This article presents a novel methodology to detect missing strings in very-large-scale photovoltaic (VLSPV) systems, utilizing only data acquired at the stringbox level. Leveraging data analysis and unsupervised machine learning techniques, the proposed method estimates the quantity of missing strings per stringbox by comparing the direct current from each stringbox with neighboring stringboxes within the same region. The approach addresses a gap in the existing literature by providing a solution tailored to the typical instrumentation level of VLSPV plants. The work encompasses an analysis of the energy losses caused by missing strings, quantifying the impact on the overall system performance. Evaluation against real-world data showed a precision of around 90% of the proposed method in detecting missing strings. The findings offer valuable insights for operations and maintenance teams, enabling identification and mitigation of problematic strings in VLSPV plants.
{"title":"A Method for the Estimation of Missing Strings in Very-Large-Scale Photovoltaic Power Plants","authors":"Tiago Edmir Simão;Bruno Castro Valle;Yago Castro Rosa;Fernando Santos Varela;Arliones Hoeller;Mario de Noronha Neto;Carlos Ernani Fries;Richard Demo Souza","doi":"10.1109/JPHOTOV.2024.3430977","DOIUrl":"10.1109/JPHOTOV.2024.3430977","url":null,"abstract":"This article presents a novel methodology to detect missing strings in very-large-scale photovoltaic (VLSPV) systems, utilizing only data acquired at the stringbox level. Leveraging data analysis and unsupervised machine learning techniques, the proposed method estimates the quantity of missing strings per stringbox by comparing the direct current from each stringbox with neighboring stringboxes within the same region. The approach addresses a gap in the existing literature by providing a solution tailored to the typical instrumentation level of VLSPV plants. The work encompasses an analysis of the energy losses caused by missing strings, quantifying the impact on the overall system performance. Evaluation against real-world data showed a precision of around 90% of the proposed method in detecting missing strings. The findings offer valuable insights for operations and maintenance teams, enabling identification and mitigation of problematic strings in VLSPV plants.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"839-847"},"PeriodicalIF":2.5,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141864222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research explores numerical modeling and simulation studies of a lead-free perovskite solar cell employing (Cs2AgBi0.75Sb0.25Br6) as the absorber layer and utilizing single-walled carbon nanotubes (SWCNTs) in conjunction with metal oxides as the electron transport layer (ETL). Systematic investigation with six different carrier transport layers (both ETL and hole transport layer) along with comprehensive exploration of device physics, coupled with diverse optimization strategies concerning thickness, bandgap, and defect density (both interfacial and bulk), has been carried out. Our study reveals that the proposed configuration can achieve a remarkable device performance, approaching 29.06% efficiency with a current density of 35 mA/cm 2 . This achievement stands in close proximity to the Shockley–Queisser limit. It has been observed that SWCNT, with a 1.4 eV bandgap, enables favorable band alignment, extracting charge carriers efficiently and yielding an impressive 1.102 V open-circuit voltage. This work is poised to catalyze further experimental research, providing valuable insights for advancing perovskite solar cell technology.
本研究探讨了无铅过氧化物太阳能电池的数值建模和模拟研究，该电池采用 (Cs2AgBi0.75Sb0.25Br6) 作为吸收层，并利用单壁碳纳米管 (SWCNT) 和金属氧化物作为电子传输层 (ETL)。我们利用六种不同的载流子传输层（包括 ETL 和空穴传输层）进行了系统研究，并对器件物理特性进行了全面探索，同时采用了有关厚度、带隙和缺陷密度（包括界面和体）的多种优化策略。我们的研究表明，所提出的配置能够实现出色的器件性能，在电流密度为 35 mA/cm2 时效率接近 29.06%。这一成绩接近肖克利-奎塞尔极限。据观察，具有 1.4 eV 带隙的 SWCNT 能够实现良好的带排列，高效提取电荷载流子，并产生令人印象深刻的 1.102 V 开路电压。这项工作有望促进进一步的实验研究，为推动过氧化物太阳能电池技术的发展提供宝贵的见解。
{"title":"Impact of Carbon Nanotube (CNT) Based Transport Layer for Electrons on Metal-Doped Lead-Free Double Perovskite Solar Cell","authors":"Snehal Mondal;Souradeep De;Parthasarathi Chakrabarti;Santanu Maity","doi":"10.1109/JPHOTOV.2024.3424844","DOIUrl":"10.1109/JPHOTOV.2024.3424844","url":null,"abstract":"This research explores numerical modeling and simulation studies of a lead-free perovskite solar cell employing (Cs2AgBi0.75Sb0.25Br6) as the absorber layer and utilizing single-walled carbon nanotubes (SWCNTs) in conjunction with metal oxides as the electron transport layer (ETL). Systematic investigation with six different carrier transport layers (both ETL and hole transport layer) along with comprehensive exploration of device physics, coupled with diverse optimization strategies concerning thickness, bandgap, and defect density (both interfacial and bulk), has been carried out. Our study reveals that the proposed configuration can achieve a remarkable device performance, approaching 29.06% efficiency with a current density of 35 mA/cm\u0000<sup>2</sup>\u0000. This achievement stands in close proximity to the Shockley–Queisser limit. It has been observed that SWCNT, with a 1.4 eV bandgap, enables favorable band alignment, extracting charge carriers efficiently and yielding an impressive 1.102 V open-circuit voltage. This work is poised to catalyze further experimental research, providing valuable insights for advancing perovskite solar cell technology.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"765-776"},"PeriodicalIF":2.5,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141770709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1109/JPHOTOV.2024.3422651
