Solar Energy Devices Research Articles

A Review on Thermal Properties Improvement of Phase Change Materials and Its Combination with Solar Thermal Energy Storage

This article summarizes measures to enhance the solar phase change thermal energy storage (TES), starting from two key points in solar phase change TES research: solar phase change materials (PCM) and solar phase transition devices. First, different types of PCM and their advantages and disadvantages are introduced. To improve thermal performance, the research progress of different dimensional thermal conductivity additives, photothermal composite phase change materials (CPCM), and phase change microcapsules is reviewed. Then, the characteristics of commonly used solar phase transition TES devices and the research status of solar energy device improvement with fins and multistage phase transition TES are summarized for the past few years. It is hoped to provide methods and ideas for the design and research of solar phase change TES systems, and to increase the overall heat transfer properties through the combination of multiple optimization methods. Finally, the future direction and research focus of solar phase change TES technology are put forward.

First principle study of lead‐free double perovskites halidesRb2Pd(Cl/Br)6for solar cells and renewable energy devices: A quantumDFT

First principle study of lead‐free double perovskites halides<scp>Rb₂Pd</scp>(Cl/Br)₆for solar cells and renewable energy devices: A quantum<scp>DFT</scp>

Hexagonal WO3·0.33H2O Hierarchical Microstructure with Efficient Photocatalytic Degradation Activity

Structural design and morphological control of semiconductors is considered to be one of the most effective ways to improve their photocatalytic degradation properties. In the present work, a hexagonal WO3·0.33H2O hierarchical microstructure (HWHMS) composed of nanorods was successfully prepared by the hydrothermal method. The morphology of the HWHMS was confirmed by field-emission scanning electron microscopy, and X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis demonstrated that the synthesized product was orthorhombic WO3·0.33H2O. Owing to the unique hierarchical microstructure, the HWHMS showed larger Brunauer–Emmett–Teller (BET) surface and narrower bandgap (1.53 eV) than the isolated WO3·0.33H2O nanorods. Furthermore, the HWHMS showed enhanced photocatalytic activity for degradation of methylene blue under visible-light irradiation compared with the isolated nanorods, which can be ascribed to the narrower bandgap, larger BET specific surface area, and orthorhombic phase structure of the HWHMS. This work provides a potential protocol for construction of tungsten trioxide counterparts and materials similar to tungsten trioxide for application in gas sensors, photocatalysts, electrochromic devices, field-emission devices, and solar-energy devices.

The analysis of characteristics of wind field on roof based on field measurement

An increasing number of solar energy or other devices have been installed on the roof, and the structure of which is very sensitive to wind load. The wind field on proof becomes the most critical premise for studying the wind load of structure. Due to the influence of buildings and parapet, the wind field on roof is completely different from that near the ground layer of atmospheric boundary layer. By analyzing the wind field characteristics on the roof of a multi-story building using field measurement method, this study acquires the variation rules and characteristics of wind characteristic parameters, such as the mean wind speed and yaw angle, turbulence intensity, gust factor, turbulence integral scale and fluctuating wind speed spectrum of wind field on multi-story building roof. The wind field on roof is also compared with the wind field on ground in this study so as to understand their difference. The analysis results show that the difference between wind fields on roof and ground, which should be considered when calculating the wind load of structure on roof.

Cu2FeSnS4 decorated Ni-TiO2 nanorods heterostructured photoanode for enhancing water splitting performance

Earth-abundant and visible light sensitive Cu2FeSnS4 layer is decorated on Ni-TiO2 nanorods (CFTS/Ni-TiO2 NRs) using wet chemical approach. First, Ni doping is performed on hydrothermally grown TiO2 nanorods to achieve Ni on the surface of TiO2. After surface doping of Ni, the bandgap of TiO2 nanorod films changes from 3.0 eV to 2.79 eV. Once the layer of Cu2FeSnS4 is decorated on the Ni doped TiO2 nanorods the absorption edge of the photoanode further shifted toward lower energy. Mott-Schottky analysis revealed more than 3-fold increase in photogenerated charge carrier density in CFTS/Ni-TiO2 NRs. This heterostructured photoanodes demonstrated a significant increase in photocurrent from 0.730 mA/cm2 to 2.09 mA/cm2 (at 1.23 V vs RHE). The lifetime of photo-generated charge carriers also improves from 10.87 s to 15.36 s for CFTS/Ni-TiO2 NRs as compared to TiO2 NRs. The CFTS/Ni-TiO2 NRs exhibit excellent photoelectrochemical properties with high stability, hence this heterostructure can be a potential candidate for solar energy device applications.

