Pub Date : 2018-06-01DOI: 10.1109/PVSC.2018.8548237
R. Campesato, C. Baur, M. Casale, M. Gervasi, E. Gombia, E. Greco, Aldo Kingma, P. Rancoita, D. Rozza, M. Tacconi
Space solar cell radiation hardness is of fundamental importance in view of the future missions towards harsh radiation environment (like the Jupiter missions) and for the new spacecraft using Electrical Propulsion. In this paper we report the radiation data for triple junction (TJ) solar cells and related component cells. Triple junction solar cells, InGaP top cells and GaAs middle cells degrade after electron radiation as expected. With proton irradiation, a high spread in the remaining factors was observed, especially for the TJ and Ge bottom cells. Radiation results have been analyzed by means of the Displacement Damage Dose method and DLTS spectroscopy. In particular with DLTS spectroscopy it was possible to analyze the nature of a few defects introduced by irradiation inside the GaAs sub cell observing a strong correlation with the Displacement Damage Dose.
{"title":"NIEL DOSE and DLTS Analyses on Triple and Single Junction solar cells irradiated with electrons and protons","authors":"R. Campesato, C. Baur, M. Casale, M. Gervasi, E. Gombia, E. Greco, Aldo Kingma, P. Rancoita, D. Rozza, M. Tacconi","doi":"10.1109/PVSC.2018.8548237","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8548237","url":null,"abstract":"Space solar cell radiation hardness is of fundamental importance in view of the future missions towards harsh radiation environment (like the Jupiter missions) and for the new spacecraft using Electrical Propulsion. In this paper we report the radiation data for triple junction (TJ) solar cells and related component cells. Triple junction solar cells, InGaP top cells and GaAs middle cells degrade after electron radiation as expected. With proton irradiation, a high spread in the remaining factors was observed, especially for the TJ and Ge bottom cells. Radiation results have been analyzed by means of the Displacement Damage Dose method and DLTS spectroscopy. In particular with DLTS spectroscopy it was possible to analyze the nature of a few defects introduced by irradiation inside the GaAs sub cell observing a strong correlation with the Displacement Damage Dose.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"129 1","pages":"3768-3772"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86384358","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547846
Gokhan Mert Yagli, Dazhi Yang, D. Srinivasan, Monika
Forecasting of solar PV generation plays an important role in power system operations. Forecasts are required on various geographical and temporal scales, which can be modeled as hierarchies. In a geographical hierarchy, the overall forecast for the region can either be obtained by directly forecasting the regional time series or by aggregating the individual forecasts generated for the sub-regions. This leads to a problem known as aggregate inconsistency as the two sets of forecasts are most likely different due to modeling uncertainties. Hence, practice is not optimal. Statistically optimal aggregation known as reconciliation, has been proven to provide aggregate consistent forecasts. Reconciliation helps system operators to have a superior foresight in a region-wise level, which eventually results in efficient system planning. The focus of this paper is on improving reconciliation accuracy. In addition, the effects of more accurate disaggregated and aggregated forecasts on the final reconciled predictions have been analyzed. A total of 318 simulated PV plants in California have been used to build a geographical hierarchy. More accurate NWP based and aggregated level forecasts are obtained with model output statistics and artificial neural network models. Significant improvements are observed in reconciled forecasts without using any exogenous information.
