Photovoltaic (PV) is one of the fastest growing electricity generation technologies in the world.... more Photovoltaic (PV) is one of the fastest growing electricity generation technologies in the world. Average annual growth rates of global PV-installations have reached around 45% for the last 15 years, which triggered a fast and ongoing reduction of production cost in PV industry. The presented work aims at consolidating historical price and cost information, deriving refined learning curves for PV modules and systems, and analysing the main factors of learning. For c-Si modules a valid learning rate of 17% is found based on a meta-analysis of various studies. In early years, even a learning rate of 30% is observed. As an example for thin-film PV, CdTe module cost reduce by 16% as the cumulated production output doubles. Interestingly, efficiency improvements contribute only in second order to the overall cost reduction for both technologies, emphasising the relevance of production excellence and economies of scale. On PV system level, a cost reduction of 14% per doubling of cumulated installed capacity is derived. Finally, a sensitivity analysis reveals that learning rate variations are only of minor influence on the overall global PV market potential.
In this work the evaluation results on industrial p-type mc-Si PERC cells using spatial atomic la... more In this work the evaluation results on industrial p-type mc-Si PERC cells using spatial atomic layer deposition for aluminum oxide from SoLayTec are shown. By optimizing the process flow and integrating a postdeposition anneal into the SiNx capping process we achieve 0.15% higher cell efficiency compared to remote microwave plasma-enhanced chemical vapor deposition. Furthermore, it is shown that the improved passivation quality resulting in Voc gain remains constant during light and elevated temperature induced degradation measurements.
Research and Development (R&D) is a major driving force for constant cost reduction in photovolta... more Research and Development (R&D) is a major driving force for constant cost reduction in photovoltaics (PV) and consequently an enabler for a fast diffusion of PV. To prove this, long-term PV market diffusion phases and updated learning curve data is presented. Energy R&D of the Organisation for Economic Co-operation and Development (OECD) is discussed in respect to renewable energy sources (RES) in general and PV in particular. For estimating current and global historic cumulated PV R&D investments a bottom-up analysis of more than 100 PV companies and a top-down analysis based on international PV patents is presented. Current annual public and corporate PV R&D investments are estimated to be about 500 m€ and 3,000 – 6,000 m€, respectively. Global historic cumulated public and corporate PV R&D investment is estimated to be about 9 and 35 – 41 bn€, respectively. Annual growth rates of R&D investments of public listed companies focussed on PV are about 40%. This has and will generate o...
In this work the carrier lifetime evolution of different passivation layers under illumination an... more In this work the carrier lifetime evolution of different passivation layers under illumination and at elevated temperatures are investigated. Multicrystalline silicon lifetime samples were treated by implementing typical industrial processing steps. The degradation was found to depend strongly on surface passivation type, but is independent of the surface doping and oxide charge. The influence of the passivation layer on the silicon bulk lifetime degradation is investigated. After reaching a degradation maximum, the lifetime samples feature a regeneration phase. Long-time degradation measurements without excess carrier injection at elevated temperatures show that the carrier lifetime degrades also in darkness. Capacitance-voltage measurements show that the oxide charge is not influenced by the degradation, but a high decrease in carrier lifetime were measured. Firing experiments show that lifetime samples passivated after firing procedure are not prone to degrade.
The surface passivation performance of Al2O3 films attracted attention in the field of solar cell... more The surface passivation performance of Al2O3 films attracted attention in the field of solar cells and semiconductor devices and depends on the conditions of the applied post-deposition annealing step. The effect of annealing temperature and different annealing atmospheres on the surface passivation quality of atomic layer deposited Al2O3 films was investigated on n-type float-zone Si wafers. Photoconductance decay measurements were carried out to characterize recombination velocities and carrier lifetimes. The chemical and field-effect passivation mechanism, i.e. the interface trap density and the fixed charge density, respectively, were studied by capacitance-voltage experiments. Low surface recombination velocities of Seff,max ~1 cm/s corresponding to a carrier lifetime of 9.0 ms were achieved for samples annealed in O2 atmosphere whereas annealing in H2 and N2 led to slightly higher Seff,max-values ~2 cm/s. The annealing temperature was found to affect both the fixed charge dens...
