Pub Date : 1996-05-13DOI: 10.1109/PVSC.1996.564241
A. Compaan, I. Matulionis, M. J. Miller, U.N. Jayamaha
In this paper, the authors report on studies of four different lasers for the scribing of thin-film photovoltaic materials including CdTe, CIS, SnO/sub 2/, ZnO, and Mo. They have used cw-lamp-pumped and flashlamp-pumped Nd:YAG lasers (/spl lambda/=532/1064 nm), a copper-vapor laser (511/578 nm), and an XeCl-excimer laser (308 nm), with pulse durations ranging from 180 nsec down to 8 nsec. The purpose of this work is to identify the effects of laser wavelength and laser pulse duration on the most effective energy utilization and on the quality of the scribe line. Ablation spots and scribe lines were examined by optical microscopy and stylus profilometry. The ablation threshold has been identified for the combinations of four lasers and five materials. The energy density for optimum removal of material has been identified for two of the laser systems (three wavelengths).
{"title":"Optimization of laser scribing for thin-film photovoltaics","authors":"A. Compaan, I. Matulionis, M. J. Miller, U.N. Jayamaha","doi":"10.1109/PVSC.1996.564241","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564241","url":null,"abstract":"In this paper, the authors report on studies of four different lasers for the scribing of thin-film photovoltaic materials including CdTe, CIS, SnO/sub 2/, ZnO, and Mo. They have used cw-lamp-pumped and flashlamp-pumped Nd:YAG lasers (/spl lambda/=532/1064 nm), a copper-vapor laser (511/578 nm), and an XeCl-excimer laser (308 nm), with pulse durations ranging from 180 nsec down to 8 nsec. The purpose of this work is to identify the effects of laser wavelength and laser pulse duration on the most effective energy utilization and on the quality of the scribe line. Ablation spots and scribe lines were examined by optical microscopy and stylus profilometry. The ablation threshold has been identified for the combinations of four lasers and five materials. The energy density for optimum removal of material has been identified for two of the laser systems (three wavelengths).","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130983027","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 : 1996-05-13DOI: 10.1109/PVSC.1996.563935
A. Barnett
The promise of solar electricity based on the photovoltaic (PV) effect is well known, but these systems are not common all over the world. Consumers in the USA are well-known for their attraction to new technology, but PV power systems are still not appearing on roof-tops in the US. The reason may be that grid-connected roof top systems are too difficult to acquire, too difficult to integrate with the grid, too difficult to measure the energy produced and too expensive. The author argues that it is essential that PV power systems are made user-friendly, while reducing the component and system costs. Elegant PV technology must be reduced to practical systems that can be used by the average person everywhere. Choosing the right problem will help achieve the promise of photovoltaics. This paper describes a methodology to choose the right problems as an approach to PV development. Solar cell and PV power system examples are presented.
{"title":"Solar electric power for a better tomorrow","authors":"A. Barnett","doi":"10.1109/PVSC.1996.563935","DOIUrl":"https://doi.org/10.1109/PVSC.1996.563935","url":null,"abstract":"The promise of solar electricity based on the photovoltaic (PV) effect is well known, but these systems are not common all over the world. Consumers in the USA are well-known for their attraction to new technology, but PV power systems are still not appearing on roof-tops in the US. The reason may be that grid-connected roof top systems are too difficult to acquire, too difficult to integrate with the grid, too difficult to measure the energy produced and too expensive. The author argues that it is essential that PV power systems are made user-friendly, while reducing the component and system costs. Elegant PV technology must be reduced to practical systems that can be used by the average person everywhere. Choosing the right problem will help achieve the promise of photovoltaics. This paper describes a methodology to choose the right problems as an approach to PV development. Solar cell and PV power system examples are presented.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129814677","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 : 1996-05-13DOI: 10.1109/PVSC.1996.563961
A. Fahrenbruch, L. Lopez-Otero, J.G. Werthern, Ta C. Wu
A novel application for high intensity GaAs-based solar cells is conversion of monochromatic light transmitted by fiber optics into electrical power for remote sensors. At present, the efficiencies of these devices are as high as 58%, and the systems can deliver 0.5 W electrical at distances of /spl ap/1 km. A typical OMCVD grown, six sector GaAs-based device, with an illuminated portion 0.15 cm in diameter, produces V/sub OC/=6.7 V, J/sub SC/=8.15 A/cm/sup 2/, and an efficiency of 55% under 820 nm illumination of 250 mW. Also reported are modeling and characterization of In/sub x/Al/sub y/Ga/sub 1-x-y/As devices for operation at 1320 nm, to examine the tradeoffs between increased fiber transmission, larger currents and lower voltages, relative to GaAs.
