International Journal of Photoenergy
[SJR: 0.348] [H-I: 28] [2 followers] Follow
Open Access journal
ISSN (Print) 1110-662X - ISSN (Online) 1687-529X
Published by Hindawi [334 journals]
- Observer-Based Load Frequency Control for Island Microgrid with
Abstract: As renewable energy is widely integrated into the power system, the stochastic and intermittent power generation from renewable energy may cause system frequency deviating from the prescribed level, especially for a microgrid. In this paper, the load frequency control (LFC) of an island microgrid with photovoltaic (PV) power and electric vehicles (EVs) is investigated, where the EVs can be treated as distributed energy storages. Considering the disturbances from load change and PV power, an observer-based integral sliding mode (OISM) controller is designed to regulate the frequency back to the prescribed value, where the neural network observer is used to online estimate the PV power. Simulation studies on a benchmark microgrid system are presented to illustrate the effectiveness of OISM controller, and comparative results also demonstrate that the proposed method has a superior performance for stabilizing the frequency over the PID control.
PubDate: Wed, 26 Apr 2017 07:13:42 +000
- Feasibility Study of a Building-Integrated PV Manager to Power a Last-Mile
Electric Vehicle Sharing System
Abstract: Transportation is one of the largest single sources of air pollution in urban areas. This paper analyzes a model of solar-powered vehicle sharing system using building-integrated photovoltaics (BIPV), resulting in a zero-emission and zero-energy mobility system for last-mile employee transportation. As a case study, an electric bicycle sharing system between a public transportation hub and a work center is modeled mathematically and optimized in order to minimize the number of pickup trips to satisfy the demand, while minimizing the total energy consumption of the system. The whole mobility system is fully powered with BIPV-generated energy. Results show a positive energy balance in e-bike batteries and pickup vehicle batteries in the worst day of the year regarding solar radiation. Even in this worst-case scenario, we achieve reuse rates of 3.8 people per bike, using actual data. The proposed system manages PV energy using only the batteries from the electric vehicles, without requiring supportive energy storage devices. Energy requirements and PV generation have been analyzed in detail to ensure the feasibility of this approach.
PubDate: Wed, 26 Apr 2017 00:00:00 +000
- An Optimal Charging Strategy for PV-Based Battery Swapping Stations in a
DC Distribution System
Abstract: Photovoltaic- (PV-) based battery swapping stations (BSSs) utilize a typical integration of consumable renewable resources to supply power for electric vehicles (EVs). The charging strategy of PV-based BSSs directly influences the availability, cost, and carbon emissions of the swapping service. This paper proposes an optimal charging strategy to improve the self-consumption of PV-generated power and service availability while considering forecast errors. First, we introduce the typical structure and operation model of PV-based BSSs. Second, three indexes are presented to evaluate operational performance. Then, a particle swarm optimization (PSO) algorithm is developed to calculate the optimal charging power and to minimize the charging cost for each time slot. The proposed charging strategy helps decrease the impact of forecast uncertainties on the availability of the battery swapping service. Finally, a day-ahead operation schedule, a real-time decision-making strategy, and the proposed PSO charging strategy for PV-based BSSs are simulated in a case study. The simulation results show that the proposed strategy can effectively improve the self-consumption of PV-generated power and reduce charging cost.
PubDate: Thu, 06 Apr 2017 00:00:00 +000
- PV-Powered CoMP-Based Green Cellular Networks with a Standby Grid Supply
Abstract: This paper proposes a novel framework for PV-powered cellular networks with a standby grid supply and an essential energy management technique for achieving envisaged green networks. The proposal considers an emerging cellular network architecture employing two types of coordinated multipoint (CoMP) transmission techniques for serving the subscribers. Under the proposed framework, each base station (BS) is powered by an individual PV solar energy module having an independent storage device. BSs are also connected to the conventional grid supply for meeting additional energy demand. We also propose a dynamic inter-BS solar energy sharing policy through a transmission line for further greening the proposed network by minimizing the consumption from the grid supply. An extensive simulation-based study in the downlink of a Long-Term Evolution (LTE) cellular system is carried out for evaluating the energy efficiency performance of the proposed framework. System performance is also investigated for identifying the impact of various system parameters including storage factor, storage capacity, solar generation capacity, transmission line loss, and different CoMP techniques.
