ALBERT

Description: In this work, we studied the effect of TiO2 sensitization with dry biomass extracted of cyanobacteria on the degradation of methylene blue dye (AM). Cyanobacterial cultures isolated from water samples were collected from the swamp of Malambo in Colombia; two main genera of cyanobacteria were identified, and they were cultivated with BG-11 culture medium. The concentrations of chlorophyll a in the exponential and stationary phases of growth were measured; the phycobilin content was quantified by spectrophotometry. Thin films of TiO2 were deposited by a doctor blade method, and they were sensitized by wet impregnation. Furthermore, a methylene blue (MB) photodegradation process was studied under visible light irradiation on the cyanobacterial biomass sensitized TiO2 material (TiO2/sensitizer); besides, the pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. The results showed that the BG-11+ treatment reported a higher amount of dry biomass and phycobiliproteins. After the sensitization process, the TiO2/sensitizer thin films showed a significant red shift in the optical activity; besides the thin film roughness decreasing, the TiO2/sensitizer showed photocatalytic activity of 23.2% under visible irradiation, and besides, the kinetic () constant for TiO2/sensitizer thin films was 3.1 times greater than the value of TiO2 thin films. Finally, results indicated that cyanobacterial biomass is a suitable source of natural sensitizers to be used in semiconductor sensitization.

Description: Constant exposure of a photovoltaic (PV) panel to sunlight causes it to overheat and, consequently, its rated efficiency decreases leading to a drop in its generated power. In this study, a PV panel was tested under standard test conditions in a halogen lamp solar simulator at different solar irradiance values. The PV panel was then fitted with heat dissipating fins and measured under identical test parameters; thereafter, repurposed materials such as high-density polyethylene (HDPE) and plastic bags were, separately, added to the PV panel with fitted heat-extraction fins and the performance was evaluated again. Passively cooling the PV panel with fins and repurposed materials resulted in a 22.7% drop in the PV panel’s temperature, while an 11.6% increase in power output occurred at 1000 W m-2. Utilizing repurposed waste materials in PV cooling improves a panel’s efficiency and saves the environment from the ecological effects of dumping these materials.

Description: Double modifications of TiO2 by doping with WO3 and by dispersing on a SiO2 support were made by the one-pot sol-gel method. Doping with W shifts the TiO2 band gap energy from 3.2 eV to around 3.06 eV. The surface area of the supported W-TiO2/SiO2 material was significantly increased, by approximately 3 times, in comparison to the bare TiO2. The photocatalytic activities of the catalysts were evaluated in the degradation reaction of p-nitrophenol in aqueous solution and basic medium. After 240 min of photodegradation, more than approximately 99% p-nitrophenol could be mineralized with the most active W-TiO2/SiO2 catalyst. Under UV irradiation, p-nitrophenol was initially photodegraded into hydroquinone and benzosemiquinone intermediates, which were further degraded into smaller fragments such as organic carboxylic acids and finally completely mineralized. A proposed photoreaction mechanism was presented based on the key roles of the surface hydroxyl species and superoxide radicals such as O2- and ⋅OH, together with W6+/W5+ couples and e-/h+ pairs in the catalysts in the p-nitrophenol photodegradation. The one-pot sol-gel synthesis method was proven to be effective to obtain W-TiO2/SiO2 catalyst with large surface area and high photocatalytic activity, and it can be also used for the preparation of other heterogeneous catalysts.

Description: The large and continuous use of fossil fuels as a primary energy source has led to several environmental problems, such as the increase of the greenhouse effect. In order to minimize these problems, attention has been drawn to renewable energy production. Solar energy is an attractive candidate as renewable source due to its abundance and availability. For this, it is necessary to develop devices able to absorb sunlight and convert it into fuels or electricity in a economical, technical and sustainable way. The so-called artificial photosynthesis has called the attention of researchers due to the possibility of using solar photocatalysts in converting water and CO2 into fuels. This manuscript presents a review of the recent developments of hybrid systems based on molecular photocatalysts immobilized on semiconductor surfaces for solar fuel production through water oxidation and CO2 reduction and also discusses the current challenges for the potential application of these photocatalyst systems.

