Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2013.6656749
S. Ishizuka, L. Mansfield, C. Dehart, M. Scott, B. To, M. Young, B. Egaas, R. Noufi
Two-step processes currently used for the industrial Cu(In,Ga)Se2 (CIGS) module production require a long process time of several hours for the CIGS absorber formation. In this paper, we are studying the reaction pathway to rapid selenization of stacked metal precursors in elemental Se vapor. The objective is to understand the reaction kinetics to find the best precursor structure and the optimal selenization conditions to form high-quality CIGS films with proper Ga depth profiles. In addition to stacked metal precursors, the effect of the use of Se-containing precursors was also examined. As expected, the stacking order of themetal precursors influences the properties of the resultingCIGS absorbers. The Cu amount deposited for the precursor formation critically affected the final film and cell properties, as well.We also found that the formation of CIGS films with large grain sizes and flat Ga depth profiles was possible even for [Cu]/([In] + [Ga]) < 1 conditions with the use of particular precursor structures and selenization conditions. The results suggest that the selenization reaction pathway can be dictated with the precursor structure, and further improvements are expected by controlling reaction kinetics with precursor structure modification.
{"title":"Rapid fabrication of Cu(In,Ga)Se2 thin films by the two-step selenization process","authors":"S. Ishizuka, L. Mansfield, C. Dehart, M. Scott, B. To, M. Young, B. Egaas, R. Noufi","doi":"10.1109/pvsc-vol2.2013.6656749","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2013.6656749","url":null,"abstract":"Two-step processes currently used for the industrial Cu(In,Ga)Se2 (CIGS) module production require a long process time of several hours for the CIGS absorber formation. In this paper, we are studying the reaction pathway to rapid selenization of stacked metal precursors in elemental Se vapor. The objective is to understand the reaction kinetics to find the best precursor structure and the optimal selenization conditions to form high-quality CIGS films with proper Ga depth profiles. In addition to stacked metal precursors, the effect of the use of Se-containing precursors was also examined. As expected, the stacking order of themetal precursors influences the properties of the resultingCIGS absorbers. The Cu amount deposited for the precursor formation critically affected the final film and cell properties, as well.We also found that the formation of CIGS films with large grain sizes and flat Ga depth profiles was possible even for [Cu]/([In] + [Ga]) < 1 conditions with the use of particular precursor structures and selenization conditions. The results suggest that the selenization reaction pathway can be dictated with the precursor structure, and further improvements are expected by controlling reaction kinetics with precursor structure modification.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"95 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83718961","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2013.6656726
C. Brandt, C. Baur, A. Caon, P. Muller-Buschbaum, C. Zimmermann, T. Andreev
We report on the isothermal annealing behavior of 1 MeV electron irradiated component cells of a GaInP2/GaAs/Ge triple-junction solar cell. The defect concentration as a function of annealing time and temperature is derived from the in-situ measured open circuit voltages. The time dependent behavior reveals the presence of partly overlapping exponential decays in defect concentration which in turn suggest the annealing of more than one defect having different activation energies.
{"title":"The influence of high temperatures on radiation damage of GaInP2/GaAs/Ge triple junction cells","authors":"C. Brandt, C. Baur, A. Caon, P. Muller-Buschbaum, C. Zimmermann, T. Andreev","doi":"10.1109/pvsc-vol2.2013.6656726","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2013.6656726","url":null,"abstract":"We report on the isothermal annealing behavior of 1 MeV electron irradiated component cells of a GaInP2/GaAs/Ge triple-junction solar cell. The defect concentration as a function of annealing time and temperature is derived from the in-situ measured open circuit voltages. The time dependent behavior reveals the presence of partly overlapping exponential decays in defect concentration which in turn suggest the annealing of more than one defect having different activation energies.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"5 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83131308","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2012.6656774
I. Repins, M. Romero, Jian V. Li, S. Wei, D. Kuciauskas, Chunsheng Jiang, C. Beall, C. Dehart, J. Mann, Wan-Ching Hsu, G. Teeter, A. Goodrich, R. Noufi
Recent years have seen dramatic improvements in the performance of kesterite devices. The existence of devices of comparable performance, made by a number of different techniques, provides some new perspective on what characteristics are likely fundamental to the material. Here, we review progress in kesterite device fabrication, aspects of the film characteristics that have yet to be understood, and challenges in device development that remain for kesterites to contribute significantly to photovoltaic manufacturing. Performance goals, as well as characteristics of midgap defect density, free carrier density, surfaces, grain boundaries, grain-to-grain uniformity, and bandgap alloying are discussed.