PubDate: Tue, 04 Apr 2017 00:00:00 +000
- Design and Optimization of Elliptical Cavity Tube Receivers in the
Parabolic Trough Solar Collector
Abstract: The nonfragile cavity receiver is of high significance to the solar parabolic trough collector (PTC). In the present study, light distributions in the cavity under different tracking error angles and PTC configurations are analyzed. A new elliptical cavity geometry is proposed and analyzed. It is obtained from this study that light distribution on the tube receiver is asymmetrical when tracking error occurs. On increasing the tracking error angle, more lights are sheltered by the cavity outer surface. The PTC focal distance has negative correlation with the cavity open length, whereas the PTC concentration ratio has positive correlation with the cavity open length. Increasing the tracking error angle and increasing the PTC focal distance would both decrease the cavity blackness. Introducing a flat plate reflector at the elliptical cavity open inlet can largely increase the cavity darkness.
PubDate: Thu, 30 Mar 2017 06:32:37 +000
- Technoeconomic Evaluation for an Installed Small-Scale Photovoltaic Power
Abstract: Solar energy production and economic evaluation are analyzed, in this study, by using daily solar radiation and average temperature data which are measured for 3 years in the Osmaniye province in Turkey. Besides, this study utilizes the photovoltaic- (PV-) based grid connected to a power plant which has an installed capacity of 1 MW investment in electricity production. Economic values show that the net present value (NPV), the first economic method in the research, is about 111941 USD, which is greater than zero. Therefore, the payback year of this investment is approximately 8.3. The second one of these methods, the payback period of the simple payback period (PBP), is 6.27 years. The last method, which is the mean value of the internal rate of return (IRR), is 10.36%. The results of this study show that Osmaniye is a considerable region for the PV investment in electricity production. As a result, investment of a PV system in Osmaniye can be applicable.
PubDate: Thu, 30 Mar 2017 06:18:09 +000
- Synergetic Control of Grid-Connected Photovoltaic Systems
Abstract: It is important to improve the dynamic performance and the low-voltage ride-through (LVRT) capability of a grid-connected photovoltaic (PV) system. This paper presents synergetic control for the control of a grid-connected PV system. Modeling of a grid-connected PV system is described, and differential-algebra equations are obtained. Two control strategies are used in normal operation and during LVRT of a PV system. Practical synergetic controllers with two control strategies are synthesized. The mathematical expressions are derived for computing control variables. The design of the synergetic controllers does not require the linearization of the grid-connected PV system. A grid-connected PV system with synergetic controllers is simulated in Simulink surroundings. The control performance is studied in normal operation and during LVRT. Simulation results show that the synergetic controllers are robust and have good dynamic characteristics under different operation states.
PubDate: Wed, 29 Mar 2017 04:29:01 +000
- Effect of the Fe Nanoparticles Generated by Pulsed Plasma in Liquid in the
Catalyzed Ozone Removal of Phenolphthalein
Abstract: We have synthesized, in this work, zero valent iron (ZVI) nanoparticles to improve the efficiency of degradation of phenolphthalein catalyzed by ozone in aqueous solution. The Fe nanoparticles were obtained using the pulsed plasma in liquid (PPL) method with water as the liquid medium. Such nanoparticles have a mean size of 12 nm and are composed of ~80% Fe0, while the rest are a mixture of Fe+2 and Fe+3 oxides. The degradation of phenolphthalein was carried on a glass reactor injecting a constant amount of ozone and introducing different concentrations of Fe nanoparticles to the system. When using pure ozone, the percentage of degradation of phenolphthalein measured by colorimetry after one hour of reaction was 84%. However, when Fe nanoparticles are used, such percentage can be as high as 98% in 50 minutes of reaction. Furthermore, the degradation rate constant was 0.0334 min−1 with only ozone and it can be as high as 0.0733 min−1 with Fe nanoparticles. Finally, the total mineralization of phenolphthalein was obtained by total organic carbon (TOC) determinations. It is shown that when using only ozone, we obtained a percentage of mineralization of 49% and 96% when using the highest concentration of Fe nanoparticles.
