Lixia Sang, Jing Zhang, Yudong Zhang, Yangbo Zhao, Jia Lin
Cu2O is an environment-friendly p-type semiconductor with narrow band gap (2.0~2.2eV), which has become a popular sensitizer of TiO2. The present work is focused on the preparation of Cu2O/TiO2 nanotube arrays heterostructures via electrochemical deposition. TiO2 nanotube arrays were prepared by anodic oxidation method and calcined at 450°C, then Cu2O were deposited on TiO2 nanotube arrays in a three-electrode system with surfactants PVP in electrolyte at different deposition potentials (-0.2V and-0.3V) for deposition time 5min. The results show that Cu2O nanoparticles deposit on TiO2 nanotube successfully. The obtained Cu2O nanoparticles were quite different in size at deposition potential -0.2V and -0.3V. The resulting Cu2O/TiO2 nanotube arrays have the significant photoresponse in visible light region. Under irradiation of solar simulator (AM1.5, 100mW/cm2), the photocurrent density of the Cu2O/TiO2 nanotube arrays when Cu2O was deposited at a voltage of -0.3V is more than that of pure TiO2 nanotube arrays.
{"title":"Preparation of Cu2O/TiO2 nanotube arrays and their photoelectrochemical properties as hydrogen-evolving photoanode","authors":"Lixia Sang, Jing Zhang, Yudong Zhang, Yangbo Zhao, Jia Lin","doi":"10.1117/12.2187908","DOIUrl":"https://doi.org/10.1117/12.2187908","url":null,"abstract":"Cu2O is an environment-friendly p-type semiconductor with narrow band gap (2.0~2.2eV), which has become a popular sensitizer of TiO2. The present work is focused on the preparation of Cu2O/TiO2 nanotube arrays heterostructures via electrochemical deposition. TiO2 nanotube arrays were prepared by anodic oxidation method and calcined at 450°C, then Cu2O were deposited on TiO2 nanotube arrays in a three-electrode system with surfactants PVP in electrolyte at different deposition potentials (-0.2V and-0.3V) for deposition time 5min. The results show that Cu2O nanoparticles deposit on TiO2 nanotube successfully. The obtained Cu2O nanoparticles were quite different in size at deposition potential -0.2V and -0.3V. The resulting Cu2O/TiO2 nanotube arrays have the significant photoresponse in visible light region. Under irradiation of solar simulator (AM1.5, 100mW/cm2), the photocurrent density of the Cu2O/TiO2 nanotube arrays when Cu2O was deposited at a voltage of -0.3V is more than that of pure TiO2 nanotube arrays.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122941229","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}
T. Lai, R. Biggie, A. Brooks, B. G. Potter, K. Simmons-Potter
Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following an equivalent year of testing.
在加速降解室中对光伏(PV)模块进行生命周期降解测试，可以预测光伏系统的性能寿命和投资回报率。由于退化结果强烈依赖于室内测试参数，因此必须确定此类研究相对于现场安装的光伏系统的有效性。在本研究中，将250w多晶硅组件的加速老化与自2013年10月以来投入使用的类似多晶硅光伏技术的实时性能退化进行了比较。环境老化效应的研究是在一个全尺寸的工业标准环境室中进行的，该环境室配备了单太阳辐照能力，在2 x 1.6 m的区域内提供98%的照明均匀度。时间依赖的光伏性能(J-V)是通过一个反复出现的、压缩的昼夜循环来评估的，该循环提供了美国西南部具有代表性的当地每日日照量，然后是黑暗(夜间)循环。该循环与热和湿度环境变化同步，旨在尽可能地模拟测试场条件，具体到亚利桑那州图森的一个现场系统的12个月天气剖面。结果证实了环境条件对模块长期性能的影响。虽然温度下降的影响可以在数据中清楚地看到，但去除这些影响可以清楚地解释模块效率随时间和环境暴露的下降。在去除温度依赖效应后，计算归一化效率，并将其与另一个类似技术的面板的性能结果进行比较，该面板先前在测试场经历了相同的气候变化。室内测试系统的相对光伏组件效率下降分析表明，在等效一年的测试后，与现场测试系统相比，光伏组件效率下降约2.5%。
{"title":"Environmental aging in polycrystalline-Si photovoltaic modules: comparison of chamber-based accelerated degradation studies with field-test data","authors":"T. Lai, R. Biggie, A. Brooks, B. G. Potter, K. Simmons-Potter","doi":"10.1117/12.2188696","DOIUrl":"https://doi.org/10.1117/12.2188696","url":null,"abstract":"Lifecycle degradation testing of photovoltaic (PV) modules in accelerated-degradation chambers can enable the prediction both of PV performance lifetimes and of return-on-investment for installations of PV systems. With degradation results strongly dependent on chamber test parameters, the validity of such studies relative to fielded, installed PV systems must be determined. In the present work, accelerated aging of a 250 W polycrystalline silicon module is compared to real-time performance degradation in a similar polycrystalline-silicon, fielded, PV technology that has been operating since October 2013. Investigation of environmental aging effects are performed in a full-scale, industrial-standard environmental chamber equipped with single-sun irradiance capability providing illumination uniformity of 98% over a 2 x 1.6 m area. Time-dependent, photovoltaic performance (J-V) is evaluated over a recurring, compressed night-day cycle providing representative local daily solar insolation for the southwestern United States, followed by dark (night) cycling. This cycle is synchronized with thermal and humidity environmental variations that are designed to mimic, as closely as possible, test-yard conditions specific to a 12 month weather profile for a fielded system in Tucson, AZ. Results confirm the impact of environmental conditions on the module long-term performance. While the effects of temperature de-rating can be clearly seen in the data, removal of these effects enables the clear interpretation of module efficiency degradation with time and environmental exposure. With the temperature-dependent effect removed, the normalized efficiency is computed and compared to performance results from another panel of similar technology that has previously experienced identical climate changes in the test yard. Analysis of relative PV module efficiency degradation for the chamber-tested system shows good comparison to the field-tested system with ~2.5% degradation following an equivalent year of testing.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116720024","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}
Z. Fan, Yahui Su, Huayong Zhang, Xiaohu Han, Feifei Ren
Plasmonics-based GaAs metal-semiconductor-metal photodetector (MSM-PD) with aluminum nano-gratings was proposed. A detailed numerical study of subwavelength nanogratings behavior to reduce the light reflection is performed by finite-difference time domain (FDTD) algorithm. The geometric parameters of nano-gratings, such as aperture width, the nano-gratings height, the duty cycles are optimized for subwavelength metal nanogratings on GaAs substrate and their impact on light reflection below the conventional MSM-PD is confirmed. Simulation results show that a light reflection factor around 15% can be obtained near the wavelength of 900 nm with optimized MSM-PDs, and in visible light spectrum, the Al nano-gratings show better performance than Au nano-gratings.
{"title":"Analysis of aluminum nano-gratings assisted light reflection reduction in GaAs metal-semiconductor-metal photodetectors","authors":"Z. Fan, Yahui Su, Huayong Zhang, Xiaohu Han, Feifei Ren","doi":"10.1117/12.2186654","DOIUrl":"https://doi.org/10.1117/12.2186654","url":null,"abstract":"Plasmonics-based GaAs metal-semiconductor-metal photodetector (MSM-PD) with aluminum nano-gratings was proposed. A detailed numerical study of subwavelength nanogratings behavior to reduce the light reflection is performed by finite-difference time domain (FDTD) algorithm. The geometric parameters of nano-gratings, such as aperture width, the nano-gratings height, the duty cycles are optimized for subwavelength metal nanogratings on GaAs substrate and their impact on light reflection below the conventional MSM-PD is confirmed. Simulation results show that a light reflection factor around 15% can be obtained near the wavelength of 900 nm with optimized MSM-PDs, and in visible light spectrum, the Al nano-gratings show better performance than Au nano-gratings.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115338016","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}
M. Theelen, Christopher Foster, H. Steijvers, N. Barreau, C. Frijters, Z. Vroon, M. Zeman
CIGS solar cells and non-covered molybdenum areas and scribes were exposed to liquid water purged with the atmospheric gases carbon dioxide (CO2), oxygen (O2), nitrogen (N2) and air in order to investigate their degradation behavior. The samples were analyzed by electrical, compositional and optical measurements before, during and after exposure in order to follow the degradation behavior of these samples as a function of time. The CIGS solar cells showed a rapid decrease in conversion efficiency when exposed to water purged with a combination of CO2 and N2 as well as to water purged with air, while their efficiency was slowly reduced in unpurged water and water purged with N2 or O2. Cross-section SEM showed that the exposure of samples to H2O with large concentrations of CO2 led to the dissolution of the ZnO:Al layer, likely starting from the grain boundaries. Preliminary studies showed that molybdenum films and scribes degraded in the combined presence of H2O and O2, while they were stable in the presence of H2O combined with N2 or CO2. Degradation was the most severe on positions where the molybdenum was mechanically damaged and the MoSe2 film was removed before exposure, for example in the middle of the P3 scribe. Exposure to H2O and O2 led to the disappearance of the metallic molybdenum, leaving behind an insoluble red brown material, which is likely a molybdenum oxide such as MoO2.
