1.
Xu, C; Vollbrecht, J; Clausing, R
Analytical model for optical permittivity in direct bandgap semiconductors with Gaussian distributed bandgap energies Journal Article
In: Optics Letters, vol. 50, no. 2, pp. 371–374, 2025.
@article{Xu2025,
title = {Analytical model for optical permittivity in direct bandgap semiconductors with Gaussian distributed bandgap energies},
author = {C Xu and J Vollbrecht and R Clausing},
doi = {10.1364/OL.542250},
year = {2025},
date = {2025-01-15},
urldate = {2025-01-01},
journal = {Optics Letters},
volume = {50},
number = {2},
pages = {371–374},
publisher = {Optica Publishing Group},
abstract = {The optical permittivity of monocrystalline direct bandgap semiconductors can be described well by critical point models based on parabolic band approximation (CPPB). However, the optical permittivity of polycrystalline direct bandgap semiconductors like halide perovskite thin films requires a more precise description. Till now, only thermal bandgap fluctuation or exponential decay of density of states is incorporated into the CPPB model. We present an analytical calculation that is based on the CPPB model with only one additional physical assumption, namely, the Gaussian distributed bandgap energies (GCPPB). Furthermore, the GCPPB model satisfies the Kramers–Kronig causality relation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The optical permittivity of monocrystalline direct bandgap semiconductors can be described well by critical point models based on parabolic band approximation (CPPB). However, the optical permittivity of polycrystalline direct bandgap semiconductors like halide perovskite thin films requires a more precise description. Till now, only thermal bandgap fluctuation or exponential decay of density of states is incorporated into the CPPB model. We present an analytical calculation that is based on the CPPB model with only one additional physical assumption, namely, the Gaussian distributed bandgap energies (GCPPB). Furthermore, the GCPPB model satisfies the Kramers–Kronig causality relation.
2.
Green, M A; Dunlop, E D; Yoshita, M; Kopidakis, N; Bothe, K; Siefer, G; Hao, X; Jiang, J Y
Solar Cell Efficiency Tables (Version 65) Journal Article
In: Progress in Photovoltaics: Research and Applications, vol. 33, no. 1, pp. 3-15, 2025.
@article{Green2025,
title = {Solar Cell Efficiency Tables (Version 65)},
author = {M A Green and E D Dunlop and M Yoshita and N Kopidakis and K Bothe and G Siefer and X Hao and J Y Jiang},
doi = {10.1002/pip.3867},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Progress in Photovoltaics: Research and Applications},
volume = {33},
number = {1},
pages = {3-15},
abstract = {Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2024 are reviewed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2024 are reviewed.
3.
Min, B; Mertens, V; Larionova, Y; Pernau, T; Haverkamp, H; Dullweber, T; Peibst, R; Brendel, R
In: Progress in Photovoltaics: Research and Applications, vol. 33, no. 1, pp. 236-244, 2025.
@article{Min2024b,
title = {24.2% efficient POLO back junction solar cell with an AlOx/SiNy dielectric stack from an industrial-scale direct plasma-enhanced chemical vapor deposition system},
author = {B Min and V Mertens and Y Larionova and T Pernau and H Haverkamp and T Dullweber and R Peibst and R Brendel},
doi = {10.1002/pip.3828},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Progress in Photovoltaics: Research and Applications},
volume = {33},
number = {1},
pages = {236-244},
abstract = {An aluminum oxide (AlOx)/silicon nitride (SiNy) dielectric stack was developed using an industrial plasma-enhanced chemical vapor deposition (PECVD) system with low-frequency (LF) plasma source for the surface passivation of undiffused textured p-type crystalline silicon. The median recombination current density is 4.3 fA cm−2 as determined from photoconductance decay lifetime measurements and numerical device modeling. To the best of our knowledge, this is the first time to present a high-quality LF-PECVD AlOx/SiNy passivation stack on undiffused textured p-type crystalline silicon wafers, which are cleaned with industrial processes using HF, HCl, and O3. The simulation agrees well with the measured effective carrier lifetime if the velocity parameters of 5.6 cm s−1 for holes and 803 cm s−1 for electrons are applied with a fixed negative charge density of −3 × 1012 cm−2. The process integration of developed AlOx/SiNy dielectric stack is successfully demonstrated by fabricating p-type back junction solar cells featuring a poly-Si-based passivating contact at the cell rear side. As the best cell efficiency, we achieve 24.2% with an open-circuit voltage of 725 mV on a M2-sized Ga-doped p-type Czochralski-grown Si wafer as independently confirmed by ISFH CalTeC.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An aluminum oxide (AlOx)/silicon nitride (SiNy) dielectric stack was developed using an industrial plasma-enhanced chemical vapor deposition (PECVD) system with low-frequency (LF) plasma source for the surface passivation of undiffused textured p-type crystalline silicon. The median recombination current density is 4.3 fA cm−2 as determined from photoconductance decay lifetime measurements and numerical device modeling. To the best of our knowledge, this is the first time to present a high-quality LF-PECVD AlOx/SiNy passivation stack on undiffused textured p-type crystalline silicon wafers, which are cleaned with industrial processes using HF, HCl, and O3. The simulation agrees well with the measured effective carrier lifetime if the velocity parameters of 5.6 cm s−1 for holes and 803 cm s−1 for electrons are applied with a fixed negative charge density of −3 × 1012 cm−2. The process integration of developed AlOx/SiNy dielectric stack is successfully demonstrated by fabricating p-type back junction solar cells featuring a poly-Si-based passivating contact at the cell rear side. As the best cell efficiency, we achieve 24.2% with an open-circuit voltage of 725 mV on a M2-sized Ga-doped p-type Czochralski-grown Si wafer as independently confirmed by ISFH CalTeC.
4.
Graf, C; Pärisch, P; Marszal-Pomianowska, A; Frandsen, M; Bendinger, B; Cadenbach, A
Domestic hot water systems in well-insulated residential buildings: A comparative simulation study on efficiency and hygiene challenges Journal Article
In: Energy, vol. 313, pp. 133587, 2024, ISSN: 0360-5442.
@article{Graf2024,
title = {Domestic hot water systems in well-insulated residential buildings: A comparative simulation study on efficiency and hygiene challenges},
author = {C Graf and P Pärisch and A Marszal-Pomianowska and M Frandsen and B Bendinger and A Cadenbach},
doi = {10.1016/j.energy.2024.133587},
issn = {0360-5442},
year = {2024},
date = {2024-12-30},
urldate = {2024-10-29},
journal = {Energy},
volume = {313},
pages = {133587},
abstract = {Domestic hot water (DHW) is essential for daily life, yet the production can be energy intensive. Advances in building insulation reduced space heating demand, while DHW energy demand remained constant or even increased. The need for a higher proportion of renewable heat amplifies the conflict in DHW systems between energy efficiency, hygiene, and comfort, since high temperatures are required for hygienic purposes. Thus, developing DHW systems efficiently utilizing renewable heat without excessive temperature requirements is essential. This paper reviews efficiency and hygiene challenges in DHW systems and assesses proposed solutions through comparative simulations in well-insulated residential buildings. Results show higher efficiencies in decentralised than centralised DHW systems. However, even in decentralised systems the necessity for circulation is a significant limitation. Lowering DHW temperature or transitioning to decentralised systems significantly reduces final energy demand, improves heat pump performance and increases the renewable heat share. Reducing DHW temperature from 60 to 50 °C increases stagnation periods in lower temperature intervals (22–34 °C) in warm water pipes. The study indicates significant potential to increase system efficiency and reduce final energy demand in decentralised or low-temperature DHW systems and introduces a novel method to compare conditions with regard to hygiene of DHW system simulations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Domestic hot water (DHW) is essential for daily life, yet the production can be energy intensive. Advances in building insulation reduced space heating demand, while DHW energy demand remained constant or even increased. The need for a higher proportion of renewable heat amplifies the conflict in DHW systems between energy efficiency, hygiene, and comfort, since high temperatures are required for hygienic purposes. Thus, developing DHW systems efficiently utilizing renewable heat without excessive temperature requirements is essential. This paper reviews efficiency and hygiene challenges in DHW systems and assesses proposed solutions through comparative simulations in well-insulated residential buildings. Results show higher efficiencies in decentralised than centralised DHW systems. However, even in decentralised systems the necessity for circulation is a significant limitation. Lowering DHW temperature or transitioning to decentralised systems significantly reduces final energy demand, improves heat pump performance and increases the renewable heat share. Reducing DHW temperature from 60 to 50 °C increases stagnation periods in lower temperature intervals (22–34 °C) in warm water pipes. The study indicates significant potential to increase system efficiency and reduce final energy demand in decentralised or low-temperature DHW systems and introduces a novel method to compare conditions with regard to hygiene of DHW system simulations.
