ALBERT

Description: The aim of this work was to couple physical-chemical approaches with photocatalysis to reduce by a simple, inexpensive way the organic load of olive mill wastewater (OMW), mandatorily prior to the final discharge. Before irradiation, different sorbents were tested to remove part of the organic fraction, monitored by measuring chemical oxygen demand (COD) and polyphenols (PP). Different low-cost, safe materials were tested, that is, Y zeolite (ZY), montmorillonite, and sepiolite. Considerable decrease of organic load was obtained, with the highest abatement (40%) provided by ZY (10 g L−1 in 1 : 10 OMW). Use of the three sorbents, in particular ZY, was convenient compared to commercial activated carbons. UV light photocatalytic tests, performed using P25 TiO2 on ZY-treated OMW, yielded quantitative remediation (ca. 90%). Also solar light provided significative results, PP being lowered by 74% and COD by 56%. Sol-gel anatase TiO2 and N-doped anatase TiO2 were also tested, obtaining good results, around 80% PP and 40% COD. Finally, an integrated approach was experimented by ZY-supported anatase TiO2 (TiO2@ZY). This photoreactive sorbent allowed one-pot treatment of OMW significative abatements of PP (77%) and COD (39%) with only 1 g L−1 material, under solar light.

Description: Molybdenum (Mo) thin films are widely used as rear electrodes in copper indium gallium diselenide (CIGS) solar cells. The challenge in Mo deposition by magnetron sputtering lies in simultaneously achieving good adhesion to the substrates while retaining the electrical and optical properties. Bilayer Mo films, comprising five different thickness ratios of a high pressure (HP) deposited bottom layer and a low pressure (LP) deposited top layer, were deposited on 40 cm × 30 cm soda-lime glass substrates by DC magnetron sputtering. We focus on understanding the effects of the individual layer properties on the resulting bilayer Mo films, such as microstructure, surface morphology, and surface oxidation. We show that the thickness of the bottom HP Mo layer plays a major role in determining the micromechanical and physical properties of the bilayer Mo stack. Our studies reveal that a thicker HP Mo bottom layer not only improves the adhesion of the bilayer Mo, but also helps to improve the film crystallinity along the preferred [] direction. However, the surface roughness and the porosity of the bilayer Mo films are found to increase with increasing bottom layer thickness, which leads to lower optical reflectance and a higher probability for oxidation at the Mo surface.

Description: Three hydrocalumite-like compounds in a Ca/Al ratio of 2 containing nitrate and acetate anions in the interlaminar region were prepared by a simple, economic, and environmentally friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, nitrogen adsorption-desorption at −196°C, scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (DRS). The catalytic activity of the calcined solids at 700°C was tested in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) where 57% degradation of 2,4-D (40 ppm) and a mineralization percentage of 60% were accomplished within 150 minutes. The photocatalytic properties were attributed to mayenite hydration, since the oxide ions in the cages are capable of reacting with water to form hydroxide anions capable of breaking down the 2,4-D molecules.

Description: Photovoltaic (PV) energy is one of the most important energy sources since it is clean and inexhaustible. It is important to operate PV energy conversion systems in the maximum power point (MPP) to maximize the output energy of PV arrays. An MPPT control is necessary to extract maximum power from the PV arrays. In recent years, a large number of techniques have been proposed for tracking the maximum power point. This paper presents a comparison of different MPPT methods and proposes one which used a power estimator and also analyses their suitability for systems which experience a wide range of operating conditions. The classic analysed methods, the incremental conductance (IncCond), perturbation and observation (P&O), ripple correlation (RC) algorithms, are suitable and practical. Simulation results of a single phase NPC grid connected PV system operating with the aforementioned methods are presented to confirm effectiveness of the scheme and algorithms. Simulation results verify the correct operation of the different MPPT and the proposed algorithm.

Description: Concentrated sunlight that is transmitted by fiber optics has been used for generating electricity, heat, and daylight. On the other hand, multijunction photovoltaic cells provide high efficiency for generating electricity from highly concentrated sunlight. This study deals with designing and simulating a high-efficiency coupler, employing a mathematical model to connect sunlight with fiber optics for multiple applications. The coupler concentrates and distributes irradiated light from a primary concentrator. In this study, a parabolic dish was used as the primary concentrator, a coupler that contains nine components called a compound truncated pyramid and a cone (CTPC), all of which were mounted on a plate. The material of both the CTPC and the plate was BK7 optical glass. Fiber optics cables and multijunction photovoltaic cells were connected to the cylindrical part of the CTPC. The fibers would transmit the light to the building to provide heat and daylight, whereas multijunction photovoltaic cells generate electricity. Theoretical and simulation results showed high performance of the designed coupler. The efficiency of the coupler was as high as , whereas the rim angle of the dish increased to an optimum angle. Distributed sunlight in the coupler increased the flexibility and simplicity of the design, resulting in a system that provided concentrated electricity, heat, and lighting for residential buildings.

Description: Water-soluble graphitic hollow carbon nanorods (wsCNRs) are exploited for their light-driven photochemical activities under outdoor sunlight. wsCNRs were synthesized by a simple pyrolysis method from castor seed oil, without using any metal catalyst or template. wsCNRs exhibited the light-induced photochemical degradation of methylene blue used as a model pollutant by the generation of singlet oxygen species. Herein, we described a possible degradation mechanism of methylene blue under the irradiation of visible photons via the singlet oxygen-superoxide anion pathway.

Description: Solar panels have become attractive in order to generate and supply electricity in commercial and residential applications. Their increased module efficiencies have caused not only a massive production but also a sensible drop on sale prices. Methods of characterization, instrumentation for in situ measurements, defect monitoring, process control, and performance are required. A temperature characterization method by means of thermograph analysis is exposed in this paper. The method was applied to multicrystalline modules, and the characterization was made with respect to two different variables, first a thermal transient and second a characterization with respect to the current. The method is useful in order to detect hot spots caused by mismatch conditions in electrical parameters. The description, results, and limitations of the proposed method are discussed.

Description: Fe-doped TiO2 (Fe/TiO2) film photocatalyst was prepared by sol-gel and dip-coating process to extend its photoresponsivity to the visible spectrum. To promote the CO2 reduction performance with the photocatalyst, some types of base materials used for coating Fe/TiO2, which were netlike glass fiber and Cu disc, were investigated. The characterization of prepared Fe/TiO2 film coated on netlike glass fiber and Cu disc was analyzed by SEM and EPMA. In addition, the CO2 reduction performance of Fe/TiO2 film coated on netlike glass disc, Cu disc, and their overlap was tested under a Xe lamp with or without ultraviolet (UV) light, respectively. The results show that the concentration of produced CO increases by Fe doping irrespective of base material used under the illumination condition with UV light as well as that without UV light. Since the electron transfer between two overlapped photocatalysts is promoted, the peak concentration of CO for the Fe/TiO2 double overlapping is approximately 1.5 times as large as the Fe/TiO2 single overlapping under the illumination condition with UV light, while the promotion ratio is approximately 1.1 times under that without UV light.

Description: The internal impedances of different dye-sensitized solar cell (DSSC) models were analyzed by electrochemical impedance spectrometer (EIS) with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the heterojunction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.

Description: This paper identifies the partial shading problem of a PV module using the one-diode model and simulating the characteristics exhibiting multiple-peak power output condition that is similar to a PV array. A modified particle swarm optimization (PSO) algorithm based on the suggested search-agent deployment, retracking condition, and multicore operation is proposed in order to continuously locate the global maximum power point for the PV system. Partial shading simulation results for up to 16 modules in series/parallel formats are presented. A distributed PV system consisting of up to 8 a-silicon thin film PV panels and also having a dedicated DC/DC buck converter on each of the modules is tested. The converter reaches its steady state voltage output in 10 ms. However for MPPT operation, voltage, and current measurement interval is set to 20 ms to avoid unnecessary noise from the entire electric circuit. Based on the simulation and experiment results, each core of the proposed PSO operation should control no more than 4 PV modules in order to have the maximum tracking accuracy and minimum overall tracking time. Tracking for the global maximum power point of a distributed PV system under various partial shading conditions can be done within 1.3 seconds.

Description: This paper discusses the utilisation of PV systems for electric vehicles charging for transportation requirements of smart cities. The gap between PV power output and vehicles charging demand is highly variable. Therefore, there is a need for additional support from a public distribution grid or a storage device in order to handle the residual power. Long term measurement data retrieved from a charging station for 15 vehicles equipped with a PV system were used in the research. Low and high irradiation seasons influenced the PV output. The charging demand of electric vehicles varied over the course of a year and was correlated to weather conditions. Therefore, the sizing and performance of a supportive storage device should be evaluated in a statistical manner using long period observations.

Description: The performance of a solar assisted heat pump dryer integrated with biomass furnace has been designed and evaluated for drying red chillies, and drying kinetics of red chillies were evaluated. The red chillies were dried from 22 kg with moisture content of 4.26 db to moisture content of 0.08 db which needed 11 hours, with the average drying chamber temperature, drying chamber relative humidity, and an air mass flow rate of 70.5°C, 10.1%, and 0.124 kg/s, respectively, while the open sun drying needed 62 hours. Compared to open sun drying, this dryer yielded 82% saving in drying time. The drying rate, the specific moisture extraction rate, and thermal efficiency of the dryer were estimated in average to be about 1.57 kg/h, 0.14 kg/kWh, and 9.03%, respectively. Three mathematical models, the Newton, Henderson-Pabis, and Page models, were fitted to the experimental data on red chillies dried by solar assisted heat pump dryer integrated with biomass furnace and open sun drying. The performance of these models was evaluated by comparing the coefficient of determination (), mean bias error (MBE), and root mean-square error (RMSE). The Page model gave the best results for representing drying kinetics of red chillies.

Description: A novel modeling tool for calculation of central receiver concentrated flux distributions is presented, which takes into account drift effects. This tool is based on a drift model that includes different geometrical error sources in a rigorous manner and on a simple analytic approximation for the individual flux distribution of a heliostat. The model is applied to a group of heliostats of a real field to obtain the resulting flux distribution and its variation along the day. The distributions differ strongly from those obtained assuming the ideal case without drift or a case with a Gaussian tracking error function. The time evolution of peak flux is also calculated to demonstrate the capabilities of the model. The evolution of this parameter also shows strong differences in comparison to the case without drift.