Comparison Analysis on the Performance of the Filtered Photovoltaic (PV) Module

The photovoltaic system is the most significant conversion device for solar energy compared to other available systems. It converts solar radiation into electricity, but the performance of the PV module degrades as the PV temperature increases. This is because only selected bands of wavelength, 0.35 to 0.82 μm, are converted into electricity while the remaining solar radiation will generate heat in the PV system. In order to maintain PV performance, the operating PV temperature can be maintained by applying various cooling methods, which are either passive or active. Some wavelengths, such as UV and Infrared, need to be eliminated. Therefore, this research aims to investigate the effects related to the presence of water in the filtered PV module. At the end of this study, the performance of the PV with and without the water filter was compared, and the results show that the PV module with the water filter achieved a higher efficiency of 9.96% compared to the filtered PV module without water, which had an efficiency of 9.61%.

A p-p+ Homojunction-Enhanced Hole Transfer in Inverted Planar Perovskite Solar Cells.

Perovskite solar cells (PSCs) have triggered a research trend in solar energy devices in view of their high power conversion efficiency and ease of fabrication. However, more delicate strategies are still required to suppress carrier recombination at charge transfer interfaces, which is the necessary path to high-efficiency solar cells. Here, a p-p+ homojunction was constructed on basis of NiO film to enhance hole transfer in an inverted planar perovskite solar cell. The homojunction was generated by fabricating a NiO/Cu:NiO bilayer film. The density functional theory calculation demonstrated the charge density difference in the two layers, which could generate a space charge region and a band bending at the junction, and the result was further proved by energy level structure analysis of NiO and Cu:NiO films. The designed homojunction could accelerate the hole transfer and inhibit carrier recombination at the interface between hole transfer layer and perovskite layer. Finally, the inverted planar perovskite solar cell with p-p+ homojunction showed an efficiency of 18.30 % and a high fill factor of 0.81, which were much higher than the counterpart of the PSCs individually using NiO or Cu:NiO as hole transfer layer. This work developed a new structure of hole transport layer to enhance the performance of PSCs, and also provided new ideas for design of charge transfer films.

STEP BY STEP ESTIMATION OF GLOBAL SOLAR RADIATION BASED ON ANGSTROM MODEL FOR BAUCHI METROPOLIS

ABSTRACT The knowledge of solar radiation distribution of a particular geographical location is an important tool for the development of many solar energy devices in testing of their performance. Measured data of solar radiation, relative humidity, and minimum and maximum temperatures for Bauchi location (latitudes 9° 3' and 12° 3' north and longitudes 8° 50' and 11° east) was obtained at Agro-weather Station Abubakar Tafawa Balewa University, Bauchi. The analysis of First order Regression for Angstrom model was obtained and the results was compared with that of the solar radiation measured in the months of March, April, May and June. Maximum value was recorded while its minimum is in the months of January, February, October, November and December for both the measured and predicted solar radiation based on temperature. Similarly, the Angstrom model based on relative humidity shows that in the months of June, July, August, September and October solar radiation is maximum while its minimum is in the months of January, February, March and April. The correlation coefficient was obtained using Kolmogoros - smirnov Microsoft excel software, the result shows that all the models are positively and perfectly correlated with correlation coefficient (R²) range (0.615 – 0.984).