5.
Lohr, C.; Peterssen, F.; Schlemminger, M.; Bensmann, A.; Niepelt, R.; Brendel, R.; Hanke-Rauschenbach, R.
Multi-criteria energy system analysis of onshore wind power distribution in climate-neutral Germany Journal Article
In: Energy Reports, vol. 12, pp. 1905-1920, 2024, ISSN: 2352-4847.
@article{Lohr2024,
title = {Multi-criteria energy system analysis of onshore wind power distribution in climate-neutral Germany},
author = {C. Lohr and F. Peterssen and M. Schlemminger and A. Bensmann and R. Niepelt and R. Brendel and R. Hanke-Rauschenbach},
doi = {10.1016/j.egyr.2024.07.064},
issn = {2352-4847},
year = {2024},
date = {2024-12-01},
urldate = {2024-01-01},
journal = {Energy Reports},
volume = {12},
pages = {1905-1920},
abstract = {Although onshore wind energy is a key pillar of renewable energy systems, installation targets in Europe have not been met. One contentious issue is its distribution, involving trade-offs between economic costs, environmental impact, public acceptance, and equity considerations. In this study, we evaluate different distribution strategies that meet Germany’s national onshore wind power target of utilizing 2 % land area, breaking it down to subordinate levels such as federal states. Therefore, we define key indicators for energy policy objectives to comprehensively analyze these strategies. We employ an energy system optimization model to address the system integration of spatial onshore wind power distribution, an aspect often overlooked in previous studies. Our results indicate that the impact of different distribution strategies on the overall energy system design is moderate, with the highest sensitivity observed in the allocation of electrolyzers, which closely align with renewable energy surpluses. However, our analysis shows that concentrating onshore wind power in areas with high energy yield can lead to an increase in electricity transport by up to 38 %, whereas more evenly distributed scenarios are preferred for environmental sustainability and distributive justice. In conclusion, we argue that energy system analysis can enhance the accuracy of assessment of onshore wind power distribution, but it must consider non-techno-economic criteria within spatially-distributed energy systems itself to address policymakers.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Although onshore wind energy is a key pillar of renewable energy systems, installation targets in Europe have not been met. One contentious issue is its distribution, involving trade-offs between economic costs, environmental impact, public acceptance, and equity considerations. In this study, we evaluate different distribution strategies that meet Germany’s national onshore wind power target of utilizing 2 % land area, breaking it down to subordinate levels such as federal states. Therefore, we define key indicators for energy policy objectives to comprehensively analyze these strategies. We employ an energy system optimization model to address the system integration of spatial onshore wind power distribution, an aspect often overlooked in previous studies. Our results indicate that the impact of different distribution strategies on the overall energy system design is moderate, with the highest sensitivity observed in the allocation of electrolyzers, which closely align with renewable energy surpluses. However, our analysis shows that concentrating onshore wind power in areas with high energy yield can lead to an increase in electricity transport by up to 38 %, whereas more evenly distributed scenarios are preferred for environmental sustainability and distributive justice. In conclusion, we argue that energy system analysis can enhance the accuracy of assessment of onshore wind power distribution, but it must consider non-techno-economic criteria within spatially-distributed energy systems itself to address policymakers.
6.
Veurman, W; Kern, J; Pflüger, L; Wagner-Mohnsen, H; Müller, M; Altermatt, P P; Lou, Z Y; Stolterfoht, M; Haase, F; Kajari-Schröder, S; Peibst, R
Deciphering hysteresis in perovskite solar cells: Insights from device simulations distinguishing shallow traps from mobile ions Journal Article
In: Solar Energy, vol. 284, pp. 113037, 2024, ISSN: 0038-092X.
@article{Veurman2024,
title = {Deciphering hysteresis in perovskite solar cells: Insights from device simulations distinguishing shallow traps from mobile ions},
author = {W Veurman and J Kern and L Pflüger and H Wagner-Mohnsen and M Müller and P P Altermatt and Z Y Lou and M Stolterfoht and F Haase and S Kajari-Schröder and R Peibst},
url = {https://authors.elsevier.com/a/1k1Uj,tRdSPwP},
doi = {10.1016/j.solener.2024.113037},
issn = {0038-092X},
year = {2024},
date = {2024-12-01},
urldate = {2024-01-01},
journal = {Solar Energy},
volume = {284},
pages = {113037},
abstract = {In perovskite solar cells, a hysteresis of the current–voltage curve is often observed and is usually attributed to moving ions. However, our device modelling forecasts that it can also be explained, at least in part, by the occupation behaviour of slow-shallow trap states in the perovskite material. A difference between the ionic and trap interpretation arises in the illumination dependence of the hysteresis. Under the assumption of slow-shallow trap states, our simulations show that a diffusion capacitive effect should be observed at high scanning rates (> 100 V/s) and low light intensities (< 0.01 sun). This effect does not appear when assuming a device model with moving ion vacancies. This offers an opportunity for experimentally distinguishing between the two explanatory models and to quantify the relative contributions to hysteresis from ion vacancies and traps, respectively.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In perovskite solar cells, a hysteresis of the current–voltage curve is often observed and is usually attributed to moving ions. However, our device modelling forecasts that it can also be explained, at least in part, by the occupation behaviour of slow-shallow trap states in the perovskite material. A difference between the ionic and trap interpretation arises in the illumination dependence of the hysteresis. Under the assumption of slow-shallow trap states, our simulations show that a diffusion capacitive effect should be observed at high scanning rates (> 100 V/s) and low light intensities (< 0.01 sun). This effect does not appear when assuming a device model with moving ion vacancies. This offers an opportunity for experimentally distinguishing between the two explanatory models and to quantify the relative contributions to hysteresis from ion vacancies and traps, respectively.
7.
Schlemminger, M; Bredemeier, D; Mahner, A; Niepelt, R; Breitner, M H; Brendel, R
Rooftop PV Potential Determined by Backward Ray Tracing: A Case Study for the German Regions of Berlin, Cologne, and Hanover Journal Article
In: Progress in Photovoltaics: Research and Applications, vol. 32, no. 12, pp. 912-929, 2024.