Description: Buildings consume large amounts of energy, and their transformation from energy users to producers has attracted increasing interest in the quest to help optimize the energy share, increasing energy efficiency and environmental protection. The use of energy-efficient materials is among the proposed approaches to increase the building’s energy balance, thus increasing the performance of building facades. Semitransparent building-integrated photovoltaic (BIPV), being one of the technologies with the potential to increase a building’s energy efficiency, is considered as a feasible method for renewable power generation to help buildings meet their own load, thus serving dual purposes. Semitransparent BIPV integration into buildings not only displaces conventional building facade materials but also simultaneously generates energy while retaining traditional functional roles. The awareness in improving building energy efficiency has increased as well as the awareness in promoting the use of clean or renewable energy technologies. In this study, semitransparent BIPV technology is reviewed in terms of energy generation, challenges, and ways to address limitations which can be used as a reference for the BIPV stakeholders.

Description: Based on the examination of the efficiency of solar plants, this study focuses on three main plants: a photovoltaic (PV) plant, a concentrated solar power (CSP) plant, and a hybrid PV/CSP plant. The modelling of the three plants has been implemented to evaluate the influence of design parameters (orientation angles, solar multiple (SM), thermal energy storage capacity (TES), and fraction of hybridization) on them. Several simulations have been recreated and discussed in details to study the optimal configuration of the two first plants and the profitability of the PV/CSP plants for Ouarzazate (Morocco) location. The findings demonstrate that the optimal orientation angles and TES/SM, respectively, affect the performances of PV and CSP plants, and they also reveal that PV/CSP systems have the benefits to increase the annual energy produced, reduce the cost, and offer a high dispatchability to supply a baseload. The implementing of optimal PV/CSP plant has a great economic impact on Ouarzazate city.

Description: Ternary nickel-cobalt lithium aluminate LiNiCoAlO2 (NCA, ) is an essential cathode material with many vital advantages, such as lower cost and higher specific capacity compared with lithium cobaltate and lithium iron phosphate materials. However, the noticeably irreversible capacity and reduced cycle performance of NCA cathode materials have restricted their further development. To solve these problems and further improve the electrochemical performance, numerous research studies on material modification have been conducted, achieving promising results in recent years. In this work, the progress of NCA cathode materials is examined from the aspects of surface coating and bulk doping. Furthermore, future research directions for NCA cathode materials are proposed.

Description: In this work, the effect of DIM on the PCE and photostability of PCDTBT:PC71BM PSCs was investigated. DIM is an effective additive in a BHJ PCDTBT:PC71BM solar cell since it fulfills the requirement of a selective PC71BM dissolution. PCE of the device based on PCDTBT:PC71BM processed with DIM is higher than that of the reference device. In terms of the device stability, the PSCs processed with DIM showed poor stability at longer light exposure time. For the device without DIM especially as the light exposure time was increased, the device stability was better because the PCDTBT could be shielded from air by an aggregated PC71BM layer. For the PCDTBT:PC71BM device processed with DIM, the results obtained from measurement indicates that it has a lower recombination rate. The result from IS measurement shows that for pristine PCDTBT:PC71BM devices with 3% DIM, the active layer resistance is lower compared to the device without DIM. However, after irradiating the device for 5 hr, the resistance of the device processed with DIM is higher and it is consistent with decreased PCE of the aged device.

Description: The aim of this work is to study the behaviour of a silicon solar cell under the irradiation of different fluences of high-energy proton radiation (10 MeV) and under constant multispectral illumination. Many theoretical et experimental studies of the effect of irradiation (proton, gamma, electron, etc.) on solar cells have been carried out. These studies point out the effect of irradiation on the behaviour of the solar cell electrical parameters but do not explain the causes of these effects. In our study, we explain fundamentally the causes of the effects of the irradiation on the solar cells. Taking into account the empirical formula of diffusion length under the effect of high-energy particle irradiation, we established new expressions of continuity equation, photocurrent density, photovoltage, and dynamic junction velocity. Based on these equations, we studied the behaviour of some electronic and electrical parameters under proton radiation. Theoretical results showed that the defects created by the irradiation change the carrier distribution and the carrier dynamic in the bulk of the base and then influence the solar cell electrical parameters (short-circuit current, open-circuit voltage, conversion efficiency). It appears also in this study that, at low fluence, junction dynamic velocity decreases due to the presence of tunnel defects. Obtained results could lead to improve the quality of the junction of a silicon solar cell.