{"title":"GaAs- and InAlGaAs-based concentrator-type cells for conversion of power transmitted by optical fibers","authors":"A. Fahrenbruch, L. Lopez-Otero, J.G. Werthern, Ta C. Wu","doi":"10.1109/PVSC.1996.563961","DOIUrl":"https://doi.org/10.1109/PVSC.1996.563961","url":null,"abstract":"A novel application for high intensity GaAs-based solar cells is conversion of monochromatic light transmitted by fiber optics into electrical power for remote sensors. At present, the efficiencies of these devices are as high as 58%, and the systems can deliver 0.5 W electrical at distances of /spl ap/1 km. A typical OMCVD grown, six sector GaAs-based device, with an illuminated portion 0.15 cm in diameter, produces V/sub OC/=6.7 V, J/sub SC/=8.15 A/cm/sup 2/, and an efficiency of 55% under 820 nm illumination of 250 mW. Also reported are modeling and characterization of In/sub x/Al/sub y/Ga/sub 1-x-y/As devices for operation at 1320 nm, to examine the tradeoffs between increased fiber transmission, larger currents and lower voltages, relative to GaAs.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129793525","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 : 1996-05-13DOI: 10.1109/PVSC.1996.563981
D. Marvin, M. Gates
Gallium arsenide on germanium (GaAs/Ge) solar cells are being used on an increasing fraction of space missions because of their increased efficiency over silicon solar cells. Three recent flight experiments in orbits that rapidly accumulate radiation exposure have included GaAs-containing cells of various designs. The data from these experiments presented in this paper verify the radiation degradation models for these solar cells and give confidence in their projected performance in proton-dominated orbits.
{"title":"Results of three recent GaAs flight experiments: Ascot, PASP-Plus, and STRV-1b","authors":"D. Marvin, M. Gates","doi":"10.1109/PVSC.1996.563981","DOIUrl":"https://doi.org/10.1109/PVSC.1996.563981","url":null,"abstract":"Gallium arsenide on germanium (GaAs/Ge) solar cells are being used on an increasing fraction of space missions because of their increased efficiency over silicon solar cells. Three recent flight experiments in orbits that rapidly accumulate radiation exposure have included GaAs-containing cells of various designs. The data from these experiments presented in this paper verify the radiation degradation models for these solar cells and give confidence in their projected performance in proton-dominated orbits.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130968585","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564230
F. Giles, R. J. Schwartz
Photoconductance decay measurements are frequently used to measure the lifetime of silicon wafers prior to processing and occasionally after various processing steps have been performed. It is an easy to use rapid measurement. However, the usual analysis of the data results in a determination of an "effective" lifetime which includes the effects of both bulk and surface recombination. This paper describes the measurement conditions and the analysis procedures which allow one to analyze photoconductance decay data to obtain the bulk lifetime and the surface recombination of the two surfaces rather than just the "effective" lifetime. Since the technique is contactless and does not require any additional processing or modification of the wafer, it is particularly promising as a process monitoring tool.
{"title":"A technique for separating bulk and surface lifetimes in the analysis of photoconductance decay measurements","authors":"F. Giles, R. J. Schwartz","doi":"10.1109/PVSC.1996.564230","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564230","url":null,"abstract":"Photoconductance decay measurements are frequently used to measure the lifetime of silicon wafers prior to processing and occasionally after various processing steps have been performed. It is an easy to use rapid measurement. However, the usual analysis of the data results in a determination of an \"effective\" lifetime which includes the effects of both bulk and surface recombination. This paper describes the measurement conditions and the analysis procedures which allow one to analyze photoconductance decay data to obtain the bulk lifetime and the surface recombination of the two surfaces rather than just the \"effective\" lifetime. Since the technique is contactless and does not require any additional processing or modification of the wafer, it is particularly promising as a process monitoring tool.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128068329","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564361
W. Holley, S. Agro, J. Galica, R.S. Yorgensen
Development work on EVA-based PV encapsulants has yielded three strategies to limit photothermal browning. (1) Use of one of four new EVA-based encapsulants-"standard-cure" X9903P, X9923P, or X9933P, or "fast-cure" X15303P. After 38-42 weeks in a Weather-Ometer, sample laminates using Starphire glass, which is highly transparent in the UV-B region, developed ASTM D-1925 Yellowness Indexes of 2.1-4.5. (2) Use of cerium-oxide-containing glass superstrates, especially with an existing encapsulant, "fast-cure" 15295P. After one year in the Weather-Ometer, sample laminates registered a Yellowness Index of 13. A 15295P control with noncerium glass had an index of 87. Similarly, samples with cerium-oxide-containing glass subjected to 15 months of EMMA accelerated outdoor exposure showed almost no measurable yellowness, while controls had a 4.2 Index. A control prepared with "standard-cure" A9918P and noncerium glass registered a 34.5 Index. (3) Use of an optically transparent, gas-transmissive superstrate in place of glass. After 60 weeks exposure in the Weather-Ometer, a Tefzel/A9918P encapsulant/glass laminate had a Yellowness Index of 2.0. Samples subjected to 15 months of EMMA showed no measurable yellowing. Mini-modules were then prepared, using six different combinations of the four experimental encapsulants, plus controls with low-iron glass, cerium-containing glass, or Tefzel superstrates. These are being aged in the Weather-Ometer, with additional sets sent to Phoenix for EMMA exposure.