@article{Schlemminger2024d,
title = {Rooftop PV Potential Determined by Backward Ray Tracing: A Case Study for the German Regions of Berlin, Cologne, and Hanover},
author = {M Schlemminger and D Bredemeier and A Mahner and R Niepelt and M H Breitner and R Brendel},
doi = {10.1002/pip.3844},
year = {2024},
date = {2024-12-01},
urldate = {2024-09-18},
journal = {Progress in Photovoltaics: Research and Applications},
volume = {32},
number = {12},
pages = {912-929},
abstract = {Photovoltaics (PV) on building rooftops is a major contributor to the decarbonization of energy systems. We simulate the PV energy yield potential for 2.5 million individual roofs in three German regions. We cumulate the results for each single roof to calculate the cost-potential curves for the three cities Berlin, Cologne, and Hanover. These curves give the amount of electricity that can be generated at less than a given cost per kWh. We find that these curves have the shape of a hockey stick. Neglecting the dependence of PV investment on building size and thus on the system sizes causes largely different cost-potential curves that differ by 11%–18% for flat roofs due to their heterogeneous building size distribution. The cost-potential curves of the three cities are very similar when appropriately normalized, for example, by the local solar irradiation and the settlement area of the city, despite substantial variations in population density. This allows for an extrapolation of our results. For Germany, we reveal an upper limit for the total electricity generation from rooftop PV of 762 TWh/a with cost as low as 6.9 ct/kWh without accounting for area losses due to chimneys, air conditioning systems, and so forth. We estimate the actual potential to be at least half of that figure.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Photovoltaics (PV) on building rooftops is a major contributor to the decarbonization of energy systems. We simulate the PV energy yield potential for 2.5 million individual roofs in three German regions. We cumulate the results for each single roof to calculate the cost-potential curves for the three cities Berlin, Cologne, and Hanover. These curves give the amount of electricity that can be generated at less than a given cost per kWh. We find that these curves have the shape of a hockey stick. Neglecting the dependence of PV investment on building size and thus on the system sizes causes largely different cost-potential curves that differ by 11%–18% for flat roofs due to their heterogeneous building size distribution. The cost-potential curves of the three cities are very similar when appropriately normalized, for example, by the local solar irradiation and the settlement area of the city, despite substantial variations in population density. This allows for an extrapolation of our results. For Germany, we reveal an upper limit for the total electricity generation from rooftop PV of 762 TWh/a with cost as low as 6.9 ct/kWh without accounting for area losses due to chimneys, air conditioning systems, and so forth. We estimate the actual potential to be at least half of that figure.
8.
Schmidt, J; Winter, M; Souren, F; Bolding, J; Vries, H
Excellent Passivation of Silicon Surfaces by HfO2 Layers Deposited using Scalable Spatial Atomic Layer Deposition (SALD) Proceedings Article
In: WIP, (Ed.): Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition, WIP-Munich, Vienna, Austria, 2024.
@inproceedings{Schmidt2024c,
title = {Excellent Passivation of Silicon Surfaces by HfO2 Layers Deposited using Scalable Spatial Atomic Layer Deposition (SALD)},
author = {J Schmidt and M Winter and F Souren and J Bolding and H Vries},
editor = {WIP},
doi = {10.4229/EUPVSEC2024/1CV.2.22},
year = {2024},
date = {2024-11-15},
urldate = {2024-11-15},
booktitle = {Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition},
publisher = {WIP-Munich},
address = {Vienna, Austria},
abstract = {Spatial Atomic Layer Deposition (SALD) had been successfully applied in the past for the Al2O3 surface passivation on silicon solar cells. In contrast to conventional sequential ALD techniques, as typically used in the labs, SALD allows for high deposition rates of a few nm per second, which are compatible with industrial solar cell production. In this contribution, we apply SALD for the first time to the electronic passivation of moderately doped (~1016 cm–3) p-type crystalline silicon surfaces with thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400°C in air, an effective surface recombination velocity Seff of only 4 cm/s is achieved, which is below what has been reported before using sequential ALD techniques. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. Firing is shown to reduce the passivation quality, however, by adding a capping layer of plasmaenhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the HfO2, the firing stability is found to improve. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future silicon solar cells.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Spatial Atomic Layer Deposition (SALD) had been successfully applied in the past for the Al2O3 surface passivation on silicon solar cells. In contrast to conventional sequential ALD techniques, as typically used in the labs, SALD allows for high deposition rates of a few nm per second, which are compatible with industrial solar cell production. In this contribution, we apply SALD for the first time to the electronic passivation of moderately doped (~1016 cm–3) p-type crystalline silicon surfaces with thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400°C in air, an effective surface recombination velocity Seff of only 4 cm/s is achieved, which is below what has been reported before using sequential ALD techniques. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. Firing is shown to reduce the passivation quality, however, by adding a capping layer of plasmaenhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the HfO2, the firing stability is found to improve. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future silicon solar cells.
9.
Dullweber, T; Mertens, V; Winter, M; Schimanke, S; Ripke, M; Dorn, S; Larionova, Y; Lange, G; Bothe, K; Schmidt, J; Brendel, R; Dahle, A K; Coskun, Ö; Sen, N Töre
Optimized Ga-Doped Cz Wafers for POLO IBC Solar Cells with High Efficiency and Minimal LeTID Degradation Proceedings Article
In: WIP, (Ed.): Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition, WIP-Munich, Vienna, Austria, 2024.
@inproceedings{Dullweber2024b,
title = {Optimized Ga-Doped Cz Wafers for POLO IBC Solar Cells with High Efficiency and Minimal LeTID Degradation},
author = {T Dullweber and V Mertens and M Winter and S Schimanke and M Ripke and S Dorn and Y Larionova and G Lange and K Bothe and J Schmidt and R Brendel and A K Dahle and Ö Coskun and N Töre Sen},
editor = {WIP},
doi = {10.4229/EUPVSEC2024/1AO.6.6},
year = {2024},
date = {2024-11-15},
urldate = {2024-11-15},
booktitle = {Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition},
publisher = {WIP-Munich},
address = {Vienna, Austria},
abstract = {The PV industry is using 0.4 to 0.8 textgreekWcm low-resistivity Ga-doped Cz-Si wafers with carrier lifetimes < 700 µs for mass production of PERC and bifacial PERC+ cells. Our Quokka3 simulations predict, that a Ga-doped Cz wafer resistivity around 1.5 textgreekWcm will increase Voc and Jsc and the POLO IBC solar cell efficiency from the presently best measured efficiency of 23.9% up to a simulated efficiency of 24.3%, because the charge carrier density in POLO IBC solar cells depends less on the doping concentration due to their much higher Voc. In this paper, we investigate Gadoped Cz wafers with higher resistivities ranging from 0.7 to 4.8 textgreekWcm from Cz-Si ingots supplied by NorSun and Kalyon PV. POLO IBC lifetime precursors processed at ISFH without metal contacts show, that the effective carrier lifetime linearly increases with higher wafer resistivity up to 3 ms at 4.0 textgreekWcm. The measured implied Voc of up to 740 mV and the implied FF of up to 86% correspond to a calculated implied efficiency of 26.7% for a wide wafer resistivity range. The measured IV parameters of POLO IBC solar cells processed with different Ga-doped Si wafer resistivities agree qualitatively with our Quokka 3 simulations. During LeTID degradation conditions at 0.5 sun, 80°C, the POLO IBC lifetime samples show a moderate degradation in implied Voc and implied FF and reveal, that the LeTID-related wafer bulk defect density is independent of the Ga doping concentration. The POLO IBC solar cells show a maximum LeTID degradation of the efficiency of 4%rel which fully recovers during extended testing. The LeTID degradation could be further minimized by adjusting the firing temperature profile. In addition, we present our near-term POLO IBC efficiency roadmap towards 25% by optimizing the POLO IBC screen-printed Ag and Al metallization.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
The PV industry is using 0.4 to 0.8 textgreekWcm low-resistivity Ga-doped Cz-Si wafers with carrier lifetimes < 700 µs for mass production of PERC and bifacial PERC+ cells. Our Quokka3 simulations predict, that a Ga-doped Cz wafer resistivity around 1.5 textgreekWcm will increase Voc and Jsc and the POLO IBC solar cell efficiency from the presently best measured efficiency of 23.9% up to a simulated efficiency of 24.3%, because the charge carrier density in POLO IBC solar cells depends less on the doping concentration due to their much higher Voc. In this paper, we investigate Gadoped Cz wafers with higher resistivities ranging from 0.7 to 4.8 textgreekWcm from Cz-Si ingots supplied by NorSun and Kalyon PV. POLO IBC lifetime precursors processed at ISFH without metal contacts show, that the effective carrier lifetime linearly increases with higher wafer resistivity up to 3 ms at 4.0 textgreekWcm. The measured implied Voc of up to 740 mV and the implied FF of up to 86% correspond to a calculated implied efficiency of 26.7% for a wide wafer resistivity range. The measured IV parameters of POLO IBC solar cells processed with different Ga-doped Si wafer resistivities agree qualitatively with our Quokka 3 simulations. During LeTID degradation conditions at 0.5 sun, 80°C, the POLO IBC lifetime samples show a moderate degradation in implied Voc and implied FF and reveal, that the LeTID-related wafer bulk defect density is independent of the Ga doping concentration. The POLO IBC solar cells show a maximum LeTID degradation of the efficiency of 4%rel which fully recovers during extended testing. The LeTID degradation could be further minimized by adjusting the firing temperature profile. In addition, we present our near-term POLO IBC efficiency roadmap towards 25% by optimizing the POLO IBC screen-printed Ag and Al metallization.