Description: TiO2/SiO2 nanoparticles with 3, 5, and 10 molar percent of silica, were synthesized by hydrothermal method and characterized by SEM, TEM, N2 adsorption-desorption isotherms, X-ray diffraction, and Raman and UV-Vis spectroscopy. While pristine TiO2 thermally treated at 500°C presents a surface area of 36 m2 g-1 (±10 m2 g-1), TiO2/SiO2 containing 3, 5, and 10 molar percent of silica present surface areas of 93, 124, and 150 m2 g-1 (±10 m2 g-1), respectively. SiO2 is found to form very small amorphous domains well dispersed in the TiO2 matrix. X-ray diffraction and Raman spectroscopy data show that anatase-to-rutile phase transition temperature is delayed by the presence of SiO2, enabling single-anatase phase photoanodes for DSSCs. According to the measurements, photoanodes with 3% of SiO2 result in improved efficiency, which is mainly related to increased surface area and dye loading. In addition, the results suggest a gain in photocurrent related to the passivation of defects by SiO2.

Description: Umuokpo Amumara is a village with an estimated population of 9,000 people and about 800 households located in the eastern region of Nigeria in West Africa. This village has no access to power grids for over a decade of existence. Umuokpo, by virtue of its location 5°2735.9N 7°1960.0E, on the average receives about 6 hours of sunlight with a daily average irradiance of 6.12 kWh/m2. The solar energy can be tapped and harnessed to generate quality electricity for this small village. Since the wind speed is low (ranging between 3.0 m/s and 3.5 m/s), the wind resource cannot be incorporated into the design. The average load demand of the village is 9.422 MWh/day with a peak load of 1.3 MW. This paper is aimed at designing a small hybrid power system that can generate sustainable electricity for the village from renewable energy sources. The design also considers a backup diesel generator and an energy storage system. The designed system consists of a 2,750 kW solar photovoltaic (PV), a 21,600 kWh battery storage, a 1,500 kW power electronic converter, and a 1,000 kW diesel generator. The simulation suggests that the proposed system can adequately meet the electricity needs of the village. A sensitivity analysis is also carried out on the system to observe its behavior with varying levels of irradiation and load.

Description: Aluminum acetylacetonate-based AlOx thin films were introduced as a low-cost, high-quality passivation layers for crystalline silicon solar cells. Films were formed by a spin coating method on p-type silicon substrates at 450°C in ambient air, O2, or water vapor (H2O/O2) for 15 or 120 min. XPS analysis confirms the AlOx formation and reveals a high intensity of interfacial SiOx at the AlOx/Si interface of processed wafers. Ambient H2O/O2 was found to be more beneficial for the activation of introduced AlOx passivation films which offers high lifetime improvements with a low thermal budget. Carrier lifetime measurements provides that symmetrically coated wafers reach 119.3 μs and 248.3 μs after annealing in ambient H2O/O2 for 15 min and 120 min, respectively.

Description: The amount of electric energy produced by photovoltaic panels depends on air temperature, humidity rate, wind velocity, photovoltaic module temperature, and particularly solar radiation. Being aware of the behaviour patterns of the panels to be used in project and planning works regarding photovoltaic applications will set forth a realistic expense form; therefore, erroneous investments will be avoided, and the country budget will benefit from added value. The power ratings obtained from the photovoltaic panels and the environmental factors were measured and recorded for a year by the measurement stations established in three diverse regions (Adiyaman-Malatya-Sanliurfa). In the developed artificial neural network models, the estimation accuracy was 99.94%. Furthermore, by taking the data of the General Directorate of Meteorology as a reference, models of artificial neural networks were developed using the data from Adiyaman province for training; by using Malatya and Sanliurfa as test data, 99.57% estimation accuracy was achieved. With the artificial neural network models developed as a result of the study, the energy efficiency for the photovoltaic energy systems desired to be established by using meteorological parameters such as temperature, humidity, wind, and solar radiation of various regions anywhere in the world can be estimated with high accuracy.

Description: In this study, the form and operation modes of a novel solar-driven cogeneration system consisted of various solar collectors (flat plat collectors (FPC), evacuated tube collectors (ETC), and parabolic trough collectors (PTC)) and ORC (organic Rankine cycle) based on building heating load are analyzed. This paper mainly obtains the fitting formula of thermal efficiency of the ORC power generation device and determines the form and operation mode of the cogeneration system. The form is the same, but the operation modes are different for PTC and FPC or ETC. There are six operating modes, respectively, based on the size relationship between the heating load of buildings and the effective heat collection of the solar collector subsystem when the solar collectors are PTC or FPC and ETC.