Description: Design, construction, and evaluation of a cylindrical-trough solar concentrator with 1.3 m aperture, 2.15 m length, and 0.54 m focal length, with heat-pipe or vacuum tube receiver and one axis tracking system, are presented. Design performance was tested under ASHRAE standard 93-1986 (RA 91). The concentrator system is lightweight and inexpensive since it was made of polymeric membranes and was pneumatically inflated to acquire its cylindrical shape achieving good optical quality. Further implementation of a flat and a cylindrical extension of the concentrating mirror as secondary mirrors was incorporated into the concentrator design in order to compensate for seasonal variations of collected radiation. Total initial investment of $163.30 or $58.5/m2 and efficiencies ranging from 33 to 25% for 25 up to 65°C show an excellent cost-performance ratio. Construction, costs, and efficiencies obtained by us and developed by other groups are compared to emphasize the high cost/benefit ratio and efficiencies of this approach.

Description: The biggest problems of our time are environmental pollution and the reduction of fossil fuel resources. In recent years, photovoltaic (PV) has started to be used efficiently in order to produce electrical energy from solar energy throughout the world. In this study, a wheat mover machine taking its energy with PV technology transformation from the sun was designed supported by smart sensors. The designed vehicle was tested in two wheat fields in Sivas in Turkey. It was seen that daily average sunshine rates were not lower than 700 Watt/m2 during the testing dates and time. The amounts of electrical charge used to mow 5 m2 and 50 m2 areas are obtained as 500 mAh and 3395 mAh, respectively. Also maximum power is calculated from used PV panel as 26.15 Watt during the day of the experiments. The range of solar radiation intensity is found 4.5 kWh/m2/day at the studied kWh which was 0.140 USD on the date of November 2015. This system is 94.5% more economic than conventional mowers over an area of 1000 m2.

Description: The mean cost price of electricity in Burkina Faso at the end of the last quarter of 2012 was 158 FCFA/kWh for a country where more than 46% of the population lives below the national poverty threshold. To look for solution to that problem, the resort to photovoltaic solar energy is justified for that country. The purpose of this study is to promote the integration of both technical and economical surveys in solar energy preliminary projects in Ouagadougou. To reach that, investigations were carried out in some households and attention was paid from the calibration of the domestic electric meters. Energy demands collected within each household allow us to design a corresponding solar kit through optimization rules. An estimate was edited and financial viability study for each household was also carried out thereafter. In this study, only households using the national electricity network calibration meter on their disadvantage favorably answered to all financial indicators and appear as the only one that could profit from such project. This work is helpful to note that photovoltaic solar energy still stays at a primitive level of competitiveness compared to conventional energy resources for small systems in Ouagadougou.

Description: Multiwall carbon nanotubes (MWCNTs) were modified by acids (H2SO4 : HNO3) for generating active groups on the nanotube surface. Unmodified- and modified-carbon nanotubes were coated on the conductive glass and conductive plastic substrates by a slurry paste method, and they were used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). Scanning electron microscopy reveals that carbon nanotubes are evenly deposited on the conductive glass. The efficiency of the glass based DSSCs of unmodified- and modified-carbon nanotubes and Pt CEs is ~4.73%, ~5.66%, and ~6.08%, respectively. The efficiency of the plastic based DSSCs of the unmodified- and modified-carbon nanotubes CEs is ~0.80% and ~2.11%, respectively. The voltammogram and electrochemical impedance spectroscopy results suggest that the superior performance of the modified-carbon nanotubes DSSCs is attributable to the high electrocatalytic activity and the low charge-transfer resistance of the modified-carbon nanotubes film over the unmodified-carbon nanotubes film.

Description: In this study, an exergy analysis of two kinds of solar-driven cogeneration systems consisting of solar collectors and an organic Rankine cycle (ORC) is presented for series mode and parallel mode. Three kinds of solar collectors are considered: flat-plate collectors (FPC), evacuated tube collectors (ETC), and parabolic trough collectors (PTC). This study mainly compares the exergy output of the two kinds of solar cogeneration systems under different temperatures of the return heating water and different inlet temperatures of the solar collectors. This study shows that, from the perspective of or , the parallel mode is superior to the series mode. From the perspective of , the parallel mode is superior to the series mode when the solar collector is FPC; however, the series mode is superior to the parallel mode when the solar collector is PTC. When the solar collector is ETC, the result depends on the temperature of the return heating water. When the temperature of the return heating water is low (below 46°C), the series mode is better, and when the temperature of the return heating water is high (above 46°C), the parallel mode is better.

Description: Pharmaceuticals are present in an aquatic environment usually in low (ng/L) concentrations. Their continuous release can lead to unwanted effects on the nontarget organisms. The main points of their collection and release into the environment are wastewater treatment plants. The wastewater treatment plants should be upgraded by new technologies, like advanced oxidation processes (AOPs), to be able to degrade these new pollutants. In this study, the degradation of albendazole (ALB), a drug against parasitic helminths, was investigated using four UV-based AOPs: UV photolysis, UV photocatalysis (over TiO2 film), UV + O3, and UV + H2O2. The ranking of the degradation process degree of the ALB and its degradation products for studied processes is as follows: UV photolysis 

Description: The energy scenario today is focused on the development and usage of solar cells, especially in the paradigm of clean energy. To readily create electron and hole pairs, solar cells utilize either photoactive or photosensitive components. A bulk heterojunction (BHJ) is a nanolayer consisting of donor and acceptor components with a large interpenetrated acceptor and donor contact area. In this context, a mix of P3HT and PCBM offers novelty for its use as an acceptor as well as a donor. In the work presented here, we address the mechanism of modelling and characterization of a BHJ-based polymer solar cell. Here, a new design of BHJ polymer solar cells have been designed, modelled, using Silvaco TCAD in the Organic Solar module, and matched with an already assembled device having similar features. Using this model, we have been able to estimate key parameters for the modelled devices, such as the short-circuit current density, open-circuit voltage, and fill factor with less than 0.25 error index compared to the fabricated counterpart, paving the way for fabless polymer solar cell design and optimization.

Description: This work undertakes both simulation and experimental studies of a new design of a photovoltaic thermal solar air collector (PV/T). In order to improve the thermal and electrical performances for a specific application, the analytical expressions for thermal parameters and efficiency are derived by developing an energy balance equation for each component of the PV/T air collector. This type of hybrid collector can be applied in the facades of buildings. The electricity and heat produced will satisfy the energy needs of the buildings, while ensuring an aesthetic view of its facades. A typical prototype was designed, constructed, and implemented in the applied research unit on renewable energies in Ghardaia, situated in the south of Algeria. This region has semiarid characteristics. Results obtained by an experimental test are presented and compared to those predicted through simulation. Results include the temperature of each component of the PV/T collector and air temperature at the inlet and outlet of the channel. It has been found that the theoretical results predicted by the developed mathematical model, for instance, outlet temperature, agree with those found through experimental work.

Description: Mismatching operating conditions negatively affect the extracted energy in photovoltaic (PV) systems. They may also lead to dangerous localized heating phenomena (hot spots) that can cause, in turn, accelerated ageing and reduced reliability. Since the adoption of bypass diodes or smart active switches does not prevent the occurrence of hotspots, it is necessary to investigate alternative strategies. A promising solution is represented by the proper regulation of the operating point of the PV cells in the current vs. voltage (-) or power vs. voltage (-) planes when mismatching conditions occur. In particular, in this paper, the existence of operating points allowing a suitable compromise between maximization of the extracted power and minimization of thermal stresses, due to hot spots, is experimentally evidenced. Experimental results highlighting the link existing between the operating point in the - plane and the PV cell temperature distribution under uniform and mismatching operating conditions are presented and discussed. On the basis of the obtained experimental results, it is possible to state that, when mismatching conditions occur, it is mandatory to properly choose the operating point: the global maximum power point may not be the best operating point. Hence, it is crucial to gain information about the eventual occurrence of mismatching conditions in order to be able to properly choose the best operating point. Therefore, another crucial aspect that is evidenced in this paper is represented by the fact that the detection of the occurrence of mismatching conditions, based on the analysis of the shape of the - and/or - characteristics, is effective only if the analysis is carried out for both positive and negative voltages.

Description: Highly light scattering structures have been generated in a poly(ethylene terephthalate) (PET) film using a CO2 laser. The haze, and in some cases the transparency, of the PET films have been improved by varying the processing parameters of the laser (namely, scanning velocity, laser output power, and spacing between processed tracks). When compared with the unprocessed PET, the haze has improved from an average value of 3.26% to a peak of 55.42%, which equates to an absolute improvement of 52.16% or a 17-fold increase. In addition to the optical properties, the surfaces have been characterised using optical microscopy and mapped with an optical profilometer. Key surface parameters that equate to the amount and structure of surface roughness and features have been analysed. The CO2 laser generates microstructures at high speed, without affecting the bulk properties of the material, and is inherently a chemical-free process making it particularly applicable for use in industry, fitting well with the high-throughput, roll to roll processes associated with the production of flexible organic photovoltaic devices.

Description: This study is aimed at providing a comparison between fuzzy systems and convectional P&O for tracking MPP of a PV system. MATLAB/Simulink is used to investigate the response of both algorithms. Several weather conditions are simulated: (i) uniform irradiation, (ii) sudden changing, and (iii) partial shading. Under partial shading on a PV panel, multipeaks appeared in - characteristics of the panel. Simulation results showed that a fuzzy controller effectively finds MPP for all weather condition scenarios. Furthermore, simulation results obtained from the FLC are compared with those obtained from the P&O controller. The comparison shows that the fuzzy logic controller exhibits a much better behavior.

Description: Currently, standard semitransparent photovoltaic (PV) modules can largely replace architectural glass installed in the windows, skylights, and facade of a building. Their main features are power generation and transparency, as well as possessing a heat insulating effect. Through heat insulation solar glass (HISG) encapsulation technology, this study improved the structure of a typical semitransparent PV module and explored the use of three types of high-reflectivity heat insulation films to form the HISG building-integrated photovoltaics (BIPV) systems. Subsequently, the authors analyzed the influence of HISG structures on the optical, thermal, and power generation performance of the original semitransparent PV module and the degree to which enhanced performance is possible. The experimental results indicated that the heat insulation performance and power generation of HISGs were both improved. Selecting an appropriate heat insulation film so that a larger amount of reflective solar radiation is absorbed by the back side of the HISG can yield greater enhancement of power generation. The numerical results conducted in this study also indicated that HISG BIPV system not only provides the passive energy needed for power loading in a building, but also decreases the energy consumption of the HVAC system in subtropical and temperate regions.

