Prozessentwicklung & Verlustanalysen für dünne monokristalline Siliziumsolarzellen und deren Prozessierung auf Modullevel

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Simulation-based Efficiency Gain Analysis of 21.2%-efficient Screen-printed PERC Solar Cells

Passivated Emitter and Rear Cells (PERC) with efficiencies well above 20% are likely to become the next mass production technology. A quantification of all power loss mechanisms of such industrial PERC cells is helpful in prioritizing future efficiency improvement measures. We report on a numerical simulation of the power losses of a 21.2%-efficient industrial PERC cell using extensive experimental input data. Our synergetic efficiency gain analysis relies on deactivating single power loss mechanisms in the simulation at a time to access the full potential power gain related to that mechanism. The complete analysis therefore explains the efficiency gap between the industrial PERC solar cell and the theoretical maximum efficiency of a crystalline Si solar cell. Based on the simulations, the largest single loss mechanism is front grid shadowing followed by recombination in the emitter and its surface. All individual resistive losses, all individual optical losses and all (avoidable) individual recombination losses sum up to efficiency gains of 0.8%, 1.6%, and 1.3%, respectively, which is 3.7% in total. The efficiency gap between real and ideal solar cell is, however, much larger with 7.3%. The discrepancy is mainly due to the non-linear behaviour of recombination-based power losses which adds synergetic efficiency enhancements

A comparison of models to optimize Partial Rear Contact solar cells

The optimization of solar cells with localized rear contacts usually requires numerical simulation. Here we compare Sentaurus Device to a simpler Conductive Boundary (CoBo) simulator and to an approximate Geometric model. Optimization examples are given for devices with linear rear contacts in low and high injection conditions. The three modelling tools are in good agreement for high quality devices with negligible bulk and rear surface recombination. Discrepancies between the three models, generally small, are identified and explained

Simultaneous Contacting and Interconnection of Passivated Emitter and Rear Solar Cells

The back end process of passivated emitter and rear cells (PERC) consists of at least one laser process and three screen-printing steps followed by the stringing and tabbing of the cells. To reduce the number of steps we have developed a process that metallizes the rear side including contact formation and simultaneously interconnects the cells. We attach an Al foil to an encapsulant layer. By laser processing we form 'laser-fired and bonding contacts' (LFBC) on the passivated rear side of the solar cells. The Al foil contacting the rear is laser welded to the Ag screen-printed front side metallization of the next cell and thus forms the cell interconnection. The laser contacts on the rear show a surface recombination velocity Scont for the contact regions of cm/s and a contact resistivity of 3.52 m?cm2. We present a first proof-of concept module combining the in-laminate Ag-Al laser welding and the LFBC reaching an efficiency of 18.4%. In accelerated aging test modules show no degradation (< 1% in efficiency) after 100 humidity-free cycles.Federal Ministry for Environment, Nature Conservation, and Nuclear Safety/FKZ/0325192State of Lower Saxon

Radon (222Rn) as tracer for submarine groundwater discharge investigation—limitations of the approach at shallow wind‐exposed coastal settings

Mapping radon (222Rn) distribution pat- terns in the coastal sea is a widely applied method for localizing and quantifying submarine groundwater discharge (SGD). While the literature reports a wide range of successful case studies, methodical problems that might occur in shallow wind-exposed coastal settings are generally neglected. This paper evalu- ates causes and effects that resulted in a failure of the radon approach at a distinct shallow wind-exposed location in the Baltic Sea. Based on a simple radon mass balance model, we discuss the effect of both wind speed and wind direction as causal for this fail- ure. We show that at coastal settings, which are domi- nated by gentle submarine slopes and shallow waters, both parameters have severe impact on coastal radon distribution patterns, thus impeding their use for SGD investigation. In such cases, the radon approach needs necessarily to allow for the impact of wind speed and wind direction not only during but also prior to the field campaign

Radon (222Rn) as Tracer for Submarine Groundwater Discharge Investigation—Limitations of the Approach at Shallow Wind-Exposed Coastal Settings

Mapping radon (222Rn) distribution patterns in the coastal sea is a widely applied method for localizing and quantifying submarine groundwater discharge (SGD). While the literature reports a wide range of successful case studies, methodical problems that might occur in shallow wind-exposed coastal settings are generally neglected. This paper evaluates causes and effects that resulted in a failure of the radon approach at a distinct shallow wind-exposed location in the Baltic Sea. Based on a simple radon mass balance model, we discuss the effect of both wind speed and wind direction as causal for this failure. We show that at coastal settings, which are dominated by gentle submarine slopes and shallow waters, both parameters have severe impact on coastal radon distribution patterns, thus impeding their use for SGD investigation. In such cases, the radon approach needs necessarily to allow for the impact of wind speed and wind direction not only during but also prior to the field campaign

Endobronchial Valve (Zephyr) Treatment in Homogeneous Emphysema:One-Year Results from the IMPACT Randomized Clinical Trial

RATIONALE: The long-term safety and effectiveness of bronchoscopic lung volume reduction with Zephyr endobronchial valves in subjects with severe homogeneous emphysema with little to no collateral ventilation beyond 3 months have yet to be established. METHODS: Ninety-three subjects were randomized to either bronchoscopic lung volume reduction with Zephyr valves or standard of care (SoC) (1:1). Zephyr valve subjects were assessed at 3, 6, and 12 months. SoC subjects were assessed at 3 and 6 months; they were then offered crossover to Zephyr valve treatment. RESULTS: The mean group difference (Zephyr valve − SoC) for change in FEV1 from baseline to 6 months was 16.3 ± 22.1% (mean ± SD; p < 0.001). Secondary outcomes showed the mean between-group difference for the six-minute walk distance of +28.3 ± 55.3 m (p = 0.016); St. George's Respiratory Questionnaire, −7.51 ± 9.56 points (p < 0.001); modified Medical Research Council, −0.42 ± 0.81 points (p = 0.019); BODE index, −0.85 ± 1.39 points (p = 0.006); and residual volume of −430 ± 830 mL (p = 0.011) in favor of the Zephyr valve group. At 6 months, there were significantly more responders based on the minimal clinically important difference for these same measures in the Zephyr valve versus the SoC group. The clinical benefits were persistent at 12 months. The percentage of subjects with respiratory serious adverse events was higher in the Zephyr valve group compared to SoC during the first 30 days post-procedure but not statistically different for the Zephyr valve and SoC groups from 31 days to 6 months, and stable in the Zephyr valve group out to 12 months. There were 2 deaths in the SoC group in the 31-day to 6-month period and none in the Zephyr valve group out to 12 months. CONCLUSIONS: Bronchoscopic lung volume reduction with Zephyr valves in subjects with severe homogeneous emphysema and little to no collateral ventilation provides clinically meaningful change from baseline in lung function, quality of life, exercise capacity, dyspnea, and the BODE index at 6 months, with benefits maintained out to 12 months