{"title":"Solar Forecast Reconciliation and Effects of Improved Base Forecasts","authors":"Gokhan Mert Yagli, Dazhi Yang, D. Srinivasan, Monika","doi":"10.1109/PVSC.2018.8547846","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547846","url":null,"abstract":"Forecasting of solar PV generation plays an important role in power system operations. Forecasts are required on various geographical and temporal scales, which can be modeled as hierarchies. In a geographical hierarchy, the overall forecast for the region can either be obtained by directly forecasting the regional time series or by aggregating the individual forecasts generated for the sub-regions. This leads to a problem known as aggregate inconsistency as the two sets of forecasts are most likely different due to modeling uncertainties. Hence, practice is not optimal. Statistically optimal aggregation known as reconciliation, has been proven to provide aggregate consistent forecasts. Reconciliation helps system operators to have a superior foresight in a region-wise level, which eventually results in efficient system planning. The focus of this paper is on improving reconciliation accuracy. In addition, the effects of more accurate disaggregated and aggregated forecasts on the final reconciled predictions have been analyzed. A total of 318 simulated PV plants in California have been used to build a geographical hierarchy. More accurate NWP based and aggregated level forecasts are obtained with model output statistics and artificial neural network models. Significant improvements are observed in reconciled forecasts without using any exogenous information.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"111 1","pages":"2719-2723"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83660656","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547777
S. MacAlpine, Chris W. Wolfrom, O. Westbrook
This work examines the accuracy of commonlyused irradiance decomposition and transposition models when modeling single-axis tracking photovoltaic (PV) arrays in the southwestern United States. Inputs to the models include measured one-minute global horizontal, diffuse horizontal, and direct normal irradiance. The bias and variability associated with decomposition models’ predictions are analyzed and compared according to sky clearness and solar zenith angle, with results varying widely depending on the model employed. Separately, transposition model predictions are compared to measured plane-of-array (POA) irradiance at an operating PV plant with single-axis tracking. Goodagreement is found between the transposition models’ predictions and measured irradiance on clear sky days, with an absolute mean bias difference of $< 2$% for all anisotropic models. The decomposition and transposition models are then combined, with their predictions compared to measured POA irradiance at a second tracking PV plant on an annual and seasonal basis. Morevariability and bias are seen when both decomposition and transposition are performed, though good agreement with measured data is still possible with some model combinations.
{"title":"Evaluation of Irradiance Transposition Models When Utilized with Single Axis Tracking PV Systems in the Southwestern United States","authors":"S. MacAlpine, Chris W. Wolfrom, O. Westbrook","doi":"10.1109/PVSC.2018.8547777","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547777","url":null,"abstract":"This work examines the accuracy of commonlyused irradiance decomposition and transposition models when modeling single-axis tracking photovoltaic (PV) arrays in the southwestern United States. Inputs to the models include measured one-minute global horizontal, diffuse horizontal, and direct normal irradiance. The bias and variability associated with decomposition models’ predictions are analyzed and compared according to sky clearness and solar zenith angle, with results varying widely depending on the model employed. Separately, transposition model predictions are compared to measured plane-of-array (POA) irradiance at an operating PV plant with single-axis tracking. Goodagreement is found between the transposition models’ predictions and measured irradiance on clear sky days, with an absolute mean bias difference of $< 2$% for all anisotropic models. The decomposition and transposition models are then combined, with their predictions compared to measured POA irradiance at a second tracking PV plant on an annual and seasonal basis. Morevariability and bias are seen when both decomposition and transposition are performed, though good agreement with measured data is still possible with some model combinations.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"59 1","pages":"2325-2330"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83992797","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547590
Gayoung Kim, M. Shin, J. Lim
Transparent and opaque hydrogenated amorphous silicon solar cells (a-Si:H) with various transparent electrodes are fabricated for indoor photovoltaics to supply power to Internet of Things devices. The performances of fabricated cells are investigated to evaluate the transparent electrode structures. The highest efficiency (6.05%) and highest average transmittance (24%) in the visible range are obtained with a transparent a-Si:H solar cell having single front and rear GZO electrodes, while the best efficiency is 9.29% with an opaque a-Si:H solar cell. Under LED indoor light, the best efficiencies are 5.12% with the opaque solar cell and 5.75% with the transparent solar cells.