Ishwor Khatri;Camden Kasik;James R. Sites
The open-circuit voltage ( V OC ) of polycrystalline state-of-the-art, arsenic-doped CdSeTe/CdTe solar cells has reached 917 mV, and the record cell efficiency has been gradually increasing. However, there is a significant difference in performance between the current CdTe-based solar cells and single-crystal GaAs cells that have a comparable band gap. The largest contribution to this difference in performance is the voltage. Between 1993 and 2023, V OC of CdTe-based solar cells improved by ∼143 mV when an appropriate adjustment was made for the band gap. This value is still about ∼180 mV below the best GaAs cells. The potential for even higher CdTe efficiencies will likely require a combination of incorporation of front-contact improvements, optimization of thickness, selenium profile, doping, and grain-boundary passivation of the absorber, better passivation of the rear interface, and assurance of back-contact conductivity and band alignment.
{"title":"Performance of State-of-the-Art CdTe-Based Solar Cells: What Has Changed?","authors":"Ishwor Khatri;Camden Kasik;James R. Sites","doi":"10.1109/JPHOTOV.2024.3422651","DOIUrl":"10.1109/JPHOTOV.2024.3422651","url":null,"abstract":"The open-circuit voltage (\u0000<italic>V</i>\u0000<sub>OC</sub>\u0000) of polycrystalline state-of-the-art, arsenic-doped CdSeTe/CdTe solar cells has reached 917 mV, and the record cell efficiency has been gradually increasing. However, there is a significant difference in performance between the current CdTe-based solar cells and single-crystal GaAs cells that have a comparable band gap. The largest contribution to this difference in performance is the voltage. Between 1993 and 2023, \u0000<italic>V</i>\u0000<sub>OC</sub>\u0000 of CdTe-based solar cells improved by ∼143 mV when an appropriate adjustment was made for the band gap. This value is still about ∼180 mV below the best GaAs cells. The potential for even higher CdTe efficiencies will likely require a combination of incorporation of front-contact improvements, optimization of thickness, selenium profile, doping, and grain-boundary passivation of the absorber, better passivation of the rear interface, and assurance of back-contact conductivity and band alignment.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"745-751"},"PeriodicalIF":2.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1109/JPHOTOV.2024.3423814
Wook-Jin Choi;Young-Woo Ok;Keeya Madani;Vijaykumar D Upadhyaya;Ajay D Upadhyaya;Brian Rounsaville;Pradeep Padhamnath;Gabby De Luna;John Derek Arcebal;Ajeet Rohatgi
This article presents a commercially viable process for fabricating a high-quality double-side tunnel oxide passivating contact (DS-TOPCon) cell precursor using atmospheric pressure chemical vapor deposition deposited boron silicate glass and ex situ POCl 3 diffusion in a single high-temperature step, eliminating the need for additional masking and diffusion processes. A two-tier temperature profile was developed, involving a preannealing at above 900 °C in nitrogen ambient followed by POCl 3 diffusion at 840 °C. We investigated the effect of varying preannealing temperatures, ranging from 875 to 950 °C, on the passivation quality and metal-Si contact properties of both n -TOPCon and p -TOPCon layers. The resultant DS-TOPCon cell precursor after silicon nitride passivation exhibited an excellent iV OC of close to 730 mV. In addition, a rapid asymmetric poly-Si thinning technique, developed in this work, enabled adjustment of the front n + poly-Si thickness while maintaining the rear p + poly-Si thickness. Two types of DS-TOPCon cell architectures can be fabricated: i) full-area thin (≈40 nm) n -TOPCon layer on the front and ii) selective-area thick (≈200 nm) n -TOPCon fingers underneath the metal grid. Device simulations suggest that full-area DS-TOPCon cell with 40 nm n+ poly-Si and selective-area DS-TOPCon cell with 200 nm n+ poly fingers on the front, fabricated from our current DS-TOPCon cell precursor, can achieve cell efficiencies of 22.1% and 23.5%, respectively. Detailed power loss analysis and device simulation reveal that further improvements in material and device parameters have the potential to push the cell efficiencies of DS-TOPCon cell structure beyond 25%, making it a promising alternative to fabricate high-efficiency next-generation solar cells at low cost.