{"title":"The impact of atmospheric species on the degradation of CIGS solar cells and molybdenum films","authors":"M. Theelen, Christopher Foster, H. Steijvers, N. Barreau, C. Frijters, Z. Vroon, M. Zeman","doi":"10.1117/12.2186316","DOIUrl":"https://doi.org/10.1117/12.2186316","url":null,"abstract":"CIGS solar cells and non-covered molybdenum areas and scribes were exposed to liquid water purged with the atmospheric gases carbon dioxide (CO2), oxygen (O2), nitrogen (N2) and air in order to investigate their degradation behavior. The samples were analyzed by electrical, compositional and optical measurements before, during and after exposure in order to follow the degradation behavior of these samples as a function of time. The CIGS solar cells showed a rapid decrease in conversion efficiency when exposed to water purged with a combination of CO2 and N2 as well as to water purged with air, while their efficiency was slowly reduced in unpurged water and water purged with N2 or O2. Cross-section SEM showed that the exposure of samples to H2O with large concentrations of CO2 led to the dissolution of the ZnO:Al layer, likely starting from the grain boundaries. Preliminary studies showed that molybdenum films and scribes degraded in the combined presence of H2O and O2, while they were stable in the presence of H2O combined with N2 or CO2. Degradation was the most severe on positions where the molybdenum was mechanically damaged and the MoSe2 film was removed before exposure, for example in the middle of the P3 scribe. Exposure to H2O and O2 led to the disappearance of the metallic molybdenum, leaving behind an insoluble red brown material, which is likely a molybdenum oxide such as MoO2.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134207245","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}
A. Kleinová, J. Huran, V. Sasinková, M. Perný, V. Šály, J. Packa
The plasma CVD reactor with parallel plate electrodes was used for plasma enhanced chemical vapor deposition (PECVD) of two type’s silicon carbide thin films on Si substrates. The concentration of elements in the films was determined by RBS and ERD analytical method simultaneously. The chemical compositions of the samples were analyzed by FTIR method. RBS and ERD results showed that the films contain silicon, carbon, hydrogen and small amount of oxygen. FTIR results confirmed the presence of Si-C, Si-H, C-H, and Si-O bonds. From the FTIR spectra the main following vibration frequencies were determined: the band from 2800 to 3000 cm-1 is attributed to stretching vibration of the CHn group in both the sp2 (2880 cm-1) and sp3 (2920 cm-1) configurations. The band at 2100 cm-1 is due to SiHm stretching vibrations. The band at 780 cm-1 can be assigned to Si-C stretching vibration. Main features of FTIR spectra were Gaussian fitted and detailed analyses of chemical bonding in SiC films were performed. Differences between two types of SiC films were discussed with the aim to using these films in the heterojunction solar cell technology.
