Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925141
L. Serenelli, M. Izzi, A. Mittiga, M. Tucci, L. Martini, R. Asquini, D. Caputo, G. de Cesare
The amorphous/crystalline silicon technology has demonstrated its potentiality leading to high efficiency solar cells. To enhance the interface quality we investigate the effect of hydrogen plasma and thermal annealing treatments performed on thin amorphous silicon layer deposited over crystalline silicon surface. To this aim we use surface photovoltage technique, as a contact-less tool for the evaluation of the energetic distribution of the state density at amorphous/crystalline silicon interface, and FTIR spectroscopy of the same samples to evaluate the evolution of Si-H and Si-H2 bonds. The surface photovoltage technique results to be very sensitive to the different experimental treatments, and therefore it can be considered a precious tool to monitor and improve the interface electronic quality. We found that thermal annealing produces a metastable state which goes back to the initial state after just 48 hours, while the effect of hydrogen plasma post-treatment results more stable. In particular the latter reduces the defect density of one order of magnitude and keeps constant also after one month. The hydrogen plasma is able to reduce the defect density but at the same time increases the surface charge within the a-Si:H film due to the H+ ions accumulated during the plasma exposure, leading to a more stable configuration.
{"title":"Evaluation of Hydrogen plasma effect in a-Si:H/c-Si interface by means of Surface Photovoltage measurement and FTIR spectroscopy","authors":"L. Serenelli, M. Izzi, A. Mittiga, M. Tucci, L. Martini, R. Asquini, D. Caputo, G. de Cesare","doi":"10.1109/PVSC.2014.6925141","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925141","url":null,"abstract":"The amorphous/crystalline silicon technology has demonstrated its potentiality leading to high efficiency solar cells. To enhance the interface quality we investigate the effect of hydrogen plasma and thermal annealing treatments performed on thin amorphous silicon layer deposited over crystalline silicon surface. To this aim we use surface photovoltage technique, as a contact-less tool for the evaluation of the energetic distribution of the state density at amorphous/crystalline silicon interface, and FTIR spectroscopy of the same samples to evaluate the evolution of Si-H and Si-H2 bonds. The surface photovoltage technique results to be very sensitive to the different experimental treatments, and therefore it can be considered a precious tool to monitor and improve the interface electronic quality. We found that thermal annealing produces a metastable state which goes back to the initial state after just 48 hours, while the effect of hydrogen plasma post-treatment results more stable. In particular the latter reduces the defect density of one order of magnitude and keeps constant also after one month. The hydrogen plasma is able to reduce the defect density but at the same time increases the surface charge within the a-Si:H film due to the H+ ions accumulated during the plasma exposure, leading to a more stable configuration.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"34 1","pages":"1248-1252"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76438334","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925114
S. Abdul Hadi, E. Polyzoeva, Tim Milakovich, M. Bulsara, J. Hoyt, E. Fitzgerald, A. Nayfeh
A novel GaAs0.71P0.29/Si tandem cell is proposed and simulated. In order to grow GaAs0.71P0.29 layers on Si, Si1-yGey (SiGe) buffer layers can be used but optical losses are expected. To reduce large optical losses a wafer bonded/layer transferred structure can be used that eliminates the SiGe buffer layer. In this work we propose a novel tandem step-cell design that partially exposes the underlying Si cell for both wafer bonded and SiGe based cells. We demonstrate by experiment and simulation mitigation of the optical losses associated with SiGe buffer layers. For an optimized GaAs0.71P0.29/Si tandem cell without the step cell design, simulations estimate ~20% efficiency for the bonded structure and ~3% for the as grown structure with a SiGe buffer. With the proposed novel step-cell design, optimum efficiency of bonded structure increases to ~32% while for structures with SiGe the simulated efficiency reaches ~23%. Optimum exposure of bottom cell area increases with increasing thickness and lifetime of layers above the bottom Si cell.