Description: We present here a new method to predict cloud concentration five minutes in advance from all-sky images using the Artificial Neural Networks (ANN). An autoregressive neural network with backpropagation (Ar-BP) was created and trained with four years of all-sky images as inputs. The pictures were taken with a hemispheric sky imager fixed on the roof at the Institute of Meteorology and Climatology (IMUK) of the Leibniz Universität Hannover, Hannover, Germany. Firstly, a statistical method is presented to obtain key information of the pictures. Secondly, a new image-processing algorithm is suggested to optimize the cloud detection process starting with the Haze Index. Finally, the cloud concentration five minutes in advance at the IMUK is forecasted using machine learning methods. A persistence model forecast to provide a reference for comparison was generated. The results are quantified in terms of the root mean square error (RMSE) and the mean absolute error (MAE). The new algorithm reduced both the RMSE and the MAE of the prediction by approximately 30% compared to the reference persistence model under diverse cloud conditions. The new algorithm could be used as a tool for the stable maintenance of the network for the transmission system operators, i.e., the primary control reserve (within 30 seconds) and the secondary control reserve (within 5 minutes).

Description: In this paper, thermal modeling of a typical rural house in Pakistan has been done using BEopt, to determine the hourly load profile. Using the load data, the design of a stand-alone PV system has been completed using HOMER Pro. The designed system consists of a 5.8 kW PV with eight batteries of 12 V, 255 Ah, and a 1.4 kW inverter. The system analyses show that such system can support mainly lighting and appliance load in a rural house. The dynamic model of the designed system has been simulated in MATLAB-Simulink. Perturbation and observation-based algorithm has been used for maximum power extraction from PV. Simulation results indicate that the system can provide a stable voltage and frequency for the domestic load. The method and analysis presented here can be used for the PV system design for other parts of the world.

Description: In the present work, the detailed mathematical model of a dual air/water solar collector (DAWC) has been developed and experimentally verified. To demonstrate the application of the DAWC, three buildings with different energy performance levels and three building locations were chosen in analyzed case studies. Four solar collector systems were compared with one another. The solar yield of the described systems was determined by simulation using the detailed theoretical model of DAWC. The results indicate that in the case of combining a domestic hot water preparation system and recirculating-air heating system based on DAWC, it is possible to achieve up to 30% higher solar energy yield compared to a conventional solar domestic hot water preparation system dependent on climate and building performance.

Description: In this paper, boron-doped Czochralski silicon (Cz-Si) wafers were fabricated into PERC solar cells by using the industrial standard process; then, the as-prepared PERC solar cells were treated by the regeneration process using electrical injection and heating and the effects of different regeneration processes (temperature, time, and injection current) on the anti-light-induced degradation (anti-LID) performance of the PERC solar cells were investigated. The results show that under the condition of 10 A injection current and 30 min processing time, the optimal processing temperature is about 180°C for PERC solar cells to obtain the best anti-LID performance. Under the conditions of a temperature of 180°C, an injection current of 10 A, and a processing time of 0-30 min, the anti-LID performance of the PERC solar cells is enhanced with the increase in the processing time. When the processing time is 20 and 30 min, the efficiency, the short-circuit current, and the open-circuit voltage of the processed PERC solar cells are slightly higher than the initial values before the regeneration and remain stable in the subsequent 12-hour light degradation process at 45°C and 1-sun illumination. At a temperature of 180°C and a processing time of 30 min, the injection current of 6 A is enough to obtain a good regeneration effect, but the optimal injection current is around 10 A.