{"title":"Development of APCVD BSG and POCl3 Codiffusion Process for Double-Side TOPCon Solar Cell Precursor Fabrication","authors":"Wook-Jin Choi;Young-Woo Ok;Keeya Madani;Vijaykumar D Upadhyaya;Ajay D Upadhyaya;Brian Rounsaville;Pradeep Padhamnath;Gabby De Luna;John Derek Arcebal;Ajeet Rohatgi","doi":"10.1109/JPHOTOV.2024.3423814","DOIUrl":"10.1109/JPHOTOV.2024.3423814","url":null,"abstract":"This article presents a commercially viable process for fabricating a high-quality double-side tunnel oxide passivating contact (DS-TOPCon) cell precursor using atmospheric pressure chemical vapor deposition deposited boron silicate glass and ex situ POCl\u0000<sub>3</sub>\u0000 diffusion in a single high-temperature step, eliminating the need for additional masking and diffusion processes. A two-tier temperature profile was developed, involving a preannealing at above 900 °C in nitrogen ambient followed by POCl\u0000<sub>3</sub>\u0000 diffusion at 840 °C. We investigated the effect of varying preannealing temperatures, ranging from 875 to 950 °C, on the passivation quality and metal-Si contact properties of both \u0000<italic>n</i>\u0000-TOPCon and \u0000<italic>p</i>\u0000-TOPCon layers. The resultant DS-TOPCon cell precursor after silicon nitride passivation exhibited an excellent iV\u0000<sub>OC</sub>\u0000 of close to 730 mV. In addition, a rapid asymmetric poly-Si thinning technique, developed in this work, enabled adjustment of the front \u0000<italic>n</i>\u0000<sup>+</sup>\u0000 poly-Si thickness while maintaining the rear \u0000<italic>p</i>\u0000<sup>+</sup>\u0000 poly-Si thickness. Two types of DS-TOPCon cell architectures can be fabricated: i) full-area thin (≈40 nm) \u0000<italic>n</i>\u0000-TOPCon layer on the front and ii) selective-area thick (≈200 nm) \u0000<italic>n</i>\u0000-TOPCon fingers underneath the metal grid. Device simulations suggest that full-area DS-TOPCon cell with 40 nm \u0000<italic>n<sup>+</sup></i>\u0000 poly-Si and selective-area DS-TOPCon cell with 200 nm \u0000<italic>n<sup>+</sup></i>\u0000 poly fingers on the front, fabricated from our current DS-TOPCon cell precursor, can achieve cell efficiencies of 22.1% and 23.5%, respectively. Detailed power loss analysis and device simulation reveal that further improvements in material and device parameters have the potential to push the cell efficiencies of DS-TOPCon cell structure beyond 25%, making it a promising alternative to fabricate high-efficiency next-generation solar cells at low cost.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"727-736"},"PeriodicalIF":2.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141718121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1109/JPHOTOV.2024.3414178
David C. Miller;Rachael L. Arnold;Peter L. Hacke;Chun-Sheng Jiang;Steven C. Hayden;Helio Moutinho;Jimmy M. Newkirk;Greg Perrin;Laura T. Schelhas;Kent Terwilliger;Soňa Uličná;Chuanxiao Xiao
The consequences of failure for balance-of-systems components (such as photovoltaic (PV) cable connectors) include offline module string(s); low system voltage; arc, ground, insulation, and overtemperature faults; triggered fuse(s); system shutdown; and fire. The degradation modes for connectors are studied here through an industry survey and its subsequent examination, which are compared with field-degraded specimens. A total of 117 specimens were obtained from a variety of locations and climates or accelerated tests. A failure analysis for connectors from PV installations was developed (and applied to 54 specimens), including nondestructive examinations (photography, a custom resistance–current scan, and X-ray computed tomography) and destructive examinations (featuring milling of the external plastic, extraction of the internal convolute spring, and potting and polishing in cross section). Surface and through-thickness composition of the metal pins and springs was quantified using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy was used to verify the base polymer materials and compare the chemical structure of the connector body, bushing, end nut, and o-ring. Thermogravimetric analysis and differential scanning calorimetry were used to further verify the degradation of the same polymeric components.