{"title":"UV stability and module testing of nonbrowning experimental PV encapsulants","authors":"W. Holley, S. Agro, J. Galica, R.S. Yorgensen","doi":"10.1109/PVSC.1996.564361","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564361","url":null,"abstract":"Development work on EVA-based PV encapsulants has yielded three strategies to limit photothermal browning. (1) Use of one of four new EVA-based encapsulants-\"standard-cure\" X9903P, X9923P, or X9933P, or \"fast-cure\" X15303P. After 38-42 weeks in a Weather-Ometer, sample laminates using Starphire glass, which is highly transparent in the UV-B region, developed ASTM D-1925 Yellowness Indexes of 2.1-4.5. (2) Use of cerium-oxide-containing glass superstrates, especially with an existing encapsulant, \"fast-cure\" 15295P. After one year in the Weather-Ometer, sample laminates registered a Yellowness Index of 13. A 15295P control with noncerium glass had an index of 87. Similarly, samples with cerium-oxide-containing glass subjected to 15 months of EMMA accelerated outdoor exposure showed almost no measurable yellowness, while controls had a 4.2 Index. A control prepared with \"standard-cure\" A9918P and noncerium glass registered a 34.5 Index. (3) Use of an optically transparent, gas-transmissive superstrate in place of glass. After 60 weeks exposure in the Weather-Ometer, a Tefzel/A9918P encapsulant/glass laminate had a Yellowness Index of 2.0. Samples subjected to 15 months of EMMA showed no measurable yellowing. Mini-modules were then prepared, using six different combinations of the four experimental encapsulants, plus controls with low-iron glass, cerium-containing glass, or Tefzel superstrates. These are being aged in the Weather-Ometer, with additional sets sent to Phoenix for EMMA exposure.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"48 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128528958","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564407
W. Knaupp
Photovoltaic energy in the building environment is a very interesting application. On existing building roofs, the installation of photovoltaic generators is a common mounting configuration. It is important to assess and predict the operational behaviour regarding energy output, power rating and critical operation limits of such modules. This contribution summarizes some detailed experimental and theoretical examinations regarding the operational behaviour of roof-installed PV power system modules. Reverse ventilation was analyzed on the basis of buoyancy forces and pressure loss mechanisms. The correlations were transferred to a computer program PVROOF and verified in the ZSW test site, Germany. Experimental and simulation results regarding the influence of roof cover and the distance between the roof and the PV module are shown. With such results, roof-mounted PV power system installations can be optimized with respect to electrical and thermal energy output.
{"title":"Operation behaviour of roof installed photovoltaic modules","authors":"W. Knaupp","doi":"10.1109/PVSC.1996.564407","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564407","url":null,"abstract":"Photovoltaic energy in the building environment is a very interesting application. On existing building roofs, the installation of photovoltaic generators is a common mounting configuration. It is important to assess and predict the operational behaviour regarding energy output, power rating and critical operation limits of such modules. This contribution summarizes some detailed experimental and theoretical examinations regarding the operational behaviour of roof-installed PV power system modules. Reverse ventilation was analyzed on the basis of buoyancy forces and pressure loss mechanisms. The correlations were transferred to a computer program PVROOF and verified in the ZSW test site, Germany. Experimental and simulation results regarding the influence of roof cover and the distance between the roof and the PV module are shown. With such results, roof-mounted PV power system installations can be optimized with respect to electrical and thermal energy output.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126592356","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564041
O. Breitenstein, K. Iwig, I. Konovalov
Dynamical Precision Contact Thermography has been used to map the forward current in the dark of 10/spl times/10 cm/sup 2/ sized multicrystalline solar cells made of block-cast silicon material. Moreover, local I-V-characteristics have been measured thermally. Extended regions of increased current density as well as local shunts at the edges, under, and between grid lines have been observed. In shunt positions the cells have been investigated in detail using scanning electron microscope techniques. Only some of the local shunts are related to accumulations of grain boundaries, others are pn-junction defects. The dominant shunts often have been found at the edges of the cells. The dependence of the shunt strength on elastic deformation of the cells, which is sometimes observed, indicates that mechanical stress may influence certain shunts. The quantitative influence of shunts on the efficiency is shown to increase to above 30% for illuminations below 0.2 suns.