{"title":"Investigation of transparent electrodes and transparent/opaque a-Si:H solar cells for indoor photovoltaics","authors":"Gayoung Kim, M. Shin, J. Lim","doi":"10.1109/PVSC.2018.8547590","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547590","url":null,"abstract":"Transparent and opaque hydrogenated amorphous silicon solar cells (a-Si:H) with various transparent electrodes are fabricated for indoor photovoltaics to supply power to Internet of Things devices. The performances of fabricated cells are investigated to evaluate the transparent electrode structures. The highest efficiency (6.05%) and highest average transmittance (24%) in the visible range are obtained with a transparent a-Si:H solar cell having single front and rear GZO electrodes, while the best efficiency is 9.29% with an opaque a-Si:H solar cell. Under LED indoor light, the best efficiencies are 5.12% with the opaque solar cell and 5.75% with the transparent solar cells.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"18 1","pages":"338-340"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82813713","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547848
M. M. Lunardi, J. Alvarez-Gaitan, N. Chang, R. Corkish
Hydrogenation processes can offer improvements to the electrical performance of silicon (Si) solar cells from different feedstocks, including low-cost feedstocks, such as upgraded metallurgical silicon (UMG-Si). The development of PV technologies should be complemented by environmental analyses of the production processes. Here we undertake an environmental analysis of Si solar modules including the addition of hydrogenation processes through the life cycle assessment (LCA) method. LCA has not been applied to Si technologies such as hydrogenation, to the best of authors' knowledge. We show that the hydrogenation methods result in better environmental outcomes, considering the assumptions made in this LCA.
{"title":"Life Cycle Assessment on Hydrogenation Processes on Silicon Solar Modules","authors":"M. M. Lunardi, J. Alvarez-Gaitan, N. Chang, R. Corkish","doi":"10.1109/PVSC.2018.8547848","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547848","url":null,"abstract":"Hydrogenation processes can offer improvements to the electrical performance of silicon (Si) solar cells from different feedstocks, including low-cost feedstocks, such as upgraded metallurgical silicon (UMG-Si). The development of PV technologies should be complemented by environmental analyses of the production processes. Here we undertake an environmental analysis of Si solar modules including the addition of hydrogenation processes through the life cycle assessment (LCA) method. LCA has not been applied to Si technologies such as hydrogenation, to the best of authors' knowledge. We show that the hydrogenation methods result in better environmental outcomes, considering the assumptions made in this LCA.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"91 1","pages":"2452-2457"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89073289","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547792
A. Danielson, A. Munshi, Anna Kindvall, S. Swain, K. Barth, K. Lynn, W. Sampath
Arsenic dopant was incorporated in CdTe absorber layers in high-efficiency CdTe cells using feedstock doped with 1018cc-1for sublimation of films. The goal of the work was to develop a feasible method for creating a hole density equal to, or greater than that currently achievable using copper doping using a CuCl treatment. Doping with arsenic resulted in a modest increase in open-circuit voltage (VOC) and a large improvement in fill-factor and conversion efficiency when compared with copper-doped devices with similar structure. All experiments were performed in the presence of cadmium overpressure to encourage dopant activation in tellurium vacancy sites. Arsenic incorporation was measured using Secondary Ion Mass Spectrometry (SIMS) at 4E +16 atoms/cc-1,about four times greater incorporation than previously seen by the authors. Using a CdSeTe/CdTe graded absorber and arsenic doping, a conversion efficiency of 16.79% was achieved.