{"title":"Novel GaAs0.71P0.29/Si tandem step-cell design","authors":"S. Abdul Hadi, E. Polyzoeva, Tim Milakovich, M. Bulsara, J. Hoyt, E. Fitzgerald, A. Nayfeh","doi":"10.1109/PVSC.2014.6925114","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925114","url":null,"abstract":"A novel GaAs0.71P0.29/Si tandem cell is proposed and simulated. In order to grow GaAs0.71P0.29 layers on Si, Si1-yGey (SiGe) buffer layers can be used but optical losses are expected. To reduce large optical losses a wafer bonded/layer transferred structure can be used that eliminates the SiGe buffer layer. In this work we propose a novel tandem step-cell design that partially exposes the underlying Si cell for both wafer bonded and SiGe based cells. We demonstrate by experiment and simulation mitigation of the optical losses associated with SiGe buffer layers. For an optimized GaAs0.71P0.29/Si tandem cell without the step cell design, simulations estimate ~20% efficiency for the bonded structure and ~3% for the as grown structure with a SiGe buffer. With the proposed novel step-cell design, optimum efficiency of bonded structure increases to ~32% while for structures with SiGe the simulated efficiency reaches ~23%. Optimum exposure of bottom cell area increases with increasing thickness and lifetime of layers above the bottom Si cell.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"34 1","pages":"1127-1131"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75973539","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925124
E. Perl, W. McMahon, J. Bowers, D. Friedman
Multijunction photovoltaic devices with four or more junctions require low reflection over a wavelength range that is nearly 50% wider than what is required for a triple-junction design. Antireflective nanostructures can drastically reduce reflection across this range; however careful design is necessary for integration with multijunction devices. In this work, we address the design trade-offs imposed by material availability by modeling absorption and reflection loss for various configurations. We find that the best performance is obtained using a hybrid design that combines antireflective nanostructures with a thin-film optical coating. Our models show that this configuration can increase transmitted power into the solar cell by 2.1% compared to the best standalone nanostructure configuration and 1.3% compared to an optimal thin-film antireflection coating. We also detail a fabrication process for integrating this hybrid design onto an active photovoltaic device.
{"title":"Material selection and fabrication parameters for antireflective nanostructures integrated with multijunction photovoltaics","authors":"E. Perl, W. McMahon, J. Bowers, D. Friedman","doi":"10.1109/PVSC.2014.6925124","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925124","url":null,"abstract":"Multijunction photovoltaic devices with four or more junctions require low reflection over a wavelength range that is nearly 50% wider than what is required for a triple-junction design. Antireflective nanostructures can drastically reduce reflection across this range; however careful design is necessary for integration with multijunction devices. In this work, we address the design trade-offs imposed by material availability by modeling absorption and reflection loss for various configurations. We find that the best performance is obtained using a hybrid design that combines antireflective nanostructures with a thin-film optical coating. Our models show that this configuration can increase transmitted power into the solar cell by 2.1% compared to the best standalone nanostructure configuration and 1.3% compared to an optimal thin-film antireflection coating. We also detail a fabrication process for integrating this hybrid design onto an active photovoltaic device.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"110 1","pages":"1174-1179"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76023014","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925200
N. Vulic, M. Patil, Y. Zou, Sri Harsha Amilineni, C. Honsberg, S. Goodnick
This paper proposes the possibility of scaling up solar generation while shifting cooling load to the daytime. The focus is on buildings equipped with a water tank used to actively store cold water produced by a series of chillers. Water has the flexibility to be chilled and stored for later use. To lower the load demand during the peak hours of the day, the cooling loads are commonly shifted to the night hours through thermal storage. The present work studies the possibility of using solar power to meet the cooling demand by taking advantage of the fact that solar generation closely precedes the peak cooling demand. Also, in cases where solar capacity is scaled up, chiller storage tanks can store excess solar power generated, thus stabilizing the grid.