{"title":"Kesterite successes, ongoing work, and challenges: A perspective from vacuum deposition","authors":"I. Repins, M. Romero, Jian V. Li, S. Wei, D. Kuciauskas, Chunsheng Jiang, C. Beall, C. Dehart, J. Mann, Wan-Ching Hsu, G. Teeter, A. Goodrich, R. Noufi","doi":"10.1109/pvsc-vol2.2012.6656774","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2012.6656774","url":null,"abstract":"Recent years have seen dramatic improvements in the performance of kesterite devices. The existence of devices of comparable performance, made by a number of different techniques, provides some new perspective on what characteristics are likely fundamental to the material. Here, we review progress in kesterite device fabrication, aspects of the film characteristics that have yet to be understood, and challenges in device development that remain for kesterites to contribute significantly to photovoltaic manufacturing. Performance goals, as well as characteristics of midgap defect density, free carrier density, surfaces, grain boundaries, grain-to-grain uniformity, and bandgap alloying are discussed.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"34 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81058721","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2013.6656754
S. Kostner, A. Hahnel, R. Mokso, H. Blumtritt, P. Werner
During crystallization of multicrystalline silicon, carbon-rich liquid-solid phase-boundary layers appear, resulting in precipitation of n-type conductive Si-C-N filaments.We present an in-depth structural analysis of distinct types of filaments to support modeling of their growth. Phase-contrast microtomography down to the submicron level is used to study morphology and seeding of precipitates while still embedded in fully functional solar cell samples. A detailed transmission electron microscopy analysis and a quantitative electron energy loss spectroscopy analysis are presented, based on tomography-assisted target preparation.
{"title":"Structural analysis of longitudinal Si-C-N precipitates in multicrystalline silicon","authors":"S. Kostner, A. Hahnel, R. Mokso, H. Blumtritt, P. Werner","doi":"10.1109/pvsc-vol2.2013.6656754","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2013.6656754","url":null,"abstract":"During crystallization of multicrystalline silicon, carbon-rich liquid-solid phase-boundary layers appear, resulting in precipitation of n-type conductive Si-C-N filaments.We present an in-depth structural analysis of distinct types of filaments to support modeling of their growth. Phase-contrast microtomography down to the submicron level is used to study morphology and seeding of precipitates while still embedded in fully functional solar cell samples. A detailed transmission electron microscopy analysis and a quantitative electron energy loss spectroscopy analysis are presented, based on tomography-assisted target preparation.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"1 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89317255","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2012.6656770
T. Ott, T. Walter, D. Hariskos, O. Kiowski, R. Schaffler
The long-term stability of solar cells is a crucial factor for the competitiveness of a technology. In this study, the accelerated aging of CIGS solar cells was studied, and the influence of an applied bias during the endurance test on the open-circuit voltage Voc and fill factor (FF) was investigated. Time constants for parameter drifts of the open-circuit voltage and the associated activation energy were determined. The observed parameter drifts will be discussed, and a model will be proposed based on SCAPS simulations, explaining the observed behavior of the electrical characteristics of the solar cells. Therefore, cells were dark annealed under dry conditions at two different temperatures and different voltage biases were applied to the cells. Our study revealed that the application of a positive bias, which is similar to light soaking, first leads to an improvement and stabilization of the open-circuit voltage and FF followed by a slow decrease of these parameters. This long-term decrease can be explained in terms of a back barrier or phototransistor, as simulated with SCAPS. However, applying a positive bias enhances the long-term stability of these devices. The appearance of a back barrier is associated with a time constant exceeding 30 years. Therefore, this degradation mechanism is not critical.
