Publications
2019 |
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M. Rienäcker, E. L. Warren, M. Schnabel, H. Schulte-Huxel, R. Niepelt, R. Brendel, P. Stradins, A. C. Tamboli, and R. Peibst Back-contacted bottom cells with three terminals: Maximizing power extraction from current-mismatched tandem cells Journal Article Progress in Photovoltaics: Research and Applications 27 (5), 410-423, (2019). Abstract | Links | BibTeX | Tags: 3T, bipolar junction transistor tandem, bottom cell, current-mismatch, interdigitated back contact cell (IBC), tandem solar cell, three terminal @article{Rienäcker2019,
title = {Back-contacted bottom cells with three terminals: Maximizing power extraction from current-mismatched tandem cells}, author = {M Rienäcker and E L Warren and M Schnabel and H Schulte-Huxel and R Niepelt and R Brendel and P Stradins and A C Tamboli and R Peibst}, doi = {10.1002/pip.3107}, year = {2019}, date = {2019-05-01}, journal = {Progress in Photovoltaics: Research and Applications}, volume = {27}, number = {5}, pages = {410-423}, abstract = {Abstract Multi-junction cells can significantly improve the energy yield of photovoltaic systems over a single-junction cell. The internal interconnection scheme of the subcells is an important aspect in determining the resulting levelized cost of electricity. For a dual-junction cell, two approaches are commonly discussed: series-connected tandem cells with two terminals or independently working subcells in a four-terminal (4T) tandem device. In this paper, we explore the working principle and the operation modes of a third, rarely discussed option: a three-terminal (3T) tandem cell using a back-contacted bottom cell with 3Ts. We use current–voltage measurements of illuminated 3T interdigitated back contact cells and confirm that the front and rear base contacts are at similar quasi-Fermi level positions, which enables the bottom cell to either efficiently collect surplus carriers, in the case of a current-limiting or carrier injecting top cell, or inject majority carriers, in the case of a current-limiting bottom cell. As a result, no current matching is needed. The power output of an idealized 3T bottom cell without resistive effects is independent of the current density applied from the top cell. These characteristics of the 3T bottom cells enable a 3T tandem to operate as efficiently as a 4T tandem, while being compatible with monolithic design and not requiring intermediate grids. We propose a simple equivalent circuit model including additional resistive effects, which describes a real 3T bottom cell and achieves excellent agreement to the experiment. We deduce design guidelines for a 3T bottom cell in different operation regimes.}, keywords = {3T, bipolar junction transistor tandem, bottom cell, current-mismatch, interdigitated back contact cell (IBC), tandem solar cell, three terminal}, pubstate = {published}, tppubtype = {article} } Abstract Multi-junction cells can significantly improve the energy yield of photovoltaic systems over a single-junction cell. The internal interconnection scheme of the subcells is an important aspect in determining the resulting levelized cost of electricity. For a dual-junction cell, two approaches are commonly discussed: series-connected tandem cells with two terminals or independently working subcells in a four-terminal (4T) tandem device. In this paper, we explore the working principle and the operation modes of a third, rarely discussed option: a three-terminal (3T) tandem cell using a back-contacted bottom cell with 3Ts. We use current–voltage measurements of illuminated 3T interdigitated back contact cells and confirm that the front and rear base contacts are at similar quasi-Fermi level positions, which enables the bottom cell to either efficiently collect surplus carriers, in the case of a current-limiting or carrier injecting top cell, or inject majority carriers, in the case of a current-limiting bottom cell. As a result, no current matching is needed. The power output of an idealized 3T bottom cell without resistive effects is independent of the current density applied from the top cell. These characteristics of the 3T bottom cells enable a 3T tandem to operate as efficiently as a 4T tandem, while being compatible with monolithic design and not requiring intermediate grids. We propose a simple equivalent circuit model including additional resistive effects, which describes a real 3T bottom cell and achieves excellent agreement to the experiment. We deduce design guidelines for a 3T bottom cell in different operation regimes.