{"title":"FTIR spectroscopy of silicon carbide thin films prepared by PECVD technology for solar cell application","authors":"A. Kleinová, J. Huran, V. Sasinková, M. Perný, V. Šály, J. Packa","doi":"10.1117/12.2186748","DOIUrl":"https://doi.org/10.1117/12.2186748","url":null,"abstract":"The plasma CVD reactor with parallel plate electrodes was used for plasma enhanced chemical vapor deposition (PECVD) of two type’s silicon carbide thin films on Si substrates. The concentration of elements in the films was determined by RBS and ERD analytical method simultaneously. The chemical compositions of the samples were analyzed by FTIR method. RBS and ERD results showed that the films contain silicon, carbon, hydrogen and small amount of oxygen. FTIR results confirmed the presence of Si-C, Si-H, C-H, and Si-O bonds. From the FTIR spectra the main following vibration frequencies were determined: the band from 2800 to 3000 cm-1 is attributed to stretching vibration of the CHn group in both the sp2 (2880 cm-1) and sp3 (2920 cm-1) configurations. The band at 2100 cm-1 is due to SiHm stretching vibrations. The band at 780 cm-1 can be assigned to Si-C stretching vibration. Main features of FTIR spectra were Gaussian fitted and detailed analyses of chemical bonding in SiC films were performed. Differences between two types of SiC films were discussed with the aim to using these films in the heterojunction solar cell technology.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131900553","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}
Defects in multicrystalline silicon solar cells such as impurities, gain boundaries, dislocations and metallic impurities have great influence to the final conversion efficiency of devices. Moreover, different kinds of defects and defects at different depth layers in multicrystalline silicon solar cell play different roles to the final performance of devices. This paper proposes a fast technique via electroluminescence imaging method to distinguish different types and depths defects. Different types of defects have various influences to the distribution of extra minority carriers which would result in the distinctions in the final luminescence spectrum and intensity. Therefore, we can recognize these defects via a group of EL images in a few seconds. Also, we found that defects at different depths show a closely relationship with electrical breakdown which would lead to the differences on the final electroluminescence properties. The EL images under different forward-biased and reversed-biased voltages give a clear separation of defects near the front surface, around p-n junction and in bulk material. Light beam induced current (LBIC) imaging is used to verify the methods we proposed. These modern imaging methods could become popular methods in photovoltaic testing field, and we hope our research could give some help in the study of silicon based devices.
{"title":"Characterizing different defects in multicrystalline silicon solar cells via modern imaging methods","authors":"Shishu Lou, Huishi Zhu, P. Han","doi":"10.1117/12.2195811","DOIUrl":"https://doi.org/10.1117/12.2195811","url":null,"abstract":"Defects in multicrystalline silicon solar cells such as impurities, gain boundaries, dislocations and metallic impurities have great influence to the final conversion efficiency of devices. Moreover, different kinds of defects and defects at different depth layers in multicrystalline silicon solar cell play different roles to the final performance of devices. This paper proposes a fast technique via electroluminescence imaging method to distinguish different types and depths defects. Different types of defects have various influences to the distribution of extra minority carriers which would result in the distinctions in the final luminescence spectrum and intensity. Therefore, we can recognize these defects via a group of EL images in a few seconds. Also, we found that defects at different depths show a closely relationship with electrical breakdown which would lead to the differences on the final electroluminescence properties. The EL images under different forward-biased and reversed-biased voltages give a clear separation of defects near the front surface, around p-n junction and in bulk material. Light beam induced current (LBIC) imaging is used to verify the methods we proposed. These modern imaging methods could become popular methods in photovoltaic testing field, and we hope our research could give some help in the study of silicon based devices.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131660387","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}
Triple junction hydrogenated amorphous silicon (a-Si:H) have shown exceptionally good reliability and durability. Cadmium telluride, CdTe PV modules have shown the lowest production cost without subsidies. Copper-indium gallium selenide sulfide (CIGS) and cadmium telluride (CdTe) cells and modules have been showing efficiencies equal or greater than those of multi-crystalline, (mx-Si), PV modules. Early generation CIGS and CdTe PV modules had a different qualification standard 61646 as compared to 61215 for crystalline silicon, (c-Si), PV modules. This, together with small vulnerability in harsh climates, was used to create doubts about their reliability. Recently CdTe and CIGS glass-to-glass modules have passed the rigorous accelerated tests, especially as long as the edge seals are not compromised. Moreover, the cumulative shipment of these modules is more than 12 GW demonstrating the customer confidence in these products. Hence it can be stated that also in terms of the reliability and durability all the thin film PV modules stand tall and compare favorably with mx-Si.