Evaluation of heat transfer during the process of heating water in containers using a solar cooker box-type

This work presents the experimental results and the evaluation of the heat transfer mechanisms by conduction, convection, and radiation that occur during the water heating process inside four containers with volumes of 250, 500, 750, and 1000 ml. using as for this process a box-type solar cooker. For the experimental measurements, a type k thermocouple arrangement was used, located in the water, the exterior surfaces of the containers, and the glass that forms part of the solar cooker cover. For the acquisition of the data perceived by the thermocouples, a Compact Field Point from National Instruments was implemented and for the measurement of global solar radiation, an Eppley 8-48 radiometer was used. The results obtained from the evaluation show that the most important heat transfer mechanism is by conduction located in the exterior glass of the solar cooker cover and the convection heat transfer in this same glass is the one with the lowest values. The evaluation of the results achieved contributes to the knowledge of the operation of solar cookers, which can contribute to the design and improvements of these solar energy devices.

Obtaining nanoscale CoSiO/Si/CoSi2 systems for increasing the range of light ray absorption energy

The morphology, composition and electronic properties of the CoSiO film obtained on the CoSi2/Si (111) surface by implantation of O2 + ions in combination with annealing were studied. Parameters of energy zones are determined and information about the density of the state of electrons of the valence zone and conductivity zone is obtained. In particular, it is shown that the band gap width of this film is ~2.4 eV. It was ascertained that the CoSiO/Si/CoSi2 heterosystem is very promising for creating efficient solar energy devices.

“Right to Dry” Laws: Protecting the Environment Over Aesthetic Considerations

This article discusses the development and passage by state legislatures of “right to dry laws” which counter the trend of homeowners associations and condominiums banning the presence of clotheslines because of aesthetics and a concern for property values. Some states have passed laws using the terms “solar energy systems”, “solar energy devices” or “solar collectors” but do not mention the term clotheslines. The problem is that the use of dryers has become so common that most people do not even consider using clotheslines. But dryers use a great amount of energy and produce large quantities of greenhouse gas emissions producing 179 million tons of metric carbon dioxide each year. Also, the use of dryers takes a toll causing more wear and tear and shortening the life of clothes. With the impetus toward the use of natural sources of energy like wind and solar, environmentalists should consider lobbying state legislatures to pass laws overruling restrictive covenants that currently ban clotheslines. In light of the urgent concerns about global warming and energy conservation, aesthetic considerations should recede in importance.

Thermodynamic analysis of a combined cooling, heating, and power system integrated with full-spectrum hybrid solar energy device

This paper proposes a combined cooling, heating, and power system integrated with full-spectrum hybrid solar energy device containing molecular solar thermal system and solar water heating system to improve solar energy utilization efficiency. This system comprehensively integrates solar energy, fuel chemical energy and waste heat energy based on methanol decomposition to optimize energy utilization method. The thermodynamic models of components are established and the system evaluation indicators are presented. Based on a rated power of 834 kW, the thermodynamic performances under the design conditions were simulated and analyzed using Engineering Equation Solver, and the Sankey diagrams of energy and exergy flows were obtained in the respective cooling and heating modes. The results indicated that the solar energy share reaches 45.07%, and the energy and exergy efficiencies in cooling mode are 70.65% and 26.59%, respectively. They are increased by 1.52% and 1.92% in heating mode, respectively. The influences of various solar irradiation and power load ratio on system performances are discussed. The results indicate that the power load ratio and direct normal irradiance have positive impacts on energy and exergy efficiencies whereas they have negative impacts on solar energy share. Compared to the conventional methanol direct-fired system, the primary energy saving ratio and carbon dioxide emission reduction ratio of the proposed system reaches 16.20% and 16.14%, respectively.

The Impacts of Fluorine-Doped Tin Oxide Photonic Crystals on a Cadmium Sulfide-Based Photoelectrode for Improved Solar Energy Conversion under Lower Incidence

Incident angle variation of light from the sun is a critical factor for the practical utilizations of solar energy devices. These devices typically receive the zenith of photon density under a solar elevation angle of 90°, and dramatic deletion of light density along with the decrease of solar elevation angle. Photonic crystals (PCs) with long range ordered arrays possess the controllable position of the photonic stop band (PSB) reliant on several factors, including incident angles, based on the Bragg–Snell law. The multiple scattering, refraction and inhibition of charge carrier recombination within the PSB suggests the potential capability for improving the efficiency of photoactive materials. In this work, we focus on the multiple scattering and refraction effects of PCs. A photoelectrode based on photonic crystal fluorine-doped tin oxide (PC FTO) film was fabricated, which allows the embedded photoactive materials (CdS nanoparticles) to benefit from the features of PCs under variable incidence, especially under lower incidence. The photoelectrode thus has enhanced overall photoelectrochemical (PEC) efficiency in different seasons, even if the increased surface area factor is deducted.