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J. Schmidt Surface Passivation of Crystalline Silicon Solar Cells: Past, Present and Future Presentation Leuven, Belgium, 10.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: surface passivation @misc{Schmidt2019,
title = {Surface Passivation of Crystalline Silicon Solar Cells: Past, Present and Future}, author = {J Schmidt}, year = {2019}, date = {2019-04-10}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {surface passivation}, pubstate = {published}, tppubtype = {presentation} } |
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L. Helmich, D. C. Walter, and J. Schmidt Direct Examination of the Boron-Oxygen Deactivation Via Electroluminescence Characterization of Cz-Si Solar Cells Under Regeneration Conditions Presentation Leuven, Belgium, 10.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: boron-oxygen @misc{Helmich2019,
title = {Direct Examination of the Boron-Oxygen Deactivation Via Electroluminescence Characterization of Cz-Si Solar Cells Under Regeneration Conditions}, author = {L Helmich and D C Walter and J Schmidt}, year = {2019}, date = {2019-04-10}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {boron-oxygen}, pubstate = {published}, tppubtype = {presentation} } |
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C. Gemmel, S. Kajari-Schröder, and R. Brendel Statistics of the Detachment Yield for Crystalline Silicon Layer Transfer Using the Porous Silicon Process Presentation Leuven, Belgium, 10.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). @misc{Gemmel2019,
title = {Statistics of the Detachment Yield for Crystalline Silicon Layer Transfer Using the Porous Silicon Process}, author = {C Gemmel and S Kajari-Schröder and R Brendel}, year = {2019}, date = {2019-04-10}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {PSI}, pubstate = {published}, tppubtype = {presentation} } |
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M. Rudolph, C. Kruse, H. Hannebauer, U. Baumann, S. Bräunig, M. Ripke, T. Falcon, R. Brendel, and T. Dullweber PERC+ Solar Cells with Screen-Printed Dashed Ag Front Contacts Presentation Leuven, Belgium, 10.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). @misc{Rudolph2019,
title = {PERC+ Solar Cells with Screen-Printed Dashed Ag Front Contacts}, author = {M Rudolph and C Kruse and H Hannebauer and U Baumann and S Bräunig and M Ripke and T Falcon and R Brendel and T Dullweber}, year = {2019}, date = {2019-04-10}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {PERC+}, pubstate = {published}, tppubtype = {presentation} } |
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S. Schäfer, F. Haase, C. Hollemann, J. Hensen, J. Krügener, R. Brendel, and R. Peibst 26%-Efficient and 2 cm Narrow Interdigitated Back Contact Silicon Solar Cells with Passivated Slits on Two Edges Presentation Leuven, Belgium, 10.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: IBC, solar cell @misc{Schäfer2019,
title = {26%-Efficient and 2 cm Narrow Interdigitated Back Contact Silicon Solar Cells with Passivated Slits on Two Edges}, author = {S Schäfer and F Haase and C Hollemann and J Hensen and J Krügener and R Brendel and R Peibst}, year = {2019}, date = {2019-04-10}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {IBC, solar cell}, pubstate = {published}, tppubtype = {presentation} } |
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D. Walter, D. Bredemeier, R. Falster, V. Voronkov, and J. Schmidt Easy-to-Apply Methodology to Measure the Hydrogen Concentration in Boron-Doped Crystalline Silicon Presentation Leuven, Belgium, 09.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: Hydrogen, silicon @misc{Walter2019,
title = {Easy-to-Apply Methodology to Measure the Hydrogen Concentration in Boron-Doped Crystalline Silicon}, author = {D Walter and D Bredemeier and R Falster and V Voronkov and J Schmidt}, year = {2019}, date = {2019-04-09}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {Hydrogen, silicon}, pubstate = {published}, tppubtype = {presentation} } |
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H. Schulte-Huxel, S. Blankemeyer, R. Brendel, and M. Köntges Interconnect-Shingling: Maximizing the Active Module Area with Conventional Module Processes Presentation Leuven, Belgium, 09.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). @misc{Schulte-Huxel2019,
title = {Interconnect-Shingling: Maximizing the Active Module Area with Conventional Module Processes}, author = {H Schulte-Huxel and S Blankemeyer and R Brendel and M Köntges}, year = {2019}, date = {2019-04-09}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {shingling}, pubstate = {published}, tppubtype = {presentation} } |
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S. Richter, Y. Larionova, S. Großer, A. Hähnel, and C. Hagendorf Evaluation of Localized Vertical Current Formation in Carrier Selective Passivation Layers of Silicon Solar Cells by TEM and Conductive AFM Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: Carrier Selective Passivation Layers @misc{Richter2019,
