Conversion Of Solar Radiation Research Articles

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The objective was to determine how solar radiation affects the electric power generation in Huancayo city, using an electric power generation system based on a Stirling engine. The solar energy characteristics described in these coordinates of the center of Peru and the solar radiation conversion characteristics into electrical energy. The research has an experimental design, an electric power generation system based on a solar collector cylinder design was implemented, which applies thermal energy to a Stirling engine to generate electric energy, each stage of these processes were analyzed; performance tests and thermal power generation, mechanical and electrical energy with the experiments were performed. As a result it was possible to implement an electric power generation module having solar energy as a source; it was possible to obtain experimental results from the solar radiation entry, the temperature in concentration focus, mechanical energy generation which generates an electrical output potential according to the generator and the Stirling engine characteristics, and according conditions to the solar radiation of the geographical area. In conclusion, the electrical generation implementation of the Stirling system allows to have an integrated system with its analyzed processes, which allowed to evaluate the electrical potential values that solar energy provides us in experimental conditions in this studied geographic region.

Performance of PVT solar collector with compound parabolic concentrator and phase change materials

In this study we examine the solar radiation conversion into thermal energy and energy storage into phase change material (PCM) in the photovoltaic thermal (PVT) collector system. In order to get better solar radiation satisfactory compound parabolic concentrator (CPC) has been mounted on PVT collector. In this study outdoor experiments were carried out to compare performance study between clear day and semi-cloudy day in winter season. PVT solar collector with CPC that act as a solar collector, a PCM tank and CPC was integrated into one piece because of simplicity structure for PCM storage in same unit. No connection pipe i,e small area needed for installation and continuous tracking was not needed for better concentration ratio. Total heat loss, total useful energy, thermal efficiency and overall efficiency of the collector by varying different parameters were evaluated using modified equations derived for the energy storage system from the basic derivation of Hottel–Bliss–Whillier. The results show that thermal efficiency of solar collector varies from 40% to 50% for clear day and around 40% for semi-cloudy day. The overall efficiency of the PVT collector between 55% and 63% for clear-day and around 46–55% for semi-cloudy day whereas corresponding top loss value around 3W/m2K for clear day and around 2.5W/m2K for semi-cloudy day. Up to around 3m from entrance, the plate temperature was increased and then it became nearly steady. But in case of applying same system without PCM temperature was increased sharply.

Photocurrent generation by dye-sensitized solar cells using natural pigments.

The development of photovoltaic panels has improved the conversion of solar radiation into electrical energy. This paper deals with the electrical and thermal characteristics (voltage, current, and temperature) of photovoltaic solar cells sensitized with natural pigments (dye-sensitized solar cell, DSSC) based on a titanium dioxide semiconductor. Several natural pigments (blackberry, beets, eggplant skin, spinach, flame tree flower, papaya leaf, and grass extracts) were evaluated to determine their sensitizing effect on titanium dioxide. The results showed the great potential of natural pigments for use in solar cells. The best results were obtained with the blackberry pigment, reaching a value of 7.1 mA current, open-circuit voltage (Voc ) of 0.72 V in 2 cm2 , and fill factor (ff) of 0.51 in the DSSC. This performance is well above than that currently offers by actual cells.

Ray Tracing Study of Optical Characteristics of the Solar Image in the Receiver for a Thermal Solar Parabolic Dish Collector

This study presents the geometric aspects of the focal image for a solar parabolic concentrator (SPC) using the ray tracing technique to establish parameters that allow the designation of the most suitable geometry for coupling the SPC to absorber-receiver. The efficient conversion of solar radiation into heat at these temperature levels requires a use of concentrating solar collectors. In this paper detailed optical design of the solar parabolic dish concentrator is presented. The system has diameter D=3800 mm and focal distance f=2260 mm. The parabolic dish of the solar system consists of 11 curvilinear trapezoidal reflective petals. For the construction of the solar collectors, mild steel-sheet and square pipe were used as the shell support for the reflecting surfaces. This paper presents optical simulations of the parabolic solar concentrator unit using the ray tracing software TracePro. The total flux on the receiver and the distribution of irradiance for absorbing flux on center and periphery receiver are given. The goal of this paper is to present the optical design of a low-tech solar concentrator that can be used as a potentially low cost tool for laboratory scale research on the medium-temperature thermal processes, cooling, industrial processes, polygeneration systems, and so forth.