{"title":"Thin film PV standing tall side-by-side with multi-crystalline silicon: also in terms of reliability","authors":"N. Dhere, A. Ward, R. Wieting, S. Guha, R. Dhere","doi":"10.1117/12.2187827","DOIUrl":"https://doi.org/10.1117/12.2187827","url":null,"abstract":"Triple junction hydrogenated amorphous silicon (a-Si:H) have shown exceptionally good reliability and durability. Cadmium telluride, CdTe PV modules have shown the lowest production cost without subsidies. Copper-indium gallium selenide sulfide (CIGS) and cadmium telluride (CdTe) cells and modules have been showing efficiencies equal or greater than those of multi-crystalline, (mx-Si), PV modules. Early generation CIGS and CdTe PV modules had a different qualification standard 61646 as compared to 61215 for crystalline silicon, (c-Si), PV modules. This, together with small vulnerability in harsh climates, was used to create doubts about their reliability. Recently CdTe and CIGS glass-to-glass modules have passed the rigorous accelerated tests, especially as long as the edge seals are not compromised. Moreover, the cumulative shipment of these modules is more than 12 GW demonstrating the customer confidence in these products. Hence it can be stated that also in terms of the reliability and durability all the thin film PV modules stand tall and compare favorably with mx-Si.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115257966","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}
M. Kempe, David C. Miller, Dylan L. Nobles, K. Sakurai, J. Tucker, J. Bokria, T. Shioda, K. Nanjundiah, T. Yoshihara, J. Birchmier, O. Zubillaga, J. Wohlgemuth
Photovoltaic (PV) modules, operate at high voltages and elevated temperatures, and are known to degrade because of leakage current to ground. Related degradation processes may include: electric/ionic corrosion, electrochemical deposition, electromigration, and/or charge build-up in thin layers. The use of polymeric materials with a high resistivity is known to reduce the rate of potential induced degradation processes. Because of this, PV materials suppliers are placing increased importance on the encapsulant bulk resistivity, but there is no universally accepted method for making this measurement. The development of a resistivity test standard is described in this paper. We have performed a number of exploratory and round-robin tests to establish a representative and reproducible method for determining the bulk resistivity of polymeric materials, including encapsulation, backsheet, edge seals, and adhesives. The duration of measurement has been shown to greatly affect the results, e.g., an increase as great as 100X was seen for different measurement times. The standard has been developed using measurements alternating between an "on" and "off" voltage state with a weighted averaging function and cycle times of an hour.
{"title":"Development of a resistivity standard for polymeric materials used in photovoltaic modules","authors":"M. Kempe, David C. Miller, Dylan L. Nobles, K. Sakurai, J. Tucker, J. Bokria, T. Shioda, K. Nanjundiah, T. Yoshihara, J. Birchmier, O. Zubillaga, J. Wohlgemuth","doi":"10.1117/12.2189662","DOIUrl":"https://doi.org/10.1117/12.2189662","url":null,"abstract":"Photovoltaic (PV) modules, operate at high voltages and elevated temperatures, and are known to degrade because of leakage current to ground. Related degradation processes may include: electric/ionic corrosion, electrochemical deposition, electromigration, and/or charge build-up in thin layers. The use of polymeric materials with a high resistivity is known to reduce the rate of potential induced degradation processes. Because of this, PV materials suppliers are placing increased importance on the encapsulant bulk resistivity, but there is no universally accepted method for making this measurement. The development of a resistivity test standard is described in this paper. We have performed a number of exploratory and round-robin tests to establish a representative and reproducible method for determining the bulk resistivity of polymeric materials, including encapsulation, backsheet, edge seals, and adhesives. The duration of measurement has been shown to greatly affect the results, e.g., an increase as great as 100X was seen for different measurement times. The standard has been developed using measurements alternating between an \"on\" and \"off\" voltage state with a weighted averaging function and cycle times of an hour.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126417177","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}
S. Abdallah, D. Herrera, B. Conlon, N. Rahimi, L. Lester
GaSb thermophotovoltaic (TPV) devices were fabricated using a Molecular Beam Epitaxy (MBE) technique. Different emitter thicknesses (de) were studied to maximize the TPV cell’s short circuit current density. In this regard, the fabricated TPV device’s emitter was incrementally wet-etched and characterized to find the optimal thickness value. Simulations were performed using the Crosslight APSYS® platform over the full-spectrum range in order to predict device performance for different designs, while maximizing the photocurrent generation and enhancing the emitter sheet resistance. TPV devices were characterized electrically and optically. These experimental data showed that the etched emitter has minimal impact on the measured short circuit current density (Jsc) while simulated results demonstrated an optimal de of 200 nm.