The invention relates to a solar cell manufacturing method and a solar cell treatments. The solar... more The invention relates to a solar cell manufacturing method and a solar cell treatments. The solar cell manufacturing method includes a tempering step on, in which a substrate (1) a tempering temperature curve (51, 52) is exposed, wherein the annealing temperature profile (51, 52) during an annealing time of at least 3 seconds in a tempering area between a range lower limit of about 400 degrees Celsius (° C) and a range upper limit of about 700 ° C.
Hanwha Q CELLS now produces its high-efficiency Q.ANTUM solar cell and module technology with p-t... more Hanwha Q CELLS now produces its high-efficiency Q.ANTUM solar cell and module technology with p-type Czochralski-grown silicon (Cz-Si) on a multi-GW scale. While maintaining a lean fabrication process, average cell efficiencies exceeding 22 % are achieved in mass production. This results in module powers of more than 330 W by applying wirebased cell interconnection technology to 120 half 6-inch Q.ANTUM cells, narrowing the gap to the highest-efficiency module technologies which use n-type silicon solar cells, at an extremely competitive manufacturing cost. In contrast to conventional passivated emitter and rear cells (PERC), Hanwha Q CELLS’ Q.ANTUM technology is shown to reliably suppress both light-induced degradation (LID) due to boron-oxygen defect formation and Light and elevated Temperature Induced Degradation (LeTID).
The invention relates to a solar cell manufacturing method in which a metallizing paste (2) on a ... more The invention relates to a solar cell manufacturing method in which a metallizing paste (2) on a surface (11) of a substrate (1) is applied and from the metallizing a metallization layer (21) is produced by subjecting a fire step, the substrate having a heating-up phase (51a, 52a), during which the substrate along a temperature profile (51, 52) is heated to a maximum temperature and a subsequent cooling phase (51b, 52b), during which the substrate along the temperature profile (51, 52) is cooled from the maximum temperature down characterized in that the temperature profile (51, 52) of the substrate during the firing step in the heating phase (51a, 52a) and / or in the cooling phase (51b, 52b) a maximum slope of 100 Kelvin per second (K / s), comprises of 70 K / s, of 50 K / s or 30 K / s.
Abstract This work investigates the impact of annealing at elevated temperatures on the light-ind... more Abstract This work investigates the impact of annealing at elevated temperatures on the light-induced degradation (LID) of passivated emitter and rear cells (PERC) processed on boron-doped Czochralski-grown silicon substrates. The boron-oxygen (BO) defect has been stabilised prior to annealing and subsequent LID treatment. Excessive LID of up to 19.1 % rel. is observed upon illumination after extended dark annealing at 150 °C for 552 h, which is well above the BO defect-related LID of 5.6 % rel. measured upon illumination after cell processing if BO is not stabilised. Light and elevated Temperature Induced Degradation (LeTID), iron-boron pairs and surface recombination are excluded as root causes for the observed increased LID, which shows a similar behaviour as the BO defect but which cannot be explained by the well-established three-state model of the BO defect with the assumption of an empty regenerated state prior to BO stabilisation. Two speculative hypothesis for an explanation are (i) that further BO defect precursors are formed, which could be described via a reservoir or (ii) that a high percentage of the in-principle available BO defects are already in the stabilised state even without dedicated BO defect stabilisation. This increased LID does not occur when at least a small level of excess carrier concentration is induced during extended annealing and, hence, is expected not to occur during field operation. However, the observed behaviour is highly relevant for accelerated aging testing such as, e.g., damp heat testing during IEC and UL certification.
2014 Ieee 40th Photovoltaic Specialist Conference, Jun 1, 2014
ABSTRACT High performance multi wafers are a new wafer class introduced some years ago. These waf... more ABSTRACT High performance multi wafers are a new wafer class introduced some years ago. These wafers are characterized by creating rather small grains at the start of crystallization leading to a reduced density of structural defects and an increase of up to 0.5% in solar cell efficiency. During the evaluation of high performance multi wafers, we observed for some wafer types very high light induced degradation of up to 10% relative in cell efficiency. More detailed investigations revealed that the affected wafers stem from the “bottom” part of the ingots with small grain size and the degraded cells show a “sponge-like” structure in electroluminescence images. The investigation of regeneration behavior revealed that this degradation is not caused by formation of boron oxygen complexes or splitting of iron boron pairs. Although we could reduce this degradation mechanism by adapting the solar cell manufacturing process, avoiding this effect on wafer / crystallization level will be needed for future cell efficiency improvements.