{"title":"Doping CdTe Absorber Cells using Group V Elements","authors":"A. Danielson, A. Munshi, Anna Kindvall, S. Swain, K. Barth, K. Lynn, W. Sampath","doi":"10.1109/PVSC.2018.8547792","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547792","url":null,"abstract":"Arsenic dopant was incorporated in CdTe absorber layers in high-efficiency CdTe cells using feedstock doped with 1018cc-1for sublimation of films. The goal of the work was to develop a feasible method for creating a hole density equal to, or greater than that currently achievable using copper doping using a CuCl treatment. Doping with arsenic resulted in a modest increase in open-circuit voltage (VOC) and a large improvement in fill-factor and conversion efficiency when compared with copper-doped devices with similar structure. All experiments were performed in the presence of cadmium overpressure to encourage dopant activation in tellurium vacancy sites. Arsenic incorporation was measured using Secondary Ion Mass Spectrometry (SIMS) at 4E +16 atoms/cc-1,about four times greater incorporation than previously seen by the authors. Using a CdSeTe/CdTe graded absorber and arsenic doping, a conversion efficiency of 16.79% was achieved.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"17 1","pages":"0119-0123"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90342945","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547888
V. Mihailetchi, H. Chu, R. Kopecek
Despite of recent improvements in silver paste technology, the open-circuit voltages $( V_{oc})$ of silicon solar cells with screen printed and firing-through silver contacts continue to be limited by the high recombination currents at the metal contacts $( J_{{0} {,met}})$. To maximize solar cell efficiencies, the contact resistance $( rho_{c})$ and $J_{{0} {,met}}$ must be simultaneously minimised. In this study we investigated the origin of $J_{{0} {,met}}$ for screen printed silver pastes on $p^{+}$ and $n^{+}$ doped regions and correlate this with contact formation phases during the firing process. We show that, during the contact firing process, the $J_{{0} {,met}}$ significantly increases and even saturates to its final value at temperatures well below 700°C, which is a temperature range below that is needed for contact formation. The same is observed on both $p^{+}$ and $n^{+}$ diffused junctions with planar or random pyramids textured Si surfaces passivated by a SiO2/SiNx layer stack. This show that most of the metal induced recombination loses originates from the etching of the dielectric layers by the glass frit and less during the contact formation process where $rho_{c}$ is minimised. Furthermore, we demonstrate that increasing the SiNx passivating layer thickness leads to a significant reduction in $J_{{0} {,met}}$, possibly due to an incomplete etching of dielectric layers under the contact, whereas the $rho_{c}$ remain low and constant under optimum firing conditions. These findings could help design metallization pastes optimised to reduce dielectric etching, and hence $J_{{0} {,met}}$, without affecting $rho_{c}$.
{"title":"Insight into Metal Induced Recombination Losses and Contact Resistance in Industrial Silicon Solar Cells","authors":"V. Mihailetchi, H. Chu, R. Kopecek","doi":"10.1109/PVSC.2018.8547888","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547888","url":null,"abstract":"Despite of recent improvements in silver paste technology, the open-circuit voltages $( V_{oc})$ of silicon solar cells with screen printed and firing-through silver contacts continue to be limited by the high recombination currents at the metal contacts $( J_{{0} {,met}})$. To maximize solar cell efficiencies, the contact resistance $( rho_{c})$ and $J_{{0} {,met}}$ must be simultaneously minimised. In this study we investigated the origin of $J_{{0} {,met}}$ for screen printed silver pastes on $p^{+}$ and $n^{+}$ doped regions and correlate this with contact formation phases during the firing process. We show that, during the contact firing process, the $J_{{0} {,met}}$ significantly increases and even saturates to its final value at temperatures well below 700°C, which is a temperature range below that is needed for contact formation. The same is observed on both $p^{+}$ and $n^{+}$ diffused junctions with planar or random pyramids textured Si surfaces passivated by a SiO2/SiNx layer stack. This show that most of the metal induced recombination loses originates from the etching of the dielectric layers by the glass frit and less during the contact formation process where $rho_{c}$ is minimised. Furthermore, we demonstrate that increasing the SiNx passivating layer thickness leads to a significant reduction in $J_{{0} {,met}}$, possibly due to an incomplete etching of dielectric layers under the contact, whereas the $rho_{c}$ remain low and constant under optimum firing conditions. These findings could help design metallization pastes optimised to reduce dielectric etching, and hence $J_{{0} {,met}}$, without affecting $rho_{c}$.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"144 1","pages":"2673-2677"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91416501","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547444
D. Chmielewski, Daniel L. Lepkowski, J. Boyer, J. Carlin, T. Grassman, S. Ringel
A high-performance metamorphic $mathbf {Al}_{mathbf {0.2}} mathbf {Ga}_{mathbf {0.8}} mathbf {As}_{mathbf {0.75}} mathbf {P}_{mathbf {0.25}}$/GaAs$_{mathbf {0.75}}{mathbf {P}}_{mathbf {0.25}}$ tunnel junction structure, grown by metal-organic chemical vapor deposition, was designed for use within GaAs$_{mathbf {0.75}} {mathbf {P}}_{mathbf {0.25}}$textbf/Si tandem solar cells. Optimized growth conditions were determined for high C (p-type) and Te (n-type) doping, and a method to mitigate the well-known Te memory effect was develop. The optimized as-grown standalone test device yielded a peak tunneling current of 279.1 Acm $^{mathbf {-2}}$ and zero-bias resistance-area product of $3.0 times 10^{mathbf {-4}} Omega mathbf {cm}^{mathbf {2}}$. Upon exposure to various post-growth thermal treatments these values were found to degrade by up to an order of magnitude, but overall performance still far exceeded the demands for the tandem solar cell operating under AM1.5G, with further extension to operation under medium to high concentration possible.