10.
Buchholz, F; Tune, D; Messmer, T; Linke, J; Prasad, M; Mihailetchi, V; Ulbikas, J; Dahle, A; Meereboer, M; Fabris, F; Eikelboom, E; Borgers, T; Dyck, R; Duerinckx, F; Sivaramakrishnan, H; Harrison, S; Kester, J; Guillevin, N; Kroon, J; Mertens, V; Dullweber, T; Shochet, O; Rosen, I; Röver, I; Palitzsch, W; Zaror, Y; Stierstorfer, J; Radzevicius, A; Lukinskas, P; Denafas, J; Vanhanen, T; Savisalo, T; Pospischil, M; Breitenbücher, M; Coşkun, Ö; l'Epine, M; Macé, P
IBC4EU: First Results of Industrialization of Low Cost, High Efficiency IBC Technology Proceedings Article
In: WIP, (Ed.): Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition, WIP-Munich, Vienna, Austria, 2024.
@inproceedings{Buchholz2024b,
title = {IBC4EU: First Results of Industrialization of Low Cost, High Efficiency IBC Technology},
author = {F Buchholz and D Tune and T Messmer and J Linke and M Prasad and V Mihailetchi and J Ulbikas and A Dahle and M Meereboer and F Fabris and E Eikelboom and T Borgers and R Dyck and F Duerinckx and H Sivaramakrishnan and S Harrison and J Kester and N Guillevin and J Kroon and V Mertens and T Dullweber and O Shochet and I Rosen and I Röver and W Palitzsch and Y Zaror and J Stierstorfer and A Radzevicius and P Lukinskas and J Denafas and T Vanhanen and T Savisalo and M Pospischil and M Breitenbücher and Ö Coşkun and M l'Epine and P Macé},
editor = {WIP},
doi = {10.4229/EUPVSEC2024/1BO.4.3},
year = {2024},
date = {2024-11-15},
urldate = {2024-11-15},
booktitle = {Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition},
publisher = {WIP-Munich},
address = {Vienna, Austria},
abstract = {This paper introduces the Horizon Europe project IBC4EU with the goal to establish a European value chain based on innovative passivated contact back contact solar cells and modules. The two key solar cell technologies – POLO-IBC and polyZEBRA – are introduced. We present simulation studies and experiments on the suitability of bulk resistance ranges for use in the two solar cell concepts indicating best solar cell efficiencies for similarly low resistance values as standard TOPCon solar cells. The higher the minority carrier lifetime of the given material, the smaller this impact becomes. The p-type based solar cell (POLO-IBC) shows to require a more confined range that is slightly higher in sheet resistance than the standard PERC requirements. Reliability data on the cells (LeTID) and modules (DH, TC) proves the excellent long-term stability of the n-typed back contact cells and modules. In addition, an innovative way to interconnect the IBC cells based on printed conductive patterns printed on glass is introduced as well as a novel recycling route for state-of-the-art back contact solar cells.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
This paper introduces the Horizon Europe project IBC4EU with the goal to establish a European value chain based on innovative passivated contact back contact solar cells and modules. The two key solar cell technologies – POLO-IBC and polyZEBRA – are introduced. We present simulation studies and experiments on the suitability of bulk resistance ranges for use in the two solar cell concepts indicating best solar cell efficiencies for similarly low resistance values as standard TOPCon solar cells. The higher the minority carrier lifetime of the given material, the smaller this impact becomes. The p-type based solar cell (POLO-IBC) shows to require a more confined range that is slightly higher in sheet resistance than the standard PERC requirements. Reliability data on the cells (LeTID) and modules (DH, TC) proves the excellent long-term stability of the n-typed back contact cells and modules. In addition, an innovative way to interconnect the IBC cells based on printed conductive patterns printed on glass is introduced as well as a novel recycling route for state-of-the-art back contact solar cells.
11.
Hoffmann, E; Gregory, G; Centazzo, M; Khan, M; Khan, N; Mertens, V; Jäger, P; Spätlich, S; Baumann, U; Dullweber, T
Self-Aligned Phase Separation for IBC Cells Using PVD Polysilicon Proceedings Article
In: WIP, (Ed.): Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition, Vienna, Austria, 2024.
@inproceedings{Hoffmann.2024,
title = {Self-Aligned Phase Separation for IBC Cells Using PVD Polysilicon},
author = {E Hoffmann and G Gregory and M Centazzo and M Khan and N Khan and V Mertens and P Jäger and S Spätlich and U Baumann and T Dullweber},
editor = {WIP},
doi = {10.4229/EUPVSEC2024/1BO.4.4},
year = {2024},
date = {2024-11-15},
urldate = {2024-11-15},
booktitle = {Proceedings of the 41st European Photovoltaic Solar Energy Conference and Exhibition},
journal = {41st European Photovoltaic Solar Energy Conference and Exhibition},
address = {Vienna, Austria},
abstract = {We introduce an innovative IBC solar cell process leveraging the directional deposition nature of doped polycrystalline silicon (poly-Si) through physical vapor deposition (PVD). This method enables the self-alignment of passivated contacts, effectively separating the polarities. The self-aligned back contact (SABC) cell incorporates n-type and p-type passivated contacts, achieved through interfacial oxide (SiOX) and doped n- and p-type poly-Si layers respectively, arranged in an interdigitated design on the back side. The insulation between the p-type and n-type poly-Si layers requires only a single structuring process of the firstly deposited p-type poly-Si. The subsequent blanket deposition of n-type poly-Si by PVD remains insulated from the p-type poly-Si layer due to the self-alignment properties inherent in our structuring and deposition processes. The SABC target process sequence can be implemented into existing TOPCon manufacturing lines requiring only two additional processing tools.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
We introduce an innovative IBC solar cell process leveraging the directional deposition nature of doped polycrystalline silicon (poly-Si) through physical vapor deposition (PVD). This method enables the self-alignment of passivated contacts, effectively separating the polarities. The self-aligned back contact (SABC) cell incorporates n-type and p-type passivated contacts, achieved through interfacial oxide (SiOX) and doped n- and p-type poly-Si layers respectively, arranged in an interdigitated design on the back side. The insulation between the p-type and n-type poly-Si layers requires only a single structuring process of the firstly deposited p-type poly-Si. The subsequent blanket deposition of n-type poly-Si by PVD remains insulated from the p-type poly-Si layer due to the self-alignment properties inherent in our structuring and deposition processes. The SABC target process sequence can be implemented into existing TOPCon manufacturing lines requiring only two additional processing tools.
12.
Jensen, J; Schiebler, B; Kabelac, S; Giovannetti, F
Modeling of solar thermal heat pipe collectors with overheating prevention in system simulations Journal Article
In: Solar Energy, vol. 282, pp. 112861, 2024, ISSN: 0038-092X.