{"title":"Matching AC loads to solar peak production using thermal energy storage in building cooling systems - A case study at Arizona State University","authors":"N. Vulic, M. Patil, Y. Zou, Sri Harsha Amilineni, C. Honsberg, S. Goodnick","doi":"10.1109/PVSC.2014.6925200","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925200","url":null,"abstract":"This paper proposes the possibility of scaling up solar generation while shifting cooling load to the daytime. The focus is on buildings equipped with a water tank used to actively store cold water produced by a series of chillers. Water has the flexibility to be chilled and stored for later use. To lower the load demand during the peak hours of the day, the cooling loads are commonly shifted to the night hours through thermal storage. The present work studies the possibility of using solar power to meet the cooling demand by taking advantage of the fact that solar generation closely precedes the peak cooling demand. Also, in cases where solar capacity is scaled up, chiller storage tanks can store excess solar power generated, thus stabilizing the grid.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"39 1","pages":"1504-1509"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87793050","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6924867
R. Brendel, Verena Steckenreiter, J. Hensen, J. Petermann, Sarah Kajari-Schroeder
We demonstrate the fabrication of a new type of wafer equivalent from the gas phase. The demonstrators are 160 μm thick and 9×9 cm2 in size. They consists of a 30 μm-thick p-type monocrystalline epitaxial layer that is carried by a CVD-deposited, 130 μm-thick, p+-type polycrystalline Si layer. A SiO2 layer in between the epitaxial Si and the poly-Si passivates the rear side of the cell and functions as a reflector. Openings in the oxide make the contact to the base and form a PERL-type rear side. The wafer bow is (0.3±0.2 mm). The wafer surface is (100)-oriented. Optical analysis demonstrates an absorption corresponding to a short circuit current density of (38.5±0.5) mA/cm2 from a 22.6 μm-thick epitaxial layer when textured with random pyramids. Small p-type demonstrator solar cells exhibit a base saturation current density of (111±20) fA/cm2 as deduced from a quantum efficiency measurement. The poly-Si-carried (PolCa) wafer equivalent shortcuts the conventional wafer production process, since it avoids crunching and melting of the poly-Si, growing of the ingot and sawing of the wafers.
{"title":"Epitaxial Si films carried by thick polycrystalline Si as a drop-in replacement for conventional Si wafers","authors":"R. Brendel, Verena Steckenreiter, J. Hensen, J. Petermann, Sarah Kajari-Schroeder","doi":"10.1109/PVSC.2014.6924867","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6924867","url":null,"abstract":"We demonstrate the fabrication of a new type of wafer equivalent from the gas phase. The demonstrators are 160 μm thick and 9×9 cm2 in size. They consists of a 30 μm-thick p-type monocrystalline epitaxial layer that is carried by a CVD-deposited, 130 μm-thick, p+-type polycrystalline Si layer. A SiO2 layer in between the epitaxial Si and the poly-Si passivates the rear side of the cell and functions as a reflector. Openings in the oxide make the contact to the base and form a PERL-type rear side. The wafer bow is (0.3±0.2 mm). The wafer surface is (100)-oriented. Optical analysis demonstrates an absorption corresponding to a short circuit current density of (38.5±0.5) mA/cm2 from a 22.6 μm-thick epitaxial layer when textured with random pyramids. Small p-type demonstrator solar cells exhibit a base saturation current density of (111±20) fA/cm2 as deduced from a quantum efficiency measurement. The poly-Si-carried (PolCa) wafer equivalent shortcuts the conventional wafer production process, since it avoids crunching and melting of the poly-Si, growing of the ingot and sawing of the wafers.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"135 1","pages":"3515-3520"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86827342","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925381
J. Videira, E. Bilotti, A. Chatten
Square and cylindrical fibre luminescent solar concentrators (FLSCs) are investigated. Standalone cylindrical FLSCs are better performing than square ones. Simulation results are compared with real-world samples, manufactured at Queen Mary University of London (QMUL) by fibre extrusion. Shading effects in 2, 3 and an infinite array of cylindrical fibres is investigated. A cylinder will divert all non-reflected incident light away from its neighbour up to a threshold zenithal angle, at which point it starts to focus light back in. Simulations were run for an FLSC array on both the summer and winter solstice days in London, UK using SMARTS spectral data. The array averages 4% efficiency on the winter solstice and 5% on the summer solstice.