{"title":"Accelerated aging and contact degradation of CIGS solar cells","authors":"T. Ott, T. Walter, D. Hariskos, O. Kiowski, R. Schaffler","doi":"10.1109/pvsc-vol2.2012.6656770","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2012.6656770","url":null,"abstract":"The long-term stability of solar cells is a crucial factor for the competitiveness of a technology. In this study, the accelerated aging of CIGS solar cells was studied, and the influence of an applied bias during the endurance test on the open-circuit voltage Voc and fill factor (FF) was investigated. Time constants for parameter drifts of the open-circuit voltage and the associated activation energy were determined. The observed parameter drifts will be discussed, and a model will be proposed based on SCAPS simulations, explaining the observed behavior of the electrical characteristics of the solar cells. Therefore, cells were dark annealed under dry conditions at two different temperatures and different voltage biases were applied to the cells. Our study revealed that the application of a positive bias, which is similar to light soaking, first leads to an improvement and stabilization of the open-circuit voltage and FF followed by a slow decrease of these parameters. This long-term decrease can be explained in terms of a back barrier or phototransistor, as simulated with SCAPS. However, applying a positive bias enhances the long-term stability of these devices. The appearance of a back barrier is associated with a time constant exceeding 30 years. Therefore, this degradation mechanism is not critical.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"1 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91145414","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2013.6656753
Taizou Kobayashi, K. Yamauchi, T. Nakada
ZnO:B films deposited by ultraviolet light-assisted metal organic chemical vapor deposition (UM-ZnO:B) were applied to CBD-ZnS(O,OH)/CIGS solar cells in order to eliminate plasma damages during the subsequent ZnO sputtering. It was verified that the conversion efficiency of CIGS solar cells with a UM-ZnO:B window layer was higher than that of the device with a sputter-deposited(Sp-) ZnO:Al window layer; in both cases, thick (120 nm) and thin (10 nm) ZnS(O,OH) buffer layers were used. The conversion efficiency of CIGS solar cell was improved from 16.3% to 17.5% upon replacement of the Sp-ZnO:Al by a UM-ZnO:B window layer when the thick ZnS(O,OH) (120nm) buffer layer was used. Notably, the conversion efficiency was remarkably improved from 0.2% to 15.6% by the replacement of the window layer even when the ultra thin ZnS(O,OH) (10nm) buffer layer was used. The temperature dependence of open-circuit voltage revealed that interface recombination decreased owing to the use of a UM-ZnO: B window layer.
{"title":"Comparison of cell performance of ZnS(O,OH)/CIGS solar cells with UV-assisted MOCVD-ZnO:B and sputter-deposited ZnO:Al window layers","authors":"Taizou Kobayashi, K. Yamauchi, T. Nakada","doi":"10.1109/pvsc-vol2.2013.6656753","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2013.6656753","url":null,"abstract":"ZnO:B films deposited by ultraviolet light-assisted metal organic chemical vapor deposition (UM-ZnO:B) were applied to CBD-ZnS(O,OH)/CIGS solar cells in order to eliminate plasma damages during the subsequent ZnO sputtering. It was verified that the conversion efficiency of CIGS solar cells with a UM-ZnO:B window layer was higher than that of the device with a sputter-deposited(Sp-) ZnO:Al window layer; in both cases, thick (120 nm) and thin (10 nm) ZnS(O,OH) buffer layers were used. The conversion efficiency of CIGS solar cell was improved from 16.3% to 17.5% upon replacement of the Sp-ZnO:Al by a UM-ZnO:B window layer when the thick ZnS(O,OH) (120nm) buffer layer was used. Notably, the conversion efficiency was remarkably improved from 0.2% to 15.6% by the replacement of the window layer even when the ultra thin ZnS(O,OH) (10nm) buffer layer was used. The temperature dependence of open-circuit voltage revealed that interface recombination decreased owing to the use of a UM-ZnO: B window layer.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"36 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89220910","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2013.6656799
Xinyu Zhang, A. Cuevas, A. Thomson
In this paper, we investigate the relationship between the deposition-process parameters of reactively sputtered aluminium oxide films and the passivation of silicon surfaces. A method of tuning the deposition process has been established that results in a reduced level of surface recombination, where surface recombination velocities as low as 8.5 cm/s have been achieved on 1 Ω·cm n-type monocrystalline silicon. We find that in order to achieve good surface passivation, the deposition need to be conducted at low power density and at high deposition pressure. We have found that effective passivation is achieved when a sputtering target is close to being fully oxidized—indicated by deposition rate—likely resulting in films that are less aluminium rich. Additionally, Fourier-transform-infrared spectroscopy measurements were used for film characterization; the correlation between effective lifetime and the integrated absorption of all Al and O related bonds shows that films with lower absorption in the wavenumber range 500–1060 cm−1 result in better passivation.