{"title":"Identification of factors reducing Voc in MC silicon solar cells","authors":"O. Breitenstein, K. Iwig, I. Konovalov","doi":"10.1109/PVSC.1996.564041","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564041","url":null,"abstract":"Dynamical Precision Contact Thermography has been used to map the forward current in the dark of 10/spl times/10 cm/sup 2/ sized multicrystalline solar cells made of block-cast silicon material. Moreover, local I-V-characteristics have been measured thermally. Extended regions of increased current density as well as local shunts at the edges, under, and between grid lines have been observed. In shunt positions the cells have been investigated in detail using scanning electron microscope techniques. Only some of the local shunts are related to accumulations of grain boundaries, others are pn-junction defects. The dominant shunts often have been found at the edges of the cells. The dependence of the shunt strength on elastic deformation of the cells, which is sometimes observed, indicates that mechanical stress may influence certain shunts. The quantitative influence of shunts on the efficiency is shown to increase to above 30% for illuminations below 0.2 suns.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127344500","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564424
C. Jennings, B. Farmer, T. Townsend, P. Hutchinson, T. Reyes, C. Whitaker, J. Gough, D. Shipman, W. Stolte, H. Wenger, T. Hoff
Photovoltaics for Utility Scale Applications (PVUSA) is a national cooperative research and development project with a mission to acquire information through field installation and testing of grid-connected photovoltaic (PV) technologies and to provide the information to utilities and other participants. This paper updates the project's progress and summarizes performance, cost, and value results obtained in the 10 years since project inception.
{"title":"PVUSA-the first decade of experience","authors":"C. Jennings, B. Farmer, T. Townsend, P. Hutchinson, T. Reyes, C. Whitaker, J. Gough, D. Shipman, W. Stolte, H. Wenger, T. Hoff","doi":"10.1109/PVSC.1996.564424","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564424","url":null,"abstract":"Photovoltaics for Utility Scale Applications (PVUSA) is a national cooperative research and development project with a mission to acquire information through field installation and testing of grid-connected photovoltaic (PV) technologies and to provide the information to utilities and other participants. This paper updates the project's progress and summarizes performance, cost, and value results obtained in the 10 years since project inception.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"183 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126779566","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564389
A. Kitamura, F. Yamamoto, H. Matsuda, K. Akhmad, Y. Hamakawa
Since power output of a PV system is DC and the commercial grid carriers AC, in any linked system, attention is paid to prevent direct mixture of these two currents. Usually alternating and direct currents mix through the inverter, and because of the great variety in types and specifications, phenomena may be extremely complex. To observe the basic phenomena, demonstration tests were conducted in which direct coupling of PV arrays and the grid have been performed. PV arrays' short circuit current is relatively weak, so the effect on transformers are not so substantial as in the case of a storage battery system linkage. After a certain time exciting current appears, and grows, on the AC side of the transformer. Consequently, with increase of the exciting current when DC and AC powers are mixed, higher harmonic currents appear on the AC side. Breakdown phenomenon on the array side is different depending on whether AC injection happens during an active power generating period, or a passive one and also the existence, or lack, of by-pass diodes or blocking diodes is significant. Blocking diodes prevent larger AC currents from flowing through the solar cells, whereas by-pass diodes let those currents get around the blocking diodes.
{"title":"Test results on DC injection phenomenon of grid connected PV system at Rokko test center","authors":"A. Kitamura, F. Yamamoto, H. Matsuda, K. Akhmad, Y. Hamakawa","doi":"10.1109/PVSC.1996.564389","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564389","url":null,"abstract":"Since power output of a PV system is DC and the commercial grid carriers AC, in any linked system, attention is paid to prevent direct mixture of these two currents. Usually alternating and direct currents mix through the inverter, and because of the great variety in types and specifications, phenomena may be extremely complex. To observe the basic phenomena, demonstration tests were conducted in which direct coupling of PV arrays and the grid have been performed. PV arrays' short circuit current is relatively weak, so the effect on transformers are not so substantial as in the case of a storage battery system linkage. After a certain time exciting current appears, and grows, on the AC side of the transformer. Consequently, with increase of the exciting current when DC and AC powers are mixed, higher harmonic currents appear on the AC side. Breakdown phenomenon on the array side is different depending on whether AC injection happens during an active power generating period, or a passive one and also the existence, or lack, of by-pass diodes or blocking diodes is significant. Blocking diodes prevent larger AC currents from flowing through the solar cells, whereas by-pass diodes let those currents get around the blocking diodes.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114335862","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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