Reliability Degradation Indicators being Observed on Terrestrial Silicon Solar Cells

A technology for processing of thin film CdS/CdTe devices has been developed in our laboratory. This in-line, continuous, pilot system enables unique processing steps and conditions not available with batch processing and allows the fabrication of a large number of devices. Results from the pilot scale system are applicable to systems processing larger areas. Utilizing the pilot system, significant progress has been made towards demonstrating consistent stability (resistance to degradation) for thin film CdTe photovoltaics. We have repeatedly shown that devices with good stability can be produced if processed at the optimum set of conditions. Small changes in processes can lead to significant differences in device stability. Among the processing steps for fabrication of CdTe devices, the CdCl/sub 2/ treatment has a significant effect on performance and stability. A metric has been developed to predict the stability of devices at the time of device fabrication. Accelerated stress testing is ongoing. Extremely long duration stress testing (65/spl deg/C, open circuit conditions for /spl sim/30,000 hours with 5 hours of illumination out of 8 hour cycle) has demonstrated that the rate of efficiency loss levels out with final efficiencies in the range of 8.5% /spl sim/ 9.5%. A production prototype system for processing nominally 2 MW/yr. is currently under construction. This system utilizes the process definition developed in the pilot system.

Fossil fuel storage is running low and scientists around the globe are involved in a big search for an optimized substitute. Photovoltaic is one of the most likely alternatives to solve this issue and replace the fossil fuels. Among all types of cells, silicon solar cells are the most economical ones to produce affordable energy. In this paper, a systematic study was done on the diffusion of phosphorous in multi-crystalline silicon during solar cell emitter formation. All parameters involved in the conversion of a multi-crystalline p-type silicon to a p–n junction were analyzed quantitatively. This systematic approach predicts the effect of inputs on the outputs which decreases the number of the trail runs. The analysis result indicate, that raising the diffusion temperature from 830 to 880 °C decreases the sheet resistance by −100 Ω/sq, and increasing POCl3 flow from 300 to 500 SCCM has an effect of −21 Ω/sq.

Light-induced Degradation of Silicon Solar Cells with Aluminiumoxide Passivated Rear Side

The various energy constraints dictated by a series of global economic and environmental social factors require the international scientific community to find viable alternatives to conventional energy sources. Renewable energies such as photovoltaics is among the most coveted and developed energy sources worldwide. Technology of inorganic semiconductor-based silicon and other developed considerably and responds more to the desired energy goals Technology of inorganic semiconductor is very expensive and requires considerable resources making it limited to the most powerful country in the world The technology of organic semiconductor is much easier and more accessible which promises a very bright. It can be considered as a real alternative for countries with limited resources for the widespread use of solar energy. This research is in the field of preparation and characterization of organic solar cells based on semiconducting polymers. After having carried out a scientific statement on the technology of organic semiconductors have been able to achieve in collaboration with the Department of Industrial Chemistry a multilayer organic cell where the polymer is polyaniline. The disadvantage of this type of solar cells is its low efficiency. The cell we have developed to present a comparison of the performance the literature. This technology must be improved to increase its performance may not be on inorganic cells but enough to meet domestic needs.

This experimental study investigates the damage effects of nanosecond pulse laser irradiation on silicon solar cells. It encompasses the analysis of transient pulse signal waveform characteristics at the cells’ output and changes in electrical parameters, such as I–V curves before and after laser irradiation under varying laser fluence and background light intensities, and explores the underlying action mechanisms of laser irradiation. The study reveals that as the laser fluence increases up to 4.0 J/cm2, the peak value of the transient pulse signal increases by 47.5%, while the pulse width augments by 88.2% compared to the initial transient pulse signal. Furthermore, certain parameters, such as open-circuit voltage, short-circuit current, and peak power obtained, from the measured I–V curve indicate a threshold laser fluence for functional degradation of the solar cell at approximately 1.18 ± 0.42 J/cm2. Results obtained from laser irradiation under different background light intensities underscore the significant influence of background light on laser irradiation of silicon cells, with the most severe damage occurring in the absence of light. Moreover, findings from laser irradiation at multiple locations on the silicon cell demonstrate a linear decrease in the output voltage of the silicon cell with an increase in the number of irradiation points.