{"title":"Process control of reactive sputter deposition of AlOx and improved surface passivation of crystalline silicon","authors":"Xinyu Zhang, A. Cuevas, A. Thomson","doi":"10.1109/pvsc-vol2.2013.6656799","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2013.6656799","url":null,"abstract":"In this paper, we investigate the relationship between the deposition-process parameters of reactively sputtered aluminium oxide films and the passivation of silicon surfaces. A method of tuning the deposition process has been established that results in a reduced level of surface recombination, where surface recombination velocities as low as 8.5 cm/s have been achieved on 1 Ω·cm n-type monocrystalline silicon. We find that in order to achieve good surface passivation, the deposition need to be conducted at low power density and at high deposition pressure. We have found that effective passivation is achieved when a sputtering target is close to being fully oxidized—indicated by deposition rate—likely resulting in films that are less aluminium rich. Additionally, Fourier-transform-infrared spectroscopy measurements were used for film characterization; the correlation between effective lifetime and the integrated absorption of all Al and O related bonds shows that films with lower absorption in the wavenumber range 500–1060 cm−1 result in better passivation.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"34 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77605403","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2013.6656707
Z. R. Abrams
The future of high efficiency photovoltaics lies in better utilizing the full solar spectrum. Spectrally splitting the solar input either by using stacked multi-junctions or advanced photonic redistribution of the light into different cell segments can approach theoretical conversion limits. However, while the algorithm for calculating the efficiency for these systems is considered to be definitive, a careful examination of some of the fundamental parameters shows that there are crucial aspects to the calculation that have been overlooked. By recognizing a new set of parameters such as the limited bandwidth of light absorbed in each cell, the non-radiative losses of each segment, and the photon management of incoming and outgoing light, a new approach to the calculation can be obtained. Here, we provide a blueprint for this calculation stemming from the perspective of Information Theory, and its association with the efficiency of solar cells via the relationship between the Entropy of the photons and the Open-Circuit Voltage of a cell. We list these important parameters, and how they relate to the overall efficiency, in a simple, elegant manner. Using these concepts we show how to compensate for these inherent losses by modifying the effective area of each cell segment.
{"title":"A new methodology for calculating the efficiency of multi-junction solar cells","authors":"Z. R. Abrams","doi":"10.1109/pvsc-vol2.2013.6656707","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2013.6656707","url":null,"abstract":"The future of high efficiency photovoltaics lies in better utilizing the full solar spectrum. Spectrally splitting the solar input either by using stacked multi-junctions or advanced photonic redistribution of the light into different cell segments can approach theoretical conversion limits. However, while the algorithm for calculating the efficiency for these systems is considered to be definitive, a careful examination of some of the fundamental parameters shows that there are crucial aspects to the calculation that have been overlooked. By recognizing a new set of parameters such as the limited bandwidth of light absorbed in each cell, the non-radiative losses of each segment, and the photon management of incoming and outgoing light, a new approach to the calculation can be obtained. Here, we provide a blueprint for this calculation stemming from the perspective of Information Theory, and its association with the efficiency of solar cells via the relationship between the Entropy of the photons and the Open-Circuit Voltage of a cell. We list these important parameters, and how they relate to the overall efficiency, in a simple, elegant manner. Using these concepts we show how to compensate for these inherent losses by modifying the effective area of each cell segment.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"46 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75811935","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}
Pub Date : 2013-01-01DOI: 10.1109/pvsc-vol2.2012.6656719
M. Lave, J. Stein, A. Ellis
Ota City, Japan and Alamosa, Colorado present contrasting cases of a small rooftop distributed PV plant versus a large central PV plant. We examine the effect of geographic smoothing on the power output of each plant. 1-second relative maximum ramp rates are found to be reduced 6–10 times for the total plant output versus a single point sensor, though smaller reductions are seen at longer timescales. The relative variability is found to decay exponentially at all timescales as additional houses or inverters are aggregated. The rate of decay depends on both the geographic diversity within the plant and the meteorological conditions (such as cloud speed) on a given day. The Wavelet Variability Model (WVM) takes into account these geographic smoothing effects to produce simulated PV powerplant output by using a point sensor as input. The WVM is tested against Ota City and Alamosa, and the WVM simulation closely matches the distribution of ramp rates of actual power output.