APPLICATION OF SOLAR CELLS IN CONTEMPORARY ARCHITECTURE

The paper outlines the basic information on photovoltaic conversion of solar radiation on solar cells made of different materials (monocrystalline, polycrystalline, amorphous silicon, etc.), as well as on building integrated photovoltaic systems (BIPV). Moreover, examples of the use of solar cells in contemporary architecture worldwide, Serbia and the Republic of Srpska are given. In conclusion, it is emphasized that the solar cells are increasingly used as façade elements and a source of electrical energy in the building sector. In future cities solar cells and BIPV systems will play evermore an increasingly significant role in façade forming and electrical energy generation in the residential and other types of objects.

A path to practical Solar Pumped Lasers via Radiative Energy Transfer.

The optical conversion of incoherent solar radiation into a bright, coherent laser beam enables the application of nonlinear optics to solar energy conversion and storage. Here, we present an architecture for solar pumped lasers that uses a luminescent solar concentrator to decouple the conventional trade-off between solar absorption efficiency and the mode volume of the optical gain material. We report a 750-μm-thick Nd3+-doped YAG planar waveguide sensitized by a luminescent CdSe/CdZnS (core/shell) colloidal nanocrystal, yielding a peak cascade energy transfer of 14%, a broad spectral response in the visible portion of the solar spectrum, and an equivalent quasi-CW solar lasing threshold of 23 W-cm−2, or approximately 230 suns. The efficient coupling of incoherent, spectrally broad sunlight in small gain volumes should allow the generation of coherent laser light from intensities of less than 100 suns.

Absorption spectra and sunlight conversion efficiency in fullerene bonded supramolecules on nanostructured ZnO

The efficiency of solar radiation conversion in a model system of artificial photosynthesis, the porphyrin-fullerene assembly, is analyzed. A study of the optical absorption spectra of the porphyrin and the fullerene molecules, as well as their assembly in organic solutions, made it possible to estimate the energy efficiency of the conversion. Numerical values of the energy efficiency, defined as the fraction of the light quantum energy converted to the chemical potential of separated charges, are calculated for low- and high-concentration solutions of such a supramolecular system. The possibility of the efficient utilization of long-wavelength solar radiation in the high-concentration porphyrin-fullerene assembly solution in toluene and benzene is shown. In the photovoltaic system consisting of such a supramolecular active element, a thin ZnO film with a nanostructured surface may be introduced as a secondary acceptor of electrons from fullerene molecules. An enhancement of the transformation of separated charges of the porphyrin-fullerene assembly into electrical current by means of the ZnO film deposited on the surface of the anode electrode in such a heterogenic photovoltaic unit is proposed.

Solar Radiation Conversion With Mesoporous Silica Activated by Rare-Earth Ions

Intrinsic and extrinsic nature of the luminescence of pure and Eu3+ and Tb3+ rare-earth ions activated mesoporous silica has been investigated by spectroscopic methods. Increasing the Eu3+ impurity concentration from 0.01 mg to 7 mg, results in an increase of the impurity particles radiation in the luminescent mesoporous colloidal silica (LMCS) matrix by several times. With an increase in the concentration of Tb3+ from 0.01 mg to 3 mg, impurity luminescence intensity increases several times while the intrinsic luminescence intensity maximum at 400 and 460 nm is decreasing. Based on the experimental evidence, it is suggested that the energy of the own electronic matrix excitation is transferred by emitters, i.e., impurities of Eu3+ and Tb3+ ions. Also, it is assumed that the emission band at 610 nm in an LMCS—Eu3+ and emission band at 543 nm in the LMCS—Tb3+ is attributed to the intracenter transitions within the Eu3+ and Tb3+ ions.

Constraints to the potential efficiency of converting solar radiation into phytoenergy in annual crops: from leaf biochemistry to canopy physiology and crop ecology.