Effect of fruit ripeness on electrical impedance spectrum parameters

The main two reasons for the shift to renewable energy are the depletion and the harmful effects of non-renewable energy, such as burning coal and fossil fuels. As a result, the use of solar cells as renewable energy resources, that prioritise high efficiency while lowering production costs, can provide a promising future for sustaining energy resources. Solar cells have been developed starting with the monocrystalline and polycrystalline solar cells (first generation), non-crystalline and thin film solar cells (second generation) and organic solar cells (third generation). The dye-sensitized solar cell (DSSC) is a new type of solar cell that has gained popularity due to its ability to convert energy at a low cost, ease of fabrication, and non-toxic nature. This paper explores the use of fungal colours as natural dyes for DSSC due to their wide range of colours, large yields, sustainable supply and non-toxic. Natural fungal colours can be extracted using proper extraction conditions and methods. Although fungal dyes have several limitations like instability, non-resistance to harsh conditions, colour loss during processing or storage and limited profitable yield, they still have promising future prospects to overcome the poor interaction of natural sensitizer with semiconductor together with other advantages of fungal colour. DSSC with dye from crude extracts from Cortinarius fungi exhibited the highest efficiency of 0.64% among reported DSSC with fungal dye.

Proton Exchange Membrane (PEM) failure is one of the key criteria in deciding the durability of the PEM fuel cell system. Physical properties such as ionic conductivity and mechanical properties depend on the microstructure. The microstructure is itself strongly dependent on the water content of the membrane (1, 2). It is therefore important to fully understand the effect of degradation stressors on the morphological changes and water-uptake characteristics in order to improve membrane durability.In this work, standard perfluorosulfonic acid (PFSA) ionomer membranes are subjected to a combined chemical and mechanical accelerated stress test (AST) used for rapid benchmarking of in-situ membrane stability. The degradation stressors in the combined chemical/mechanical AST was previously shown by our group to change the molecular structure and lead to membrane material loss (3). The chemical phase of the AST generates hydroxyl radicals that attack both the side chain and main chain of the polymer, while the mechanically generated stresses due to humidity cycling accelerate mechanical failures. The observed structural changes are anticipated to alter the water-uptake properties of the membrane, as shown previously for ex-situ testing (4). The degradation also alters the morphology, ion exchange capacity, mechanical properties, and proton conductivity of the membrane (5). Water-uptake measurements of partially AST degraded catalyst coated membrane (CCM) samples are carried out at room temperature using a dynamic vapor sorption system. In spite of severe fluoride release and membrane thinning, the water-uptake per unit mass of the AST degraded CCMs is found to be relatively constant. Since the test specimens are CCMs which contain a significant amount of catalyst layer material, an attempt is made to measure and separate the mass of the ionomer by thermogravimetric analysis (TGA). The ionomer material loss throughout the AST process is significant due to fluoride release and ionomer degradation, up to roughly 50% at end-of-life (3). The water-uptake per unit mass of ionomer in the CCM is determined by extracting the ionomer weight obtained by heating the CCM in the TGA chamber. In contrast to the previous results normalized by specimen dry weight, the water-uptake increases significantly per unit mass of the ionomer in the CCM, as shown in Fig. 1. Although the increased water-uptake may indicate enlarged solvated hydrophilic domains in the membrane, which is good for enhanced proton mobility, the proton conductivity is found to decrease (Fig. 1). This may be attributed to a decay in proton concentration due to sulfonic acid functional group loss during side chain degradation. The overall effects of the combined chemical/mechanical AST on the membrane morphology and properties are presented and compared to provide additional insight into the complex degradation mechanism.ACKNOWLEDGMENTSResearch funding provided by Automotive Partnership Canada (APC), Natural Sciences and Engineering Research Council of Canada (NSERC) and Ballard Power Systems (BPS) is gratefully acknowledged. BPS is also acknowledged for providing access to experimental facilities, material samples and technical support. REFERENCES1. J.Benziger, A. Bocarsly, M. J. Cheah, P. Majsztrik, B. Satterfield, and Q. Zhao, in Fuel Cells and Hydrogen Storage 141, Bocarly and Mingos, Editors, p. 85 Springer, Berlin Heidelberg 141 (2011).2. Y. Yang, A. Siu, T. J. Peckham, S. Holdcroft, in Advances in Polymer Sciences 215: Fuel cells 1, G. G. Scherer, Editor p. 55 Springer, Berlin Heidelberg 215 (2008).3. C. Lim, L. Ghassemzadeh, F. Van Hove, M. Lauritzen, J. Kolodziej, G.G. Wang, S. Holdcroft, E. Kjeang, J. Power Sources 257 102 (2014).4. L. Ghassemzadeh and S. Holdcroft, J.Am.Chem.Soc. 135 8181 (2013).5. S. V. Venkatesan and E. Kjeang, 11th International Fuel Cell Science, Engineering and Technology Conference, ASME, Minneapolis, MN (2013).