{"title":"Analyzing and simulating the reduction in PV powerplant variability due to geographic smoothing in Ota City, Japan and Alamosa, CO","authors":"M. Lave, J. Stein, A. Ellis","doi":"10.1109/pvsc-vol2.2012.6656719","DOIUrl":"https://doi.org/10.1109/pvsc-vol2.2012.6656719","url":null,"abstract":"Ota City, Japan and Alamosa, Colorado present contrasting cases of a small rooftop distributed PV plant versus a large central PV plant. We examine the effect of geographic smoothing on the power output of each plant. 1-second relative maximum ramp rates are found to be reduced 6–10 times for the total plant output versus a single point sensor, though smaller reductions are seen at longer timescales. The relative variability is found to decay exponentially at all timescales as additional houses or inverters are aggregated. The rate of decay depends on both the geographic diversity within the plant and the meteorological conditions (such as cloud speed) on a given day. The Wavelet Variability Model (WVM) takes into account these geographic smoothing effects to produce simulated PV powerplant output by using a point sensor as input. The WVM is tested against Ota City and Alamosa, and the WVM simulation closely matches the distribution of ramp rates of actual power output.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"107 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83426228","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}
Pub Date : 2013-01-01DOI: 10.1109/PVSC.2012.6317933
P. Hacke, Ryan M. Smith, K. Terwilliger, S. Glick, D. Jordan, S. Johnston, M. Kempe, S. Kurtz
Acceleration factors are calculated for crystalline silicon photovoltaic modules under system voltage stress by comparing the module power during degradation outdoors with that in accelerated testing at three temperatures and 85% relative humidity. A lognormal analysis is applied to the accelerated lifetime test data, considering failure at 80% of the initial module power. Activation energy of 0.73 eV for the rate of failure is determined for the chamber testing at constant relative humidity, and the probability of module failure at an arbitrary temperature is predicted. To obtain statistical data for multiple modules over the course of degradation in situ of the test chamber, dark I–V measurements are obtained and transformed using superposition, which is found to be well suited for rapid and quantitative evaluation of potential-induced degradation. It is determined that shunt resistance measurements alone do not represent the extent of power degradation. This is explained with a two-diode model analysis that shows an increasing second diode recombination current and ideality factor as the degradation in module power progresses. Failure modes of the modules stressed outdoors are examined and compared with those stressed in accelerated tests.
{"title":"Testing and analysis for lifetime prediction of crystalline silicon PV modules undergoing degradation by system voltage stress","authors":"P. Hacke, Ryan M. Smith, K. Terwilliger, S. Glick, D. Jordan, S. Johnston, M. Kempe, S. Kurtz","doi":"10.1109/PVSC.2012.6317933","DOIUrl":"https://doi.org/10.1109/PVSC.2012.6317933","url":null,"abstract":"Acceleration factors are calculated for crystalline silicon photovoltaic modules under system voltage stress by comparing the module power during degradation outdoors with that in accelerated testing at three temperatures and 85% relative humidity. A lognormal analysis is applied to the accelerated lifetime test data, considering failure at 80% of the initial module power. Activation energy of 0.73 eV for the rate of failure is determined for the chamber testing at constant relative humidity, and the probability of module failure at an arbitrary temperature is predicted. To obtain statistical data for multiple modules over the course of degradation in situ of the test chamber, dark I–V measurements are obtained and transformed using superposition, which is found to be well suited for rapid and quantitative evaluation of potential-induced degradation. It is determined that shunt resistance measurements alone do not represent the extent of power degradation. This is explained with a two-diode model analysis that shows an increasing second diode recombination current and ideality factor as the degradation in module power progresses. Failure modes of the modules stressed outdoors are examined and compared with those stressed in accelerated tests.","PeriodicalId":6420,"journal":{"name":"2012 IEEE 38th Photovoltaic Specialists Conference (PVSC) PART 2","volume":"23 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76164901","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}
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