Photovoltaic (PV) is one of the fastest growing electricity generation technologies in the world.... more Photovoltaic (PV) is one of the fastest growing electricity generation technologies in the world. Average annual growth rates of global PV-installations have reached around 45% for the last 15 years, which triggered a fast and ongoing reduction of production cost in PV industry. The presented work aims at consolidating historical price and cost information, deriving refined learning curves for PV modules and systems, and analysing the main factors of learning. For c-Si modules a valid learning rate of 17% is found based on a meta-analysis of various studies. In early years, even a learning rate of 30% is observed. As an example for thin-film PV, CdTe module cost reduce by 16% as the cumulated production output doubles. Interestingly, efficiency improvements contribute only in second order to the overall cost reduction for both technologies, emphasising the relevance of production excellence and economies of scale. On PV system level, a cost reduction of 14% per doubling of cumulated installed capacity is derived. Finally, a sensitivity analysis reveals that learning rate variations are only of minor influence on the overall global PV market potential.
In this work the evaluation results on industrial p-type mc-Si PERC cells using spatial atomic la... more In this work the evaluation results on industrial p-type mc-Si PERC cells using spatial atomic layer deposition for aluminum oxide from SoLayTec are shown. By optimizing the process flow and integrating a postdeposition anneal into the SiNx capping process we achieve 0.15% higher cell efficiency compared to remote microwave plasma-enhanced chemical vapor deposition. Furthermore, it is shown that the improved passivation quality resulting in Voc gain remains constant during light and elevated temperature induced degradation measurements.
Research and Development (R&D) is a major driving force for constant cost reduction in photovolta... more Research and Development (R&D) is a major driving force for constant cost reduction in photovoltaics (PV) and consequently an enabler for a fast diffusion of PV. To prove this, long-term PV market diffusion phases and updated learning curve data is presented. Energy R&D of the Organisation for Economic Co-operation and Development (OECD) is discussed in respect to renewable energy sources (RES) in general and PV in particular. For estimating current and global historic cumulated PV R&D investments a bottom-up analysis of more than 100 PV companies and a top-down analysis based on international PV patents is presented. Current annual public and corporate PV R&D investments are estimated to be about 500 m€ and 3,000 – 6,000 m€, respectively. Global historic cumulated public and corporate PV R&D investment is estimated to be about 9 and 35 – 41 bn€, respectively. Annual growth rates of R&D investments of public listed companies focussed on PV are about 40%. This has and will generate o...
In this work the carrier lifetime evolution of different passivation layers under illumination an... more In this work the carrier lifetime evolution of different passivation layers under illumination and at elevated temperatures are investigated. Multicrystalline silicon lifetime samples were treated by implementing typical industrial processing steps. The degradation was found to depend strongly on surface passivation type, but is independent of the surface doping and oxide charge. The influence of the passivation layer on the silicon bulk lifetime degradation is investigated. After reaching a degradation maximum, the lifetime samples feature a regeneration phase. Long-time degradation measurements without excess carrier injection at elevated temperatures show that the carrier lifetime degrades also in darkness. Capacitance-voltage measurements show that the oxide charge is not influenced by the degradation, but a high decrease in carrier lifetime were measured. Firing experiments show that lifetime samples passivated after firing procedure are not prone to degrade.
The surface passivation performance of Al2O3 films attracted attention in the field of solar cell... more The surface passivation performance of Al2O3 films attracted attention in the field of solar cells and semiconductor devices and depends on the conditions of the applied post-deposition annealing step. The effect of annealing temperature and different annealing atmospheres on the surface passivation quality of atomic layer deposited Al2O3 films was investigated on n-type float-zone Si wafers. Photoconductance decay measurements were carried out to characterize recombination velocities and carrier lifetimes. The chemical and field-effect passivation mechanism, i.e. the interface trap density and the fixed charge density, respectively, were studied by capacitance-voltage experiments. Low surface recombination velocities of Seff,max ~1 cm/s corresponding to a carrier lifetime of 9.0 ms were achieved for samples annealed in O2 atmosphere whereas annealing in H2 and N2 led to slightly higher Seff,max-values ~2 cm/s. The annealing temperature was found to affect both the fixed charge dens...