{"title":"High Performance Metamorphic Tunnel Junctions for GaAsP/Si Tandem Solar Cells Grown via MOCVD","authors":"D. Chmielewski, Daniel L. Lepkowski, J. Boyer, J. Carlin, T. Grassman, S. Ringel","doi":"10.1109/PVSC.2018.8547444","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547444","url":null,"abstract":"A high-performance metamorphic $mathbf {Al}_{mathbf {0.2}} mathbf {Ga}_{mathbf {0.8}} mathbf {As}_{mathbf {0.75}} mathbf {P}_{mathbf {0.25}}$/GaAs$_{mathbf {0.75}}{mathbf {P}}_{mathbf {0.25}}$ tunnel junction structure, grown by metal-organic chemical vapor deposition, was designed for use within GaAs$_{mathbf {0.75}} {mathbf {P}}_{mathbf {0.25}}$textbf/Si tandem solar cells. Optimized growth conditions were determined for high C (p-type) and Te (n-type) doping, and a method to mitigate the well-known Te memory effect was develop. The optimized as-grown standalone test device yielded a peak tunneling current of 279.1 Acm $^{mathbf {-2}}$ and zero-bias resistance-area product of $3.0 times 10^{mathbf {-4}} Omega mathbf {cm}^{mathbf {2}}$. Upon exposure to various post-growth thermal treatments these values were found to degrade by up to an order of magnitude, but overall performance still far exceeded the demands for the tandem solar cell operating under AM1.5G, with further extension to operation under medium to high concentration possible.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"32 1","pages":"2631-2634"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80566316","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547739
A. M. Karimi, Justin S. Fada, Jiqi Liu, J. Braid, Mehmet Koyutürk, R. French
Lifetime performance and degradation analysis of laboratory and field deployed PV modules is paramount to the continued success of solar energy. Image characterization techniques capture spatially resolved macroscopic manifestations of microscopic mechanistic behavior. Automated data processing and analytics allow for a large-scale systematic study of PV module health. In this study, degradation features seen in periodic EL images taken during test-to-failure damp-heat, thermal cycling, ultra-violet irradiance, and dynamic mechanical loading accelerated exposures are extracted and classified using supervised and unsupervised methods. Image corrections, including planar indexing to align module images, are applied. On extracted cell images, degradation states such as busbar corrosion, cracking, wafer edge darkening, and between-busbar dark spots can be studied in comparison to new cells using supervised and unsupervised machine learning. The systematic feature groupings provide a scalable method without bias to quantitatively monitor the degradation of laboratory and commercial systems alike. The evolution of these degradation features through varied exposure conditions provides insight into mechanisms causing degradation in field deployed modules. The supervised algorithms used in this application are Convolutional Neural Networks (CNN) and Support Vector Machines (SVM). With the increase in data and diversity of features, unsupervised learning can be employed to find relations between inherent image properties. Feature extraction techniques help identify intrinsic geometric patterns formed inthe images due to degradation. Principal component analysis is then applied to the extracted set of features to filter the most relevant components from the set, which are then passed to an agglomerative hierarchical clustering algorithm. Google’s Tensorflow library was utilized to enhance the computational efficiency of the CNN model by providing GPUbased parallel matrix operations. Using supervised methods on 5 features an accuracy greater than 98% was achieved. For unsupervised clustering, the classification was done into two clusters of degraded and non-degraded cells with 66% coherence.