系统平衡部件（如光伏（PV）电缆连接器）发生故障的后果包括：模块串脱机；系统电压过低；电弧、接地、绝缘和过温故障；触发熔断器；系统停机；以及起火。本文通过行业调查和随后的检查，并与现场降解试样进行比较，对连接器的降解模式进行了研究。我们从不同地点、不同气候条件或加速试验中获得了 117 个试样。针对光伏装置连接器的失效分析已经完成（并应用于 54 个试样），包括非破坏性检查（摄影、定制电阻-电流扫描和 X 射线计算机断层扫描）和破坏性检查（铣削外部塑料、提取内部卷曲弹簧、灌封和抛光横截面）。使用扫描电子显微镜和能量色散 X 射线光谱仪对金属插针和弹簧的表面和厚度成分进行了量化。傅立叶变换红外光谱法用于验证基础聚合物材料，并比较连接器主体、衬套、端螺母和 O 形圈的化学结构。热重分析和差示扫描量热法用于进一步验证相同聚合物成分的降解情况。
{"title":"Photovoltaic Cable Connectors: A Comparative Assessment of the Present State of the Industry","authors":"David C. Miller;Rachael L. Arnold;Peter L. Hacke;Chun-Sheng Jiang;Steven C. Hayden;Helio Moutinho;Jimmy M. Newkirk;Greg Perrin;Laura T. Schelhas;Kent Terwilliger;Soňa Uličná;Chuanxiao Xiao","doi":"10.1109/JPHOTOV.2024.3414178","DOIUrl":"10.1109/JPHOTOV.2024.3414178","url":null,"abstract":"The consequences of failure for balance-of-systems components (such as photovoltaic (PV) cable connectors) include offline module string(s); low system voltage; arc, ground, insulation, and overtemperature faults; triggered fuse(s); system shutdown; and fire. The degradation modes for connectors are studied here through an industry survey and its subsequent examination, which are compared with field-degraded specimens. A total of 117 specimens were obtained from a variety of locations and climates or accelerated tests. A failure analysis for connectors from PV installations was developed (and applied to 54 specimens), including nondestructive examinations (photography, a custom resistance–current scan, and X-ray computed tomography) and destructive examinations (featuring milling of the external plastic, extraction of the internal convolute spring, and potting and polishing in cross section). Surface and through-thickness composition of the metal pins and springs was quantified using scanning electron microscopy with energy-dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy was used to verify the base polymer materials and compare the chemical structure of the connector body, bushing, end nut, and o-ring. Thermogravimetric analysis and differential scanning calorimetry were used to further verify the degradation of the same polymeric components.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"793-802"},"PeriodicalIF":2.5,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1109/JPHOTOV.2024.3421252
Tanvir M. Mahim;A.H.M.A. Rahim;M. Mosaddequr Rahman
A generalized model for predicting the relative efficiency of photovoltaic (PV) panels responsive to weather dynamics is developed in this article. The mathematical framework is derived using correlation analysis of experimental testbed measurements. The testbed included a mono and a custom-built bifacial panel with single-axis tracking. The bifacial panel was made using two mono-facials with a gap between the front and back surfaces, making the panel highly sensitive to the dynamics of weather variations. The proposed bifacial as well as commercial PVs are modeled based on the developed mathematical framework. PV systems with the proposed and commercial panels are investigated. Simulation results show that the developed model accurately portrays the values achieved in the experimental testbed for the proposed panel. Performance study of the proposed panel-based PV system produced the highest energy with space consideration in contrast to commercial panels while being economically effective.