A new simple framework was proposed to quantify the efficiency of converting incoming solar radiation into phytoenergy in annual crops. It emphasizes the need to account for (i) efficiency gain when scaling up from the leaf level to the canopy level, and (ii) efficiency loss due to incomplete canopy closure during early and late phases of the crop cycle. Equations are given to estimate losses due to the constraints in various biochemical or physiological steps. For a given amount of daily radiation, a longer daytime was shown to increase energy use efficiency, because of the convex shape of the photosynthetic light response. Due to the higher cyclic electron transport, C4 leaves were found to have a lower energy loss via non-photochemical quenching, compared with C3 leaves. This contributes to the more linear light response in C4 than in C3 photosynthesis. Because of this difference in the curvature of the light response, canopy-to-leaf photosynthesis ratio, benefit from the optimum acclimation of the leaf nitrogen profile in the canopy, and productivity gain from future improvements in leaf photosynthetic parameters and canopy architecture were all shown to be higher in C3 than in C4 species. The indicative efficiency of converting incoming solar radiation into phytoenergy is ~2.2 and 3.0% in present C3 and C4 crops, respectively, when grown under well-managed conditions. An achievable efficiency via future genetic improvement was estimated to be as high as 3.6 and 4.1% for C3 and C4 crops, respectively.

A high-efficiency hybrid high-concentration photovoltaic system

Photovoltaic power generation is a growing renewable primary energy source, expected to assume a major role as we strive toward fossil fuel free energy production. However, the photovoltaic efficiencies limit the conversion of solar radiation into useful power output. Hybrid systems extend the functionality of concentrating photovoltaics (CPV) from simply generating electricity, to providing simultaneously electricity and heat. The utilization of otherwise wasted heat significantly enhances the overall system efficiency and boosts the economic value of the generated power output. The current system consists of a scalable hybrid photovoltaic–thermal receiver package, cooled with an integrated high performance microchannel heat sink. The package can be operated at elevated temperatures due to its overall low thermal resistance between solar cell and coolant. The effect of the harvested elevated coolant temperature on the photovoltaic efficiency is investigated. The higher-level available heat can be suitable for sophisticated thermal applications such as space heating, desalination or cooling (polygeneration approaches). A total hybrid conversion efficiency of solar radiation into useful power of 60% has been realized. The exergy content of the overall output power was increased by 50% through the exergy content of the extracted heat. An analysis based on the economic value of heat illustrates that the reused heat can double the economic value of such a system.

Nanotechnology for Photovoltaic Cells and Energy Efficiency

Abstract. The intent of this paper is to connect science and technology in order to demonstrate how, in the field of on photovoltaic technologies, thin film solar cells have been the focus of many research facilities in recent years that are working to decrease manufacturing costs and increase cell efficiency. New research suggests that it might be possible to add a nanoscopic relief pattern to the surface of solar cells that makes them non-reflective significantly boosting efficiency and at the same time making them highly non-stick and self-cleaning. The paper presents the challenges and approaches to engineer the active layer of the cell, in order to obtain cells made up of components assembled with precision on the nanometer scale and with such properties as to increase the yield of conversion of solar radiation into electricity.

Model of the Plasma Photovoltaic Conversion of Concentrated Solar Radiation: Short-Circuit Current and Open-Circuit Voltage

A model of the direct photoelectric conversion of concentrated solar radiation in a plasma ignited in a heat pipe filled with a mixture of sodium vapor and krypton is developed. The model considers the non-homogeneous distribution of the alkali atom density in the heat-pipe volume and the thermionic effect of a cathode. The model treats a hot plasma core in a local thermal equilibrium (LTE) state and takes into account non-equilibrium layers near the converter walls. The model is employed to calculate an open-circuit voltage, a plasma resistance, a short-circuit current, an energy flux of positive ions directed toward the cathode, and a conversion efficiency of the solar radiation. Two different approaches were used to estimate a value of the electron temperature in the ionization non-equilibrium layer near the cathode. We assumed within the framework of an isothermal approximation that the electron temperature in the ionization layer near the cathode is equal to the temperature of the LTE plasma. This isothermal model predicted a rather low value (approximately 3 %) for the conversion efficiency. We found within the framework of a two-temperature model that the reduction of the electron temperature by 20 % compared with the LTE plasma temperature took place at the outer boundary of the ionization layer near the cathode. This non-isothermal model predicts a rather high value (approximately 33 %) for the conversion efficiency for a 300× solar radiation concentration ratio.