PubDate: Tue, 28 Mar 2017 10:39:02 +000
- A Density Peak-Based Clustering Approach for Fault Diagnosis of
Abstract: Fault diagnosis of photovoltaic (PV) arrays plays a significant role in safe and reliable operation of PV systems. In this paper, the distribution of the PV systems’ daily operating data under different operating conditions is analyzed. The results show that the data distribution features significant nonspherical clustering, the cluster center has a relatively large distance from any points with a higher local density, and the cluster number cannot be predetermined. Based on these features, a density peak-based clustering approach is then proposed to automatically cluster the PV data. And then, a set of labeled data with various conditions are employed to compute the minimum distance vector between each cluster and the reference data. According to the distance vector, the clusters can be identified and categorized into various conditions and/or faults. Simulation results demonstrate the feasibility of the proposed method in the diagnosis of certain faults occurring in a PV array. Moreover, a 1.8 kW grid-connected PV system with array is established and experimentally tested to investigate the performance of the developed method.
PubDate: Tue, 28 Mar 2017 08:40:49 +000
- One-Pot Solid-State Reaction Approach to Synthesize Ag-Cu2O/GO Ternary
Nanocomposites with Enhanced Visible-Light-Responsive Photocatalytic
Abstract: A facile ball milling-assisted solid-state reaction method was developed to synthesize Ag-Cu2O/graphene oxide (GO) nanocomposites. In the resultant complex heterostructures, Ag nanocrystals were mainly deposited on the surface of Cu2O, while Ag-Cu2O composites were anchored onto GO sheets. The resultant Ag-Cu2O/GO nanocomposites exhibited excellent photocatalytic activity with 90% of methyl orange (MO) dye degradation efficiency after 60 min of visible-light irradiation, which was much higher than that of either Cu2O or Ag-Cu2O. This study opens a new avenue to fabricate visible-light-responsive photocatalyst with high performance for environmental pollution purification.
PubDate: Tue, 28 Mar 2017 00:00:00 +000
- Recent Developments of Photovoltaics Integrated with Battery Storage
Systems and Related Feed-In Tariff Policies: A Review
Abstract: The paper presents a review of the recent developments of photovoltaics integrated with battery storage systems (PV-BESs) and related to feed-in tariff policies. The integrated photovoltaic battery systems are separately discussed in the regulatory context of Germany, Italy, Spain, United Kingdom, Australia, and Greece; the attention of this paper is focused on those integrated systems subject to incentivisation policies such as feed-in tariff. Most of the contributions reported in this paper consider already existing incentive schemes; the remaining part of the contributions proposes interesting and novel feed-in tariff schemes. All the contributions provide an important resource for carrying out further research on a new era of incentive policies in order to promote storage technologies and integrated photovoltaic battery systems in smart grids and smart cities. Recent incentive policies adopted in Germany, Italy, Spain, and Australia are also discussed.
PubDate: Thu, 16 Mar 2017 08:22:58 +000
- Influence of Front and Back Contacts on Photovoltaic Performances of p-n
Homojunction Si Solar Cell: Considering an Electron-Blocking Layer
Abstract: In this simultion work, the effect of front and back contacts of p-n homojunction Si solar cell with an electron-blocking layer (EBL) has been studied with the help of a strong solar cell simulator named AMPS-1D (analysis of microelectronic and photonic structures one dimensional). Without the effect of these contact parameters, low solar cell efficiency has been observed. Fluorine-doped tin oxide (FTO) with high work function (5.45 eV) has been used as the front contact to the proposed solar cell. Zinc (Zn) metal which has a work function of 4.3 eV has been used as the back contact of the proposed model. With FTO as the front contact and Zn as the back contact, the optimum efficiency of 29.275% (Voc = 1.363 V, Jsc = 23.747 mA/cm2, FF = 0.905) has been observed. This type of simple Si-based p-n homojunction solar cell with EBL of high efficiency has been proposed in this paper.