{"title":"Weather Responsive Multidimensional Photovoltaic Efficiency Model for Simulation of Custom-Built Bifacial Panel","authors":"Tanvir M. Mahim;A.H.M.A. Rahim;M. Mosaddequr Rahman","doi":"10.1109/JPHOTOV.2024.3421252","DOIUrl":"10.1109/JPHOTOV.2024.3421252","url":null,"abstract":"A generalized model for predicting the relative efficiency of photovoltaic (PV) panels responsive to weather dynamics is developed in this article. The mathematical framework is derived using correlation analysis of experimental testbed measurements. The testbed included a mono and a custom-built bifacial panel with single-axis tracking. The bifacial panel was made using two mono-facials with a gap between the front and back surfaces, making the panel highly sensitive to the dynamics of weather variations. The proposed bifacial as well as commercial PVs are modeled based on the developed mathematical framework. PV systems with the proposed and commercial panels are investigated. Simulation results show that the developed model accurately portrays the values achieved in the experimental testbed for the proposed panel. Performance study of the proposed panel-based PV system produced the highest energy with space consideration in contrast to commercial panels while being economically effective.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"848-860"},"PeriodicalIF":2.5,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141567052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-03DOI: 10.1109/JPHOTOV.2024.3417025
Z. Ju;X. Qi;S. Schaefer;M. R. McCartney;D. J. Smith;A. V. G. Chizmeshya;T. McCarthy;A. McMinn;S. Grover;Y.-H. Zhang
The II–VI compound semiconductor CdSe, which has both zincblende (ZB) and wurtzite (WZ) phases with bandgap energies of 1.67 and 1.74 eV, respectively, is an ideal candidate material for the top cell in a tandem solar cell with a Si bottom cell to achieve higher power conversion efficiency. In this work, molecular beam epitaxy growth of CdSe thin films on lattice-matched InAs(100) substrates reveals a single-phase ZB structure with high crystallinity and a low defect density. In contrast, all CdSe layers grown on InAs(111)B substrates have mixed ZB and WZ phases in coexistence, as confirmed by high-resolution X-ray diffraction, transmission electron microscopy (TEM), and photoluminescence (PL) measurements. The PL efficiencies of the CdSe layers grown on (111)B substrates are substantially lower than those grown on (100) substrates. This result is attributed to defects at the boundaries between the two different phases. Postgrowth annealing of CdSe layers grown on InAs(111)B at 250–450 °C converts most of the CdSe ZB material into the WZ phase, as evidenced by improved PL efficiency and TEM images. Density functional theory simulations confirm that the formation energy difference between the ZB and WZ phases for CdSe is very small compared with other conventional compound semiconductors, which is in good agreement with the experimental observations.
{"title":"CdSe With Mixed Zincblende and Wurtzite Phases Grown on Lattice-Matched InAs Substrates Using Molecular Beam Epitaxy","authors":"Z. Ju;X. Qi;S. Schaefer;M. R. McCartney;D. J. Smith;A. V. G. Chizmeshya;T. McCarthy;A. McMinn;S. Grover;Y.-H. Zhang","doi":"10.1109/JPHOTOV.2024.3417025","DOIUrl":"10.1109/JPHOTOV.2024.3417025","url":null,"abstract":"The II–VI compound semiconductor CdSe, which has both zincblende (ZB) and wurtzite (WZ) phases with bandgap energies of 1.67 and 1.74 eV, respectively, is an ideal candidate material for the top cell in a tandem solar cell with a Si bottom cell to achieve higher power conversion efficiency. In this work, molecular beam epitaxy growth of CdSe thin films on lattice-matched InAs(100) substrates reveals a single-phase ZB structure with high crystallinity and a low defect density. In contrast, all CdSe layers grown on InAs(111)B substrates have mixed ZB and WZ phases in coexistence, as confirmed by high-resolution X-ray diffraction, transmission electron microscopy (TEM), and photoluminescence (PL) measurements. The PL efficiencies of the CdSe layers grown on (111)B substrates are substantially lower than those grown on (100) substrates. This result is attributed to defects at the boundaries between the two different phases. Postgrowth annealing of CdSe layers grown on InAs(111)B at 250–450 °C converts most of the CdSe ZB material into the WZ phase, as evidenced by improved PL efficiency and TEM images. Density functional theory simulations confirm that the formation energy difference between the ZB and WZ phases for CdSe is very small compared with other conventional compound semiconductors, which is in good agreement with the experimental observations.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"752-757"},"PeriodicalIF":2.5,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1109/JPHOTOV.2024.3417420
