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[IEEE 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - Santos, Brazil (2019.12.1-2019.12.4)] 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - A Curve Tracer for Photovoltaic Modules Based on The Capacitive Load Method
摘要： This work presents the development of a current versus voltage (I-V) curve tracer of photovoltaic (PV) modules based on the capacitive load method, being this an important approach for checking the integrity of PV devices and also the extraction of intrinsic parameters for modeling purposes. The tracer employs a microcontroller to manipulate the data required from current and voltage sensors associated with the module output quantities. For comparison purposes, three different values of capacitance are used to trace the I-V characteristic of a 5-Wp module, as it is possible to verify that the capacitor charging time has direct influence on the number of acquired points that constitute the curve.
关键词： photovoltaic solar energy,photovoltaic system modeling,curve tracer,capacitive load method
更新于2025-09-23 15:19:57
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Photoelectric evaluation of dye-sensitized solar cells based on prodigiosin pigment derived from Serratia marcescens 11E
摘要： Prodigiosin, a natural pigment produced as a secondary metabolite by the non-photosynthetic bacterium Serratia marcescens, was tested as a sensitizer in dye-sensitized solar cells (DSSC). The strain S. marcescens 11E, which was isolated from a natural spring located in the northeastern Mexican state of Nuevo Leon, was cultivated on peanut oil broth 1% v/v, a culture medium which is known to enhance the production of prodigiosin. The resulting pigment was extracted with chloroform and identified as prodigiosin based on the spectroscopic and structural characteristics obtained by UV–Vis spectrophotometry along with FTIR and 1H-NMR spectroscopies. The initial absorbance decomposition test performed on the bacterial pigment demonstrated that prodigiosin exhibited high photostability after five days, while the photovoltaic performance test of the sensitized DSSC, resulted in an open voltage circuit of 560 mV, a current density of 0.096 mA/cm2, and efficiency of 0.032 %. Structurally, the DSSC consisted of a titanium dioxide (TiO2) photoanode sensitized with the pigment by direct adsorption, an electrolyte containing a redox pair I?/I3? and a cathode or counter electrode prepared from a carbon paste. Since the overproduction of prodigiosin can be easily achieved on a large scale through the rapid fermentation of agro-industrial residues throughout the year without the need to allocate surfaces for the cultivation of pigment-producing plants or wait for specific seasons for their cultivation, our results suggest that prodigiosin could be considered an excellent candidate to be used in the development of a low-tech, low-cost DSSC.
关键词： Low-cost DSSC,Solar energy,Bacterial pigments,Native strain
更新于2025-09-23 15:19:57
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Heating Behavior of Photovoltaic Panels and Front Side Water Cooling Efficiency
摘要： The use of solar energy is very promising for favorable Sun Belt countries. However, in these regions the hot climate leads to high temperatures which conduct to significant power losses in photovoltaic panels. In this paper we study the heating behavior of photovoltaic panels and front side water cooling efficiency. A standalone cooling system is designed as prototype which helps to proposal for a methodology for large-scale application through energy estimation of this system. Two typical situations were studied: the first one with a uniform distribution of the temperature and the second one with a non-uniform distribution of temperature under partial shadowing leading to hot spot effect. The gain in electrical power with cooling is about 45% in the case of a non-uniform distribution compared to 12% in the case of a uniform distribution at 30°C outdoor temperature. It was also noticed that temperature on hot spot point depends of the shadow type (direct and indirect). The estimation of the supplement of energy obtained from the cooling system demonstrates that the cooling system used in this study will be beneficial with using of string of PV panels with a minimum of three panels. This makes the autonomous cooling system very efficient.
关键词： solar energy,photovoltaic,hot-spot,cooling,temperature
更新于2025-09-23 15:19:57
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Eco-friendly sugar-based natural deep eutectic solvents as effective electrolyte solutions for dye-sensitized solar cells
摘要： Dye-sensitized solar cells containing sugar-based Natural Deep Eutectic Solvents (NADESs) as active electrolyte solvents have been studied in their photovoltaic (PV) properties, including main PV characteristics, IPCE, and EIS. Five monosaccharides were selected as NADES H-bond donors and investigated with a phenothiazine-based sensitizer carrying a glucose functionality and a glucose-based co-adsorbent (glucuronic acid) to explore directional intermolecular interactions and improve the PV performance. The highest power conversion efficiencies were recorded for cells containing the glucose-based sensitizer in the presence of glucuronic acid in the sugar-based NADES. When one of these components was omitted, performances were lower suggesting that the best response came from an interplay between the sugar-based units. Not only has the unprecedented use of a NADES as a fully natural and bio-renewable DSSC medium been presented, but for the first time an active role of the electrolyte solvent has been reported and exploited to increase the performance of the solar device.