title = {Evaluation of Localized Vertical Current Formation in Carrier Selective Passivation Layers of Silicon Solar Cells by TEM and Conductive AFM}, author = {S Richter and Y Larionova and S Großer and A Hähnel and C Hagendorf}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {Carrier Selective Passivation Layers}, pubstate = {published}, tppubtype = {presentation} } |
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B. Veith-Wolf, and J. Schmidt Low-Temperature Silicon Surface Passivation for Bulk Lifetime Studies Based on Corona-Charged Al2O3 Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: silicon, surface passivation @misc{Veith-Wolf2019,
title = {Low-Temperature Silicon Surface Passivation for Bulk Lifetime Studies Based on Corona-Charged Al2O3}, author = {B Veith-Wolf and J Schmidt}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {silicon, surface passivation}, pubstate = {published}, tppubtype = {presentation} } |
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G. Wetzel, J. Krügener, R. Peibst, A. Dietrich, B. Nacke, and H-J. Osten Simulation of Solar Cell Performance Based on in the Field Measured Ambience Parameters Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: solar cell @misc{Wetzel2019,
title = {Simulation of Solar Cell Performance Based on in the Field Measured Ambience Parameters}, author = {G Wetzel and J Krügener and R Peibst and A Dietrich and B Nacke and H-J Osten}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {solar cell}, pubstate = {published}, tppubtype = {presentation} } |
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D. Bredemeier, D. Walter, R. Heller, and J. Schmidt Impact of SiNx:H Material Properties on Light and Elevated Temperature Induced Degradation (LeTID) in Mc-Si Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). @misc{Bredemeier2019,
title = {Impact of SiNx:H Material Properties on Light and Elevated Temperature Induced Degradation (LeTID) in Mc-Si}, author = {D Bredemeier and D Walter and R Heller and J Schmidt}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {LeTID}, pubstate = {published}, tppubtype = {presentation} } |
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M. Winter, D. Walter, D. Bredemeier, and J. Schmidt Absence of Light and Elevated Temperature Induced Degradation (LeTID) of the Carrier Lifetime in Boron-Doped Cz-Silicon Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). @misc{Winter2019,
title = {Absence of Light and Elevated Temperature Induced Degradation (LeTID) of the Carrier Lifetime in Boron-Doped Cz-Silicon}, author = {M Winter and D Walter and D Bredemeier and J Schmidt}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {Cz-Si, LeTID}, pubstate = {published}, tppubtype = {presentation} } |
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N. Wehmeier, F. Kiefer, T. Brendemühl, L. Mettner, F. Haase, R. Peibst, S. Kajari-Schröder, M. Holthausen, C. Mader, C. Daeschlein, and O. Wunnicke Inkjet-Printing of Phosphorus- and Boron-Doped Liquid Silicon Ink for Interdigitated Back Contact Solar Cells Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). BibTeX | Tags: Liquid silicon @misc{Wehmeier2019,
title = {Inkjet-Printing of Phosphorus- and Boron-Doped Liquid Silicon Ink for Interdigitated Back Contact Solar Cells}, author = {N Wehmeier and F Kiefer and T Brendemühl and L Mettner and F Haase and R Peibst and S Kajari-Schröder and M Holthausen and C Mader and C Daeschlein and O Wunnicke}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {Liquid silicon}, pubstate = {published}, tppubtype = {presentation} } |
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P. Jäger, V. Mertens, U. Baumann, T. Dullweber, and R. Brendel Impact of the Thermal Budget of the Emitter Formation on the pFF of PERC+ Solar Cells Presentation Leuven, Belgium, 08.04.2019, (SiliconPV 2019, 9th International Conference on Silicon Photovoltaics). @misc{Jäger2019,
title = {Impact of the Thermal Budget of the Emitter Formation on the pFF of PERC+ Solar Cells}, author = {P Jäger and V Mertens and U Baumann and T Dullweber and R Brendel}, year = {2019}, date = {2019-04-08}, address = {Leuven, Belgium}, note = {SiliconPV 2019, 9th International Conference on Silicon Photovoltaics}, keywords = {PERC+, pFF}, pubstate = {published}, tppubtype = {presentation} } |
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M. Bliss, T. Betts, R. Gottschalg, E. Salis, H. Müllejans, S. Winter, I. Kroeger, K. Bothe, D. Hinken, and J. Hohl-Ebinger Interlaboratory comparison of short-circuit current versus irradiance linearity measurements of photovoltaic devices Journal Article Solar Energy 182 , 256 - 263, (2019), ISSN: 0038-092X. Abstract | Links | BibTeX | Tags: Interlaboratory comparison, Linearity measurement, Photovoltaics characterization, Uncertainty @article{Bliss2019b,