Nathan Roosloot;Josefine H. Selj;Gaute Otnes
Moisture ingress into photovoltaic (PV) modules is one of the main drivers behind module midlife- and wear-out-failures, particularly when modules are installed in locations with high humidity stress. To minimize moisture ingress, impermeable front- and backsheets in combination with an edge sealant around the module perimeter can be used. Besides low water vapor transmission rates through the sealant material, mechanical durability of the sealant is of utmost importance. In this work, we assess the durability of a double edge sealant design used in a floating PV (FPV) concept in which the float and PV module are integrated. Strength of attachment testing, combined with measurements of failure type, are performed on samples taken from an FPV prototype after outdoor exposure and are compared to measurements on lab samples that are unexposed or exposed to indoor accelerated stress. We observe a significant decrease of lap shear strength for the double edge sealant after field exposure, coupled with more adhesive failure. Correlation to accelerated stress test results indicates that the observed adhesion losses can partly be attributed to degradation driven by ultraviolet light. By reporting on observations of FPV field degradation and exploring how indoor accelerated stress testing can be used to understand the origins of the observed degradation, this work constitutes an important early contribution to the field of FPV reliability.
{"title":"Evaluating Durability of a Double Edge Sealant in a Floating Photovoltaic Application","authors":"Nathan Roosloot;Josefine H. Selj;Gaute Otnes","doi":"10.1109/JPHOTOV.2024.3417420","DOIUrl":"10.1109/JPHOTOV.2024.3417420","url":null,"abstract":"Moisture ingress into photovoltaic (PV) modules is one of the main drivers behind module midlife- and wear-out-failures, particularly when modules are installed in locations with high humidity stress. To minimize moisture ingress, impermeable front- and backsheets in combination with an edge sealant around the module perimeter can be used. Besides low water vapor transmission rates through the sealant material, mechanical durability of the sealant is of utmost importance. In this work, we assess the durability of a double edge sealant design used in a floating PV (FPV) concept in which the float and PV module are integrated. Strength of attachment testing, combined with measurements of failure type, are performed on samples taken from an FPV prototype after outdoor exposure and are compared to measurements on lab samples that are unexposed or exposed to indoor accelerated stress. We observe a significant decrease of lap shear strength for the double edge sealant after field exposure, coupled with more adhesive failure. Correlation to accelerated stress test results indicates that the observed adhesion losses can partly be attributed to degradation driven by ultraviolet light. By reporting on observations of FPV field degradation and exploring how indoor accelerated stress testing can be used to understand the origins of the observed degradation, this work constitutes an important early contribution to the field of FPV reliability.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"785-792"},"PeriodicalIF":2.5,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141524875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The laser contact opening in passivated emitter and rear cell (PERC) is essential for establishing contact between silicon and aluminum. On bifacial PERC solar cells, dashed patterns are commonly employed as an alternative to continuous openings to mitigate excessive losses associated with passivation film removal. In this work, we investigate the optimization of dashed patterns in detail. First, under the condition of the same 50% opening ratio, the optimal total length of segments is determined to be 1.2 mm. Subsequently, testing various opening ratio patterns on wafers with different resistivities reveals that low-resistivity wafers are better suited for low opening ratio patterns. Finally, simulation analyses using Quokka2 software assess the variations in power loss associated with different opening patterns, the simulation results align with those of experiments. This work provides a guidance for the rear-side laser opening pattern design of bifacial PERC solar cells.