关键词： deep eutectic solvents,solar energy,glucose,hydrogen bond,photovoltaics
更新于2025-09-23 15:19:57
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Multi-criteria decision-making model for assessment of large photovoltaic farms in Brazil
摘要： The decision of the location for the installation of photovoltaic power plants is a critical issue for large-scale projects due to climatic aspects, the proximity to other facilities, and the presence of protected environmental areas. The objective of this study is to propose a model capable of indicating the best location for the implantation of large-scale photovoltaic projects in the Brazilian territory. According to the proposed modeling, the relevant factors were identified to be considered in the choice of the ideal place, which were combined with the GIS-MCDM tools. The analysis of the areas was processed by the gvSIG software, using AHP methods for the evaluation of the factors and TOPSIS for ranking the alternatives. In application of this model, a total of 453 areas were identified that could receive a large photovoltaic installation, equivalent to 1823.35 km2 of the study area. Among these study areas, 67.23% of them are improper, 0.52% is good, 12.34% are very good, and only 19.91% are excellent. In order to validate the quality of the solution obtained by the proposed methodology was applied a detailed analysis with two scenarios. In the first one are used weights equal to all the criteria and in the second, the MAUT method was applied to rank the alternatives. The modeling proposed in this paper combining with GIS-MCDM is applicable to similar investigations in other regions and also to evaluate the spatial adequacy of other renewable energy technologies.
关键词： Solar energy,Geographic Information System (GIS),Determinant factors,Multi-Criteria Decision Making (MCDM),Restrictive Factors
更新于2025-09-23 15:19:57
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Field experimental study on a novel beehive integrated with solar thermal/photovoltaic system
摘要： Bees not only produce honey but also provide the main pollination for most crops, while long maturation cycle, low yield of honey and even mass death of bees are observed in traditional hives due to the unfriendly internal thermal condition. In the present paper, a new beehive system integrated with solar thermal/PV system was introduced to optimize the internal thermal condition of the beehive and then to improve the yield and quality of honey. A local bee farm was selected to evaluate the operating performance of the solar beehive in a real natural environment. Comparative ?led testing of the solar hive and traditional hive were carried out under di?erent operating modes depending on the weather conditions all the year round. The variation of hive temperature, the quantity of honey collected, Baume degree and the amount of sugar feed consumption were measured and analyzed. The results showed that the air temperature in solar beehive was higher than that in traditional beehive in winter and transition seasons and lower in summer. The quantity of collected honey in the solar beehive was 15.8% more than that in the traditional beehive. The Baume degree indicated that honey can mature 2 days earlier in solar beehive. As to sugar feed consumption in winter, the corresponding quality in solar beehive was lower than that in traditional hive. These results indicated the feasibility of the conjunctive use of solar thermal/photovoltaic technology with the beehive that enlarges the solar energy applications.
关键词： Hive temperature,Solar energy,Baume degree,Beehive system
更新于2025-09-23 15:19:57
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Heat transfer model of a 50 kW solar receiver-reactor for thermochemical redox cycling using cerium dioxide
摘要： This work reports on the development of a transient heat transfer model of a solar receiver-reactor designed for thermochemical redox cycling by temperature and pressure swing of pure cerium dioxide in the form of a reticulated porous ceramic (RPC). In the first, endothermal, step the cerium dioxide RPC is directly heated with concentrated solar radiation to 1500 °C while under vacuum pressure of less than 10 mbar, thereby releasing oxygen from its crystal lattice. In the subsequent, exothermic, step the reactor is re-pressurized with carbon dioxide as it cools, and at temperatures below 1000 °C the partially reduced cerium dioxide is re-oxidized with a flow of carbon dioxide. To analyze the performance of the solar reactor and to gain insight into improved design and operational conditions, a transient heat transfer model of the solar reactor for a solar radiative input power of 50 kW during the reduction step was developed and implemented in ANSYS CFX. The numerical model couples the incoming concentrated solar radiation using Monte-Carlo ray tracing, incorporates the reduction chemistry by assuming thermodynamic equilibrium, and accounts for internal radiation heat transfer inside the porous ceria by applying effective heat transfer properties. The model was experimentally validated using data acquired in a high-flux solar simulator, where temperature evolution and oxygen production results from model and experiment agreed well. The numerical results indicate the prominent influence of solar radiative input power, where increasing it substantially reduces reduction time of the cerium dioxide structure. Consequently, the model predicts a solar-to-fuel energy conversion efficiency of > 6% at a solar radiative power input of 50 kW; efficiency > 10% can be obtained provided the RPC macro porosity is substantially increased and better volumetric absorption and uniform heating is achieved. Managing the ceria surface temperature during reduction to avoid sublimation is a critical design consideration for direct absorption solar receiver-reactors.