title = {Interlaboratory comparison of short-circuit current versus irradiance linearity measurements of photovoltaic devices}, author = {M Bliss and T Betts and R Gottschalg and E Salis and H Müllejans and S Winter and I Kroeger and K Bothe and D Hinken and J Hohl-Ebinger}, doi = {10.1016/j.solener.2019.02.031}, issn = {0038-092X}, year = {2019}, date = {2019-04-01}, journal = {Solar Energy}, volume = {182}, pages = {256 - 263}, abstract = {This work presents the results of the first interlaboratory comparison of linearity measurements of short-circuit current versus irradiance that includes a wide variety of photovoltaic (PV) device types, from reference cells to full-size modules. The aim of this inter-comparison was to compare the methods employed and to collect new inputs useful for the revision of the standard IEC 60904-10, which deals with linearity measurements for PV devices. The procedures and facilities employed by the partners include the differential spectral responsivity, the white light response, the solar simulator method and the two-lamp method. The facilities are generically described and compared and their main sources of uncertainty are discussed. Comparison results show good agreement within declared uncertainties between all partners. A few minor exceptions under low-light conditions raise questions of possible uncertainty underestimation for these specific conditions. The overall outcome of the comparison also highlights the importance of considering correlations in the uncertainty budget, which can potentially improve the overall stated uncertainty. A critical review is made of the data analysis adopted in the standard IEC 60904-10 to calculate the linearity degree of the short-circuit current towards irradiance. The analysis review suggests a way to make results based on different methods more comparable and less prone to erroneous linearity assessment.}, keywords = {Interlaboratory comparison, Linearity measurement, Photovoltaics characterization, Uncertainty}, pubstate = {published}, tppubtype = {article} } This work presents the results of the first interlaboratory comparison of linearity measurements of short-circuit current versus irradiance that includes a wide variety of photovoltaic (PV) device types, from reference cells to full-size modules. The aim of this inter-comparison was to compare the methods employed and to collect new inputs useful for the revision of the standard IEC 60904-10, which deals with linearity measurements for PV devices. The procedures and facilities employed by the partners include the differential spectral responsivity, the white light response, the solar simulator method and the two-lamp method. The facilities are generically described and compared and their main sources of uncertainty are discussed. Comparison results show good agreement within declared uncertainties between all partners. A few minor exceptions under low-light conditions raise questions of possible uncertainty underestimation for these specific conditions. The overall outcome of the comparison also highlights the importance of considering correlations in the uncertainty budget, which can potentially improve the overall stated uncertainty. A critical review is made of the data analysis adopted in the standard IEC 60904-10 to calculate the linearity degree of the short-circuit current towards irradiance. The analysis review suggests a way to make results based on different methods more comparable and less prone to erroneous linearity assessment.
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M. Knoop, M. Littwin, T. Ohrdes, and O. Kastner Gebäudeversorgungskonzepte mit PV, Batterie, Wärmepumpe und Blockheizkraftwerk – Energetische Kennwerte und CO2-Wirkung Inproceedings Conexio. GmbH (Ed.): Tagungsunterlagen 34. PV-Symposium, 160-161, Bad Staffelstein, Germany, (2019). @inproceedings{Knoop2019,
title = {Gebäudeversorgungskonzepte mit PV, Batterie, Wärmepumpe und Blockheizkraftwerk – Energetische Kennwerte und CO2-Wirkung}, author = {M Knoop and M Littwin and T Ohrdes and O Kastner}, editor = {Conexio GmbH}, year = {2019}, date = {2019-03-21}, booktitle = {Tagungsunterlagen 34. PV-Symposium}, pages = {160-161}, address = {Bad Staffelstein, Germany}, abstract = {Der Anteil erneuerbarer Energien am deutschen Nettostromverbrauch ist 2018 mit 40,4 % so hoch wie noch nie. Der Zubau von Photovoltaik (PV)-Anlagen auf Mehrfamilienhäusern (MFH) bleibt allerdings mit nur 305 bei der Bundesnetzagentur gemeldeten Mieterstrom-Projekten (6,8 MW Gesamtleistung) in 2018 auf einem niedrigen Niveau. Zur Berechnung derartiger Versorgungskonzepte hat das ISFH auf dem PV-Symposium 2018 in Bad Staffelstein ein Modell veröffentlicht. Dieses basiert auf Microsoft Excel®, ist frei verfügbar (https://isfh.de/tools/mieterstrom) und wird im Folgenden dazu genutzt verschiedene Gebäudeversorgungskonzepte anhand von energetischen Kennwerten und des CO2-Ausstoßes zu bewerten. Als energetische Bewertungsgrößen werden in diesem Beitrag der Direktverbrauchsanteil (DV) von lokal generiertem Strom und der lokale Lastdeckungsgrad (DG) verwendet. In dem Beitrag wird als erstes der Einfluss von äußeren Rahmenbedingungen (Standort, Verbrauchsverhalten und PV-Anlagenausrichtung) auf Versorgungskonzepte mit PV-Anlage untersucht. Im zweiten Teil des Beitrages werden komplexere Versorgungs-konzepte berechnet und miteinander verglichen.