The primary mission of the PSSC Testbed is to provide space flight data on two types of advanced solar cells, XTJ and ZTJ, produced by the two U.S. solar cell manufacturers, Spectrolab and Emcore, respectively. The PSSC Testbed flight data confirmed that the picosatellite can be used for measuring l-V characteristics of solar cells. Continuing monitoring of the l-V measurement will allow determining the actual degradation of the solar cells due to exposure to the space environment. Mission success for the initial low earth orbit (LEO) space flight provided proof of concept for the PSSC Testbed. Subsequent mission will fly in a geosynchronous transfer orbit (GTO), in which a 450-day radiation exposure of the solar cells will be equivalent to that of 15 years radiation exposure in geosynchronous orbit.

Analyzing S-Shaped I–V characteristics of solar cells by solving three-diode lumped-parameter equivalent circuit model explicitly

Design of 4-terminal Solar Modules Combining Thin-film Wide-Bandgap Top Cells and c-Si Bottom Cells

A voltage decrease in the long‐term operation of hydrogen fuel cell (FC) electric cars under steady settings under constant load and dynamic operating conditions is a performance constraint of concern. Although accelerated stress test (AST) procedures have been sought to diagnose degradation, the AST results of FC stacks have not been reported extensively. The purpose of this article is to discuss the generation of AST of FC stacks based on real load profiles and the consequences of load changes and start‐stop circumstances, which are mostly generated by common driven cycles in urban regions with high driving speeds and traffic jams. The highlight of this study is to analyze the effects of cycle repetition on the aging FC stack, especially the voltage degradation factor, degradation kinetics, and energy consumption. The relation between actual system temperatures in side cells assembled in the FC stacks and material degradation was also analyzed. The results presented high heat accumulation, related to chemical degradation, that occurred during load cycling and may result in membrane thinning and pinholes in the membrane. Temperature cycling corresponded to mechanical degradation generated during the start‐stop cycling test, which may lead to membrane degradations—cracking, tearing, and pinholes.

As the lifetime of photovoltaic modules increases toward the goal of 50 years, accelerated stress testing is critical to assessing the viability of newer, improved, and often cheaper materials in the field. However, the validation of accelerated testing to reproduce field failure has remained elusive. The recent developments of more advanced stress testing protocols utilizing sequential and combined stressors have provided another opportunity for validation. Using a suite of mechanical, chemical, and structural characterization methods we report the development of our approach using a known bad backsheet “AAA.” We then apply this approach to PVDF-based backsheets to further confirm the generalizability of this approach. The outcome of this work is two-fold: (1) validation of advanced accelerated testing protocols which will enable the prediction of field failures in new materials, and (2) deeper insights into the degradation mechanisms observed through the extensive characterization allowing for improved materials engineering and development.