{"title":"Emitter thickness optimization for GaSb thermophotovoltaic cells grown by molecular beam epitaxy","authors":"S. Abdallah, D. Herrera, B. Conlon, N. Rahimi, L. Lester","doi":"10.1117/12.2187487","DOIUrl":"https://doi.org/10.1117/12.2187487","url":null,"abstract":"GaSb thermophotovoltaic (TPV) devices were fabricated using a Molecular Beam Epitaxy (MBE) technique. Different emitter thicknesses (de) were studied to maximize the TPV cell’s short circuit current density. In this regard, the fabricated TPV device’s emitter was incrementally wet-etched and characterized to find the optimal thickness value. Simulations were performed using the Crosslight APSYS® platform over the full-spectrum range in order to predict device performance for different designs, while maximizing the photocurrent generation and enhancing the emitter sheet resistance. TPV devices were characterized electrically and optically. These experimental data showed that the etched emitter has minimal impact on the measured short circuit current density (Jsc) while simulated results demonstrated an optimal de of 200 nm.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132895665","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}
Major sources of performance degradation and failure in glass-encapsulated PV modules include moisture-induced gridline corrosion, potential-induced degradation (PID) of the cell, and stress-induced busbar delamination. Recent studies have shown that PV modules operating in damp heat at -600 V are vulnerable to large amounts of degradation, potentially up to 90% of the original power output within 200 hours. To improve module reliability and restore power production in the presence of PID and other failure mechanisms, a fundamental rethinking of accelerated testing is needed. This in turn will require an improved understanding of technology choices made early in development that impact failures later. In this work, we present an integrated approach of modeling, characterization, and validation to address these problems. A hierarchical modeling framework will allows us to clarify the mechanisms of corrosion, PID, and delamination. We will employ a physics-based compact model of the cell, topology of the electrode interconnection, geometry of the packaging stack, and environmental operating conditions to predict the current, voltage, temperature, and stress distributions in PV modules correlated with the acceleration of specific degradation modes. A self-consistent solution will capture the essential complexity of the technology-specific acceleration of PID and other degradation mechanisms as a function of illumination, ambient temperature, and relative humidity. Initial results from our model include specific lifetime predictions suitable for direct comparison with indoor and outdoor experiments, which are qualitatively validated by prior work. This approach could play a significant role in developing novel accelerated lifetime tests.
{"title":"A modeling framework for potential induced degradation in PV modules","authors":"P. Bermel, R. Asadpour, Chao Zhou, M. Alam","doi":"10.1117/12.2188813","DOIUrl":"https://doi.org/10.1117/12.2188813","url":null,"abstract":"Major sources of performance degradation and failure in glass-encapsulated PV modules include moisture-induced gridline corrosion, potential-induced degradation (PID) of the cell, and stress-induced busbar delamination. Recent studies have shown that PV modules operating in damp heat at -600 V are vulnerable to large amounts of degradation, potentially up to 90% of the original power output within 200 hours. To improve module reliability and restore power production in the presence of PID and other failure mechanisms, a fundamental rethinking of accelerated testing is needed. This in turn will require an improved understanding of technology choices made early in development that impact failures later. In this work, we present an integrated approach of modeling, characterization, and validation to address these problems. A hierarchical modeling framework will allows us to clarify the mechanisms of corrosion, PID, and delamination. We will employ a physics-based compact model of the cell, topology of the electrode interconnection, geometry of the packaging stack, and environmental operating conditions to predict the current, voltage, temperature, and stress distributions in PV modules correlated with the acceleration of specific degradation modes. A self-consistent solution will capture the essential complexity of the technology-specific acceleration of PID and other degradation mechanisms as a function of illumination, ambient temperature, and relative humidity. Initial results from our model include specific lifetime predictions suitable for direct comparison with indoor and outdoor experiments, which are qualitatively validated by prior work. This approach could play a significant role in developing novel accelerated lifetime tests.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125179172","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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