}, keywords = {MFH}, pubstate = {published}, tppubtype = {inproceedings} } Der Anteil erneuerbarer Energien am deutschen Nettostromverbrauch ist 2018 mit 40,4 % so hoch wie noch nie. Der Zubau von Photovoltaik (PV)-Anlagen auf Mehrfamilienhäusern (MFH) bleibt allerdings mit nur 305 bei der Bundesnetzagentur gemeldeten Mieterstrom-Projekten (6,8 MW Gesamtleistung) in 2018 auf einem niedrigen Niveau. Zur Berechnung derartiger Versorgungskonzepte hat das ISFH auf dem PV-Symposium 2018 in Bad Staffelstein ein Modell veröffentlicht. Dieses basiert auf Microsoft Excel®, ist frei verfügbar (https://isfh.de/tools/mieterstrom) und wird im Folgenden dazu genutzt verschiedene Gebäudeversorgungskonzepte anhand von energetischen Kennwerten und des CO2-Ausstoßes zu bewerten. Als energetische Bewertungsgrößen werden in diesem Beitrag der Direktverbrauchsanteil (DV) von lokal generiertem Strom und der lokale Lastdeckungsgrad (DG) verwendet. In dem Beitrag wird als erstes der Einfluss von äußeren Rahmenbedingungen (Standort, Verbrauchsverhalten und PV-Anlagenausrichtung) auf Versorgungskonzepte mit PV-Anlage untersucht. Im zweiten Teil des Beitrages werden komplexere Versorgungs-konzepte berechnet und miteinander verglichen.
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R. Peibst PERC ist die Si-Solarzellen-Mainstreamtechnologie – kommt danach noch etwas? Presentation Bad Staffelstein, Germany, 20.03.2019, (34. PV-Symposium). @misc{Peibst2019b,
title = {PERC ist die Si-Solarzellen-Mainstreamtechnologie – kommt danach noch etwas?}, author = {R Peibst}, year = {2019}, date = {2019-03-20}, address = {Bad Staffelstein, Germany}, note = {34. PV-Symposium}, keywords = {PERC}, pubstate = {published}, tppubtype = {presentation} } |
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K. T. VanSant, J. Simon, J. F. Geisz, E. L. Warren, K. L. Schulte, A. J. Ptak, M. S. Young, M. Rienäcker, H. Schulte-Huxel, R. Peibst, and A. C. Tamboli Toward Low-Cost 4-Terminal GaAs//Si Tandem Solar Cells Journal Article Forthcoming ACS Applied Energy Materials Forthcoming. Abstract | Links | BibTeX | Tags: Tandem @article{VanSant2019,
title = {Toward Low-Cost 4-Terminal GaAs//Si Tandem Solar Cells}, author = {K T VanSant and J Simon and J F Geisz and E L Warren and K L Schulte and A J Ptak and M S Young and M Rienäcker and H Schulte-Huxel and R Peibst and A C Tamboli}, doi = {10.1021/acsaem.9b00018}, year = {2019}, date = {2019-03-18}, journal = {ACS Applied Energy Materials}, abstract = {Mechanically stacked III–V-on-Si (III–V//Si) tandem solar cells have demonstrated efficiencies beyond what can theoretically be achieved by single junction Si solar cells, but III–V costs are currently at least an order of magnitude higher than Si costs. Recent techno-economic analysis shows that costs could be substantially reduced by replacing traditional metalorganic vapor phase epitaxy (MOVPE) with a lower-cost III–V deposition technique, such as hydride vapor phase epitaxy (HVPE). This study analyzes the performance of an HVPE-grown GaAs top cell incorporated into a 4-terminal (4T) GaAs//Si tandem cell that achieved an efficiency of 29%, which is the highest solar cell efficiency fabricated without expensive deposition techniques such as MOVPE or MBE. We compare these results to an MOVPE-grown GaAs//Si tandem cell that has the same structure. Finally, we model optimizations to the HVPE-grown GaAs top cell and provide a near-term pathway to 31.4% efficiency with a low-cost III–V deposition technique.}, keywords = {Tandem}, pubstate = {forthcoming}, tppubtype = {article} } Mechanically stacked III–V-on-Si (III–V//Si) tandem solar cells have demonstrated efficiencies beyond what can theoretically be achieved by single junction Si solar cells, but III–V costs are currently at least an order of magnitude higher than Si costs. Recent techno-economic analysis shows that costs could be substantially reduced by replacing traditional metalorganic vapor phase epitaxy (MOVPE) with a lower-cost III–V deposition technique, such as hydride vapor phase epitaxy (HVPE). This study analyzes the performance of an HVPE-grown GaAs top cell incorporated into a 4-terminal (4T) GaAs//Si tandem cell that achieved an efficiency of 29%, which is the highest solar cell efficiency fabricated without expensive deposition techniques such as MOVPE or MBE. We compare these results to an MOVPE-grown GaAs//Si tandem cell that has the same structure. Finally, we model optimizations to the HVPE-grown GaAs top cell and provide a near-term pathway to 31.4% efficiency with a low-cost III–V deposition technique.