Description: Photovoltaic (PV) generators suffer from fluctuating output power due to the highly fluctuating primary energy source. With significant PV penetration, these fluctuations can lead to power system instability and power quality problems. The use of energy storage systems as fluctuation compensators has been proposed as means to mitigate these problems. In this paper, the behavior of PV power fluctuations in Northern European climatic conditions and requirements for sizing the energy storage systems to compensate them have been investigated and compared to similar studies done in Southern European climate. These investigations have been performed through simulations that utilize measurements from the Tampere University of Technology solar PV power station research plant in Finland. An enhanced energy storage charging control strategy has been developed and tested. Energy storage capacity, power, and cycling requirements have been derived for different PV generator sizes and power ramp rate requirements. The developed control strategy leads to lesser performance requirements for the energy storage systems compared to the methods presented earlier. Further, some differences on the operation of PV generators in Northern and Southern European climates have been detected.

Description: Recent research and development of clean energy have become essential due to the global climate change problem, which is caused largely by fossil fuels burning. Therefore, biodiesel, a renewable and ecofriendly biofuel with less environmental impact than diesel, continues expanding worldwide. The process for biodiesel production involves a significant energy demand, specifically in the methanol recovery stage through a flash separator and a distillation column. Traditionally, the energy required for this process is supplied by fossil fuels. It represents an opportunity for the application of renewable energy. Hence, the current study presents a system of thermal energy storage modeled in TRNSYS® and supported by simulations performed in ASPEN PLUS®. The aim of this research was to supply solar energy for a methanol recovery stage in a biodiesel production process. The results highlighted that it is feasible to meet 91% of the energy demand with an array of 9 parabolic trough collectors. The array obtained from the simulation was 3 in series and 3 in parallel, with a total area of 118.8 m2. It represents an energy saving of 70 MWh per year.

Description: Solar energy conversion is an object of continuous research, focusing on improving the energy efficiency as well as the structure of photovoltaic cells. With efficiencies continuously increasing, state-of-the-art PV cells offer a good solution to harvest solar energy. However, they are still lacking the flexibility and conformability to be integrated into common objects or clothing. Moreover, many sun-exposed surface areas are textile-based such as garments, tents, truck coverings, boat sails, and home or outdoor textiles. Here, we present a new textile-based dye-sensitized solar cell (DSC) which takes advantage from the properties inherent to fabrics: flexibility, low weight, and mechanical robustness. Due to the necessary thermostability during manufacturing, our DSC design is based on heat-resistant glass-fiber fabrics. After applying all needed layers, the overall structure was covered by a transparent and simultaneously conductive protective film. The light and still flexible large-area devices (up to 6 cm2 per individual unit) are working with efficiencies up to 1.8% at 1/5 of the sun. Stability tests assure no loss of photovoltaic activity over a period of at least seven weeks. Therefore, our technology has paved the way for a new generation of flexible photovoltaic devices, which can be used for the generation of power in the mentioned applications as well as in modern textile architecture.

Description: Shunting is one of the key issues in industrial silicon solar cells which degrade cell performance. This paper presents an approach for investigation of the performance degradation caused by the presence of ohmic extended shunts at various locations in industrial silicon solar cells. Location, nature, and area of the shunts existing in solar cells have been examined by lock-in infrared thermography (LIT). Based on LIT images and experimental dark I-V curves of solar cell, shunted cell has been modeled, from which loss in fill factor and efficiency due to the specific shunt has been obtained. Distributed diode modeling approach of solar cell has been exploited for obtaining simulation results which were supported by experimental measurements. The presented approach is useful to estimate performance reduction due to specific shunts and to quantify losses, which can help in improving the efficiency of solar cell during production by tackling the shunt related problems based on the level of severity and tolerance.

Description: Solar photovoltaic (PV) energy sources are rapidly gaining potential growth and popularity compared to conventional fossil fuel sources. As the merging of PV systems with existing power sources increases, reliable and accurate PV system identification is essential, to address the highly nonlinear change in PV system dynamic and operational characteristics. This paper deals with the identification of a PV system characteristic with a switch-mode power converter. Measured input-output data are collected from a real PV panel to be used for the identification. The data are divided into estimation and validation sets. The identification methodology is discussed. A Hammerstein-Wiener model is identified and selected due to its suitability to best capture the PV system dynamics, and results and discussion are provided to demonstrate the accuracy of the selected model structure.

Description: An atmospheric pressure chemical vapor deposition (AP-CVD) system has been newly developed for boron silicate glass (BSG) film deposition dedicating to solar cell manufacturing. Using the system, thermal boron diffusion from the BSG film is investigated and confirmed in terms of process stability for surface property before BSG deposition and BSG thickness. No degradation in carrier lifetime is also confirmed. A boron diffusion simulator has been newly developed and demonstrated for optimization of this process. Then, the boron thermal diffusion from AP-CVD BSG is considered to be the suitable method for N-type silicon solar cell manufacturing.

Description: Energy supply together with the data management is one of the key challenges of our century. Specifically, to decrease the climate change effects as energy requirement increases day by day poses a serious dilemma. It can be adequately reconciled with innovative data management in (renewable) energy technologies. The new environmental-friendly planning methods and investments that are discussed by researchers, governments, NGOs, and companies will give the basic and most important variables in shaping the future. We use modern data mining methods (SOM and -Means) and official governmental statistics for clustering cities according to their consumption similarities, the level of welfare, and growth rate and compare them with their potential of renewable resources with the help of Rapid Miner 5.1 and MATLAB software. The data mining was chosen to make the possible secret relations visible within the variables that can be unpredictable at first sight. Here, we aim to see the success level of the chosen algorithms in validation process simultaneously with the utilized software. Additionally, we aim to improve innovative approach for decision-makers and stakeholders about which renewable resource is the most suitable for an exact region by taking care of different variables at the same time.

Description: To quickly and precisely extract the parameters for solar cell models, inspired by simplified bird mating optimizer (SBMO), a new optimization technology referred to as population classification evolution (PCE) is proposed. PCE divides the population into two groups, elite and ordinary, to reach a better compromise between exploitation and exploration. For the evolution of elite individuals, we adopt the idea of parthenogenesis in nature to afford a fast exploitation. For the evolution of ordinary individuals, we adopt an effective differential evolution strategy and a random movement of small probability is added to strengthen the ability to jump out of a local optimum, which affords a fast exploration. The proposed PCE is first estimated on 13 classic benchmark functions. The experimental results demonstrate that PCE yields the best results on 11 functions by comparing it with six evolutional algorithms. Then, PCE is applied to extract the parameters for solar cell models, that is, the single diode and the double diode. The experimental analyses demonstrate that the proposed PCE is superior when comparing it with other optimization algorithms for parameter identification. Moreover, PCE is tested using three different sources of data with good accuracy.

Description: We have studied the p-type hydrogenated silicon oxide (:H) films prepared in the amorphous-to-microcrystalline transition region as a window layer in a-Si:H/a-:H multijunction solar cells. By increasing the -to- flow ratio () from 10 to 167, the :H(p) films remained amorphous and exhibited an increased hydrogen content from 10.2% to 12.2%. Compared to the amorphous :H(p) film prepared at low , the :H(p) film deposited at of 167 exhibited a higher bandgap of 2.04 eV and a higher conductivity of 1.15 × 10−5 S/cm. With the employment of :H(p) films prepared by increasing from 10 to 167 in a-Si:H single-junction cell, the FF improved from 65% to 70% and the efficiency increased from 7.4% to 8.7%, owing to the enhanced optoelectrical properties of :H(p) and the improved p/i interface. However, the cell that employed :H(p) film with over 175 degraded the p/i interface and degraded the cell performance, which were arising from the onset of crystallization in the window layer. Compared to the cell using standard a-:H(p), the a-Si:H/a-:H tandem cells employing :H(p) deposited with of 167 showed an improved efficiency from 9.3% to 10.3%, with of 1.60 V, of 9.3 mA/cm2, and FF of 68.9%.

Description: Subpicosecond transient absorption spectroscopy is a powerful tool used to clarify the exciton and carrier dynamics within the organic solar cells (OSCs). In this review article, we introduce a method to determine the absolute numbers of the excitons and carriers against delay time (t) only from the photoinduced absorption (PIA) and electrochemically induced absorption (EIA) spectra. Application of this method to rr-P3HT-, PTB7-, and SMDPPEH-based OSCs revealed common aspects of the carrier formation dynamics. First, the temporal evolution of the numbers of the excitons and carriers indicates that the late decay component of exciton does not contribute to the carrier formation process. This is probably because the late component has not enough excess energy to separate into the electron and hole across the donor/acceptor (D/A) interface. Secondly, the spectroscopy revealed that the exciton-to-carrier conversion process is insensitive to temperature. This observation, together with the fast carrier formation time in OSCs, is consistent with the hot exciton picture.

Description: Here we report a facile, efficient, and catalyst-free method to realize C-C cross-coupling of aryl chlorides and inert arenes under UV light irradiation. The aryl radical upon homolytic cleavage of C-Cl bond initiated the nucleophilic substitution reaction with inert arenes to give biaryl products. This mild reaction mode can also be applied to other synthetic reactions, such as the construction of C-N bonds and trifluoromethylated compounds.

Description: Al doped SnO2 microspheres were prepared through hydrothermal method. As-prepared SnO2 microspheres were applied as photoanode materials in dye-sensitized solar cells (DSCs). The properties of the assembled DSCs were significantly improved, especially the open-circuit voltage. The reason for the enhancement was explored through the investigation of dark current curves and electrochemistry impedance spectra. These results showed that the Al doping significantly increased the reaction resistance of recombination reactions and restrained the dark current. The efficient lifetime of photoexcited electrons was also obviously lengthened.

Description: We have explored the effective approach to fabricate GZO/ZnO films that can make the pyramidal surface structures of GZO films for effective light scattering by employing a low temperature ZnO buffer layer prior to high temperature GZO film growth. The GZO thin films exhibit the typical preferred growth orientations along the (002) crystallographic direction at deposition temperature of 400°C and SEM showed that column-like granule structure with planar surface was formed. In contrast, GZO films with a pyramidal texture surface were successfully developed by the control of (110) preferred orientation. We found that the light diffuse transmittance of the film with a GZO (800 nm)/ZnO (766 nm) exhibited 13% increase at 420 nm wavelength due to the formed large grain size of the pyramidal texture surface. Thus, the obtained GZO films deposited over ZnO buffer layer have high potential for use as front TCO layers in Si-based thin film solar cells. These results could develop the potential way to fabricate TCO based ZnO thin film using MOCVD or sputtering techniques by depositing a low temperature ZnO layer to serve as a template for high temperature GZO film growth. The GZO films exhibited satisfactory optoelectric properties.