The invention relates to a solar cell manufacturing method and a solar cell treatments. The solar... more The invention relates to a solar cell manufacturing method and a solar cell treatments. The solar cell manufacturing method includes a tempering step on, in which a substrate (1) a tempering temperature curve (51, 52) is exposed, wherein the annealing temperature profile (51, 52) during an annealing time of at least 3 seconds in a tempering area between a range lower limit of about 400 degrees Celsius (° C) and a range upper limit of about 700 ° C.
Hanwha Q CELLS now produces its high-efficiency Q.ANTUM solar cell and module technology with p-t... more Hanwha Q CELLS now produces its high-efficiency Q.ANTUM solar cell and module technology with p-type Czochralski-grown silicon (Cz-Si) on a multi-GW scale. While maintaining a lean fabrication process, average cell efficiencies exceeding 22 % are achieved in mass production. This results in module powers of more than 330 W by applying wirebased cell interconnection technology to 120 half 6-inch Q.ANTUM cells, narrowing the gap to the highest-efficiency module technologies which use n-type silicon solar cells, at an extremely competitive manufacturing cost. In contrast to conventional passivated emitter and rear cells (PERC), Hanwha Q CELLS’ Q.ANTUM technology is shown to reliably suppress both light-induced degradation (LID) due to boron-oxygen defect formation and Light and elevated Temperature Induced Degradation (LeTID).
The invention relates to a solar cell manufacturing method in which a metallizing paste (2) on a ... more The invention relates to a solar cell manufacturing method in which a metallizing paste (2) on a surface (11) of a substrate (1) is applied and from the metallizing a metallization layer (21) is produced by subjecting a fire step, the substrate having a heating-up phase (51a, 52a), during which the substrate along a temperature profile (51, 52) is heated to a maximum temperature and a subsequent cooling phase (51b, 52b), during which the substrate along the temperature profile (51, 52) is cooled from the maximum temperature down characterized in that the temperature profile (51, 52) of the substrate during the firing step in the heating phase (51a, 52a) and / or in the cooling phase (51b, 52b) a maximum slope of 100 Kelvin per second (K / s), comprises of 70 K / s, of 50 K / s or 30 K / s.
Abstract This work investigates the impact of annealing at elevated temperatures on the light-ind... more Abstract This work investigates the impact of annealing at elevated temperatures on the light-induced degradation (LID) of passivated emitter and rear cells (PERC) processed on boron-doped Czochralski-grown silicon substrates. The boron-oxygen (BO) defect has been stabilised prior to annealing and subsequent LID treatment. Excessive LID of up to 19.1 % rel. is observed upon illumination after extended dark annealing at 150 °C for 552 h, which is well above the BO defect-related LID of 5.6 % rel. measured upon illumination after cell processing if BO is not stabilised. Light and elevated Temperature Induced Degradation (LeTID), iron-boron pairs and surface recombination are excluded as root causes for the observed increased LID, which shows a similar behaviour as the BO defect but which cannot be explained by the well-established three-state model of the BO defect with the assumption of an empty regenerated state prior to BO stabilisation. Two speculative hypothesis for an explanation are (i) that further BO defect precursors are formed, which could be described via a reservoir or (ii) that a high percentage of the in-principle available BO defects are already in the stabilised state even without dedicated BO defect stabilisation. This increased LID does not occur when at least a small level of excess carrier concentration is induced during extended annealing and, hence, is expected not to occur during field operation. However, the observed behaviour is highly relevant for accelerated aging testing such as, e.g., damp heat testing during IEC and UL certification.
2014 Ieee 40th Photovoltaic Specialist Conference, Jun 1, 2014
ABSTRACT High performance multi wafers are a new wafer class introduced some years ago. These waf... more ABSTRACT High performance multi wafers are a new wafer class introduced some years ago. These wafers are characterized by creating rather small grains at the start of crystallization leading to a reduced density of structural defects and an increase of up to 0.5% in solar cell efficiency. During the evaluation of high performance multi wafers, we observed for some wafer types very high light induced degradation of up to 10% relative in cell efficiency. More detailed investigations revealed that the affected wafers stem from the “bottom” part of the ingots with small grain size and the degraded cells show a “sponge-like” structure in electroluminescence images. The investigation of regeneration behavior revealed that this degradation is not caused by formation of boron oxygen complexes or splitting of iron boron pairs. Although we could reduce this degradation mechanism by adapting the solar cell manufacturing process, avoiding this effect on wafer / crystallization level will be needed for future cell efficiency improvements.
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Papers by Dr. Friederike Kersten