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K. Bothe, S. Herlufsen, and J. D. Murphy Impact of iron on the room temperature luminescence efficiency of oxygen-containing precipitates in silicon Journal Article Semiconductor Science and Technology 34 (3), 035030, (2019). Abstract | Links | BibTeX | Tags: luminescence @article{Bothe2019,
title = {Impact of iron on the room temperature luminescence efficiency of oxygen-containing precipitates in silicon}, author = {K Bothe and S Herlufsen and J D Murphy}, doi = {10.1088/1361-6641/ab0518}, year = {2019}, date = {2019-03-01}, journal = {Semiconductor Science and Technology}, volume = {34}, number = {3}, pages = {035030}, publisher = {IOP Publishing}, abstract = {Oxygen precipitation in silicon has been associated with a weak room temperature sub-bandgap luminescence emission at around 1600 nm. We show that the additional presence of iron impurities enhances this emission by an order of magnitude and results in a red shift of the peak luminescence by approximately 45 nm. We not only observe an increase in the luminescence emission with iron contamination level but also with the density and size of the oxide precipitates. Moreover, we provide evidence that the sub-bandgap luminescence emission increases proportionally with the concentration of iron segregated to oxide precipitates after high temperature (>700 °C) annealing and thus allows evaluation of the gettering efficiency of oxygen-containing precipitates. Annealing of iron-contaminated samples at low temperatures (550 °C) results in a considerable reduction in the interstitial iron concentration without changing the sub-bandgap luminescence, indicating that the sink to which iron diffuses depends upon temperature.}, keywords = {luminescence}, pubstate = {published}, tppubtype = {article} } Oxygen precipitation in silicon has been associated with a weak room temperature sub-bandgap luminescence emission at around 1600 nm. We show that the additional presence of iron impurities enhances this emission by an order of magnitude and results in a red shift of the peak luminescence by approximately 45 nm. We not only observe an increase in the luminescence emission with iron contamination level but also with the density and size of the oxide precipitates. Moreover, we provide evidence that the sub-bandgap luminescence emission increases proportionally with the concentration of iron segregated to oxide precipitates after high temperature (>700 °C) annealing and thus allows evaluation of the gettering efficiency of oxygen-containing precipitates. Annealing of iron-contaminated samples at low temperatures (550 °C) results in a considerable reduction in the interstitial iron concentration without changing the sub-bandgap luminescence, indicating that the sink to which iron diffuses depends upon temperature.
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H. Francke, O. Kastner, J. Meixner, and H. Shao Effizienter Stromeinsatz zur Bereitstellung geothermischer Wärme Inproceedings FVEE (Ed.): Die Energiewende - smart und digital (Themen 2018), Berlin, Germany, (2019). BibTeX | Tags: Geothermie @inproceedings{Francke2018,
title = {Effizienter Stromeinsatz zur Bereitstellung geothermischer Wärme}, author = {H Francke and O Kastner and J Meixner and H Shao}, editor = {FVEE}, year = {2019}, date = {2019-03-01}, booktitle = {Die Energiewende - smart und digital (Themen 2018)}, address = {Berlin, Germany}, keywords = {Geothermie}, pubstate = {published}, tppubtype = {inproceedings} } |
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T. Ohrdes, D. Büchner, M. Zobel, J. von Appen, N. Rehault, A. Xhonneux, A. Wagner, and B. Büttner Smarte Gebäude im Energiesystem Inproceedings FVEE (Ed.): Die Energiewende - smart und digital (Themen 2018), Berlin, Germany, (2019). BibTeX | Tags: Smarte Gebäude @inproceedings{Ohrdes2018,
title = {Smarte Gebäude im Energiesystem}, author = {T Ohrdes and D Büchner and M Zobel and J von Appen and N Rehault and A Xhonneux and A Wagner and B Büttner}, editor = {FVEE}, year = {2019}, date = {2019-03-01}, booktitle = {Die Energiewende - smart und digital (Themen 2018)}, address = {Berlin, Germany}, keywords = {Smarte Gebäude}, pubstate = {published}, tppubtype = {inproceedings} } |
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B. Lim, A. Merkle, R. Peibst, T. Dullweber, YC. Wang, and R. Zhou Beyond boron–oxygen deactivation: Industrially feasible LID-free p-type Czochralski silicon Miscellaneous Photovoltaics International Volume 42, (2019). @misc{Lim2019,