Description: The work presents results of studies on 2,4-dichlorophenol (2,4-DCP) degradation in aqueous solutions using photochemically initiated processes by simulated and natural sunlight. A number of possible substrate photodegradation routes were investigated, by both direct photolysis and photosensitized oxidation process. The major role of singlet oxygen in 2,4-DCP photodegradation was proved. Rose Bengal and derivatives of porphine and phthalocyanine were used as sensitizers. The influences of various process parameters on the reaction rate were investigated. On the basis of experimental data reaction rate constants of 2,4-DCP photosensitized oxidation were determined. The possibility of using natural sunlight to degrade 2,4-DCP in water in the middle latitudes was stated. The acute toxicity bioassay was conducted with the marine bacterium Vibrio fischeri as a bioluminescent indicator. The obtained results encourage further research on this process.

Description: Medium-scale photovoltaic (PV) systems using cascaded H-bridge multilevel inverters have a capability to perform individual maximum power point tracking (MPPT) for each PV panel or each small group of panels, resulting in minimization of both power losses from panel mismatch and effect of partial shading. They also provide high power quality, modularity, and possibility of eliminating dc-dc boost stage and line-frequency transformer. However, each PV panel in the system is subjected to a double-line-frequency voltage ripple at the dc-link which reduces the MPPT efficiency. This paper proposes a dc-link voltage ripple reduction by third-harmonic zero-sequence voltage injection for improving the MPPT efficiency. Moreover, a control method to achieve individual MPPT control of each inverter cell is also presented. The validity and effectiveness of the proposed methods were verified by computer simulation.

Description: Free radicals formed by UV irradiation of the two magistral formulas applied on the skin, salicylic acid and urea, were examined by X-band (9.3 GHz) EPR spectroscopy. The influence of the time of UVA (315–400 nm) irradiation on free radical properties and concentrations in the drug samples was determined. The nonirradiated magistral formula did not contain free radicals. Amplitudes () and linewidths () of EPR spectra were analysed. Fast spin-lattice relaxation process existed in the tested drugs. UV irradiation did not change spin-lattice interactions in the tested magistral formula. Concentrations of free radicals formed by UV irradiation in salicylic acid and urea were ~1017–1018 spins/g. The strongest formation of free radicals under UV irradiation was observed for salicylic acid than for urea. Free radical concentration in salicylic acid increased with the increase of UV irradiation time from 15 minutes to 30 minutes, and after its value remained unchanged. The increase of free radical concentration in urea with UV irradiation time was stated. Salicylic acid is characterized with higher photosensitivity than urea. Salicylic acid, urea, and the skin treated by them should not be stored on UV exposure. The usefulness of EPR spectroscopy to optimize storage conditions of recipe drugs was conformed.

Description: We investigated the antireflective (AR) effect of hydrogenated nanocrystalline cubic silicon carbide (nc-3C-SiC:H) emitter and its application in the triple layer AR design for the front side of silicon heterojunction (SHJ) solar cell. We found that the nc-3C-SiC:H emitter can serve both as an emitter and antireflective coating for SHJ solar cell, which enables us to realize the triple AR design by adding one additional dielectric layer to normally used SHJ structure with a transparent conductive oxide (TCO) and an emitter layer. The optimized SHJ structure with the triple layer AR coating (LiF/ITO/nc-3C-SiC:H) exhibit a short circuit current density () of 38.65 mA/cm2 and lower reflectivity of about 3.42% at wavelength range of 300 nm–1000 nm.

Description: The objective of this work is to investigate the performance of chlorophyll sensitized solar cells (CSSCs) with gel electrolyte based on polyvinyl alcohol (PVA) with single iodide salt (potassium iodide (KI)) and double salt (KI and tetrapropylammonium iodide (TPAI)). Chlorophyll was extracted from the bryophyte Hyophila involuta. The CSSC with electrolyte containing only KI salt produced a short circuit current density () of 4.59 mA cm−2, open circuit voltage () of 0.61 V, fill factor (FF) of 0.64, and efficiency () of 1.77%. However, the CSSC with double salt electrolyte exhibited of 5.96 mA cm−2, of 0.58 V, fill factor FF of 0.58, and of 2.00%. Since CSSC with double salt electrolyte showed better efficiency, other cells fabricated will use the double salt electrolyte. On addition of 0.7 M tetrabutyl pyridine (TBP) to the double salt electrolyte, the cell’s efficiency increased to 2.17%,  mA cm−2,  V, and FF = 0.73. With 5 mM chenodeoxycholic acid (CDCA) added to the chlorophyll, the light to electricity efficiency increased to 2.62% with of 8.44 mA cm−2, of 0.54 V, and FF of 0.58.

Description: In this paper, the effects that photovoltaic (PV) panels have on the rooftop temperature in the EnergyPlus simulation environment were investigated for the following cases: with and without PV panels, with and without exposure to sunlight, and using roof materials with different thermal conductivities and for different climatic zones. The results demonstrate that heat transfer by convection, radiation, and conduction in the air gaps between PV panels and the building envelope can be simulated in the EnergyPlus environment when these air gaps are in the “air conditioning zone.” Nevertheless, in most cases, particularly on the rooftop, the air gaps between the PV panels and the building envelope cannot be set as the “air conditioning zone.” Therefore, in this case, none of the EnergyPlus models are appropriate to simulate the effect that PV panels have on the rooftop temperature. However, all the terms of the Heat Balance Model, including the absorbed direct and diffuse solar radiation, net long-wave radiation with the air and surroundings, convective exchange with the outside air, and conduction flux in or out of the surface, can still be used to calculate the temperature and heat flux within the BIPV’s air gap.

Description: Photobiomodulation at a wavelength of 670 nm has been shown to be effective in preventing photoreceptor cell death in the retina. We treated Sprague-Dawley (SD) rats with varying doses of 670 nm light (9; 18; 36; 90 J/cm2) before exposing them to different intensities of damaging white light (750; 1000; 1500 lux). 670 nm light exhibited a biphasic response in its amelioration of cell death in light-induced degeneration in vivo. Lower light damage intensities required lower doses of 670 nm light to reduce TUNEL cell death. At higher damage intensities, the highest dose of 670 nm light showed protection. In vitro, the Seahorse XFe96 Extracellular Flux Analyzer revealed that 670 nm light directly influences mitochondrial metabolism by increasing the spare respiratory capacity of mitochondria in 661 W photoreceptor-like cells in light damaged conditions. Our findings further support the use of 670 nm light as an effective treatment against retinal degeneration as well as shedding light on the mechanism of protection through the increase of the mitochondrial spare respiratory capacity.

Description: TiO2 has been widely used as a key catalyst in photocatalytic reactions; it also shows good catalytic activity for esterification reactions. Different sulfated M-TiO2 nanoparticles (M = Ag, Au, Rh, and Pt) were prepared by photodeposition and ultrasonic methods. The results show that the noble metal nanoparticles, which were loaded onto a TiO2 surface, slightly affected the crystal phase and particle size of TiO2. Among all the catalysts, /Au-TiO2 exhibited the best catalytic activity in the esterification reaction for the synthesis of citric acid n-butyl acetate and in the decomposition of methyl orange, as confirmed by a high conversion rate of up to 98.2% and 100% degradation rate, respectively. This can be attributed to an increase in the Lewis acidity of the catalyst and increased separation efficiency of electron-hole pairs. This superior catalyst has great potential applications in esterification reactions and wastewater treatments.

Description: Perfluorinated chemicals have attracted worldwide concern owing to their wide occurrence and resistance to most conventional treatment processes. In this work, a novel photocatalyst was fabricated by modifying TiO2 nanotube arrays with molecularly imprinted polymers. The molecularly imprinted polymer-modified TiO2 nanotubes (MIP-TiO2 NTs) were characterized and tested for the selective removal of perfluorooctanoic acid (PFOA) from water. The amount of PFOA adsorbed by the MIP-TiO2 NTs was as high as 0.8125 μg/cm2. PFOA decomposition and defluorination by the MIP-TiO2 NTs reached 84% and 30.2% after 8 h reaction, respectively. The Freundlich model and pseudo-first-order kinetics were used to describe the observed adsorption and decomposition of PFOA, respectively. Compared with TiO2 NTs and nonmolecularly imprinted polymer-modified TiO2 NTs, the MIP-TiO2 NTs exhibited not only a higher PFOA degradation rate but also enhanced selectivity for target chemicals. The MIP-TiO2 NTs could also selectively and rapidly remove PFOA from secondary effluent, exhibiting a decomposition of 81.1%, almost as high as that observed in pure water. Investigation of the effects of scavengers on the photocatalytic reaction indicated that photogenerated holes were the main oxidant for PFOA decomposition, and the PFOA degradation mechanism and pathway were proposed.

Description: A series of CdS/ nanocomposites with different Cd to Ti molar ratio were synthesized from P25- nanopowder using microwave-assisted hydrothermal method. The as-produced powders were characterized by XRD, electron microscopy, EDX, and UV-Vis diffuse reflectance spectroscopy. The adsorption capacity and photocatalytic activity of the samples were investigated using methylene blue as a model pollutant. Sorption tests revealed that the adsorption of MB onto the samples obeys the Freundlich-Langmuir isotherm model. The sorption capacity decreased as follows: . The results of the photocatalytic tests under high-intensity discharge (HID) lamp revealed that CdS/ powders with low Cd to Ti molar ratios exhibited much higher activities than P25-. The CdS/ sample with 20% CdS/(TCd2) showed the most activity among all these samples. The results also show that the Cd to Ti molar ratio of the nanocomposite has a significant effect on the photodegradation of MB and the enhanced activities exhibited by the nanocomposites are because of the low rate of electron-hole recombination.

Description: The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS) cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature () on Gibbs free energy related to the H2 production step were examined in detail. The cycle () and solar-to-fuel energy conversion () efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that and increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (). It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At  K, by applying 60% heat recuperation, maximum of 39.0% and of 47.1% for the Tb-WS cycle can be attained.

Description: Eight coumarin derivative dyes were studied by varying the π-bridge size with different thiophene and thiazole units for their potential use in dye-sensitized solar cells (DSSC). Geometry optimization, the energy levels and electron density of the Highest Occupied Molecular Orbital and the Lowest Unoccupied Molecular Orbital, and ultraviolet-visible absorption spectra were calculated by Density Functional Theory (DFT) and Time-Dependent-DFT. All molecular properties were analyzed to decide which dye was the most efficient. Furthermore, chemical reactivity parameters, such as chemical hardness, electrophilicity index, and electroaccepting power, were obtained and analyzed, whose values predicted the properties of the dyes in addition to the rest of the studied molecular properties. Our calculations allow us to qualitatively study dye molecules and choose the best for use in a DSSC. The effects of π-bridges based on thiophenes, thiazoles, and combinations of the two were reviewed; dyes with three units mainly of thiazole were chosen as the best photosensitizers for DSSC.