Ultra-low loading Ru/γ-Al2O3: A highly active and stable catalyst for low temperature solar thermal reforming of methane

Converting solar radiation into chemical energy is an attractive method to increase the energy content of methane by driving endothermic upgrading processes, such as methane steam reforming. Although such solar thermochemical conversions would increase natural gas product yields and reduce greenhouse gas emissions, current costs of solar facilities are prohibitively high. Parabolic troughs, which are a mature and relatively inexpensive form of solar concentrator, are limited to temperatures of ca. 400–600°C. In this regime, commercial methane steam reforming Ni-based catalysts have low activity and rapidly deactivate due to oxidation and coking. Catalysts based on platinum group metals are much more active and stable but their high cost limits their use. Here, we investigate Ru-based catalysts with ultra-low metal loadings for low-temperature methane steam reforming. We show that a Ru/γ-Al2O3 (0.15wt% loading) catalyst outperforms the commercial (12wt% Ni) catalyst by two orders of magnitude in terms of methane conversion normalized by metal loading. Systematic evaluation of catalytic performance over a range of Ru loadings and operating conditions shows a pronounced optimum in catalytic activity versus metal loading. Characterization studies reveal a strong correlation between the catalytic activity and the Ru nanoparticle size distribution. The catalyst features excellent stability at industrially relevant conditions and low steam-to-carbon ratios, making it an attractive option for low-temperature solar reforming of methane.

Physical Limits of Solar Energy Conversion in the Earth System.

Solar energy provides by far the greatest potential for energy generation among all forms of renewable energy. Yet, just as for any form of energy conversion, it is subject to physical limits. Here we review the physical limits that determine how much energy can potentially be generated out of sunlight using a combination of thermodynamics and observed climatic variables. We first explain how the first and second law of thermodynamics constrain energy conversions and thereby the generation of renewable energy, and how this applies to the conversions of solar radiation within the Earth system. These limits are applied to the conversion of direct and diffuse solar radiation - which relates to concentrated solar power (CSP) and photovoltaic (PV) technologies as well as biomass production or any other photochemical conversion - as well as solar radiative heating, which generates atmospheric motion and thus relates to wind power technologies. When these conversion limits are applied to observed data sets of solar radiation at the land surface, it is estimated that direct concentrated solar power has a potential on land of up to 11.6 PW (1 PW=10(15) W), whereas photovoltaic power has a potential of up to 16.3 PW. Both biomass and wind power operate at much lower efficiencies, so their potentials of about 0.3 and 0.1 PW are much lower. These estimates are considerably lower than the incoming flux of solar radiation of 175 PW. When compared to a 2012 primary energy demand of 17 TW, the most direct uses of solar radiation, e.g., by CSP or PV, have thus by far the greatest potential to yield renewable energy requiring the least space to satisfy the human energy demand. Further conversions into solar-based fuels would be reduced by further losses which would lower these potentials. The substantially greater potential of solar-based renewable energy compared to other forms of renewable energy simply reflects much fewer and lower unavoidable conversion losses when solar radiation is directly converted into renewable energy.

Influence of climate and air pollution on solar energy development in Serbia

The paper introduces basic information on the geographical location, climate and solar radiation in Serbia. It focuses particularly on the air pollution in Serbia and its influence on the solar cells energy efficiency. Moreover, detailed information on the development of solar energy in Serbia and the examples of the application of the low, medium and high temperature and photovoltaic conversion of solar radiation is provided. The paper also gives an overview of the installed greater capacity solar power stations related to the electricity network and the smaller capacity solar power stations as the independent sources of electricity in Serbia. In conclusion, the paper stresses Serbia’s favourite climate and other conditions for the prospective successful development of solar energy.