关键词： design optimization,reactor modelling,ceria,thermochemical cycles,solar energy,reticulated porous ceramic
更新于2025-09-23 15:19:57
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Transparent Ta3N5 Photoanodes for Efficient Oxygen Evolution toward the Development of Tandem Cells
摘要： Photoelectrochemical water splitting is regarded as a promising approach to the production of hydrogen, and the development of efficient photoelectrodes is one aspect of realizing practical systems. In this work, transparent Ta3N5 photoanodes were fabricated on n-type GaN/sapphire substrates to promote O2 evolution in tandem with a photocathode, to realize overall water splitting. Following the incorporation of an underlying GaN layer, a photocurrent of 6.3 mA cm-2 was achieved at 1.23 V vs. a reversible hydrogen electrode. The transparency of Ta3N5 to wavelengths longer than 600 nm allowed incoming solar light to be transmitted to a CuInSe2 (CIS), which absorbs up to 1100 nm. A stand-alone tandem cell with a serially-connected dual-CIS unit terminated with a Pt/Ni electrode was thus constructed for H2 evolution. This tandem cell exhibited a solar-to-hydrogen energy conversion efficiency greater than 7% at the initial stage of the reaction.
关键词： (oxy)nitrides,photoelectrochemistry,water splitting,photoelectrochemical tandem cell,solar energy conversion
更新于2025-09-23 15:19:57
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Enhanced heat capacity of binary nitrate eutectic salt-silica nanofluid for solar energy storage
摘要： In concentrating solar power plants, the heat capacity of thermal storage media is a key factor that affects the cost of electricity generation. This work investigated the effective specific heat capacity of binary nitrate eutectic salts seeded with silica nanoparticles, using both experimental measurements and molecular dynamics simulations. The effects of the mass concentration (0–2.0 wt%) and average size (10, 20, and 30 nm) of the nanoparticles on the specific heat capacity value of nanofluids were analyzed. The results show that specific heat capacity increases when adding 10 nm silica nanoparticles up to 1.0 wt%, and then it decreases at higher concentrations. At this optimal mass concentration, the 20 nm nanoparticles displayed a maximum enhancement in the average specific heat capacity (by ~26.7%). The simulation results provided information about the different energy components in the system. The rate of potential energy change versus nanoparticle mass concentration was found to be maximized at 1.0 wt% concentration, which agrees with the experimental measurements. The potential energy components in the simulation system indicate that the change of Coulombic energy contributes the most to the variation of specific heat capacity.
关键词： Molten salt based nanofluids,Molecular dynamics simulation,Solar energy storage,Specific heat capacity
更新于2025-09-23 15:19:57
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Engineering Efficient Photon Upconversion in Semiconductor Heterostructures
摘要： Photon upconversion is a photophysical process in which two low-energy photons are converted into one high-energy photon. Photon upconversion has broad appeal for a range of applications from biomedical imaging and targeted drug-release to solar energy harvesting. Current upconversion nanosystems, including lanthanide-doped nanocrystals and triplet-triplet annihilation (TTA) molecules, have achieved upconversion quantum yields of order 10-30%. However, the performance of these materials is hampered by inherently narrow absorption cross-sections and fixed energy levels originating in atomic, ionic, or molecular states. Semiconductors, on the other hand, have inherently wide absorption cross-sections. Moreover, recent advances enable the synthesis of colloidal semiconductor nanoparticles with complex heterostructures that can control band alignments and tune optical properties. We synthesize and characterize a three-component heterostructure that successfully upconverts photons under continuous-wave (CW) illumination and solar-relevant photon fluxes. The heterostructure is composed of two cadmium selenide (CdSe) quantum dots (QDs), an absorber and emitter, spatially separated by a cadmium sulfide (CdS) nanorod (NR). We demonstrate that the principles of semiconductor heterostructure engineering can be applied to engineer improved upconversion efficiency. We first eliminate electron trap-states near the surface of the absorbing QD and then tailor the bandgap of the NR such that charge carriers are funneled to the emitting QD. When combined, these two changes result in a 100-fold improvement in photon upconversion performance.
关键词： solar energy,semiconductors,upconversion,coupled quantum dots,nanostructures,core/rod/emitter
更新于2025-09-23 15:19:57