钝化发射极和后部电池（PERC）中的激光接触开口对于建立硅和铝之间的接触至关重要。在双面 PERC 太阳能电池上，通常采用虚线图案来替代连续开口，以减少因去除钝化膜而产生的过多损耗。在这项工作中，我们详细研究了虚线图案的优化问题。首先，在相同的 50%开口率条件下，确定了最佳的分段总长度为 1.2 毫米。随后，在不同电阻率的晶片上测试各种开口率图案，结果表明低电阻率晶片更适合低开口率图案。最后，使用 Quokka2 软件进行的模拟分析评估了与不同开口模式相关的功率损耗变化，模拟结果与实验结果一致。这项工作为双面 PERC 太阳能电池的后侧激光开口模式设计提供了指导。
{"title":"Improvement of Laser Contact Opening in Bifacial PERC Solar Cells by Optimizing the Dashed Pattern","authors":"Junhu Cui;Dichun Yuan;Jianming Ding;Chonggui Zhong","doi":"10.1109/JPHOTOV.2024.3416445","DOIUrl":"10.1109/JPHOTOV.2024.3416445","url":null,"abstract":"The laser contact opening in passivated emitter and rear cell (PERC) is essential for establishing contact between silicon and aluminum. On bifacial PERC solar cells, dashed patterns are commonly employed as an alternative to continuous openings to mitigate excessive losses associated with passivation film removal. In this work, we investigate the optimization of dashed patterns in detail. First, under the condition of the same 50% opening ratio, the optimal total length of segments is determined to be 1.2 mm. Subsequently, testing various opening ratio patterns on wafers with different resistivities reveals that low-resistivity wafers are better suited for low opening ratio patterns. Finally, simulation analyses using Quokka2 software assess the variations in power loss associated with different opening patterns, the simulation results align with those of experiments. This work provides a guidance for the rear-side laser opening pattern design of bifacial PERC solar cells.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"720-726"},"PeriodicalIF":2.5,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The lamination process plays a crucial role in the long-term reliability of photovoltaic (PV) modules. Monitoring the degree of encapsulant crosslinking in the modules can help ensure the quality of the lamination process, which is affected by factors like lamination temperature and process time. A consistent vertical temperature distribution during lamination is important for achieving uniform crosslinking across the module depth. In this study, thermocouple measurements were conducted to obtain temperature profiles and assess the degree of encapsulant crosslinking in glass-backsheet and glass-glass (GG) modules with and without cells. Four different encapsulants were analyzed, including two types of ethylene-co-vinyl acetates (EVA) and two types of polyolefin elastomers (POE). The measurements data were compared with simulations that allow to determine the temperature profile of the different layers of the module as well as the degree of crosslinking of the encapsulants over the process time. The simulation results showed good agreement with the measured values, effectively capturing the temperature trends during lamination. It was found that inadequate processing led to a crosslinking discrepancy between the front and back sides of the modules of 6.5% for EVA, and 14% for POE. To address this issue, a 1) plate-plate chamber was used for GG modules or; the 2) process time was extended in the plate-membrane chamber. The study also highlighted the significant influence of the cells on the degree of crosslinking, whereas the implementation of the cells decreases the crosslinking by up to 12.8%. In addition, the simulated encapsulant crosslinking was validated against Soxhlet extraction results.
{"title":"Simulation and Experimental Analysis of Temperature Profiles and Crosslinking in PV Module Lamination","authors":"Aksel Kaan Öz;Japan Vasani;Christian Reichel;Christine Wellens;Max Mittag;Martin Heinrich;Dirk Holger Neuhaus","doi":"10.1109/JPHOTOV.2024.3414117","DOIUrl":"10.1109/JPHOTOV.2024.3414117","url":null,"abstract":"The lamination process plays a crucial role in the long-term reliability of photovoltaic (PV) modules. Monitoring the degree of encapsulant crosslinking in the modules can help ensure the quality of the lamination process, which is affected by factors like lamination temperature and process time. A consistent vertical temperature distribution during lamination is important for achieving uniform crosslinking across the module depth. In this study, thermocouple measurements were conducted to obtain temperature profiles and assess the degree of encapsulant crosslinking in glass-backsheet and glass-glass (GG) modules with and without cells. Four different encapsulants were analyzed, including two types of ethylene-co-vinyl acetates (EVA) and two types of polyolefin elastomers (POE). The measurements data were compared with simulations that allow to determine the temperature profile of the different layers of the module as well as the degree of crosslinking of the encapsulants over the process time. The simulation results showed good agreement with the measured values, effectively capturing the temperature trends during lamination. It was found that inadequate processing led to a crosslinking discrepancy between the front and back sides of the modules of 6.5% for EVA, and 14% for POE. To address this issue, a 1) plate-plate chamber was used for GG modules or; the 2) process time was extended in the plate-membrane chamber. The study also highlighted the significant influence of the cells on the degree of crosslinking, whereas the implementation of the cells decreases the crosslinking by up to 12.8%. In addition, the simulated encapsulant crosslinking was validated against Soxhlet extraction results.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"14 5","pages":"777-784"},"PeriodicalIF":2.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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