In multi-layer printed wiring boards (PWBs), electrical connections between different layers are accomplished with plated through holes (PTHs). The reliability of the PTH barrel and the PTH-inner plane (IP) connection depends not only on the design but also on the conditions of manufacturing and assembly processes of the board. The concerns associated with manufacturing arise from drilling which heats up and smears the surrounding epoxy onto the copper inner plane surfaces and also from subsequent chemical hole-clean operations which desmear the drilled holes. Good adhesion of the PTH copper to the desmeared PTH wall and to the copper inner planes is important for the reliability of the PTHs during assembly and field service. PWB coupons consisting of resin-glass bundle areas as well as resin filled clearance areas surrounding the PTH have been considered for a series of experiments and tests. On these coupons, accelerated stress tests and failure analysis of the PTHs at the end of these tests have been conducted. An elasto-plastic finite element analysis of the PTH strains for a temperature excursion of 102°C has been carried out for signal PTHs without and with IP connections. A peel test, using a micro-mechanical tester, has also been carried out to assess the adhesion of PTH copper to different regions along the drilled hole. All of the testing techniques have been supplemented by suitable analytical techniques for studying the distribution of smear on the copper inner planes. A birefringence technique to estimate the temperature of the hole wall during drilling has been described. All of the fails observed during stress testing are in the form of cracks in the PTH barrel, the plane of the crack being perpendicular to the barrel axis. The cracks are localized near the glass bundle-resin rich interface. It has also been observed in the failure analysis that the PTH/IP connections are not susceptible to failure during the accelerated stress testing conditions considered. These observations are also supported by the results of stress analysis. The results of stress analysis show that the interior clearance holes show higher strains than those closer to board surfaces, suggesting that the PTH barrel failure is likely to occur at the clearance hole and that the likelihood of failure at the interior clearance holes is higher than those closer to the PWB surfaces. The results of the peel test reveal that in the glass bundle-resin regions, the adhesion along the PTH wall is determined by the mechanical interlocking between the plated copper and the glass bundles and is relatively insensitive to desmear operations. However, adhesion in the resin-rich areas is a strong function of the desmear operation, which enhances the adhesion of the PTH to the resin. Finally, it is shown that the birefringence technique may be used effectively to estimate the drilling temperature and, hence, the degree of smearing and PTH quality. It is concluded that while smear may play an important role in the failure of PTHs in PWBs, for thick packaging boards with high aspect ratio PTHs, the predominant failure mechanism is less likely to be smear related. Such a failure mechanism would be preceded by failure in the PTH barrels as a result of the large strain concentrations imposed at specific locations within the cross-section.

Stress tests are developed for proton exchange membrane electrolyzers that utilize low catalyst loading, elevated potential, and frequent cycling with square- and triangle-waves to accelerate anode catalyst layer degradation during intermittent operation. Kinetics drive performance losses (ohmic/transport secondary) and are accompanied by decreasing exchange current density, decreasing cyclic voltammetric capacitance, and increasing polarization resistance. Decreased kinetics are likely due to a combination of iridium (Ir) migration into electrochemically inaccessible locations in the anode or membrane, Ir particle growth (supported by X-ray scattering), changes in the extent of the Ir oxidation state (supported by X-ray absorption spectroscopy), and anode catalyst layer reordering. Decreasing catalyst/transport layer contact and catalyst/membrane interfacial tearing may add contact resistances and account for increasing ohmic losses. Performance losses for low and moderate catalyst loading, as well as from accelerated and model wind/solar cycling protocols, were likewise dominated by kinetics but vary in severity. Accelerated cycling (1 cycle per minute) appears to reasonably accelerate relevant loss mechanisms and can be used to project electrolyzer lifetime from anode deterioration. Ongoing accelerated stress test development and studies into performance loss mechanisms will continue to be critical as electrolysis shifts to intermittent power and low-cost applications.