PubDate: Sun, 12 Mar 2017 06:59:08 +000
- Non-Toxic Buffer Layers in Flexible Cu(In,Ga)Se2 Photovoltaic Cell
Applications with Optimized Absorber Thickness
Abstract: Absorber layer thickness gradient in Cu(In1−xGax)Se2 (CIGS) based solar cells and several substitutes for typical cadmium sulfide (CdS) buffer layers, such as ZnS, ZnO, ZnS(O,OH), Zn1−xSnxOy (ZTO), ZnSe, and In2S3, have been analyzed by a device emulation program and tool (ADEPT 2.1) to determine optimum efficiency. As a reference type, the CIGS cell with CdS buffer provides a theoretical efficiency of 23.23% when the optimum absorber layer thickness was determined as 1.6 μm. It is also observed that this highly efficient CIGS cell would have an absorber layer thickness between 1 μm and 2 μm whereas the optimum buffer layer thickness would be within the range of 0.04–0.06 μm. Among all the cells with various buffer layers, the best energy conversion efficiency of 24.62% has been achieved for the ZnO buffer layer based cell. The simulation results with ZnS and ZnO based buffer layer materials instead of using CdS indicate that the cell performance would be better than that of the CdS buffer layer based cell. Although the cells with ZnS(O,OH), ZTO, ZnSe, and In2S3 buffer layers provide slightly lower efficiencies than that of the CdS buffer based cell, the use of these materials would not be deleterious for the environment because of their non-carcinogenic and non-toxic nature.
PubDate: Wed, 01 Mar 2017 00:00:00 +000
- Influence of the Porosity of the TiO2 Film on the Performance of the
Perovskite Solar Cell
Abstract: The structure of mesoporous TiO2 (mp-TiO2) films is crucial to the performance of mesoporous perovskite solar cells (PSCs). In this study, we fabricated highly porous mp-TiO2 films by doping polystyrene (PS) spheres in TiO2 paste. The composition of the perovskite films was effectively improved by modifying the mass fraction of the PS spheres in the TiO2 paste. Due to the high porosity of the mp-TiO2 film, PbI2 and CH3NH3I could sufficiently infiltrate into the network of the mp-TiO2 film, which ensured a more complete transformation to CH3NH3PbI3. The surface morphology of the mp-TiO2 film and the photoelectric performance of the perovskite solar cells were investigated. The results showed that an increase in the porosity of the mp-TiO2 film resulted in an improvement in the performance of the PSCs. The best device with the optimized mass fraction of 1.0 wt% PS in TiO2 paste exhibited an efficiency of 12.69%, which is 25% higher than the efficiency of the PSCs without PS spheres.
PubDate: Wed, 01 Feb 2017 06:41:17 +000
- Investigation on the Synthesis and Photocatalytic Property of Uranyl
Complexes of the -Diketonates Biscatecholamide Ligand
Abstract: A series of uranyl complexes have been synthesized by reacting hexadentate ligands CH2[COO (CH2)nCAM; , 3, 4]2 [CAM = 2,3-Ph(OH)2CONH] containing the catecholamide (CAM) group and β-diketonates framework with uranyl nitrate. They were characterized by FTIR, UV-vis, 1H NMR, XPS, TGA, and elemental analysis. The analysis revealed that oxygen atom of β-diketonate did not bind to uranyl ion in complexes 1–3. The photocatalytic degradation properties of the target complexes for degradation of rhodamine B (RhB) were investigated. The result indicated that approximately 74%, 71%, and 67% RhB were degraded in the presence of complexes 1–3 after about 210 min, respectively. Consequently, complexes 1–3 have excellent photocatalytic degradation property.