Description: Solar cell parameter identification problem (SCPIP) is one of the most studied optimization problems in the field of renewable energy since accurate estimation of model parameters plays an important role to increase their efficiency. The SCPIP is aimed at optimizing the performance of solar cells by estimating the best parameter values of the solar cells that produce an accurate approximation between the current vs. voltage () measurements. To solve the SCPIP efficiently, this paper introduces an adaptive variant of the electromagnetic field optimization (EFO) algorithm, named adaptive EFO (AEFO). The EFO simulates the attraction-repulsion mechanism between particles of electromagnets having different polarities. The main idea behind the EFO is to guide electromagnetic particles towards global optimum by the attraction-repulsion forces and the golden ratio. Distinct from the EFO, the AEFO searches the solution space with an adaptive search procedure. In the adaptive search strategy, the selection probability of a better solution is increased adaptively whereas the selection probability of worse solutions is reduced throughout the search progress. By employing the adaptive strategy, the AEFO is able to maintain the balance between exploration and exploitation more efficiently. Further, new boundary control and randomization procedures for the candidate electromagnets are presented. To identify the performance of the proposed algorithm, two different benchmark problems are taken into account in the computational studies. First, the AEFO is performed on global optimization benchmark functions and compared to the EFO. The efficiency of the AEFO is identified by statistical significance tests. Then, the AEFO is implemented on a well-known SCPIP benchmark problem set formed as a result of real-life physical experiments based on single- and double-diode models. To validate the performance of the AEFO on the SCPIP, extensive experiments are carried out, where the AEFO is tested against the original EFO, AEFO variants, and novel metaheuristic algorithms. Results of the computational studies reveal that the AEFO exhibits superior performance and outperforms other competitor algorithms.

Description: Nano-silver-titanium dioxide (Ag-TiO2) composites were prepared from commercial TiO2 (P25, Degussa) and silver nitrate (AgNO3) by gamma Co-60 irradiation method with various initial concentrations of AgNO3. The nano-AgTiO2 composites are utilized as the photoanode for dye-sensitized solar cells (DSCs). Under full sunlight illumination (1000 W/m2, AM 1.5), the efficiency of DSCs has improved significantly despite the Ag content of below 1%. The DSC—assembled with 0.75 Ag-TiO2 (0.75% Ag) photoanode—showed that the photocurrent was significantly enhanced from 8.1 mA.cm−2 to 9.5 mA.cm−2 compared to the DSCs using bared TiO2 photoanode. The unchanged open-circuit voltage resulted in the overall energy conversion efficiency to be increased by 25% from 3.75% to 4.86%. Electrochemical impedance spectroscopy (EIS) analysis showed that the charge transfer resistance is reduced when increasing Ag content, demonstrating that the charge transfer at TiO2/dye interface was enhanced in the presence of silver nanoparticles.

Description: Monitoring and prediction of the climatic phenomenon are of keen interest in recent years because it has great influence in the lives of people and their environments. This paper is aimed at reporting the variation of daily and monthly solar radiation, air temperature, relative humidity (RH), and dew point over the year of 2013 based on the data obtained from the weather station situated in Damak, Nepal. The result shows that on a clear day, the variation of solar radiation and RH follows the Gaussian function in which the first one has an upward trend and the second one has a downward trend. However, the change in air temperature satisfies the sine function. The dew point temperature shows somewhat complex behavior. Monthly variation of solar radiation, air temperature, and dew point shows a similar pattern, lower at winter and higher in summer. Maximum solar radiation (331 Wm-2) was observed in May and minimum (170 Wm-2) in December. Air temperature and dew point had the highest value from June to September nearly at 29°C and 25°C, respectively. The lowest value of the relative humidity (55.4%) in April indicates the driest month of the year. Dew point was also calculated from the actual readings of air temperature and relative humidity using the online calculator, and the calculated value showed the exact linear relationship with the observed value. The diurnal and nocturnal temperature of each month showed that temperature difference was relatively lower (less than 10°C) at summer rather than in winter.

Description: The organic-inorganic hybrid perovskites such as CH3NH3PbI3 have been considered as one of the most promising candidates for the next-generation photovoltaic materials due to its high absorption coefficient, low exciton binding energy, and long diffusion length. Herein, we have chosen NiOx as the hole transport material because metal oxides exhibit robust properties in air. We synthesized the NiOx film by a common sol-gel method. It is found that high-temperature annealing (500°C) is required to ensure the perovskite solar cell (PSC) with an efficiency over 15%. Low-temperature annealing (100°C) cannot convert the precursor materials to fully covered NiOx film, while the PSC based on mediate-temperature annealing (300°C) NiOx has larger resistance and thus lower efficiency. Fortunately, we have found that UV-ozone treatment on the NiOx film can reduce the resistance of the device based on 300°C annealed NiOx. The champion device can reach 16% efficiency with UV-ozone-treated 300°C annealed NiOx. This work has made it possible to reduce the annealing temperature of the sol-gel NiOx for high-efficiency PSCs, and it is believed that this simple surface treatment can be further employed in other metal oxide-based optoelectronic devices.