Description: PV power plants have been recently installed in very large scale. So the effects of the solar eclipse are of big importance especially for grid connected photovoltaic (PV) systems. There was a partial solar eclipse in Prague on 20th March 2015. We have evaluated the data from our facility in order to monitor the impact of this natural phenomenon on the behavior of PV system, and these results are presented in the paper. The behavior of PV system corresponds with the theoretical assumption. The power decrease of the PV array corresponds with the relative size of the solar eclipse. - characteristics of the PV panel correspond to the theoretical model presented in our previous work.

Description: Environmental problems related to the generation of wastewater contaminated with organic compounds and the emissions of pollutants from fuel burning have become major global problems. Thus, there is a need for the development of alternative and economically viable technologies for the remediation of the affected ecosystems. Therefore, this work describes the preparation and characterization of a Ti(OH)4 catalyst with the modified surface for application in the photodegradation of organic compounds (methylene blue (MB) dye and the drug amiloride (AML)) and in the artificial photosynthesis process. Characterization results reveal that peroxo groups on the surface of the catalyst had a great influence on the optical properties of the Ti(OH)4 and consequently in its photocatalytic property. This catalyst showed a high photocatalytic activity for the degradation of organic pollutants under visible radiation, reaching approximately 98% removal of both the dye and the drug in 150 min of reaction. In addition, the catalyst presented a great potential for the reduction of CO2 under ultraviolet (UV) radiation when compared to P25, which is a classic catalyst used in photocatalytic processes. The highest photocatalytic activity can be attributed to the strong visible light absorption, due to the narrow band gap, and the effective separation of photogenerated electron-hole pairs caused by the peroxo groups on the Ti(OH)4 surface.

Description: Copper Indium Gallium Selenide- (CIGS-) based solar cells have become one of the most promising candidates among the thin film technologies for solar power generation. The current record efficiency of CIGS has reached 22.6% which is comparable to the crystalline silicon- (c-Si-) based solar cells. However, material properties and efficiency on small area devices are crucial aspects to be considered before manufacturing into large scale. The process for each layer of the CIGS solar cells, including the type of substrate used and deposition condition for the molybdenum back contact, will give a direct impact to the efficiency of the fabricated device. In this paper, brief introduction on the production, efficiency, etc. of a-Si, CdTe, and CIGS thin film solar cells and c-Si solar cells are first reviewed, followed by the recent progress of substrates. Different deposition techniques’ influence on the properties of molybdenum back contact for CIGS are discussed. Then, the formation and thickness influence factors of the interfacial MoSe2 layer are reviewed; its role in forming ohmic contact, possible detrimental effects, and characterization of the barrier layers are specified. Scale-up challenges/issues of CIGS module production are also presented to give an insight into commercializing CIGS solar cells.

Description: The photocatalyzed water splitting reaction in aqueous methanol solution is an efficient preparation method for hydrogen and methanal under mild conditions. In this work, metal sulfide-loaded TiO2 photocatalysts for hydrogen and methanol production were synthesized by hydrothermal method (180°C/12 h) and characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The crystal structures of the samples are the typical anatase phase of TiO2 and exhibit a spherical morphology. When TiO2 was loaded with CoS, ZnS, and Bi2S3, respectively, the resulting catalysts showed photocatalytic activities for water decomposition to hydrogen in aqueous methanol solution under 300 W Xe lamp irradiation. Among the photocatalysts with various compositions, the 20 wt% CoS/TiO2 sample with a 2.1 eV band gap showed the maximum photocatalytic activity for the photocatalytic reaction, which indicated that CoS improved the separation ratio of photoexcited electrons and holes. The enhanced activity can be attributed to the intimate junctions that are formed between CoS and TiO2, which can reduce the electron-hole recombination. The production rate of hydrogen with 20 wt% CoS/TiO2 photocatalyst was about 5.6 mmol/g/h, which was 67 times higher than that of pure TiO2. The formation rate of HCHO was 1.9 mmol/g/h with 98.7% selectivity. Moreover, the CoS/TiO2 photocatalyst demonstrated good reusability and stability. In the present study, it is demonstrated that CoS can act as an effective cocatalyst to enhance the photocatalytic hydrogen and methanal production activity of TiO2. The highly improved performance of the CoS/TiO2 composite was mainly ascribed to the efficient charge separation.

Description: The demand for clean and sustainable energy has spurred research in all forms of renewable energy sources, including solar energy from photovoltaic systems. Grid-connected photovoltaic systems (GCPS) provide an effective solution to integrate solar energy into the existing grid. A key component of the GCPS is the inverter. The inverter can have a significant impact on the overall performance of the GCPS, including maximum power point (MPP) tracking, total harmonic distortion (THD), and efficiency. Multilevel inverters are one of the most promising classes of converters that offer a low THD. In this paper, we propose a new multilevel inverter topology with the motivation to improve all the three aforementioned aspects of performance. The proposed topology is controlled through direct model predictive control (DMPC), which is state of the art in control techniques. We compare the performance of the proposed topology with the topologies reported in literature. The proposed topology offers one of the best efficiency, MPP tracking, and voltage THD.

Description: In this work, thin CdS films have been deposited using the chemical bath deposition technique (CBD). Different synthesis parameters, such as number of runs, deposition time, and postannealing temperature, are studied and optimized in order to avoid the supersaturation phenomenon and to achieve a low-temperature growth. CdS thin films, of cubic structure, oriented along the (111) direction with homogenous and smooth surface, have been deposited by using the CBD growth process without any annealing treatment. Based on a set of experimental observations, we show that the solution saturation phenomenon can be avoided if the deposition is performed in several runs at a short deposition time. Throughout the CBD technique, it is then possible not only to overcome any film thickness limitation but also to grow the CdS films in a single technological step at a low temperature and without any postdeposition annealing treatment. CdS films with excellent structural quality and a controllable thickness are obtained when the deposition bath temperature is fixed at 65°C. In addition, deposited films exhibit an optical transmittance ranging from 70 to 95% depending on the synthesis parameters, with band gap energy around 2.42 eV. The process developed in this work might be useful for depositing CdS films on flexible substrates.

Description: This paper deals with the analysis and interpretation of flow visualization and residence time distribution (RTD) in a compound parabolic concentrator (CPC) reactor using computational fluid dynamics (CFD). CFD was calculated under turbulent flow conditions solving the Reynolds averaged Navier–Stokes (RANS) equation expressed in terms of turbulent viscosity and the standard k−ε turbulent model in 3D. A 3D diffusion-convection model was implemented in the CPC reactor to determine the RTD. The fluid flow visualization and RTD were validated with experimental results. The CFD showed that the magnitude of the velocity field remains almost uniform in most of the bulk reactor, although near and inside the 90° connectors and the union segments, the velocity presented low- and high-speed zones. Comparisons of theoretical and experimental RTD curves showed that the k−ε model is appropriate to simulate the nonideal flow inside the CPC reactor under turbulent flow conditions.

Description: Recently, binary metal oxides have been proven to be the most investigated semiconductors due to their high activity for the removal of organic pollutants. In this paper, to improve the photocatalytic efficiency of MgFe2O4, a MgFe2O4/reduced graphene oxide (MFO/rGO) photocatalyst was synthesized by a facile generalized solvothermal method. The morphology, structure, and photocatalytic activities in the degradation of methyl orange (MO) reaction were systematically characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and UV-vis absorption spectroscopy, respectively. The results showed that the MFO/rGO composite exhibited enhanced photocatalytic performance in the photodegradation of MO under visible-light irradiation and reached a maximum degradation rate of 99% within 60 min of irradiation. This excellent photocatalytic performance is attributed to the introduction of rGO in the composite, which can effectively reduce the photoproduction of the electron-hole pair recombination rate. The excellent photocatalytic activity reveals that the MFO/rGO composite photocatalyst is a promising photocatalyst with good visible-light response and has potential applications in the field of water treatment.

Description: Luminous efficacy model uses solar radiation data to generate illuminance data, and its performance also depends on the quality of solar radiation data. Various luminous efficacy models are reviewed and evaluated to select a universal luminous efficacy model. Since most luminous efficacy models are fitted with specific local climate characteristics, the model that has the least locality as well as accuracy is a mandatory requirement. Three representative luminous efficacy models are selected and evaluated with measured solar radiation and illuminance data from four worldwide cities. It was found that all the evaluated models provide good predictions (over 0.96 value) for both global and diffuse illuminance. Among them, the Perez luminous efficacy model shows the highest performance in terms of accuracy and bias. However, illuminance data prediction based on estimated solar radiation data is more common practice rather than those from measured solar data. The performance of the selected luminous efficacy models is evaluated when recently proposed universal solar radiation model supplies predicted solar radiation data. The result indicates that the quality of estimated solar radiation data has a much deeper impact on the performance of the luminous efficacy model. Within the current limited technology and measured data resource, the consecutive processing of the modified Zhang and Huang solar model and Perez luminous efficacy model could provide the best option to predict both global and diffuse solar radiation and illuminance. But, users of the model-based illuminance data should interpret their simulation results with the error (30%~40% in RMSE and ±6% in MBE) in predicting global and diffuse illuminance.

Description: The outdoor operating photovoltaic arrays have two different shading conditions, shadowing and covering. The shading causes a decrease in output power of photovoltaic system and may bring hot spots which causes physical damage to the array. This paper studies the electrical parameter distribution feature of photovoltaic array under different shading conditions by means of analog simulation and empirical testing. Through introducing theoretical computational method of the electrical parameters, it describes the distribution features of the electrical parameters of photovoltaic array. The results indicate that the influence of local shadowing on the current of array can be neglected. Shadowing decreases the optimal operating voltage while covering leads to a decrease in the optimal operating voltage and the open-circuit voltage. The drop magnitude of voltage is associated with the number of the shaded cell strings and the string voltage. The two shading types can be identified on the basis of distribution rules of open-circuit voltage and optimal operating voltage. Simulations and experiments verify the consistency of the rules. Relevant conclusions provide a reference for modeling, online fault diagnosis, and optimization design of the maximum power tracking algorithm of photovoltaic array under different shading conditions.