Models for solar radiation prediction based on different measurement sites

The modeling of solar radiation for forecasting its availability is a key tool for managing photovoltaic (PV) plants and, hence, is of primary importance for energy production in a smart grid scenario. However, the variability of the weather phenomena is an unavoidable obstacle in the prediction of the energy produced by the solar radiation conversion. The use of the data collected in the past can be useful to capture the daily and seasonal variability, while measurement of the recent past can be exploited to provide a short term prediction. It is well known that a good measurement of the solar radiation requires not only a high class radiometer, but also a correct management of the instrument. In order to reduce the cost related to the management of the monitoring apparatus, a solution could be to evaluate the PV plant performance using data collected by public weather station installed near the plant. In this paper, two experiments are conducted. In the first, the plausibility of the short term prediction of the solar radiation, based on data collected in the near past on the same site is investigated. In the second experiment, the same prediction is operated using data collected by a public weather station located at ten kilometers from the solar plant. Several prediction techniques belonging from both computational intelligence and statistical fields have been challenged in this task. In particular, Support Vector Machine for Regression, Extreme Learning Machine and Autoregressive models have been used and compared with the persistence and the k-NN predictors. The prediction accuracy achieved in the two experimental conditions are then compared and the results are discussed.

Advanced tendencies in development of photovoltaic cells for power engineering

Development of solar power engineering must be based on original innovative Russian and world technologies. It is necessary to develop promising Russian technologies of manufacturing of photovoltaic cells and semiconductor materials: chlorine-free technology for obtaining solar silicon; matrix solar cell technology with an efficiency of 25–30% upon the conversion of concentrated solar, thermal, and laser radiation; encapsulation technology for high-voltage silicon solar modules with a voltage up to 1000 V and a service life up to 50 years; new methods of concentration of solar radiation with the balancing illumination of photovoltaic cells at 50–100-fold concentration; and solar power systems with round-the-clock production of electrical energy that do not require energy storage devices and reserve sources of energy. The advanced tendency in silicon power engineering is the use of high-temperature reactions in heterogeneous modular silicate solutions for long-term (over one year) production of heat and electricity in the autonomous mode.

New generation thermodynamic autonomously managed space solar power plant

A comparative analysis of promising projects of solar radiation transformation by photovoltaic and thermodynamic devices into electric power at space solar power plants is given, the problems in implementation of these projects are revealed. A solution to the problems by means of the alternative project of concentrated solar radiation conversion to electricity by means of the autonomously managed space power plant is suggested. The effectiveness of the produced electric power is provided by the constructive solution with the use of carbon and lightweight, heat-resistant, durable materials, superconducting elements on its basis.

Rapid charging of thermal energy storage materials through plasmonic heating.

Direct collection, conversion and storage of solar radiation as thermal energy are crucial to the efficient utilization of renewable solar energy and the reduction of global carbon footprint. This work reports a facile approach for rapid and efficient charging of thermal energy storage materials by the instant and intense photothermal effect of uniformly distributed plasmonic nanoparticles. Upon illumination with both green laser light and sunlight, the prepared plasmonic nanocomposites with volumetric ppm level of filler concentration demonstrated a faster heating rate, a higher heating temperature and a larger heating area than the conventional thermal diffusion based approach. With controlled dispersion, we further demonstrated that the light-to-heat conversion and thermal storage properties of the plasmonic nanocomposites can be fine-tuned by engineering the composition of the nanocomposites.

Effect of annealing time and substrates nature on the physical properties of CuSbS2 thin films

In this study, the annealing time and substrates nature effects on the physical properties of CuSbS2 thin films were investigated. CuSbS2 thin films were prepared on various substrates via thermal evaporation technique. The as_deposited films were annealed in air for 60 and 120 min at 250 °C. The atomic force microscope micrographs of as_made and annealed thin films show that the surface morphology is affected by annealing time and substrate variation. X_ray diffraction results show that crystallinity increased with annealing time. The microstructure parameters: crystallite size and dislocation density were calculated. The optical properties were obtained from the analysis of the experimental recorded transmittance and reflectance spectral data over the wavelength range 300–1800 nm. High absorption coefficients (105–106 cm−1) are reached. Values of Eg are close to the theoretical optimum for efficient conversion of solar radiation into electrical power making the material suitable for photovoltaic applications.