PubDate: Sun, 29 Jan 2017 08:08:05 +000
- Copper Sulfide Catalyzed Porous Fluorine-Doped Tin Oxide Counter Electrode
for Quantum Dot-Sensitized Solar Cells with High Fill Factor
Abstract: The performance of quantum dot-sensitized solar cell (QDSSC) is mainly limited by chemical reactions at the interface of the counter electrode. Generally, the fill factor (FF) of QDSSCs is very low because of large charge transfer resistance at the interface between the counter electrode and electrolyte solution containing redox couples. In the present research, we demonstrate the improvement of the resistance by optimization of surface area and amount of catalyst of the counter electrode. A facile chemical synthesis was used to fabricate a composite counter electrode consisting of fluorine-doped tin oxide (FTO) powder and CuS nanoparticles. The introduction of a sputtered gold layer at the interface of the porous-FTO layer and underlying glass substrate also markedly reduced the resistance of the counter electrode. As a result, we could reduce the charge transfer resistance and the series resistance, which were 2.5 [Ω] and 6.0 [Ω], respectively. This solar cell device, which was fabricated with the presently designed porous-FTO counter electrode as the cathode and a PbS-modified electrode as the photoanode, exhibited a FF of 58%, which is the highest among PbS-based QDSSCs reported to date.
PubDate: Thu, 26 Jan 2017 12:28:12 +000
- Performance Enhancement of Dye-Sensitized Solar Cells Using a Natural
Abstract: Dye-sensitized solar cells (DSSCs) based on natural sensitizers have become a topic of significant research because of their urgency and importance in the energy conversion field and the following advantages: ease of fabrication, low-cost solar cell, and usage of nontoxic materials. In this study, the chlorophyll extracted from papaya leaves was used as a natural sensitizer. Dye molecules were adsorbed by TiO2 nanoparticle surfaces when submerged in the dye solution for 24 h. The concentration of the dye solution influences both the amount of dye loading and the DSSC performance. The amount of adsorbed dye molecules by TiO2 nanoparticle was calculated using a desorption method. As the concentration of dye solution was increased, the dye loading capacity and power conversion efficiency increased. Above 90 mM dye solution concentration, however, the DSSC efficiency decreased because dye precipitated on the TiO2 nanostructure. These characteristics of DSSCs were analyzed under the irradiation of 100 mW/cm2. The best performance of DSSCs was obtained at 90 mM dye solution, with the values of , , FF, and efficiency of DSSCs being 0.561 V, 0.402 mA/cm2, 41.65%, and 0.094%, respectively.
PubDate: Tue, 24 Jan 2017 05:58:32 +000
- Mismatch Based Diagnosis of PV Fields Relying on Monitored String Currents
Abstract: This paper presents a DC side oriented diagnostic method for photovoltaic fields which operates on string currents previously supplied by an appropriate monitoring system. The relevance of the work relies on the definition of an effective and reliable day-by-day target for the power that every string of the field should have produced. The procedure is carried out by comparing the instantaneous power produced by all solar strings having the same orientation and by attributing, as producible power for all of them, the maximum value. As figure of merit, the difference between the maximum allowed energy production (evaluated as the integral of the power during a defined time interval) and the energy actually produced by the strings is defined. Such a definition accounts for both weather and irradiance conditions, without needing additional sensors. The reliability of the approach was experimentally verified by analyzing the performance of two medium size solar fields that were monitored over a period of four years. Results allowed quantifying energy losses attributable to underperforming solar strings and precisely locating their position in the field.
PubDate: Mon, 16 Jan 2017 00:00:00 +000
- Monitoring, Diagnosis, and Power Forecasting for Photovoltaic Fields: A
Abstract: A wide literature review of recent advance on monitoring, diagnosis, and power forecasting for photovoltaic systems is presented in this paper. Research contributions are classified into the following five macroareas: (i) electrical methods, covering monitoring/diagnosis techniques based on the direct measurement of electrical parameters, carried out, respectively, at array level, single string level, and single panel level with special consideration to data transmission methods; (ii) data analysis based on artificial intelligence; (iii) power forecasting, intended as the ability to evaluate the producible power of solar systems, with emphasis on temporal horizons of specific applications; (iv) thermal analysis, mostly with reference to thermal images captured by means of unmanned aerial vehicles; (v) power converter reliability especially focused on residual lifetime estimation. The literature survey has been limited, with some exceptions, to papers published during the last five years to focus mainly on recent developments.