title = {Beyond boron–oxygen deactivation: Industrially feasible LID-free p-type Czochralski silicon}, author = {B Lim and A Merkle and R Peibst and T Dullweber and YC Wang and R Zhou}, year = {2019}, date = {2019-03-01}, abstract = {Today’s industry-standard B-doped monocrystalline silicon still suffers from light-induced degradation (LID) of the carrier lifetime. Illumination at elevated temperatures leads to a so-called regeneration, i.e. a recovery of both the carrier lifetime and the solar cell efficiency. However, even though the carrier lifetime on test wafers increases from about 1ms after processing to 3ms after regeneration, the corresponding PERC+ cell efficiencies in both states are identical; possible reasons for this discrepancy are discussed in this paper. Additionally, B-doped Czochralski silicon wafers with an ultralow oxygen content of 2.6 ppma are evaluated, as well as industrial Ga-doped wafers. Both wafer materials are completely LID free, as demonstrated in lifetime measurements and PERC+ cell efficiencies, and enable up to 0.4%abs. higher efficiencies than current industry-typical boron-doped wafers.}, howpublished = {Photovoltaics International Volume 42}, keywords = {LID}, pubstate = {published}, tppubtype = {misc} } Today’s industry-standard B-doped monocrystalline silicon still suffers from light-induced degradation (LID) of the carrier lifetime. Illumination at elevated temperatures leads to a so-called regeneration, i.e. a recovery of both the carrier lifetime and the solar cell efficiency. However, even though the carrier lifetime on test wafers increases from about 1ms after processing to 3ms after regeneration, the corresponding PERC+ cell efficiencies in both states are identical; possible reasons for this discrepancy are discussed in this paper. Additionally, B-doped Czochralski silicon wafers with an ultralow oxygen content of 2.6 ppma are evaluated, as well as industrial Ga-doped wafers. Both wafer materials are completely LID free, as demonstrated in lifetime measurements and PERC+ cell efficiencies, and enable up to 0.4%abs. higher efficiencies than current industry-typical boron-doped wafers.
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E. Salis, D. Pavanello, I. Kröger, S. Winter, K. Bothe, D. Hinken, T. Gandy, J. Hohl-Ebinger, G. Friesen, S. Dittmann, J. Dubard, and H. Müllejans Results of four European round-robins on short-circuit current temperature coefficient measurements of photovoltaic devices of different size Journal Article Solar Energy 179 , 424 - 436, (2019), ISSN: 0038-092X. Abstract | Links | BibTeX | Tags: Bare cells to full-size modules, photovoltaics, Short-circuit current temperature coefficient intercomparisons, Spectral temperature coefficients @article{Salis2019b,
title = {Results of four European round-robins on short-circuit current temperature coefficient measurements of photovoltaic devices of different size}, author = {E Salis and D Pavanello and I Kröger and S Winter and K Bothe and D Hinken and T Gandy and J Hohl-Ebinger and G Friesen and S Dittmann and J Dubard and H Müllejans}, doi = {10.1016/j.solener.2018.10.051}, issn = {0038-092X}, year = {2019}, date = {2019-02-01}, journal = {Solar Energy}, volume = {179}, pages = {424 - 436}, abstract = {Within the EURAMET ENG55 “PhotoClass” project, several characteristics of photovoltaic (PV) devices beyond their performance at Standard Test Conditions were investigated, including measurements at varying irradiance and temperature. Four groups of PV devices of different size and technology were prepared and corresponding round-robins were run between partner laboratories with substantially different facilities and methods – namely based on spectral or integral measurements. This paper presents the outcome of the four inter-laboratory comparisons dealing with temperature coefficient measurements of the short-circuit current of PV devices, from reference-cell size to full-size commercial modules of mainly several c-Si technologies, but also with some examples of CIGS and GaAs devices. The measurement results are compared via En number assessment, hence including measurement uncertainties. The main outcome of this measurement exercise is a very good agreement of all the laboratories although completely different approaches were applied. In some cases, laboratory measurement uncertainties are even considered rather conservative and could therefore be revised. Furthermore, a comparison between bare cells and commercial modules of the same technology is made, which may represent useful information for PV manufacturers.}, keywords = {Bare cells to full-size modules, photovoltaics, Short-circuit current temperature coefficient intercomparisons, Spectral temperature coefficients}, pubstate = {published}, tppubtype = {article} } Within the EURAMET ENG55 “PhotoClass” project, several characteristics of photovoltaic (PV) devices beyond their performance at Standard Test Conditions were investigated, including measurements at varying irradiance and temperature. Four groups of PV devices of different size and technology were prepared and corresponding round-robins were run between partner laboratories with substantially different facilities and methods – namely based on spectral or integral measurements. This paper presents the outcome of the four inter-laboratory comparisons dealing with temperature coefficient measurements of the short-circuit current of PV devices, from reference-cell size to full-size commercial modules of mainly several c-Si technologies, but also with some examples of CIGS and GaAs devices. The measurement results are compared via En number assessment, hence including measurement uncertainties. The main outcome of this measurement exercise is a very good agreement of all the laboratories although completely different approaches were applied. In some cases, laboratory measurement uncertainties are even considered rather conservative and could therefore be revised. Furthermore, a comparison between bare cells and commercial modules of the same technology is made, which may represent useful information for PV manufacturers.