@article{Jensen2024,
title = {Modeling of solar thermal heat pipe collectors with overheating prevention in system simulations},
author = {J Jensen and B Schiebler and S Kabelac and F Giovannetti},
doi = {10.1016/j.solener.2024.112861},
issn = {0038-092X},
year = {2024},
date = {2024-11-01},
urldate = {2024-01-01},
journal = {Solar Energy},
volume = {282},
pages = {112861},
abstract = {Solar thermal collectors can provide renewable heat in an efficient way. They face however issues of overheating under certain circumstances, which can lead to thermal stress and steam formation. One solution to this issue consists in using solar thermal collectors with overheating prevention based on heat pipes. This paper presents the new TRNSYS type 839 that accurately reproduces the heat pipe overheating prevention effect. The model is validated using data from high accuracy solar tracker measurements as well as real solar thermal systems. A mean absolute deviation in the validation of less than 2% shows the functionality and accuracy of type 839. The results were compared with simulations using the existing Type 832 (without heat pipe limitation) and the simpler 2-part efficiency curve approach adapted from practice-oriented planning tools. By comparison, type 832 shows a mean absolute deviation of 44.8% using the same data. The use of the 2-part efficiency curve approach results in a mean absolute deviation of 49 %. With type 839 it is possible to design and evaluate solar thermal collectors with heat pipe limitation in TRNSYS and assess their use in a wide variety of systems. The new model is particularly recommended for applications with a relatively high and constant temperature level (e.g. process or district heating), for gross heat yield simulations or for the design of systems in order to correctly analyze the influence of the heat pipe limitation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Solar thermal collectors can provide renewable heat in an efficient way. They face however issues of overheating under certain circumstances, which can lead to thermal stress and steam formation. One solution to this issue consists in using solar thermal collectors with overheating prevention based on heat pipes. This paper presents the new TRNSYS type 839 that accurately reproduces the heat pipe overheating prevention effect. The model is validated using data from high accuracy solar tracker measurements as well as real solar thermal systems. A mean absolute deviation in the validation of less than 2% shows the functionality and accuracy of type 839. The results were compared with simulations using the existing Type 832 (without heat pipe limitation) and the simpler 2-part efficiency curve approach adapted from practice-oriented planning tools. By comparison, type 832 shows a mean absolute deviation of 44.8% using the same data. The use of the 2-part efficiency curve approach results in a mean absolute deviation of 49 %. With type 839 it is possible to design and evaluate solar thermal collectors with heat pipe limitation in TRNSYS and assess their use in a wide variety of systems. The new model is particularly recommended for applications with a relatively high and constant temperature level (e.g. process or district heating), for gross heat yield simulations or for the design of systems in order to correctly analyze the influence of the heat pipe limitation.
13.
Katkus, T; Ng, S H; Mu, H; Le, N H An; Stonytė, D; Khajehsaeidimahabadi, Z; Seniutinas, G; Baltrukonis, J; Ulčinas, O; Mikutis, M; Sabonis, V; Nishijima, Y; Rienäcker, M; Römer, U; Krügener, J; Peibst, R; John, S; Juodkazis, S
Bessel-Beam Direct Write of the Etch Mask in a Nano-Film of Alumina for High-Efficiency Si Solar Cells Journal Article
In: Advanced Engineering Materials, vol. 26, no. 21, pp. 2400711, 2024.
@article{Katkus2024,
title = {Bessel-Beam Direct Write of the Etch Mask in a Nano-Film of Alumina for High-Efficiency Si Solar Cells},
author = {T Katkus and S H Ng and H Mu and N H An Le and D Stonytė and Z Khajehsaeidimahabadi and G Seniutinas and J Baltrukonis and O Ulčinas and M Mikutis and V Sabonis and Y Nishijima and M Rienäcker and U Römer and J Krügener and R Peibst and S John and S Juodkazis},
doi = {10.1002/adem.202400711},
year = {2024},
date = {2024-11-01},
urldate = {2024-08-29},
journal = {Advanced Engineering Materials},
volume = {26},
number = {21},
pages = {2400711},
abstract = {Large surface area applications such as high efficiency >26% solar cells require surface patterning with 1–10 μm periodic patterns at high fidelity over 1–10 cm2$1 - łeft(textcmright)^2$ areas (before up scaling to 1 m2$ łeft(textmright)^2$) to perform at, or exceed, the Lambertian (ray optics) limit of light trapping. Herein, a pathway is shown to high-resolution sub-1 μm etch mask patterning by ablation using direct femtosecond laser writing performed at room conditions (without the need for a vacuum-based lithography approach). A Bessel beam is used to alleviate the required high surface tracking tolerance for ablation of 0.3–0.8 μm diameter holes in 40 nm alumina Al2O3$łeft(textAlright)_2 łeft(textOright)_3$–mask at high writing speed, 7.5 cm s−1; a patterning rate 1 cm2 per 20 min. Plasma etching protocol was optimized for a zero-mesa formation of photonic-crystal-trapping structures and smooth surfaces at the nanoscale level. The maximum of minority carrier recombination time of 2.9 ms was achieved after the standard wafer passivation etch; resistivity of the wafer was 3.5 Ω cm. Scaling up in area and throughput of the demonstrated approach is outlined.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Large surface area applications such as high efficiency >26% solar cells require surface patterning with 1–10 μm periodic patterns at high fidelity over 1–10 cm2$1 - łeft(textcmright)^2$ areas (before up scaling to 1 m2$ łeft(textmright)^2$) to perform at, or exceed, the Lambertian (ray optics) limit of light trapping. Herein, a pathway is shown to high-resolution sub-1 μm etch mask patterning by ablation using direct femtosecond laser writing performed at room conditions (without the need for a vacuum-based lithography approach). A Bessel beam is used to alleviate the required high surface tracking tolerance for ablation of 0.3–0.8 μm diameter holes in 40 nm alumina Al2O3$łeft(textAlright)_2 łeft(textOright)_3$–mask at high writing speed, 7.5 cm s−1; a patterning rate 1 cm2 per 20 min. Plasma etching protocol was optimized for a zero-mesa formation of photonic-crystal-trapping structures and smooth surfaces at the nanoscale level. The maximum of minority carrier recombination time of 2.9 ms was achieved after the standard wafer passivation etch; resistivity of the wafer was 3.5 Ω cm. Scaling up in area and throughput of the demonstrated approach is outlined.
14.
Baumann, S; Eperon, G E; Virtuani, A; Jeangros, Q; Sulas-Kern, D B; Barrit, D; Schall, J; Nie, W; Oreski, G; Khenkin, M; Ulbrich, C; Peibst, R; Stein, J S; Köntges, M
Stability and reliability of perovskite containing solar cells and modules: degradation mechanisms and mitigation strategies Journal Article
In: Energy Environ. Sci., vol. 17, pp. 7566-7599, 2024.
@article{Baumann2024,
title = {Stability and reliability of perovskite containing solar cells and modules: degradation mechanisms and mitigation strategies},
author = {S Baumann and G E Eperon and A Virtuani and Q Jeangros and D B Sulas-Kern and D Barrit and J Schall and W Nie and G Oreski and M Khenkin and C Ulbrich and R Peibst and J S Stein and M Köntges},
doi = {10.1039/D4EE01898B},
year = {2024},
date = {2024-10-21},
urldate = {2024-08-02},
journal = {Energy Environ. Sci.},
volume = {17},
pages = {7566-7599},
publisher = {The Royal Society of Chemistry},
abstract = {Perovskite solar cells have shown a strong increase in efficiency over the last 15 years. With a record power conversion efficiency on small area above 34%, perovskite/silicon tandem solar cells already exceed the efficiency limit of silicon solar cells and their efficiency is expected to increase further. While predicted to take large markets shares in a few years thanks to their high efficiency and low manufacturing cost potential, perovskite/silicon tandem devices are not yet sufficiently reliable, which brings into question the commercial viability of this new technology. This review provides an extensive summary of degradation mechanisms occurring in perovskite solar cells and modules. In particular, instabilities triggered by the presence and generation of mobile ions in the perovskite absorber and/or by extrinsic stress factors are discussed in detail. In addition, mitigation strategies developed so far to improve the reliability of the technology are also presented.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Perovskite solar cells have shown a strong increase in efficiency over the last 15 years. With a record power conversion efficiency on small area above 34%, perovskite/silicon tandem solar cells already exceed the efficiency limit of silicon solar cells and their efficiency is expected to increase further. While predicted to take large markets shares in a few years thanks to their high efficiency and low manufacturing cost potential, perovskite/silicon tandem devices are not yet sufficiently reliable, which brings into question the commercial viability of this new technology. This review provides an extensive summary of degradation mechanisms occurring in perovskite solar cells and modules. In particular, instabilities triggered by the presence and generation of mobile ions in the perovskite absorber and/or by extrinsic stress factors are discussed in detail. In addition, mitigation strategies developed so far to improve the reliability of the technology are also presented.