Description: This work targets to control the growth orientation of sol-gel-derived ZnO thin films in order to allow different modes of excitation (longitudinal and transverse) when targeted to be used in piezoelectric applications. For that, the effect of solvents and stabilizer molar ratio on the structural and optical characteristics of the obtained films is investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometry. The XRD results show clearly that the synthesized films exhibit hexagonal wurtzite structure without any secondary phases and that the crystallite average size, estimated by the Scherrer formula, is ranged between 13 and 30 nm. The main finding of this work is to show that the control of the crystalline growth orientation is possible simply by varying the solvent nature and/or the stabilizer molar ratio. These later parameters are therefore considered as key factors when seeking to develop the ZnO-based transducers. Actually, the ZnO thin films synthesized with propanol as solvent are oriented only along the -axis; meanwhile, when using the isopropanol or ethanol, other preferential orientations appear. Additionally, the effect of MEA molar ratio () has been studied on the propanol-derived films (the unfavorable case). It has been found that this parameter has a direct effect on the crystalline growth orientation of these films and that a new preferential orientation (100) appears at low . On the other hand, SEM images show the formation of homogeneous nanocrystalline thin films with an average grain size ranged between 19 and 35 nm. Moreover, the ZnO thin films exhibit a high transparency in the visible region, and the measured transmittance is ranged from 85 to 97%. However, the change of ZnO film orientation has no significant effect on the direct bandgap energy which is closed to 3.30 eV.

Description: Photovoltaic and physical characteristics of screen-printed monocrystalline silicon solar cells (SPMSCs) were presented with electroplated copper (EPC) as the rear contact. The boron back surface field (B-BSF) formed by spin-on doping and laser doping (LD) was prepared as a seed layer for the EPC. The LD parameters, including the laser focus, laser power, laser speed, and laser line pitch, were investigated. Moreover, the effects of KOH etching on the surface properties after the LD process were explored. Furthermore, to enhance the adhesion between the B-BSF seed layer and EPC contact layer, a laser pinhole process was proposed. Finally, the EPC processes with various electroplating times were addressed. The results revealed that the mechanism of enhancements could be attributed to a continuous B-BSF seed layer and a reduction of series resistance, as well as an increase of open-circuit voltage and adhesion between the B-BSF seed layer and EPC contact layer.

Description: Developing a concentrated solar power (CSP) technology is one of the most effective methods to solve energy shortage and environmental pollution all over the world. Thermal energy storage (TES) system coupling with phase change materials (PCM) is one of the most significant methods to mitigate the intermittence of solar energy. In this paper, firstly, a 2D physical and mathematical model of a novel truncated cone shell-and-tube TES tank has been proposed based on enthalpy method. Secondly, the performance during the charging/discharging process of the truncated cone tank has been compared with the traditional cylindrical tank. Finally, the effects of inlet conditions of heat transfer fluid (HTF), and thickness of tube on the charging/discharging process, stored/released energy capacity; energy storage/release rate and heat storage efficiency have been investigated. The results show that the performance of truncated cone tank is better, and the charging/discharging time reduces 32.08% and 21.59%, respectively, compared with the cylindrical tank. The effect of wall thickness on the truncated cone TES tank can be ignored. And the inlet temperature and velocity of HTF have the significant influence on the charging/discharging performance of TES tank. And the maximum heat storage efficiency of the truncated cone TES tank can reach 93%. However, some appropriate methods should be taken for improving the thermal energy utilization rate of HTF in the future. This research will provide insights and significant reference towards geometric design and operating conditions in TES system.

Description: The environmentally clean nature of solar photovoltaic (PV) technology causes PV power generation to be embraced by all countries across the globe. Consequently, installation and utilization of PV power systems have seen much growth in recent years. Although PV arrays of such systems are robust, they are not immune to faults. To guarantee reliable power supply, economic returns, and safety of both humans and equipment, highly accurate fault detection, diagnosis, and interruption devices are required. In this paper, an overview of four major PV array faults and their causes are presented. Specifically, ground fault, line-line fault, arc fault, and hot spot fault have been covered. Next, conventional and advanced fault detection and diagnosis (FDD) techniques for managing these faults are reviewed. Moreover, a single evaluation metric has been proposed and utilized to evaluate the performances of the advanced FDD techniques. Finally, based on the papers reviewed, PV array fault management future trends and possible recommendations have been outlined.

