FLATCON® CPV module with 36.7% efficiency equipped with four‐junction solar cells

In this paper we present the application of high efficiency four‐junction solar cells using SOITEC bonding technology under a Fresnel lens optic and in a FLATCON®‐type CPV module. We demonstrate very high performance. The measurement of a sub‐module, consisting of a four‐junction solar cell adjusted under a single Fresnel lens, showed an efficiency of 38.9%. An 829.6 cm² sized FLATCON®‐type CPV module yielded in an efficiency of 35.0% and 36.7% at CSOC and CSTC, respectively. Thus, both, the sub‐module and the CPV module showed record values, which prove the usefulness of high efficiency four‐junction solar cells in CPV applications. Copyright © 2014 John Wiley & Sons, Ltd.     

Genotypic abundance of carotenoids and polyphenolics in the hull of field pea (Pisum sativum L.)

BACKGROUND: Consumption of pulse crops, including field pea, is considered effective for a healthy diet. Hulls (seed coats) play an important role for protection of the cotyledon and embryo, but also as mediating positive effects on health outcomes. The biochemical attributes of field pea hulls were thus assessed to determine the occurrence of specific phytochemicals and their genotypic variability. RESULTS: Sequestered bioproducts in mature hulls predominantly consisted of trans‐lutein and chlorophylls a and b. Trace amounts of other carotenoid and pheophytin metabolites were identified. In developing hulls, violaxanthin, neoxanthin, lutein, zeaxanthin, chlorophylls a and b and β‐carotene were detected. Genotypic differences in the accumulation of lutein and chlorophylls a and b were observed over years and locations. Polyphenolics and hydroxybenzoic acids were detected in the ‘dun’ and ‘maple’ field pea types—the only genotypes to have pigmented hulls. Unextractable patches of condensed tannin influenced the visual uniformity of the maple and dun genotypes, CDC Rocket and CDC Dundurn. CONCLUSIONS: Within the yellow and green market classes, carotenoid and chlorophyll accumulation was consistent. Green cotyledon varieties sequestered higher concentrations of lutein than the yellow cotyledon varieties. Maple and dun types were more variable, reflective of different selection criteria. The occurrence of flavonoid‐related compounds was correlated only with pigmented seed coat genotypes. The dietary potential of the chlorophylls and carotenoids that accumulated in the hulls split from the green and yellow field pea types is discussed as a value‐added prospect in food supplements. © 2012 Society of Chemical Industry     

Metamorphic GayIn1−yP/Ga1−xInxAs tandem solar cells for space and for terrestrial concentrator applications at C > 1000 suns

The use of Ga_1−xIn_xAs instead of GaAs as a bottom solar cell in a Ga_yIn_1−yP/Ga_1−xIn_xAs tandem structure increases the flexibility of choosing the optimum bandgap combination of materials for a multijunction solar cell. Higher theoretical efficiencies are calculated and different cell concepts are suggested for space and terrestrial concentrator applications. Various Ga_yIn_1−yP/Ga_1−xIn_xAs material combinations have been investigated for the first time and efficiencies up to 24·1% (AM0) and 27·0% (AM1·5 direct) have been reached under one-sun conditions. An efficiency of 30·0–31·3% was measured for a Ga_0·35In_0·65P/Ga_0·83In_0·17As tandem concentrator cell with prismatic cover at 300 suns. The top and bottom cell layers of this structure are grown lattice-matched to each other, but a large mismatch is introduced at the interface to the GaAs substrate. This cell structure is well suited for the use in next-generation terrestrial concentrators working at high concentration ratios. For the first time a cell efficiency up to 29–30% has been measured at concentration levels up to 1300 suns. A small prototype concentrator with Fresnel lenses and four tandem solar cells working at C = 120 has been constructed, with an outdoor efficiency of 23%. Copyright © 2001 John Wiley & Sons, Ltd.     

Reducing Carryover Effects on the Migration and Spawning Success of Sockeye Salmon through a Management Experiment of Dam Flows

Effective dam management requires an understanding of the ecological impact of a facility and its operations on individual fish and fish populations. Traversing high flows downstream of dams is an energetically challenging activity that could influence survival and spawning success following passage. Carryover effects, however, are an underappreciated consequence of dam passage that have been overlooked by researchers and natural resource managers. We conducted a large‐scale management experiment to determine if the operation of dam attraction flows could be changed to reduce high sockeye salmon Oncorhynchus nerka mortality following passage and increase spawning success. We tested two flow conditions: (i) a baseline condition—currently used by managers—that released high attraction flows directly adjacent to the entrance to a vertical‐slot fishway and (ii) an alternative condition that released attraction flows 10 m away from the fishway entrance to reduce the flows fish swim through while approaching the passage structure. We tagged 637 sockeye salmon with telemetry tags to monitor dam passage, post‐passage survival to spawning grounds and spawning success under the two flow conditions. Validated fish counters at the exit of the fishway and on spawning grounds were used to generate population level estimates of survival to spawning grounds. Individuals exposed to baseline flow conditions spent two times longer recovering from dam passage and exhibited 10% higher mortality following passage than those exposed to alternative flows. Release of alternative flows for 10 days assisted approximately 550 fish (or 3% of total spawners) in reaching spawning grounds. Once on spawning grounds, female spawning success was strongly influenced by individual spawning characteristics (longevity and date of arrival on spawning grounds) and not dam flow condition. Our findings highlight a cost‐effective solution that decreases mortality following passage simply by altering the location of dam flow releases and not reductions in discharge. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.     