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C. Hollemann, F. Haase, S. Schäfer, J. Krügener, R. Brendel, and R. Peibst 26.1%-efficient POLO-IBC cells: Quantification of electrical and optical loss mechanisms Journal Article Forthcoming Progress in Photovoltaics: Research and Applications Forthcoming. Abstract | Links | BibTeX | Tags: efficiency potential, IBC solar cells, lifetime monitoring, passivating contacts, POLO @article{Hollemann0000,
title = {26.1%-efficient POLO-IBC cells: Quantification of electrical and optical loss mechanisms}, author = {C Hollemann and F Haase and S Schäfer and J Krügener and R Brendel and R Peibst}, doi = {10.1002/pip.3098}, year = {2019}, date = {2019-01-16}, journal = {Progress in Photovoltaics: Research and Applications}, abstract = {Abstract We present experimental results for interdigitated back contacted (IBC) solar cells with passivating POLO contacts for both polarities with a nominal intrinsic poly-Si region between them. We reach efficiencies of 26.1% and 24.9% on a 1.3 Ω cm and 80 Ω cm p-type FZ wafer and 24.6% on a 2 Ω cm n-type Cz wafer, respectively. The initially measured implied efficiency potentials of the cells after passivating the surfaces are very similar, namely, 26.8%, 26.8%, and 26.4%, respectively. We attribute the difference between the efficiency potential and the final current-voltage measurement to degradation, perimeter, and series and shunt resistance losses, which we quantify by lifetime measurements. With these measurements in combination with a finite element simulation, we determine the surface recombination velocity in the nominal intrinsic poly-Si region to be in the range from 13 to 21 cm s−1. Using the same approach, we analyze the increase of the front surface recombination velocity during cell processing from 2 to 10 cm s−1 for the 1.3 Ω cm and from 0.5 to 2.3 cm s−1 for the 80 Ω cm. This leads to the fact that cells fabricated on lowly doped bulk material are more vulnerable to a process-induced degradation of the surface passivation quality. We further determine the theoretical limits of the cells by firstly idealizing the recombination (28% for 1.3 Ω cm and 28.2% for 80 Ω cm) and secondly also idealizing the optics of the solar cells (29.4% and 29.5%).}, keywords = {efficiency potential, IBC solar cells, lifetime monitoring, passivating contacts, POLO}, pubstate = {forthcoming}, tppubtype = {article} } Abstract We present experimental results for interdigitated back contacted (IBC) solar cells with passivating POLO contacts for both polarities with a nominal intrinsic poly-Si region between them. We reach efficiencies of 26.1% and 24.9% on a 1.3 Ω cm and 80 Ω cm p-type FZ wafer and 24.6% on a 2 Ω cm n-type Cz wafer, respectively. The initially measured implied efficiency potentials of the cells after passivating the surfaces are very similar, namely, 26.8%, 26.8%, and 26.4%, respectively. We attribute the difference between the efficiency potential and the final current-voltage measurement to degradation, perimeter, and series and shunt resistance losses, which we quantify by lifetime measurements. With these measurements in combination with a finite element simulation, we determine the surface recombination velocity in the nominal intrinsic poly-Si region to be in the range from 13 to 21 cm s−1. Using the same approach, we analyze the increase of the front surface recombination velocity during cell processing from 2 to 10 cm s−1 for the 1.3 Ω cm and from 0.5 to 2.3 cm s−1 for the 80 Ω cm. This leads to the fact that cells fabricated on lowly doped bulk material are more vulnerable to a process-induced degradation of the surface passivation quality. We further determine the theoretical limits of the cells by firstly idealizing the recombination (28% for 1.3 Ω cm and 28.2% for 80 Ω cm) and secondly also idealizing the optics of the solar cells (29.4% and 29.5%).
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