OTSun, a python package for the optical analysis of solar-thermal collectors and photovoltaic cells with arbitrary geometry.

Ray tracing software systems are commonly used to analyze the optics of solar energy devices, since they allow to predict the energy gains of devices in real conditions, and also to compare them with other systems constantly emerging in the market. However, the available open-source packages apply excessive simplifications to the model of light-matter interaction, making that the optical behaviour of the systems can not be properly characterized, which in turn implies disagreements between physical experiments and computer simulations. We present here the open source python package OTSun, which applies the Fresnel equations in their most general form, without further simplifications, and is suitable for the simulation of both solar-thermal and photovoltaic systems. The geometrical objects used in this package are created using the parametric 3D modeler FreeCAD, which is also a free and open source program and allows for the construction of arbitrary geometries that can be analyzed with OTSun. These, and other software capabilities, make OTSun extremely flexible and accurate for the optical analysis of solar devices with arbitrary geometry. Additionally, OTSun has a companion webtool, OTSunWebApp, that allows for the usage of certain features of the package without the need to install anything locally. We also show here two numerical experiments that we performed in order to validate the model and implementation: The analysis of the optical efficiency of a Linear Fresnel Reflector (with moving objects), and of a second surface mirror (with variable wavelengths). In each case, the numerical computations had deviations of less than 0.25% from reference models (either computed with another program or with exact formulas).

Integrated Design of Solar Energy Utilization and Building Based on PLC

At present, fossil energy consumption still occupies a dominant position in China’s energy consumption structure, and problems such as low energy consumption efficiency, high degree of carbonization and large environmental pollution persist for a long time. Under the background of advocating environmental protection and energy saving, the combination of solar energy and building is the inevitable trend of building energy saving development, and the integrated design of solar energy and building has become a concern of the architectural circles. With the deepening of people’s understanding of environmental problems and the further deterioration of energy problems, more and more buildings begin to use clean and energy-saving solar energy devices. At present, the construction and development of urban residential buildings in China are mainly multi-storey and high-rise buildings. Therefore, higher requirements are put forward for the application form and scale of solar water heating system in residential buildings. In this paper, according to the current situation of solar energy utilization in buildings in China, based on PLC (programmable logic controller), the paper puts forward some suggestions to promote the integrated design of solar energy buildings.

Rational modification in the photochromic and self-bleaching performance of hierarchical microsphere Cu@h-WO3/WO3·nH2O composites

Herein, we used a self-assembly method to synthesize novel Cu@h-WO3/WO3·nH2O hierarchical microsphere composites with enhanced photochromism and self-bleaching performance. The composite fabricated with 1.0% Cu-WO displayed a rapid change from light-yellow to dark-gray after 2 min of ultraviolet irradiation and self-bleached in less than 1 h in the dark. Composite samples were characterized to investigate changes in their morphology and structure after being doped with different amounts of Cu. The hierarchical microspheres were composed of small, well-dispersed nanorods that provided active sites capable of absorbing light. Ensuring the proper Cu content in the WO3 lattice promoted the separation of carriers through interfacial charge transfer (IFCT) and prevented the recombination of electron-hole pairs due to excessive doping. Combing hexagonal WO3 with WO3·nH2O and Cu provided unobstructed channels, proton sources, and interactions with W species, which improved the efficiency of proton insertion and extraction. The WO3 hybrid materials described in this research displayed high coloration efficiencies and reversibility and may find applications in solar energy devices.