PubDate: Wed, 11 Jan 2017 12:54:18 +000
- Silver/Carbon Codoped Titanium Dioxide Photocatalyst for Improved Dye
Degradation under Visible Light
Abstract: Herein, we report the synthesis of quartz supported TiO2 photocatalysts codoped with carbon and silver through the hydrolysis of titanium tetrachloride followed by calcination at 500°C. The prepared samples were characterized by UV-Vis diffuse reflectance spectroscopy, high resolution scanning electron microscopy (HRSEM), Raman spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Codoping of TiO2 with Ag and carbon resulted in an increase in the surface area of the photocatalyst and altered the ratio of the anatase to rutile phase. The absorption edge of all the doped TiO2 photocatalysts redshifted and the band gap was reduced. The lowest band gap of 1.95 eV was achieved by doping with 0.5% Ag. Doping TiO2 using carbon as the only dopant resulted in a quartz supported photocatalyst that showed greater photocatalytic activity towards methyl orange than undoped TiO2 and also all codoped TiO2 photocatalysts under visible light irradiation.
PubDate: Wed, 11 Jan 2017 00:00:00 +000
- Enhanced Efficiency of PTB7 : PC61BM Organic Solar Cells by Adding a
Low Efficient Polymer Donor
Abstract: Ternary blend polymer solar cells combining two electron-donor polymers, poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl] (PTB7) and poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (pBTTT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), as electron-acceptor, were fabricated. The power conversion efficiency of the ternary cells was enhanced by 18%, with respect to the reference binary cells, for a blend composition with 25% (wt%) of pBTTT in the polymers content. The optimized device performance was related to the blend morphology, nonrevealing pBTTT aggregates, and improved charge extraction within the device.
PubDate: Wed, 11 Jan 2017 00:00:00 +000
- Effect of Modulating Spin-Coating Rate of TiO2 Precursor for Mesoporous
Layer on Hysteresis of Solar Cells with Polar CH3NH3PbI3 Perovskite Thin
Abstract: Compared with the crystalline Si solar cells, the - characteristics of CH3NH3PbI3 perovskite solar cells are different under forward and reverse scan, and the CH3NH3PbI3 film exhibits some polarization properties. To explore those performances of the mesoporous TiO2 layer based perovskite solar cells, we focus on the effect of modulating the spin-coating rate of the TiO2 precursor for mesoporous layer on - hysteresis of solar cells with the polar film by - curves, atomic force microscopy topographic images, and piezoresponse force microscopy phase images. Firstly, the AFM images illustrate that the polarization behaviors exist and the deformation scale is large at the corresponding position when the DC bias voltage increases. Secondly, it is suggested that the polar films which applied the positive DC biases voltage show a tendency to 0° phase angle, while the polar films which applied the negative DC biases voltage show a tendency to −180° phase angle. Thirdly, a weak polar hysteresis loop relation for CH3NH3PbI3 film was observed. Finally, the hysteresis index for the 1500 rpm mesostructured solar cell shows relatively low - hysteresis compared with the 3000 rpm mesostructured and the planar-structured solar cell. Our experimental results bring novel routes for reducing the hysteresis and investigating the polar nature for CH3NH3PbI3 material.