Description: Nowadays, organo-lead halide is one of the most interesting materials for perovskite solar cells. This is because of its ease of fabrication, long absorption wavelength region, and long diffusion length. In this study, we investigated the bandgap tuning of hybrid mixed-halide perovskite films. The films were prepared by sequential two-step deposition technique, using 5-ammonium valeric acid iodide (5-AVAI), PbI2, and a mixture of CH3NH3I and CH3NH3Br as precursor solutions. The results confirmed the formation of 2D perovskites in the presence of 5-AVAI. The obtained films had higher moisture resistance, better surface coverage, and smaller grain size, compared to the films without 5-AVAI. With the introduction of Br− ions, the change in the lattice parameter was observed. The bandgap was also found to increase with increasing Br− content.

Description: Access to solar energy is a prerequisite to remedy CO2 and improve the standard of human living. Green solar energy is only an immediate solution to add its zero emission profile and provide carbon footprint reduction benefits. This energy does not emit greenhouse gases which means it is a renewable free source of energy when producing electricity. The purpose of this paper is to investigate the accurate annul energy production data reducing uncertainty in solar energy estimates. This work investigated the solar energy assessment taking into account a detailed solar resource and energy production assessment for a 3 × 50 MW PV project with uncertainty analysis. The authors defined a total uncertainty of energy production which is estimated at 9.5% for one year and 8.9% for ten years as well as future variability of 3.4% for one year and 1.1% for ten years. The annual power degradation and expected energy production over the plant lifespan at dissimilar 99%, 90%, 75%, 60%, 50%, and 25% probability of surplus are also observed in this paper.

Description: This work summarizes progresses achieved in the physical chemistry aspects of the growth of anodic oxides under high-field conditions for the synthesis of semiconducting thin solid films and their implementation as photocatalytic materials. We discuss the scope and mechanisms for anodic oxide growth, describing the development of kinetic models and the correlations between theory and kinetic data, leading to fundamental information to characterize the primary processes occurring during the anodization of valve metals under high fields. The main features related to the widely used self-assembly of nanostructures by valve metal anodization are highlighted and briefly discussed. This is followed by general considerations of heterogeneous photocatalysis on these functional materials, considering the kinetics of the heterogeneous catalytic processes involved and the overall photoelectrochemical performance. High control of the characteristics of the materials obtained with the method described, combined with the possibility of electrochemically assisting photocatalysis, allows application of this technology to the treatment of wastewaters, energy conversion, and related fields.

Description: Quantum dots are drawing great attention as a material for the next-generation solar cells because of the high absorption coefficient, tunable band gap, and multiple exciton generation effect. In search of the viable way to enhance the power conversion efficiency of quantum dot-sensitized solar cells, we have succeeded in preparing the quantum dot solar cells with high efficiency based on CdSe:X (Mn2+ or Cu2+) nanocrystal by successive ionic layer absorption and reaction. The morphological observation and crystalline structure of photoanode were characterized by field-emission scanning electron microscopy, X-ray diffraction, and the EDX spectra. In addition, the electrochemical performance of photoelectrode was studied by the electrochemical impedance spectra. As a result, we have succeeded in designing QDSSCs with a high efficiency of 4.3%. Moreover, the optical properties, the direct optical energy gap, and both the conduction band and the valence band levels of the compositional CdSe:X were estimated by the theory of Tauc and discussed details. This theory is useful for us to understand the alignment energy structure of the compositions in electrodes, in particular, the conduction band and valence band levels of CdSe:X nanoparticles.

Description: This study is aimed at developing a simple and low-cost method to fabricate ZnO-loaded porous activated carbon (AC-ZnO) prepared from the Algerian olive-waste cakes and utilize it as a photocatalyst for the degradation of Ethyl Violet dye. The synthesized AC-ZnO material was characterized using powder X-ray diffraction, BET surface area measurements, Raman microscopy, thermogravimetric analysis, UV-visible diffuse reflectance spectroscopy, and zeta potential measurements. The degradation efficiency was evaluated with Ethyl Violet (EV) dye in aqueous solution under UV irradiation supplied by a Xenon arc lamp through a Pyrex glass filter (cutoff 280 nm), and the degraded products were identified by using electrospray ionization mass spectroscopy. Additional experiments were carried out under N2 flow and with isopropyl alcohol to examine the role of superoxide and hydroxyl radicals, respectively. The amount of ●OH radical formed on irradiated AC-ZnO was tested with terephthalic acid which can act as a chemical trap for the ●OH radicals. The results from this study indicate that the AC-ZnO is a potential catalyst for the pollutant removal and the ●OH radicals are the key species for the degradation of EV. Further, this study opens up an opportunity to produce cheaper activated carbon support from olive wastes for environmental remediation applications.