Scalable On-Chip Radiative Coolers for Concentrated Solar Energy Devices

Radiative coolers spectrally tailored at mid-infrared wavelengths (5–30 μm) achieve passive and efficient heat dissipation, thereby working together with existing conduction and convection channels...

ZrO2-TiO2/Carbon core-shell composites as highly efficient solar-driven photo-catalysts: An approach for removal of hazardous water pollutants

ZrO2-TiO2/C core-shell composites (CTiXZrYs) were synthesized at different Zr-to-Ti ratios by a facile and economical sol-gel approach to obtain highly efficient solar light-responsive photocatalysts. ZrO2-(CZrXs) and TiO2-covered carbon microspheres (CTiXs) were also prepared as reference materials. SEM and TEM images reveal a coverage formed mainly by fused nanosized spherical particles in CTiXs and CZrXs composites, while in bimetallic ones (CTiXZrYs) 3D-structures or nanofilaments are observed. Zirconium titanate was identified by XRD corroborating the observation obtained by TEM and SEM. XPS confirm that hybridized ZrO2–TiO2 nanostructures are formed due to the incorporation of ZrO2 into TiO2. The low band-gaps of composites (2.60–2.96 eV) provide absorbance of solar light and thus, photoactivity. The photocatalytic activity in the removal of hazardous compounds is enhanced in CTiXZrYs and increases with the amount of zirconium titanate present on the composite due to a synergistic effect between the carbon and coupled-semiconductors phases. These newly synthesized coupled-semiconductor/carbon composites open the gate of the synthesis of new cost-effective light harvesting energy materials for future fuel generation and solar energy devices.

Modified multiferroic properties in narrow bandgap (1-x)BaTiO3-xBaNb1/3Cr2/3O3-δ ceramics

Perovskite oxides of formula (1-x)BaTiO3-xBaNb1/3Cr2/3O3-δ ((1-x)BT-xBNC), a series of lead-free ferroelectric photovoltaic compounds, have been sintered via the solid-state reaction technology and simultaneously show ferromagnetic orders and bandgap narrowing effects at room-temperature (RT). X-ray diffraction patterns reveal the doping-induced transition from tetragonal to cubic phase, which is explained by a possible mechanism. Raman spectroscopy analysis not only further confirms the presence of structural transition, but also indicates the difference in local crystal symmetry compared with the idealized cubic phase. Moreover, the minimum bandgap of as-prepared samples is about 2.1 eV, much smaller than that of the pure BT ceramic (3.1 eV), which is attributed to Cr3+ 3d orbits within the highest occupied orbital and the lowest unoccupied orbital of BT. It is noted that the higher doping concentration is conducive to the ferromagnetic order but unfavourable to the ferroelectric polarization. The above results exhibit the abundant physical phenomena and provide a method to design the solar-energy device and the multiferroic information storage application.

Abrupt degenerately-doped silicon nanowire tunnel junctions

We have confirmed the presence of narrow, degenerately-doped axial silicon nanowire (SiNW) p-n junctions via off-axis electron holography (EH). SiNWs were grown via the vapor-solid-liquid (VLS) mechanism using gold (Au) as the catalyst, silane (SiH4), diborane (B2H6) and phosphine (PH3) as the precursors, and hydrochloric acid (HCl) to stabilize the growth. Two types of growth were carried out, and in each case we explored growth with both n/p and p/n sequences. In the first type, we abruptly switched the dopant precursors at the desired junction location, and in the second type we slowed the growth rate at the junction to allow the dopants to readily leave the Au catalyst. We demonstrate degenerately-doped p/n and n/p nanowire segments with abrupt potential profiles of 1.02 ± 0.02 and 0.86 ± 0.3 V, and depletion region widths as narrow as 10 ± 1 nm via EH. Low temperature current-voltage measurements show an asymmetric curvature in the forward direction that resemble planar gold-doped tunnel junctions, where the tunneling current is hidden by a large excess current. The results presented herein show that the direct VLS growth of degenerately-doped axial SiNW p-n junctions is feasible, an essential step in the fabrication of more complex SiNW-based devices for electronics and solar energy.