Degradation study of III–V solar cells for concentrator applications

AlGaAs/GaAs heteroface solar cells with a high aluminium content tend to degrade. The degradation mechanism has been examined and appropriate accelerated ageing procedures have been established. They effectively test the ruggedness of the device against oxidation. Changing the window layer material to (Al_xGa_1−x)_0.51In_0.49P with x = 0, 0.5 or 1 leads to stable devices. In addition, III–V tandem solar cells for concentrator applications were subjected to accelerated ageing tests. They proved to be robust against oxidation. The potential degradation due to the high current density involved in concentrator solar cells was assessed in preliminary experiments. Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of beer‐battering on the frying properties of rice and wheat batters and their coated foods

BACKGROUND: Beer in batter formulation or beer‐battering has been popular in fried food recipes, but the topic is rarely reported in scientific journals or the claims substantiated with reliable studies. In this research, we prepared and characterized rice and wheat batters with and without using beer to replace water in the formulation. We studied and provided data on the effect of beer on the frying properties of batter and its coated foods. RESULTS: With beer in the formulation, oil uptake of fried batters generally increased by up to 18%. Instrumental textural analyses indicate that beer‐battering treatment generally decreased the hardness, increased the fracturability and improved the crispness of the fried batters. Sensory evaluations show similar trends, though to a lesser extent, that fish and onion rings coated with batters were softer but crispier with beer than without. CONCLUSION: In general, beer‐battering caused an increase in the oil uptake of the batter during frying. It also made the texture of fried batters slightly softer and crispier. The effects are more pronounced for rice batters than wheat batters. Copyright © 2010 Society of Chemical Industry     

Validated front contact grid simulation for GaAs solar cells under concentrated sunlight

In a common approach, the electric behavior of a solar cell is modeled by dividing it into smaller sub‐circuits and solving the resulting network by a circuit simulator. In this paper detailed network simulations are presented for a GaAs single‐junction solar cell. All resistive losses and losses influencing the diode saturation currents, such as recombination in the depletion region or at the perimeter are taken into account. With this model the maximum power point of a solar cell can be calculated for one‐sun and for higher illumination intensities. The results were validated experimentally using suitable test structures. This includes solar cell devices with varying dimensions, grid finger spacing and lengths. An excellent agreement between theoretical and experimental results was obtained. The network simulation model allows determining the optimum size and concentration ratio at which a solar cell operates at its maximum efficiency. In the case of a GaAs single‐junction solar cell this global efficiency maximum was found for an area of 1 mm² and at a concentration ratio of 450 suns. Under these conditions the largest loss mechanisms are the finger shading with 36.1% and the emitter resistance losses with 21.5% of the total power losses. Copyright © 2010 John Wiley & Sons, Ltd.     

YieldOpt,a model to predict the power output and energy yield for concentrating photovoltaic modules

In this work, we discuss three empirical models and introduce one more detailed model named YieldOpt. All models can be used to calculate the power output and energy yield of concentrating photovoltaic (CPV) modules under different ambient conditions. The YieldOpt model combines various modeling approaches: simple model of the atmospheric radiative transfer of sunshine for the spectral irradiance, a finite element method for thermal expansion, ray tracing for the optics, and a SPICE network model for the triple‐junction solar cell. YieldOpt uses a number of constant and variable input parameters, for example, the external quantum efficiency of the cells, the temperature‐dependent spectral optical efficiencies of the optics, the tracking accuracy, the direct normal irradiance, the aerosol optical depth, and the temperature of the lens and the solar cell. To verify the accuracy of the models, the I‐V characteristics of five CPV modules have been measured in a 10‐min interval over a period of 1 year in Freiburg, Germany. Four modules equipped with industrial‐standard lattice‐matched triple‐junction solar cells and one module equipped with metamorphic triple‐junction solar cells are investigated. The higher accuracy of YieldOpt compared with the three empirical models in predicting the power output of all five CPV modules during this period is demonstrated. The energy yield over a period of 1 year was predicted for all five CPV modules with a maximum deviation of 5% by the three empirical models and 3% by YieldOpt. Copyright © 2014 John Wiley & Sons, Ltd.     

Platinum-macrocycle co-catalysts for the electrochemical oxidation of methanol

Metal phthalocyanines (Fe, Co, Ni and Sn) and ruthenium tetramethylcyclam 14 and 15 were studied as cocatalysts for methanol oxidation on platinum supported catalysts. The formation of well defined monolayers of the adsorbed complexes was inferred from the Langmuirian form of the adsorption isotherms in solutions of macrocycles. The coverage at monolayer levels was low, e.g. 1.25 to 2.25×10¹³ molecules cm⁻² or 400 to 800 Ų molecule⁻¹. Enhancement for the methanol oxidation reaction was observed for Pt co-catalyzed with Sn phthalocyanine and Ru tetramethylcyclam. Ru tetramethylcyclam showed an enhancement for methanol oxidation on a per unit weight basis over pure Pt, approaching the activity of PtRu at lower potentials. Increasing the size of the nitrogen ring from 14 to 15 resulted in a lower redox potential and increase in the activity of methanol oxidation. The activity of Pt co-catalyzed with Ru TMC 15 decreased with time suggesting that the macrocycle was desorbing from the supported catalyst surface.