15.
Köntges, M
ZUPER - Zuverlässigkeit und Performance von PV-Modulen, Systemen und Anwendungen – Herausforderungen bei Perowskit/Silizium Tandemsolarmodulen Presentation
Online Event, 09.10.2024, (PV-Dialog: Perspektiven und Projekte aus der Photovoltaikforschung - Perowskit-Technologien).
@misc{Köntges2024c,
title = {ZUPER - Zuverlässigkeit und Performance von PV-Modulen, Systemen und Anwendungen – Herausforderungen bei Perowskit/Silizium Tandemsolarmodulen},
author = {M Köntges},
year = {2024},
date = {2024-10-09},
address = {Online Event},
note = {PV-Dialog: Perspektiven und Projekte aus der Photovoltaikforschung - Perowskit-Technologien},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
16.
Schmidt, J; Winter, M; Souren, F; Bolding, J; Vries, H
Electronic Passivation of Crystalline Silicon Surfaces Using Spatial-Atomic-Layer-Deposited HfO2 Films and HfO2/SiN Stacks Journal Article Forthcoming
In: physica status solidi (RRL) – Rapid Research Letters, pp. 2400255, Forthcoming.
@article{Schmidt2024,
title = {Electronic Passivation of Crystalline Silicon Surfaces Using Spatial-Atomic-Layer-Deposited HfO2 Films and HfO2/SiN Stacks},
author = {J Schmidt and M Winter and F Souren and J Bolding and H Vries},
doi = {10.1002/pssr.202400255},
year = {2024},
date = {2024-10-07},
urldate = {2024-10-07},
journal = {physica status solidi (RRL) – Rapid Research Letters},
pages = {2400255},
abstract = {Spatial atomic layer deposition (SALD) is applied to the electronic passivation of moderately doped (≈1016 cm−3) p-type crystalline silicon surfaces by thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400 °C, an effective surface recombination velocity Seff of 4 cm s−1 is achieved, which is below what has been reported before on moderately doped p-type silicon. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. After firing at 700 °C peak temperature in a conveyor-belt furnace, as applied in the production of solar cells, still a good level of surface passivation with an Seff of 21 cm s−1 is attained. Reducing the HfO2 thickness to 1 nm, the passivation virtually vanishes after firing (i.e., Seff > 1000 cm s−1). However, by adding a capping layer of plasma-enhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the 1 nm HfO2, a substantially improved firing stability is attained, as demonstrated by Seff values as low as 30 cm s−1 after firing, which is attributed to the hydrogenation of interface states. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future solar cells.},
keywords = {},
pubstate = {forthcoming},
tppubtype = {article}
}
Spatial atomic layer deposition (SALD) is applied to the electronic passivation of moderately doped (≈1016 cm−3) p-type crystalline silicon surfaces by thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400 °C, an effective surface recombination velocity Seff of 4 cm s−1 is achieved, which is below what has been reported before on moderately doped p-type silicon. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. After firing at 700 °C peak temperature in a conveyor-belt furnace, as applied in the production of solar cells, still a good level of surface passivation with an Seff of 21 cm s−1 is attained. Reducing the HfO2 thickness to 1 nm, the passivation virtually vanishes after firing (i.e., Seff > 1000 cm s−1). However, by adding a capping layer of plasma-enhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the 1 nm HfO2, a substantially improved firing stability is attained, as demonstrated by Seff values as low as 30 cm s−1 after firing, which is attributed to the hydrogenation of interface states. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future solar cells.
17.
Kafedjiska, I; Breyer, C; Busto, C; Cherradi, N; Fath, P; Lim, B; Moser, D; Preu, R; Roman, E; Schlatmann, R; Topič, M; Trube, J; Vartiainen, E
European PV Manufacturing and LCOE: Ensuring Resilience and Competitiveness Through R&I and Industrial Policies Presentation
Vienna, Austria, 27.09.2024, (41st European Photovoltaic Solar Energy Conference and Exhibition).
@misc{Kafedjiska2024,
title = {European PV Manufacturing and LCOE: Ensuring Resilience and Competitiveness Through R&I and Industrial Policies},
author = {I Kafedjiska and C Breyer and C Busto and N Cherradi and P Fath and B Lim and D Moser and R Preu and E Roman and R Schlatmann and M Topič and J Trube and E Vartiainen},
year = {2024},
date = {2024-09-27},
address = {Vienna, Austria},
abstract = {The European Solar PV Industry Alliance (ESIA) aims to reach 30 GW of annual solar PV manufacturing capacity in Europe by 2025 [1] and to make the PV module supply more “resilient”. Currently, Europe depends almost entirely on PV module imports from one country (China) or from regions which in turn rely on silicon wafer supply from China [2]. PV Magazine estimates that this corresponds to subsidies ranging from 600 to 900 million €/year in 2025, and from 3.7 to 5.6 billion €/year in 2030, assuming a 10-15 €ct/Wp cost gap between EU-made modules and inverters and the global competition [3]. To explore the question of resilience even further, the European Technology and Innovation Platform for Photovoltaic (ETIP-PV) analysed the Cost of Ownership (CoO) for a 10 GW integrated PV manufacturing factory for three PV technologies (TOPCon, HJT, or IBC) and four locations (China, India, USA, and the EU) [4]. For China and the EU two electricity prices were considered: low (3 and 7 €ct/kWh, respectively) and high (8.5 and 12 €ct/kWh, respectively). China (low) produces at 16 $ct/Wp (TOPCon and IBC) and 17 $ct/Wp (HJT). China (high) and India have a 19 – 21 $ct/Wp for all technologies. EU (low) has a 24 – 25 $ct/Wp, while EU (high) has around 30 $ct/Wp. The USA has around 28 – 29 $ct/Wp for all technologies. The cost variations are present due to different material, labour, equipment, and building costs – all of which are higher in the EU and the USA than in China and India [4]. Additionally, it should be mentioned that latest spot market factory gate prices in China for PERC and N-type mono-crystalline Si modules are 10.6 and 11.4 $ct/Wp, respectively [5]. Thus, 16 $ct/Wp for TOPCon/IBC manufacturing are not reflective of the real cost of the Chinese players, even though the current market cost is likely below the average manufacturing cost. Next, ETIP-PV performed LCOE calculations for varying Weighted Average Cost of Capital (WACC) for residential (5 kWp) PV systems (WACC = 0, 2, 4, or 6%), commercial (50 kWp), industrial (10 MWp), and utility-scale (100 MWp) PV systems (WACC = 2, 4, 7, or 10%) for five different locations in Europe: Helsinki, Munich, Toulouse, Rome, and Malaga. Compared with the average variable retail electricity prices, even excluding the fixed fees which cannot be saved by own PV consumption, PV electricity is already cheaper in all five locations with realistic WACC rates and consumer segments [6]. However, the above-mentioned LCOE calculations did not distinguish between Chinese or EU-manufactured PV modules. Therefore, the question whether the EU-manufactured PV modules on European markets can be LCOE-competitive with the Chinese-manufactured PV modules remains open. Initial calculations indicate that even though the EU-manufacturing costs are higher, they can have little to no effect on the LCOE and the end-user costs, especially if suitable policy incentives and investments are put into place. For instance, a price difference between European and Chinese modules of 10 €ct/Wp (e.g. 20 vs. 10 €ct/Wp) would lead to a 3.8 €/MWh (~13%) LCOE difference in Malaga (annual yield of 1790 kWh/kWp) and 6.5 €/MWh (~14%) in Helsinki (annual yield of 1050 kWh/kWp) in a utility-scale system with a nominal WACC 7%, inflation 2%, degradation 0.5%/a, 30 years lifetime and 12.5 €/kWp/a OPEX. For rooftop systems, this difference is almost insignificant and even in utility-scale in Southern Europe not decisive. However, in the Nordics, the utility-scale LCOE value difference of more than 6 €/MWh can be significant. One of the key challenges for policy makers is how to find a balance between the need of rapid scale-up of manufacturing capacity and renewable-energy deployment vs. the need to sustain competitiveness through R&I. Therefore, the final part of the talk will cover industrial policies and R&I efforts that can further decrease this LCOE difference and make the European PV manufacturing significantly more resilient, price competitive, and end-user friendly. },