PubDate: Tue, 10 Jan 2017 12:35:08 +000
- Synergetic Enhancement of the Photocatalytic Activity of TiO2 with Visible
Light by Sensitization Using a Novel Push-Pull Zinc Phthalocyanine
Abstract: A new one-pot synthesis of a novel A3B-type asymmetric zinc phthalocyanine (AZnPc) was developed. The phthalocyanine complex was characterized unambiguously and used to prepare a TiO2 hybrid photocatalyst to enhance its photocatalytic activity in the visible range. Different compositions of the phthalocyanine dye were tested in order to find the optimum amount of sensitizer to get the highest activity during the photocatalytic tests. The hybrid photocatalyst was characterized by UV-Vis diffuse reflectance (DRS) and Fourier transform infrared spectroscopy (FT-IR) and its photocatalytic activity was compared with that of the individual components considering the effects of sensitization on their efficiency to degrade Rhodamine B as a model reaction. A synergic improvement of the photocatalytic activity for the hybrid system was explained in terms of an improved electron injection from the photo-activated phthalocyanine to the TiO2. Considering the structural features of the phthalocyanine sensitizer and their effect on aggregation, some mechanistic aspects of its binding to TiO2 are suggested to account for the photocatalytic activity enhancement. Finally, the inhibitory effect on the sprouting of chia seeds (Salvia hispanica) was evaluated in order to test the toxicity of the water effluent obtained after the photodegradation process. According to our growth inhibition assays, it was found that the Rh-B degradation by-products do not lead to an acute toxicity.
PubDate: Tue, 10 Jan 2017 11:27:00 +000
- Sprayed and Spin-Coated Multilayer Antireflection Coating Films for
Nonvacuum Processed Crystalline Silicon Solar Cells
Abstract: Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm) was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1) without antireflection coating (ARC) layer, (2) with TiO2-compact ARC film, and (3) with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88%) owing to the multilayer ARC. was improved further by 2 mA cm−2 (from 35.3 mA cm−2 to 37.2 mA cm−2) when compared with a single TiO2-compact ARC.
PubDate: Mon, 02 Jan 2017 14:43:00 +000
- Study on the Optimizing Operation of Exhaust Air Heat Recovery and Solar
Energy Combined Thermal Compensation System for Ground-Coupled Heat Pump
Abstract: This study proposed an exhaust air heat recovery and solar energy combined thermal compensation system (ESTC) for ground-coupled heat pumps. Based on the prediction of the next day’s exhaust air temperature and solar irradiance, an optimized thermal compensation (OTC) method was developed in this study as well, in which the exhaust air heat recovery compensator and solar energy compensator in the ESTC system run at high efficiency throughout various times of day. Moreover, a modified solar term similar days group (STSDG) method was proposed to improve the accuracy of solar irradiance prediction in hazy weather. This modified STSDG method was based on air quality forecast and AQI (air quality index) correction factors. Through analyzing the operating parameters and the simulation results of a case study, the ESTC system proved to have good performance and high efficiency in eliminating the heat imbalance by using the OTC method. The thermal compensation quantity per unit energy consumption (TEC) of ESTC under the proposed method was 1.25 times as high as that under the traditional operation method. The modified STSDG method also exhibited high accuracy. For the accumulated solar irradiance of the four highest daily radiation hours, the monthly mean absolute percentage error (MAPE) between the predicted values and the measured values was 6.35%.
PubDate: Sun, 01 Jan 2017 09:25:37 +000
- Enhanced Photocatalytic Degradation and Mineralization of Furfural Using
UVC/TiO2/GAC Composite in Aqueous Solution
Abstract: Titanium dioxide nanoparticles were immobilized on granular activated carbon (GAC) as a porous and low-density support for photocatalytic degradation of furfural. The TiO2/GAC composite was synthetized using the simple sol-gel method and fully characterized. The effects of the operational parameters of furfural concentration (200–700 mg/L), initial pH (2–12), TiO2/GAC composite dosage (1–3.5 g/L), and irradiation time (20–120 min) were studied. The synthetized TiO2/GAC composite exhibited a total pore volume of 0.13 cm3/g and specific surface area of 35.91 m2/g. Removal efficiency of up to 95% was observed at initial pH of 10, TiO2/GAC dosage of 2.5 g/L, irradiation time of 80 min, and initial furfural concentration of 500 mg/L. The photocatalyst could be reused at least four consecutive times with a mere 2% decrease in furfural removal efficiency. Mineralization efficiency of 94% was obtained within 80 min. Pseudo-first-order kinetics best fit the photocatalytic degradation of furfural under experimental conditions.