Description: Wickless gravity loop thermosiphons (LTs) have been widely used in heat collection for distances up to several meters. This two-phase closed device, which is operating under reduced pressure, is useful in solar water heating (SWH) systems because it could address the freezing problem during winter. Compared to the normal type, forced-circulation wickless LTs have significant advantages in the long-distance heat transfer and installation freedom of condensation section. In this study, a pump-forced wickless LT-SWH system with a remolded flat-plate solar collector was put forward. Solar collector acted as the evaporation section of the wickless LT, while the spiral heat exchanger in the water tank acted as the condensation section. R600a was employed as the working fluid, and long-term outdoor experiments were carried out. Results show that the instantaneous and daily average photothermal efficiency of the proposed system can reach 69.54% and 58.22%, respectively. Temperature differences between the top and bottom and the middle and bottom of the evaporation section of the wickless LT were small, and it usually ranged between 1.1 and 3.9°C. Linear fittings of the collector and system overall performance of the pump-forced wickless LT-SWH system demonstrate the promising potential application of the system.

Description: In this paper, two main contributions are presented to manage the power flow between a wind turbine and a solar power system. The first one is to use the fuzzy logic controller as an objective to find the maximum power point tracking, applied to a hybrid wind-solar system, at fixed atmospheric conditions. The second one is to respond to real-time control system constraints and to improve the generating system performance. For this, a hardware implementation of the proposed algorithm is performed using the Xilinx System Generator. The experimental simulation results show that the suggested system presents high accuracy and acceptable execution time performances. The proposed model and its control strategy offer a proper tool for optimizing the hybrid power system performance which we can use in smart house applications.

Description: A series of three-dimensional microflower-like Ag/Bi2WO6 composites were synthesized through a simple and practical photoreduction process with different photoreduction times. The UV-visible diffuse reflectance spectra indicate that the spectrum of Ag/Bi2WO6 is significantly red-shifted compared to pure Bi2WO6 microspheres in the visible light region. The photocatalytic activities of the as-prepared samples were evaluated by the decolorization of rhodamine B under visible light irradiation. The photocatalytic reaction rate constants of the Ag/Bi2WO6 with a photoreduction time of 20 min was 3.60 times bigger than those of pure Bi2WO6. The enhanced photocatalytic activity could be attributed to the synergistic effect of increased light absorption range and the effective separation of photogenerated carriers caused by Ag nanoparticles.

Description: Anatase TiO2 presents a large bandgap of 3.2 eV, which inhibits the use of visible light radiation ( 〉 387 nm) for generating charge carriers. We studied the activation of TiO2 (101) anatase with visible light by doping with C, N, S, and F atoms. For this purpose, density functional theory and the Hubbard approach are used. We identify two ways for activating the TiO2 with visible light. The first mechanism is broadening the valence or conduction band; for example, in the S-doped TiO2 (101) system, the valence band is broadened. A similar process can occur in the conduction band when the undercoordinated Ti atoms are exposed on the TiO2 (101) surface. The second mechanism, and more efficient for activating the anatase, is to generate localized states in the gap: N-doping creates localized empty states in the bandgap. For C-doping, the surface TiO2 (101) presents a “cleaner” gap than the bulk TiO2, resulting in fewer recombination centers. The dopant valence electrons determine the number and position of the localized states in the bandgap. The formation of charge carriers with visible light is highly favored by the oxygen vacancies on TiO2 (101). The catalytic activity of C-doping using visible radiation can be explained by its high absorption intensity generated by oxygen vacancies on the surface. The intensity of the visible absorption spectrum of doped TiO2 (101) follows the order: C 〉 N 〉 F 〉 S dopant.

Description: The focus of this paper is to predict the transient response of a nanoengineered photovoltaic thermal (PV/T) system in view of energy and exergy analyses. Instead of a circular-shaped receiver, a trapezoidal-shaped receiver is employed to increase heat transfer surface area with photovoltaic (PV) cells for improvement of heat extraction and thus achievement of a higher PV/T system efficiency. The dynamic mathematical model is developed using MATLAB® software by considering real-time heat transfer coefficients. The proposed model is validated with experimental data from a previous study. Negligible discrepancies were found between measured and predicted data. The validated model was further investigated in detail using different nanofluids by dispersing copper oxide (CuO) and aluminum oxide (Al2O3) in pure water. The overall performance of the nanoengineered PV/T system was compared to that of a PV/T system using water only, and optimal operating conditions were determined for maximum useful energy and exergy rates. The results indicated that the CuO/water nanofluid has a notable impact on the energy and exergy efficiencies of the PV/T system compared to that of Al2O3/water nanofluid and water only cases.

Description: The existence of H2S has limited the biogas energy promotion. The traditional photodegradation of H2S is usually conducted in the presence of O2, yet this is unsuitable for biogas desulfurization which should be avoided. Therefore, the ultraviolet degradation of H2S in the absence of O2 was investigated for the first time in the present study from a mathematical point of view. Light wavelength and intensity applied were 185 nm and 2.16 × 10−12 Einstein/cm2·s, respectively. Firstly, the mathematical model of H2S photodegradation was established with MATLAB software, including the gas flow distribution model and radiation model of photoreactor, kinetics model, mass balance model, and calculation model of the degradation rate. Then, the influence of the initial H2S concentration and gas retention time on the photodegradation rate were studied, for verification of the mathematical model. Results indicated that the photodegradation rate decreased with the increase in initial H2S concentration, and the maximum photodegradation rate reached 62.8% under initial concentration of 3 mg/m3. In addition, the photodegradation rate of H2S increased with the increase in retention time. The experimental results were in good accordance with the modeling results, indicating the feasibility of the mathematical model to simulate the photodegradation of H2S. Finally, the intermediate products were simulated and results showed that the main photodegradation products were found to be H2 and elemental S, and concentrations of the two main products were close and agreed well with the reaction stoichiometric coefficients. Moreover, the concentration of free radicals of H• and SH• was rather low.

Description: The objective of this paper is to establish the performance of 8 kWp grid-connected photovoltaic (PV) power systems based on different PV module technologies in Nanjing, China. Nanjing has a hot summer and a cold winter which are considered based on monthly average solar irradiation and ambient temperature specifically for the deployment of grid-connected PV systems. The study focuses on performance assessment of grid-connected PV systems using typical PV modules made of monocrystalline silicon (m-Si), polycrystalline silicon (p-Si), edge-defined film-fed growth silicon (EFG-Si), cadmium telluride (CdTe) thin film, copper indium selenide (CIS) thin film, heterojunction with intrinsic thin layer (HIT), and hydrogenated amorphous silicon single-junction (a-Si:H single-PV) installed on location. The yearly average energy output, PV module and system efficiency, array yield, final yield, reference yield, performance ratio, monthly average array capture losses, and system losses of seven PV module technologies are all analyzed. The results show that grid-connected PV power system performance depends on geographical location, PV module types, and climate conditions such as solar radiation and ambient temperature. In addition, based on energy output and efficiency, the HIT PV power technology can be considered as the best option and CdTe and p-Si as the least suitable options for this area. The monthly average performance ratio of the CdTe technology was higher than those of other technologies over the monitoring period in Nanjing.

Description: In this work, the seasonal and yearly optical performance of supported catalyst CPC solar photocatalytic reactors has been theoretically analyzed. A detailed model for the optical response of the anatase catalyst films is utilized, based on the characteristic matrix method, together with Monte Carlo ray tracing simulations. The catalyst is supported over glass tubes contained inside a larger glass tube that functions as receiver of the CPC reflector. Arrangements with four, five, and six tubes are considered. Overall, the four-tube scenario presents the worst performance of all, followed by the five-tube case. In general, the six-tube configuration is better. Nevertheless, important differences can be observed depending on the specific arrangement of tubes. The six-tube case surpasses the absorption rate of all the other configurations when the distance between tubes is extended. This configuration exhibits 27% increased yearly energy absorption with respect to the reference case and 47% with respect to the worst case scenario.

Description: Effects of polysilane additions on CH3NH3PbI3 perovskite solar cells were investigated. Photovoltaic cells were fabricated by a spin-coating method using perovskite precursor solutions with polymethyl phenylsilane, polyphenylsilane, or decaphenyl cyclopentasilane (DPPS), and the microstructures were examined by X-ray diffraction and optical microscopy. Open-circuit voltages were increased by introducing these polysilanes, and short-circuit current density was increased by the DPPS addition, which resulted in the improvement of the photoconversion efficiencies to 10.46%. The incident photon-to-current conversion efficiencies were also increased in the range of 400~750 nm. Microstructure analysis indicated the formation of a dense interfacial structure by grain growth and increase of surface coverage of the perovskite layer with DPPS, and the formation of PbI2 was suppressed, leading to the improvement of photovoltaic properties.

Description: Photochromic 5-phenylpyrazolidin-3-one-based azomethine imines containing 2-((1H-imidazol-2-yl)methylene) 1, 2-(pyridin-2-ylmethylene) 2, 2-(quinolin-2-ylmethylene) 3, and 2-((8-hydroxyquinolin-2-yl)methylene) 4 substituents were synthesized. All the compounds exist in the ring-opened O forms. Under irradiation with light of 365 nm, compounds 1–4 undergo thermally reversible isomerization into ring-closed bicyclic diaziridine isomers C. Azomethine imines 1–3 exhibit properties of ion-active molecular “off-on” switches of fluorescence when interacting with F− or AcO− anions. Compound 4 represents a bifunctional chemosensor demonstrating a colorimetric “naked-eye” effect for Ni2+ cation and complete fluorescence quenching in the presence of H+, F−, and CN− ions.

Description: Photocatalytic materials based on silica-titania (SiO2-TiO2) were synthesized by sol-gel and dip-coating method. TEOS and titanium butoxide were used as precursors of the silica-titania, respectively. A thin film with anatase phase was obtained on the surface of the support. The effect of variables as dispersion mechanism, immersion time, and number of treatment cycles were studied. The materials were characterized using X-ray diffraction, scanning electron microscopy, energy dispersion scanning, and N2 adsorption-desorption. The highest crystallinity of TiO2 on silica, high specific surface area in TiO2-SiO2 materials, and thin film formation were obtained by using a stirring plate and minimum immersion time. The so synthesized catalyst allowed the production of formaldehyde from the photocatalyzed methanol oxidation in a packed-bed reactor.

Description: The shape and connection type of MOx are critical to the physical and chemical properties. A series of new material Sr2-xNaxNbO4 containing NbO4 tetrahedra was prepared by controlling the ratio of SrCO3 to sodium niobate under ambient air. With increasing the content of Sr in the sample, the MOx shape will change from NbO6 octahedra to NbO4 tetrahedra, which is confirmed by the Raman scattering spectra. With increasing the content of NbO4 in the sample, the lattice parameter increases, optical band gap becomes larger, and the surface changes to be more active for oxygen adsorption, resulting in a higher photocatalytic activity.