{"title":"Feature Extraction, Supervised and Unsupervised Machine Learning Classification of PV Cell Electroluminescence Images","authors":"A. M. Karimi, Justin S. Fada, Jiqi Liu, J. Braid, Mehmet Koyutürk, R. French","doi":"10.1109/PVSC.2018.8547739","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547739","url":null,"abstract":"Lifetime performance and degradation analysis of laboratory and field deployed PV modules is paramount to the continued success of solar energy. Image characterization techniques capture spatially resolved macroscopic manifestations of microscopic mechanistic behavior. Automated data processing and analytics allow for a large-scale systematic study of PV module health. In this study, degradation features seen in periodic EL images taken during test-to-failure damp-heat, thermal cycling, ultra-violet irradiance, and dynamic mechanical loading accelerated exposures are extracted and classified using supervised and unsupervised methods. Image corrections, including planar indexing to align module images, are applied. On extracted cell images, degradation states such as busbar corrosion, cracking, wafer edge darkening, and between-busbar dark spots can be studied in comparison to new cells using supervised and unsupervised machine learning. The systematic feature groupings provide a scalable method without bias to quantitatively monitor the degradation of laboratory and commercial systems alike. The evolution of these degradation features through varied exposure conditions provides insight into mechanisms causing degradation in field deployed modules. The supervised algorithms used in this application are Convolutional Neural Networks (CNN) and Support Vector Machines (SVM). With the increase in data and diversity of features, unsupervised learning can be employed to find relations between inherent image properties. Feature extraction techniques help identify intrinsic geometric patterns formed inthe images due to degradation. Principal component analysis is then applied to the extracted set of features to filter the most relevant components from the set, which are then passed to an agglomerative hierarchical clustering algorithm. Google’s Tensorflow library was utilized to enhance the computational efficiency of the CNN model by providing GPUbased parallel matrix operations. Using supervised methods on 5 features an accuracy greater than 98% was achieved. For unsupervised clustering, the classification was done into two clusters of degraded and non-degraded cells with 66% coherence.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"14 1","pages":"0418-0424"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79058542","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 : 2018-06-01DOI: 10.1109/PVSC.2018.8547883
Umang Desai, Sudha Rathore, A. Agarwal, Aparna Singh
Efficient and uninhibited production of power from PV module depends on all parts of the module performing without getting degraded. Continuous flow of sand particles in deserts can erode backsheet during day and night alike. Erosion of this kind is insidious in nature and can curtail the longevity of PV modules. In the current study, erosion rates have been compared for two backsheets from different manufacturers when eroded by Indian sand. Erosion mechanisms for each backsheet for different sets of experimental conditions are presented in this work. It has been found that the tensile properties of the backsheet play a critical role in influencing the erosion.
{"title":"Comparative study of sand erosion of backsheet of PV modules","authors":"Umang Desai, Sudha Rathore, A. Agarwal, Aparna Singh","doi":"10.1109/PVSC.2018.8547883","DOIUrl":"https://doi.org/10.1109/PVSC.2018.8547883","url":null,"abstract":"Efficient and uninhibited production of power from PV module depends on all parts of the module performing without getting degraded. Continuous flow of sand particles in deserts can erode backsheet during day and night alike. Erosion of this kind is insidious in nature and can curtail the longevity of PV modules. In the current study, erosion rates have been compared for two backsheets from different manufacturers when eroded by Indian sand. Erosion mechanisms for each backsheet for different sets of experimental conditions are presented in this work. It has been found that the tensile properties of the backsheet play a critical role in influencing the erosion.","PeriodicalId":6558,"journal":{"name":"2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC)","volume":"45 1","pages":"3413-3416"},"PeriodicalIF":0.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79112678","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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