucial. The quality of the porous layers plays an important role regarding a successful detachment. Therefore, we present a fast and non-destructive investigation algorithm of thin, porous silicon layers. We predict the layer parameters directly from inline reflectance data by using a convolutional neural network (CNN), which is inspired by a comprehensive optical modelling approach from literature. There, a numerical fitting approach on reflection curves calculated with a physical model is performed. By adding the physical model to the CNN, we create a hybrid model, that not only predicts layer parameters, but also recalculates reflection curves. This allows a consistency check for a self-supervised network optimization. Evaluation on experimental data shows a high similarity with Scanning Electron Microscopy (SEM) measurements. Since parallel computation is possible with the CNN, 30.000 samples can be evaluated in roughly 100 ms.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57828499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}