Description: This experimental research comparatively investigates the Escherichia coli (E. coli) bacterial inactivation of the TiO2 photocatalytic thin films fabricated by the sol–gel dip-coating (SG) and low-temperature spray-coating (SP) techniques, with low-intensity (12 μW·cm−2) UVA-light-emitting diodes (UVA-LED) as the light source. The bacteriostatic experiments were undertaken using the nutrient broth (NB) and 0.85% NaCl with the initial E. coli concentrations of 102, 104, 106, and 108 CFU·mL−1. Moreover, the essential physical characteristics of the SG-TiO2 and SP-TiO2 photocatalytic thin films were determined prior to the experimental bacterial inactivation. The findings showed that both photocatalytic thin films possessed the ideal physical characteristics, especially the SP-TiO2 thin film. In addition, the viable cell counts, the cell morphology, and the bioluminescence-based adenosine triphosphate (ATP) indicated that both SG-TiO2 and SP-TiO2 thin films under UVA could effectively inhibit the proliferation of the E. coli cells in both NB and 0.85% NaCl.

Description: Three kinds of anthracene-based organic dyes for dye-sensitized solar cells (DSSCs) were studied, and their structures are based on a push–pull framework with anthracenyl diphenylamine as the donor connected to a carboxyphenyl or carboxyphenyl-bromothiazole (BTZ) as the acceptor via an acetylene bridge. The photoelectric properties of the three dyes were investigated using density functional theory (DFT). The simulations indicate that the improvement of anthracene-based dyes (the addition of BTZ and the change of alkyl groups to alkoxy chains) can reduce the energy gap and produce a red shift. This structural modification also improves the light capturing and the electron injection capability, making it excellent in photoelectric conversion efficiency (PCE). In addition, twelve molecules have been designed to regulate photovoltaic performance.

Description: An interconnect electrode called conductive belt was applied to modules instead of interconnection ribbons. The conductive belt has multiple wires and can achieve a multibusbar structure by forming ohmic contacts with the cell electrodes. The following problems were studied with innovative approaches to optimize the multibusbar modules: the shading rate and the contact resistance of the conductive belts, the relationship between the finger series resistance and the wire number, and the influence of the series resistance variation on the maximum power output. Furthermore, the wire number and diameter were optimized according to the following conditions: the cell sizes were full, half, and one-third, and the finger wet weights of a full cell were 80 mg, 40 mg, and 20 mg. The result showed that multibusbar and half-cell structures could achieve the maximum power output, the wire number was 16 and the wire diameter was 200 μm, and the finger wet weight was reduced to 20 mg. Finally, the reliability of the modules made with conductive belts was tested and was qualified according to International Electrotechnical Commission standards.

Description: In recent years, research on noncatalytic methods for biodiesel production has increased, mainly processes under supercritical conditions that allow the processing of waste vegetable oils (WVO) without the need to use catalysts, where the absence of catalyst simplifies the processes of purification of biodiesel. The high consumption of alcohol and energy to maintain the appropriate conditions of pressure and temperature of the reaction has turned the processes of supercritical conditions into an unfeasible method. However, the stages of biodiesel purification and methanol recovery are more straightforward, allowing the reduction of the total energy consumption by 25% compared to alkaline methods. Therefore, the present work describes a study through Aspen Plus® of the production of biodiesel by a process in supercritical conditions with WVO as raw material. Also, a solar collector arrangement was structured using the TRNSYS® simulator to supply energy to the process. To evaluate the economic feasibility of the proposed process, the installation of a pilot plant in Mexicali, Baja California, was considered. The internal rate of return (IRR) and the net present value (NPV) were determined for ten-year period. The planned system allows supplying solar energy, 69.5% of the energy required by the process, thus reducing the burning of fossil fuels and the operation cost. Despite the additional investment cost, for the solar collectors, the process manages to maintain a competitive production cost of USD 0.778/l of biodiesel. With an IRR of 31.7%, the investment is recovered before the fifth year of operation. The integration and implementation of clean technologies are vital in the development of the biofuels.

Description: This paper presents a comparative study of “life cycle cost” or LCC of a building school rooftop element in Jakarta. The simulation applied two different types of roof: a concrete roof and a PV rooftop. The aim of this study is to investigate the electricity production of the solar panels, the saving to investment ratio or SIR, and the total life cycle cost of each rooftop element. To accommodate those objectives, the calculation utilized a software called “Building Life Cycle Cost (BLCC) version 5” which is a product of the US Department of Energy. The simulation results showed that the LCC can be improved by 27.6%, and the “discounted payback” is reached at year 15. Indeed, this indicates that a roof made of solar panels is promising to replace the existing concrete roof.

Description: TiO2/carbon fiber composite is achieved by loading TiO2 nanoparticles on biomass carbon fiber, which originates from the carbonized natural bast. The carbonized process and the loading amount of TiO2 are researched in detail. It is found that the carbonized bast fiber shows robust adsorption characteristics for TiO2 nanoparticles in aqueous dispersion, and TiO2 nanoparticles with ~15 wt.% in total weight are uniformly loaded onto the fiber surface. The photocatalytic properties of TiO2/carbon fiber composite are evaluated by photocatalytic degradation of rhodamine B and water splitting for hydrogen production. The results indicate that 90% RhB molecules could be attacked in 60 min under UV light irradiation, and the hydrogen production rate of water splitting is up to 338.51 μmol/h. The highlight is that TiO2/carbon fiber composite is easy to be recycled due to the incorporation of macroscopical biomass carbon fiber.

Description: As the need to use green chemistry routes increases, environmentally friendly catalytic processes are a demand. One of the most important and abundant naturally occurring catalysts is chlorophyll. Chlorophyll is the first recognized catalyst; it is a reducing agent due to its electron-rich structure. The effects of spinach on the preparation of zinc oxide nanoparticles and the photocatalytic degradation of methyl orange and paraquat in sunlight and under a UV lamp and photocatalytic degradation in sunlight were studied. Different parameters of the catalytic preparation process and photocatalytic degradation process were studied. Characterization of differently prepared samples was carried out using different analytical techniques such as XRD, SEM, and EDX and finally the photocatalytic activity towards decomposition of methyl orange and paraquat.

Description: The photocatalytic degradation of 4-chlorophenol in water using Ru-doped ZnO mixed oxides (0, 0.5, 1, and 3 wt% RuO2) synthesized by the one-pot homogeneous coprecipitation method is reported. ZnO with wurtzite structure was present in the mixed oxide as corroborated by Raman spectroscopy and X-ray diffraction analysis. All the samples showed nanorod morphological features. The presence of Ru6+/Ru4+ couples on ZnO modified the band gap of the mixed oxides and led to a shift of the band gap energy from 3.20 eV to 3.07 eV. Ru addition increased the surface area and significantly promoted the formation of active surface oxygen species such as hydroradicals evidenced by the fluorescence spectroscopy measurement. In the photodegradation of 4-chlorophenol solution under UV irradiation, a notable increase in photoactivity was obtained as the amount of RuO2 in the mixed oxides increased to 3 wt%. The charge transfer between Ru6+/Ru4+ couples and ZnO nanoparticles together with the formation of free radical oxidant species effectively inhibits electron-hole recombination rate, thus favoring the photodegradation of 4-chlorophenol.

Description: Delayed postoperative infection is known as a major complication after bone surgeries using osteosynthetic biomaterial such as titanium (Ti) and bioresorbable organic materials. However, the precise cause of this type of infection is still unclear and no effective prevention has been established. The purpose of this study is to investigate the effect of irradiation with a 405 nm blue-violet laser on the bacteria adhered on the Ti and hydroxyapatite-poly-L-lactic acid- (HA-PLLA) based material surfaces and to verify the possibility of its clinical application to prevent the delayed postoperative infection after bone surgeries using osteosynthetic biomaterial. The suspension of Staphylococcus aureus FDA 209P was delivered onto the surface of disks composed of Ti or HA-PLLA. Bacterial adhesion on each disk was observed using a scanning electron microscope (SEM). After thorough washing with distilled water, the growth of bacteria attached to the material surfaces was examined with an alamar blue-based redox indicator. Moreover, a bactericidal effect of 405 nm blue-violet laser irradiation on residual bacteria on both materials was investigated using colony-forming assay. As a result, there was no significant difference in the bacterial adhesion between Ti and HA-PLLA materials. In contrast, 45 J/cm2 of irradiation with 405 nm blue-violet laser inhibited the bacterial growth at approximately 93% on Ti disks and at approximately 99% on HA-PLLA disks. This study clearly demonstrated the possibility that the irradiation with a 405 nm blue-violet laser is useful as an alternative management strategy for the prevention of delayed postoperative infection after bone surgeries using osteosynthetic biomaterials.

Description: In this study, laser-treated polycrystalline Si (pc-Si) wafers, fabricated by wire sawing of hot-pressed ingots sintered from Si powder, have been investigated. As-cut wafers and those with high-quality thin Si layers deposited on top of them by e-beam have been subjected to laser irradiation to clarify typical trends of structural modifications caused by laser treatments. Moreover, possibility to use laser-treated Si powder-based substrates for fabrication of advanced Si structures has been analysed. It is established that (i) Si powder-based wafers with thicknesses ~180 μm can be fully (from the front to back side) or partly (subsurface region) remelted by a diode laser and grain sizes in laser-treated regions can be increased; (ii) a high-quality top layer can be fabricated by crystallization of an additional a-Si layer deposited by e-beam evaporation on top of the pc-Si; and (iii) silicon nanowires can be formed by metal-assisted wet chemical etching (MAWCE) of polished Si powder-based wafers and as-cut wafers irradiated with medium laser power, while a surface texturing on the as-cut pc-Si wafers occur, and no nanowires can form in the region subject to a liquid phase crystallization (LPC) caused by high-power laser treatments.

Description: Solar energy is the most abundant renewable energy and it has a great potential for development. There are two ways to transfer solar energy to electricity: photovoltaic power generation (PV) and concentrated solar power (CSP). CSP-PV hybrid system can be fully integrated with the advantages of the two systems to achieve low cost, stable output, and manageable to generate electricity. In this paper, the operation strategy of the CSP-PV system is proposed for parabolic trough CSP system and PV system which are now commercially operated. Genetic algorithm is used to optimize the design of the system and calculate PV-installed capacity, battery capacity, and storage capacity of CSP system, making the system to achieve the lowest cost of electricity generation. The results show that the introduction of the CSP system makes it possible to ensure the stability of the output power of hybrid system when the battery capacity is small, which greatly improves the annual utilization time of the PV and reduces solar abandonment. When the system is optimized by operation characteristics of Spring Equinox, the lowest LCOE is 0.0627 $/kWh, the rated capacity of PV and CSP system are 222.462 MW and 30 MW, respectively, and the capacity of heat storage and battery are 356.562 MWh and 14.687 MWh. When the system is optimized by the operation characteristics of the whole year, the lowest LCOE is 0.0555 $/kWh, the rated capacity of PV and CSP system are 242.954 MW and 30 MW, respectively, and the capacity of heat storage and battery are 136.059 MWh and 8.977 MWh. The comparison shows that the power generation curves of the hybrid system are similar in the two optimization-based methods—Spring Equinox based and annual based, but LCOE is lower when optimized by the annual operation characteristic, and the annual utilization rate of the system is higher when optimized by Spring Equinox based.