{"title":"Cylindrical and square fibre luminescent solar concentrators: Experimental and simulation comparisons","authors":"J. Videira, E. Bilotti, A. Chatten","doi":"10.1109/PVSC.2014.6925381","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925381","url":null,"abstract":"Square and cylindrical fibre luminescent solar concentrators (FLSCs) are investigated. Standalone cylindrical FLSCs are better performing than square ones. Simulation results are compared with real-world samples, manufactured at Queen Mary University of London (QMUL) by fibre extrusion. Shading effects in 2, 3 and an infinite array of cylindrical fibres is investigated. A cylinder will divert all non-reflected incident light away from its neighbour up to a threshold zenithal angle, at which point it starts to focus light back in. Simulations were run for an FLSC array on both the summer and winter solstice days in London, UK using SMARTS spectral data. The array averages 4% efficiency on the winter solstice and 5% on the summer solstice.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"33 1","pages":"2280-2285"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86922901","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925357
David C. Miller, Scott L. Deibert, J. Wohlgemuth
Engineering robust adhesion of the junction box (j-box) is a hurdle typically encountered by photovoltaic module manufacturers during product development and manufacturing process control. There are historical incidences of adverse effects (e.g., fires) caused when the j-box/adhesive/module system has failed in the field. The addition of a weight to the j-box during the “damp-heat,” “thermal-cycle,” or “creep” tests within the IEC qualification protocol is proposed to verify the basic robustness of the adhesion system. The details of the proposed test are described, in addition to a trial-run of the test procedure. The described experiments examine four moisture-cured silicones, four foam tapes, and a hot-melt adhesive used in conjunction with glass, KPE, THV, and TPE substrates. For the purpose of validating the experiment, j-boxes were adhered to a substrate, loaded with a prescribed weight, and then subjected to aging. The replicate mock-modules were aged in an environmental chamber (at 85°C/85% relative humidity for 1000 hours; then 100°C/<;10% relative humidity for 200 hours) or fielded in Golden (CO), Miami (FL), and Phoenix (AZ) for one year. Attachment strength tests, including pluck and shear test geometries, were also performed on smaller component specimens.
{"title":"Trial-run of a junction-box attachment test for use in photovoltaic module qualification","authors":"David C. Miller, Scott L. Deibert, J. Wohlgemuth","doi":"10.1109/PVSC.2014.6925357","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925357","url":null,"abstract":"Engineering robust adhesion of the junction box (j-box) is a hurdle typically encountered by photovoltaic module manufacturers during product development and manufacturing process control. There are historical incidences of adverse effects (e.g., fires) caused when the j-box/adhesive/module system has failed in the field. The addition of a weight to the j-box during the “damp-heat,” “thermal-cycle,” or “creep” tests within the IEC qualification protocol is proposed to verify the basic robustness of the adhesion system. The details of the proposed test are described, in addition to a trial-run of the test procedure. The described experiments examine four moisture-cured silicones, four foam tapes, and a hot-melt adhesive used in conjunction with glass, KPE, THV, and TPE substrates. For the purpose of validating the experiment, j-boxes were adhered to a substrate, loaded with a prescribed weight, and then subjected to aging. The replicate mock-modules were aged in an environmental chamber (at 85°C/85% relative humidity for 1000 hours; then 100°C/<;10% relative humidity for 200 hours) or fielded in Golden (CO), Miami (FL), and Phoenix (AZ) for one year. Attachment strength tests, including pluck and shear test geometries, were also performed on smaller component specimens.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"37 1","pages":"2182-2187"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87063835","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925389
Amin Emrani, T. Dhakal, Chien-Yi Peng, C. Westgate
Synthesis of Cu2ZnSnS4 (CZTS) thin films by fast sulfurization of sputtered Sn/Zn/Cu precursors under ambient H2S has been studied. Surface morphology and cross section of the films at different sulfurization processes were investigated by scanning electron microscopy (SEM). To further explore the CZTS layer, the following additional layers were deposited to complete the solar cells: CdS with chemical bath deposition; ZnO and AZO with RF magnetron deposition; and, silver fingers as the front contact as the last layer. The efficiency and characteristics of the thin film solar cells were measured and a detailed comparison is presented. An efficiency of 3.8 % has been achieved.