note = {41st European Photovoltaic Solar Energy Conference and Exhibition},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
The European Solar PV Industry Alliance (ESIA) aims to reach 30 GW of annual solar PV manufacturing capacity in Europe by 2025 [1] and to make the PV module supply more “resilient”. Currently, Europe depends almost entirely on PV module imports from one country (China) or from regions which in turn rely on silicon wafer supply from China [2]. PV Magazine estimates that this corresponds to subsidies ranging from 600 to 900 million €/year in 2025, and from 3.7 to 5.6 billion €/year in 2030, assuming a 10-15 €ct/Wp cost gap between EU-made modules and inverters and the global competition [3]. To explore the question of resilience even further, the European Technology and Innovation Platform for Photovoltaic (ETIP-PV) analysed the Cost of Ownership (CoO) for a 10 GW integrated PV manufacturing factory for three PV technologies (TOPCon, HJT, or IBC) and four locations (China, India, USA, and the EU) [4]. For China and the EU two electricity prices were considered: low (3 and 7 €ct/kWh, respectively) and high (8.5 and 12 €ct/kWh, respectively). China (low) produces at 16 $ct/Wp (TOPCon and IBC) and 17 $ct/Wp (HJT). China (high) and India have a 19 – 21 $ct/Wp for all technologies. EU (low) has a 24 – 25 $ct/Wp, while EU (high) has around 30 $ct/Wp. The USA has around 28 – 29 $ct/Wp for all technologies. The cost variations are present due to different material, labour, equipment, and building costs – all of which are higher in the EU and the USA than in China and India [4]. Additionally, it should be mentioned that latest spot market factory gate prices in China for PERC and N-type mono-crystalline Si modules are 10.6 and 11.4 $ct/Wp, respectively [5]. Thus, 16 $ct/Wp for TOPCon/IBC manufacturing are not reflective of the real cost of the Chinese players, even though the current market cost is likely below the average manufacturing cost. Next, ETIP-PV performed LCOE calculations for varying Weighted Average Cost of Capital (WACC) for residential (5 kWp) PV systems (WACC = 0, 2, 4, or 6%), commercial (50 kWp), industrial (10 MWp), and utility-scale (100 MWp) PV systems (WACC = 2, 4, 7, or 10%) for five different locations in Europe: Helsinki, Munich, Toulouse, Rome, and Malaga. Compared with the average variable retail electricity prices, even excluding the fixed fees which cannot be saved by own PV consumption, PV electricity is already cheaper in all five locations with realistic WACC rates and consumer segments [6]. However, the above-mentioned LCOE calculations did not distinguish between Chinese or EU-manufactured PV modules. Therefore, the question whether the EU-manufactured PV modules on European markets can be LCOE-competitive with the Chinese-manufactured PV modules remains open. Initial calculations indicate that even though the EU-manufacturing costs are higher, they can have little to no effect on the LCOE and the end-user costs, especially if suitable policy incentives and investments are put into place. For instance, a price difference between European and Chinese modules of 10 €ct/Wp (e.g. 20 vs. 10 €ct/Wp) would lead to a 3.8 €/MWh (~13%) LCOE difference in Malaga (annual yield of 1790 kWh/kWp) and 6.5 €/MWh (~14%) in Helsinki (annual yield of 1050 kWh/kWp) in a utility-scale system with a nominal WACC 7%, inflation 2%, degradation 0.5%/a, 30 years lifetime and 12.5 €/kWp/a OPEX. For rooftop systems, this difference is almost insignificant and even in utility-scale in Southern Europe not decisive. However, in the Nordics, the utility-scale LCOE value difference of more than 6 €/MWh can be significant. One of the key challenges for policy makers is how to find a balance between the need of rapid scale-up of manufacturing capacity and renewable-energy deployment vs. the need to sustain competitiveness through R&I. Therefore, the final part of the talk will cover industrial policies and R&I efforts that can further decrease this LCOE difference and make the European PV manufacturing significantly more resilient, price competitive, and end-user friendly.
18.
Schulte-Huxel, H; Manthey, T; Brinker, T; Ranft, P; Woock, H; Hahn, T; Moerlein, L; Blankemeyer, S; Skorcz, A; Köntges, M; Manteuffel, D; Friebe, J
Fully Integrated and System-Optimized Electronic Solutions on Solar Modules Presentation
Vienna, Austria, 27.09.2024, (41st European Photovoltaic Solar Energy Conference and Exhibition).
@misc{Schulte-Huxel2024c,
title = {Fully Integrated and System-Optimized Electronic Solutions on Solar Modules },
author = {H Schulte-Huxel and T Manthey and T Brinker and P Ranft and H Woock and T Hahn and L Moerlein and S Blankemeyer and A Skorcz and M Köntges and D Manteuffel and J Friebe},
year = {2024},
date = {2024-09-27},
address = {Vienna, Austria},
abstract = {Alternating current PV modules offer various advantages such as easier installation, safer operation and increased efficiency for residential and building-integrated PV systems including small balcony power plants. Although there is a growing market for module level electronics, there are still only limited solutions available. Here, we present the combination of different innovations to raise the potential of simplification and synergies by fully integration of the power electronics into the PV module. We developed a novel, highly efficient and compact power electronics with galvanic isolation offering a fully reactive power-capable inverter topology, utilizing 650 V gallium nitride (GaN) power semiconductors. The communication is enabled by wireless communication based on Wirepas mesh connectivity, allowing a safe and robust operation and flexible expansion of the PV system. The module electronics are connected directly to the cross-connectors of the PV modules, allowing for novel circuit configurations in contrast to conventional bypass diodes that have shown to be a cost-effective approach of limiting the operating range of each substring to prevent hot spot events on the module without significant yield losses. Furthermore, a slot antenna is introduced into the cross connectors of the PV module. The antenna is capacitively fed (through the backsheet) by an aperture coupling printed circuit board (PCB) on the rear side of the module. The fully integrated electronics is attached to the PV module, encapsulated and electrically isolated from the environment by low-pressure molding, which has shown high reliability in accelerated aging tests. We will show experimental results on test structures and finished PV modules being installed on an outdoor test stand. },
note = {41st European Photovoltaic Solar Energy Conference and Exhibition},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Alternating current PV modules offer various advantages such as easier installation, safer operation and increased efficiency for residential and building-integrated PV systems including small balcony power plants. Although there is a growing market for module level electronics, there are still only limited solutions available. Here, we present the combination of different innovations to raise the potential of simplification and synergies by fully integration of the power electronics into the PV module. We developed a novel, highly efficient and compact power electronics with galvanic isolation offering a fully reactive power-capable inverter topology, utilizing 650 V gallium nitride (GaN) power semiconductors. The communication is enabled by wireless communication based on Wirepas mesh connectivity, allowing a safe and robust operation and flexible expansion of the PV system. The module electronics are connected directly to the cross-connectors of the PV modules, allowing for novel circuit configurations in contrast to conventional bypass diodes that have shown to be a cost-effective approach of limiting the operating range of each substring to prevent hot spot events on the module without significant yield losses. Furthermore, a slot antenna is introduced into the cross connectors of the PV module. The antenna is capacitively fed (through the backsheet) by an aperture coupling printed circuit board (PCB) on the rear side of the module. The fully integrated electronics is attached to the PV module, encapsulated and electrically isolated from the environment by low-pressure molding, which has shown high reliability in accelerated aging tests. We will show experimental results on test structures and finished PV modules being installed on an outdoor test stand.