Description: Photocatalytic processes are present in natural biochemical pathways as well as in the organic synthetic ones. This minireview will cover the field of photocatalysis that uses both the free-base and specially metallated porphyrins as catalysts. While free-base porphyrins are valuable sensitizers to output singlet oxygen, metalloporphyrins are even more adjustable as photocatalysts because of their coordination capacity, generating a wider range of oxidation reactions. They can be applied in autooxidation reactions, hydroxylations, or direct oxygen transfer producing epoxides. This review will mainly focus on how manganese and some iron porphyrins can be utilized for the functionalization of compounds that have a polycyclic skeleton in their structure. These kinds of compounds are notoriously taxing to obtain and difficult to further functionalize by conventional organic synthetic methods. We have focused on photocatalytic oxygenation reactions in mild conditions with the use of water-soluble porphyrins, as this has been proven to be a good tool for these transformations. In the photocatalytic reactions of some polycyclic heteroaromatic compounds, new polycyclic epoxides, enediones, ketones, alcohols, and/or hydroperoxides are yielded, depending on the catalyst applied. The application of anionic and cationic Mn(III) porphyrins under different reaction parameters results in different reaction pathways generating a vast number of photocatalytic products. Recently, Co and Ni complexes have been also photophysically investigated and confirmed as potential photocatalysts for the functionalization of organic substrates.

Description: The forecast for photovoltaic (PV) power generation is of great significance for the operation and control of power system. In this paper, a short-term combination forecasting model for PV power based on similar day and cross entropy theory is proposed. The main influencing factors of PV power are analyzed. From the perspective of entropy theory, considering distance entropy and grey relation entropy, a comprehensive index is proposed to select similar days. Then, the least square support vector machine (LSSVM), autoregressive and moving average (ARMA), and back propagation (BP) neural network are used to forecast PV power, respectively. The weights of three single forecasting methods are dynamically set by the cross entropy algorithm and the short-term combination forecasting model for PV power is established. The results show that this method can effectively improve the prediction accuracy of PV power and is of great significance to real-time economical dispatch.

Description: A tetra-n-butoxy zinc phthalocyanine (n-BuO)4ZnPc has been synthesized in a single step, starting from commercial precursors, and easily purified. The molecule can be solution processed to form an effective and inexpensive hole transport layer for organic and perovskite solar cells. These appealing features are suggested by the results of a series of chemical, optical, and voltammetric characterizations of the molecule, supported by the results of ab initio simulations. Preliminary measurements of (n-BuO)4ZnPc-methylammonium lead triiodide perovskite-based devices confirm such suggestion and indicate that the interface between the photoactive layer and the hole transporting layer is characterized by hole-extracting and electron-blocking properties, potentially competitive with those of other standards de facto in the field of organic hole transport materials, like the expensive Spiro-OMeTAD.

Description: Photoconductivity is a fundamental and highly applicable phenomenon for semiconductor oxide-based devices, and the presence of defects plays a significant role in this mechanism. Here, we present an investigation based on different atmospheres and light excitation (above and below bandgap) dependences of zinc oxide thin film grown by spray-pyrolysis. As-grown ZnO presents a representative Urbach tail associated to the presence of localized levels in the bandgap. Photoconductivity response and decay times are investigated for air and inert atmospheres as well as under vacuum conditions with significant features due to light excitation conditions. The observed characteristics are explained based on oxygen photodesorption when excitation is above bandgap while this process is suppressed when excitation is below bandgap.

Description: In this work, we synthesized Ag nanoparticles on TiO2 thin films deposited on soda lime glass substrates. Ag nanoparticles were synthesized by photoreduction under UV irradiation silver nitrate solution. X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) measurements were used for physicochemical characterization. The structural study showed that all samples were polycrystalline, main phases were anatase and rutile, and no additional signals were detected after surface modification. Raman spectroscopy suggested that silver aggregates deposited on the TiO2 films could exhibit the surface plasmon resonance (SPR) phenomenon; XPS and SEM analysis confirmed TiO2 film morphological modification after photoreduction process. Photocatalytic degradation of methylene blue (MB) was studied under UV irradiation in aqueous solution, and, besides, pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. Results indicated that Ag-TiO2 showed an important increase in photocatalytic activity under UV (from 20% to 35%); finally, Ag-TiO2 thin films had value 2.4 × 10−3 ± 0.003 min−1 of 1.8 times greater than the value 1.3 × 10−4 ± 0.0004 min−1 of TiO2 thin films.

Description: The regular performance deterioration of P-type crystalline silicon solar modules and module strings caused by potential-induced degradation in a photovoltaic power plant was found in the field. The PID-affected solar modules dismounted from the photovoltaic power plant were further investigated systematically in the laboratory. For the first time, we found that the neutral point of voltage in a module string moved forward to the positive pole for a PID-affected module string as time goes on. Even if low positive voltage is applied to a PID-prone module, it could cause PID. The thermographic and electroluminescence (EL) images of a PID-affected module string also exhibit a regular degradation pattern. This is in good agreement with the measured power loss of the dismounted solar modules under standard test conditions. The results obtained in this paper show that the maximum power degradation rate of solar modules was as high as 53.26% after only one year of operation because of PID in the field. Due to the vast amount of solar modules and incomplete recovery, this is a terrible catastrophe for the owner of a power plant and module producer.

Description: Photocatalytic degradation of polychlorinated biphenyls (PCBs) in seawater was successfully achieved at laboratory level with UV light and at pilot-plant scale under natural solar radiation using carbon-modified titanium oxide (CM-n-TiO2) nanoparticles. The photocatalytic performance of CM-n-TiO2 was comparatively evaluated with reference n-TiO2 under identical conditions. As a result of carbon incorporation, significant enhancement of photodegradation efficiency using CM-n-TiO2 was clearly observed. To optimize the operating parameters, the effects of catalyst loading and pH of the solution on the photodegradation rate of PCBs were investigated. The best degradation rate was obtained at pH 5 and CM-n-TiO2 loading of 0.5 g L−1. The photodegradation results fitted the Langmuir-Hinshelwood model and obeyed pseudo-first-order reaction kinetics.

Description: Nanostructured materials (NSMs) of silver (Ag@TiO2) and copper (TiO2-Cu2+) doped titanium dioxide were synthesized, fully characterized, and evaluated for their antimicrobial efficiency and effects on Arabidopsis thaliana. The NSMs were prepared using an environmentally benign route. The physicochemical properties of the materials were determined with analytical techniques. These materials are active under visible light, exhibit a small size (10–12 nm), are crystalline (anatase), and liberate metal ions (Ag+ and Cu2+) in solution. Microbicide activity was observed in E. coli C600 and S. cerevisiae W303 strains treated with several concentrations of Ag@TiO2 and TiO2-Cu2+, radiated and nonradiated, and after different times. Higher inactivation was achieved with Ag@TiO2 in E. coli, with value of log inactivation of 2.2 with 0.5 mg/mL after 4 h, than in S. cerevisiae, with a log inactivation of 2.6 with 10 mg/mL after 24 h. The impact of these NSMs in plants was evaluated in Arabidopsis thaliana Col-0 strain exposed to such materials at different conditions and concentrations, and physical and biochemical effects were analyzed. Seeds exposed to NSMs did not show effects on germination and growth. However, seedlings treated with these materials modified their growth and their total chlorophyll content.

Description: The present paper reports on the facile formation of ZnO nanorod photocatalyst electrodeposited on Zn foil in the production of hydrogen gas via water photoelectrolysis. Based on the results, ZnO nanorod films were successfully grown via electrochemical deposition in an optimum electrolyte set of 0.5 mM zinc chloride and 0.1 M potassium chloride at pH level of 5-6 and electrochemical deposition temperature of around 70°C. The study was also conducted at a very low stirring rate with different applied potentials. Applied potential was one of the crucial aspects in the formation of self-organized ZnO nanorod film via control of the field-assisted dissolution and field-assisted deposition rates during the electrochemical deposition process. Interestingly, low applied potentials of 1 V during electrochemical deposition produced a high aspect ratio and density of self-organized ZnO nanorod distribution on the Zn substrate with an average diameter and length of ~37.9 nm and ~249.5 nm, respectively. Therefore, it exhibited a high photocurrent density that reached 17.8 mA/cm2 under ultraviolet illumination and 12.94 mA/cm2 under visible illumination. This behaviour was attributed to the faster transport of photogenerated electron/hole pairs in the nanorod’s one-dimensional wall surface, which prevented backward reactions and further reduced the number of recombination centres.

Description: Zinc oxide has been the focus of material research due to its potential applications in a variety of novel fields. The material exhibits anisotropic growth in the form of single crystal rods/wires of length in microns and thickness in several tens of nanometers through a facile and low temperature hydrothermal route wherein size, morphology, orientation, and growth rate are strongly dependent on a number of synthesis parameters. In this review article we intend to present/discuss the effects of important growth parameters of zinc oxide that have been reported in the literature. These parameters include concentration of the precursor solution, growth time, role of hexamine, synthesis temperature, pH of the precursor, and seeding layer deposited on a substrate.

Description: Inverted PTB7/PC71BM polymer solar cells are prepared on solution-processed Al:ZnO transparent contacts on PET substrates. Al:ZnO is deposited by a low temperature chemical bath deposition route (T 〈 100°C at any step) to comply with the temperature sensitive substrate. A maximum conversion efficiency of 6.4% and 6.9% is achieved for the indium-free solar cells on PET and glass substrates, respectively. The devices are relatively stable in air whereby an initial efficiency loss in the order of 15% after storage for 15 days can be fully recovered by light soaking.

Description: Deposition of poly(4-vinyl phenol) insulator layer is carried out by applying the spin coating technique onto p-type GaAs substrate so as to create Al/poly(4-vinyl phenol)/p-GaAs metal-oxide-semiconductor (MOS) structure. Temperature was set to 80–320 K while the current-voltage (I-V) characteristics of the structure were examined in the study. Ideality factor (n) and barrier height () values found in the experiment ranged from 3.13 and 0.616 eV (320 K) to 11.56 and 0.147 eV (80 K). Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.