PubDate: Thu, 29 Dec 2016 07:09:10 +000
- Preparation of Titanium Dioxide Nanoparticles Immobilized on
Polyacrylonitrile Nanofibres for the Photodegradation of Methyl Orange
Abstract: Herein, we describe the synthesis of titanium dioxide (TiO2) nanoparticles by the hydrolysis and condensation of titanium tetrachloride. The resulting nanoparticles were immobilized on polyacrylonitrile (PAN) based nanofibres by an electrospinning technique in order to allow simple isolation and reuse of titania semiconductor photocatalyst. The composite nanofibres were heat treated to convert the polymer nanofibres to carbon nanofibres and to convert amorphous TiO2 to crystalline TiO2. X-ray diffraction (XRD) analysis showed that the rutile phase was the major phase and the equatorial peaks of PAN disappeared after heat treatment at 600°C. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis confirmed that some TiO2 nanoparticles were encapsulated whereas some were surface residing on the electrospun nanofibres. The TiO2 nanoparticles were found to lower the cyclization temperature of PAN as indicated by differential scanning colorimetry (DSC) and differential thermal analysis (DTA). Photocatalytic studies on the degradation of methyl orange dye under UV light irradiation showed that composite nanofibres were capable of degrading organic contaminants in water. The carbon nanofibres with surface residing titanium dioxide nanoparticles (TiO2/CNF-SR) showed the highest photocatalytic activity (59.35% after 210 minutes) due to direct contact between the TiO2 photocatalyst and methyl orange.
PubDate: Tue, 27 Dec 2016 09:44:31 +000
- Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar
Cell due to Ageing
Abstract: This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs). The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V) characteristics are analyzed. Short circuit current density () decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS). An increase in net resistance results in a lower for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degraded DSC. It is also confirmed from EIS that the degradation leads to a better contact formation between the electrolyte and Pt electrode, which improves the fill factor of the DSC. But the recombination throughout the DSC is found to increase along with degradation. This study suggests that the DSC should be used under low illumination conditions and around room temperature for a longer life.
PubDate: Tue, 06 Dec 2016 14:18:50 +000
- Analysis on Photovoltaic Energy-Assisted Drying of Green Peas
Abstract: A photovoltaic energy-assisted industrial dryer has been analyzed. The dryer has been tested in various weather and working conditions with 3 kg of green peas from 75.6% initial moisture content to 20% final moisture content (w.b.). The effect of various drying air temperatures at three levels (40, 50, and 60°C) and two distinct air velocities (3 m/s and 4 m/s) was examined. Drying performance was assessed with regard to criteria including drying kinetics, specific and total energy consumption, and color and rehydration ratio. The results have proved that total drying duration reduces as air velocity rate and drying air temperature raise. Relying upon the drying durations, the generation performances of photovoltaic panels were between 5.261 and 3.953 W. On the other part, energy consumptions of dryer were between 37.417 and 28.111 W. The best specific energy consumption was detected in 50°C at 3 m/s for 600 minutes with 7.616 kWh/kg. All drying conditions caused darkening as color parameters. Rehydration assays have showed that rehydrated green peas attained higher capacity with raised air temperature and air velocity.
PubDate: Mon, 05 Dec 2016 08:36:36 +000
- ZnSnS3: Structure Prediction, Ferroelectricity, and Solar Cell
Abstract: The rapid growth of the solar energy industry is driving a strong demand for high performance, efficient photoelectric materials. In particular, ferroelectrics composed of earth-abundant elements may be useful in solar cell applications due to their large internal polarization. Unfortunately, wide band gaps prevent many such materials from absorbing light in the visible to mid-infrared range. Here, we address the band gap issue by investigating the effects of substituting sulfur for oxygen in the perovskite structure ZnSnO3. Using evolutionary methods, we identify the stable and metastable structures of ZnSnS3 and compare them to those previously characterized for ZnSnO3. Our results suggest that the most stable structure of ZnSnS3 is the monoclinic structure, followed by the metastable ilmenite and lithium niobate structures. The latter structure is highly polarized, possessing a significantly reduced band gap of 1.28 eV. These desirable characteristics make it a prime candidate for solar cell applications.
PubDate: Sun, 04 Dec 2016 14:23:41 +000