19.
Hu, H; An, S X; Li, Y; Orooji, S; Singh, R; Schackmar, F; Laufer, F; Jin, Q; Feeney, T; Diercks, A; Gota, F; Moghadamzadeh, S; Pan, T; Rienäcker, M; Peibst, R; Fassl, P; Nejand, B Abdollahi; Paetzold, U W
Triple-Junction Perovskite-Perovskite-Silicon Photovoltaics Presentation
Vienna, Austria, 25.09.2024, (41st European Photovoltaic Solar Energy Conference and Exhibition).
@misc{Hu2024b,
title = {Triple-Junction Perovskite-Perovskite-Silicon Photovoltaics},
author = {H Hu and S X An and Y Li and S Orooji and R Singh and F Schackmar and F Laufer and Q Jin and T Feeney and A Diercks and F Gota and S Moghadamzadeh and T Pan and M Rienäcker and R Peibst and P Fassl and B Abdollahi Nejand and U W Paetzold},
year = {2024},
date = {2024-09-25},
address = {Vienna, Austria},
abstract = {Over the past decade, metal halide perovskite semiconductors emerged as the prime candidate materials for next generation high-efficiency multi-junction photovoltaics (PVs). The recent remarkable advancements in monolithic perovskite-based double-junction solar cells (i.e., perovskite/CIGS or perovskite/Si tandem PV) denote just the beginning of a new era in multi-junction PVs. However, to date, the performance of triple-junction PV architectures, such as perovskite–perovskite–silicon architecture, lags considerably behind, with only a limited number of reports on prototypes. In this contribution, we present triple-junction perovskite–perovskite–silicon solar cells, achieving a power conversion efficiency of 24.4%. Achieving such high performances in triple-junction perovskite–perovskite–Si solar cells requires addressing several challenges. These include (1) the sequential processing of high-quality perovskite thin films within the progressively complicated multi-layer architecture, (2) light management to ensure efficient absorption and utilization of sunlight, (3) current matching among the monolithically interconnected sub-cells, as well as (4) the development of low-loss tunnel/recombination junctions for efficient charge transport across the junction. Overcoming these challenges is essential for realizing the full potential of triple-junction perovskite–perovskite–Si solar cells and pushing the boundaries of ultra-high-efficiency PV technologies. A significant challenge in processing triple junctions to date is the most critical junction, the middle perovskite sub-cell. This sub-cell is processed on top of the silicon bottom cell and must withstand the subsequent processing of the wide-bandgap perovskite top cell. In this study, we show that by optimizing the light management for each perovskite sub-cell (with bandgaps of ~1.84 eV and ~1.52 eV for the top and middle cells, respectively), we maximize the current generation to 11.6 mA cm–2. The key to this achievement is the development of a high-performance middle perovskite sub-cell, utilizing a stable pure-α-phase formamidinium lead iodide perovskite thin film that is free of wrinkles, cracks, and pinholes. This enables a high open-circuit voltage of 2.84 V in the triple-junction architecture. Notably, non-encapsulated triple-junction devices retain up to 96.6% of their initial efficiency when stored in the dark at 85°C for 1081 hours. },
note = {41st European Photovoltaic Solar Energy Conference and Exhibition},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Over the past decade, metal halide perovskite semiconductors emerged as the prime candidate materials for next generation high-efficiency multi-junction photovoltaics (PVs). The recent remarkable advancements in monolithic perovskite-based double-junction solar cells (i.e., perovskite/CIGS or perovskite/Si tandem PV) denote just the beginning of a new era in multi-junction PVs. However, to date, the performance of triple-junction PV architectures, such as perovskite–perovskite–silicon architecture, lags considerably behind, with only a limited number of reports on prototypes. In this contribution, we present triple-junction perovskite–perovskite–silicon solar cells, achieving a power conversion efficiency of 24.4%. Achieving such high performances in triple-junction perovskite–perovskite–Si solar cells requires addressing several challenges. These include (1) the sequential processing of high-quality perovskite thin films within the progressively complicated multi-layer architecture, (2) light management to ensure efficient absorption and utilization of sunlight, (3) current matching among the monolithically interconnected sub-cells, as well as (4) the development of low-loss tunnel/recombination junctions for efficient charge transport across the junction. Overcoming these challenges is essential for realizing the full potential of triple-junction perovskite–perovskite–Si solar cells and pushing the boundaries of ultra-high-efficiency PV technologies. A significant challenge in processing triple junctions to date is the most critical junction, the middle perovskite sub-cell. This sub-cell is processed on top of the silicon bottom cell and must withstand the subsequent processing of the wide-bandgap perovskite top cell. In this study, we show that by optimizing the light management for each perovskite sub-cell (with bandgaps of ~1.84 eV and ~1.52 eV for the top and middle cells, respectively), we maximize the current generation to 11.6 mA cm–2. The key to this achievement is the development of a high-performance middle perovskite sub-cell, utilizing a stable pure-α-phase formamidinium lead iodide perovskite thin film that is free of wrinkles, cracks, and pinholes. This enables a high open-circuit voltage of 2.84 V in the triple-junction architecture. Notably, non-encapsulated triple-junction devices retain up to 96.6% of their initial efficiency when stored in the dark at 85°C for 1081 hours.
20.
Schmidt, J; Winter, M; Souren, F; Bolding, J; de Vries, H
Excellent Passivation of Silicon Surfaces by HfO2 Layers Deposited Using Scalable Spatial Atomic Layer Deposition Presentation
Vienna, Austria, 25.09.2024, (41st European Photovoltaic Solar Energy Conference and Exhibition).
@misc{Schmidt2024b,
title = {Excellent Passivation of Silicon Surfaces by HfO2 Layers Deposited Using Scalable Spatial Atomic Layer Deposition},
author = {J Schmidt and M Winter and F Souren and J Bolding and H de Vries},
year = {2024},
date = {2024-09-25},
address = {Vienna, Austria},
abstract = {Spatial Atomic Layer Deposition (SALD) had been successfully applied in the past for the Al2O3 surface passivation on silicon solar cells. In contrast to conventional sequential ALD techniques, as typically used in the labs, SALD allows for high deposition rates of a few nm per second, which are compatible with industrial solar cell production. In this contribution, we apply SALD for the first time to the electronic passivation of moderately doped (~1016 cm–3) p-type crystalline silicon surfaces with thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400°C in air, an effective surface recombination velocity Seff of only 4 cm/s is achieved, which is below what has been reported before using sequential ALD techniques. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. Firing is shown to reduce the passivation quality, however, by adding a capping layer of plasmaenhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the HfO2, the firing stability is found to improve. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future silicon solar cells. },
note = {41st European Photovoltaic Solar Energy Conference and Exhibition},
keywords = {},
pubstate = {published},
tppubtype = {presentation}
}
Spatial Atomic Layer Deposition (SALD) had been successfully applied in the past for the Al2O3 surface passivation on silicon solar cells. In contrast to conventional sequential ALD techniques, as typically used in the labs, SALD allows for high deposition rates of a few nm per second, which are compatible with industrial solar cell production. In this contribution, we apply SALD for the first time to the electronic passivation of moderately doped (~1016 cm–3) p-type crystalline silicon surfaces with thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400°C in air, an effective surface recombination velocity Seff of only 4 cm/s is achieved, which is below what has been reported before using sequential ALD techniques. The one-sun implied open-circuit voltage amounts to iVoc = 727 mV. Firing is shown to reduce the passivation quality, however, by adding a capping layer of plasmaenhanced-chemical-vapor-deposited hydrogen-rich silicon nitride (SiNx) onto the HfO2, the firing stability is found to improve. The presented study demonstrates that SALD-deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future silicon solar cells.