{"title":"CZTS solar cells fabricated by fast sulfurization of sputtered Sn/Zn/Cu precursors under H2S atmosphere","authors":"Amin Emrani, T. Dhakal, Chien-Yi Peng, C. Westgate","doi":"10.1109/PVSC.2014.6925389","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925389","url":null,"abstract":"Synthesis of Cu2ZnSnS4 (CZTS) thin films by fast sulfurization of sputtered Sn/Zn/Cu precursors under ambient H2S has been studied. Surface morphology and cross section of the films at different sulfurization processes were investigated by scanning electron microscopy (SEM). To further explore the CZTS layer, the following additional layers were deposited to complete the solar cells: CdS with chemical bath deposition; ZnO and AZO with RF magnetron deposition; and, silver fingers as the front contact as the last layer. The efficiency and characteristics of the thin film solar cells were measured and a detailed comparison is presented. An efficiency of 3.8 % has been achieved.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"144 1","pages":"2314-2316"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87569566","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925178
G. Yordanov
The European PV Geographical Information System (PVGIS) describes module performance in terms of the relative efficiency with respect to Standard Testing Conditions (STC). The efficiency's dependence on irradiance and operating temperature is modeled with a bi-quadratic polynomial with respect to the relative temperature and the logarithm of relative irradiance. In earlier works, the present author derived relations between two model coefficients describing the irradiance dependence at 25°C, k1 and k2, and I-V curve model parameters such as the series resistance RS and the ideality factor n. There was good agreement between the theoretical and fitted values of k1, but the fitted values of k2 were overestimated for most of the studied crystalline-silicon (c-Si) modules. The present paper derives a correction factor for k2 and equations for k3 - k6. The results are limited to the case of PV modules behaving well according to the one-exponential I-V curve model, with negligible current leakage via cell shunts. The effects of several I-V curve non-idealities on performance are discussed.
{"title":"Relative efficiency revealed: Equations for k1–k6 of the PVGIS model","authors":"G. Yordanov","doi":"10.1109/PVSC.2014.6925178","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925178","url":null,"abstract":"The European PV Geographical Information System (PVGIS) describes module performance in terms of the relative efficiency with respect to Standard Testing Conditions (STC). The efficiency's dependence on irradiance and operating temperature is modeled with a bi-quadratic polynomial with respect to the relative temperature and the logarithm of relative irradiance. In earlier works, the present author derived relations between two model coefficients describing the irradiance dependence at 25°C, k1 and k2, and I-V curve model parameters such as the series resistance RS and the ideality factor n. There was good agreement between the theoretical and fitted values of k1, but the fitted values of k2 were overestimated for most of the studied crystalline-silicon (c-Si) modules. The present paper derives a correction factor for k2 and equations for k3 - k6. The results are limited to the case of PV modules behaving well according to the one-exponential I-V curve model, with negligible current leakage via cell shunts. The effects of several I-V curve non-idealities on performance are discussed.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"124 1","pages":"1393-1398"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88104005","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925224
J. J. Chavez, Xiaowang W. Zhou, D. Ward, J. Cruz-Campa, D. Zubia
Recently developed molecular dynamics models have been applied to study the formation of defects during growth of ZnTe-on-CdS multilayers. Our studies indicated that misfit dislocations are formed during growth, and the dislocation density can be reduced if the ZnTe layer is grown in a nano island configuration as opposed to a continuous film. These results highlight the use of molecular dynamics methods in providing valuable defect formation mechanism insight and guiding experimental efforts to produce high efficiency Cd1-xZnxTe solar cells.
{"title":"A molecular dynamics study on defect reduction in thin film Cd1−xZnxTe/CdS solar cells","authors":"J. J. Chavez, Xiaowang W. Zhou, D. Ward, J. Cruz-Campa, D. Zubia","doi":"10.1109/PVSC.2014.6925224","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925224","url":null,"abstract":"Recently developed molecular dynamics models have been applied to study the formation of defects during growth of ZnTe-on-CdS multilayers. Our studies indicated that misfit dislocations are formed during growth, and the dislocation density can be reduced if the ZnTe layer is grown in a nano island configuration as opposed to a continuous film. These results highlight the use of molecular dynamics methods in providing valuable defect formation mechanism insight and guiding experimental efforts to produce high efficiency Cd1-xZnxTe solar cells.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"71 1","pages":"1593-1595"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86127544","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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