Description: In recent years, the upturn demand of electricity and the generation of electrical power demand from fossil fuels are increasing day by day which results in environmental impacts on the atmosphere by greenhouse gases, and a high cost of electric power from these sources makes it unaffordable. The use of renewable energy sources can overcome this problem. Therefore, in this work, we present a solution by implementing the solar car parking lots. A detailed work has been done for solar car parking site selection and maximum solar electric power generation and its capacity effects with the shading of nearby trees and buildings by using the HelioScope online software developed by Folsom Labs. A detailed optimization and selection of car parking canopies are performed at different standard tilt angles to produce maximum solar photovoltaic energy, and it is analyzed that the monopitch canopy is the best to mount at solar car parking lots at a tilt angle of 10°. We have done a detailed economic analysis which shows that 14% electricity cost was offset by the installation of a solar car parking lot with 17% reduction in annual energy consumption from the grid at the proposed site. The total investment cost of the parking structure and the photovoltaic (PV) system can be paid back in 6-7 years.

Description: In the past few years, the prime focus of supplying electricity to the longhouse communities in the rural areas of Sarawak has been initiated based on the utilization of a single-source microgrid configuration. The existing AC power supply-based solar photovoltaic (PV) systems in these areas pose many problems, mainly owing to the stages of conversion, energy losses, and the quality of power transfer. As the solar PV system is a DC source and most of the appliances in longhouse communities could be operated using DC source, an opportunity to design a microgrid with high reliability and efficiency would be achieved by the implementation of an optimal DC microgrid configuration. With this aim, the paper proposes a multiple-source DC microgrid configuration for the longhouse communities in Sarawak. Initially, a framework has been developed to design simulation models for both microgrid configurations (single and multiple sources) using MATLAB Simulink. The configuration of each system consists of a solar PV and energy storage to form a standalone microgrid. Due to the change in system configuration of DC microgrid, in the modeling approach, the standard power flow equations are modified to include solely the DC parameters. To validate the proposed configuration with the associated modeling approach in terms of the power flow reliability, system efficiency, and power-voltage curve, an experimental setup representing the Simulink model has been designed for each standalone microgrid configuration. The configurations have been assessed in the same location with different daily weather conditions. The obtained simulation and experimental results confirm that the proposed configuration of multiple sources is more reliable and efficient than the existing single-source configuration.

Description: By employing phase change slurry (PCS) as working fluid for the heat pipe solar PV/T system, the study is designed to investigate the electrical and thermal energy performance of the system. Meanwhile, through examining the performance difference between water-based and PCS-based heat pipe solar PV/T systems, 30% alkyl hydrocarbon PCS is proved to be a suitable working fluid for optimized energy performance based on the combined consideration of the thermophysical and rheological properties. Both static and dynamic stability tests show that 30% alkyl hydrocarbon PCS has a good stability for low-temperature thermal energy storage. A testing rig is constructed consisting of two identical heat pipe solar PV/T cogeneration systems A and B, in which water and 30% alkyl hydrocarbon PCS are, respectively, employed as working fluids; the energy performance of those two PV/T systems are investigated and compared with each other under the same testing condition. The results indicate that the application of PCS to the heat pipe PV/T system leads to a significant improvement in thermal performance and a modest growth in electrical performance. The daily heat gains and overall average efficiency of system B are 4.2 MJ/m2 (per unit area of PV/T panel) and 59.3%, respectively, 27.3% and 9.3% higher than those of system A. Per unit area of the heat pipe PV/T panel could produce 55.2 L domestic hot water of about 45°C on a sunny day.

Description: The electricity in Gaza, Palestine, is limited and scheduled for 4-10 hours per day due to political reasons. This status represents a real problem for different sectors. This paper presents an effective solution especially for the energy supply problem in the residential sector by using an unconventional PV system which operates in stand-alone and grid-connected modes. The system includes a storage battery block with a proper capacity to secure for continuous power supply of a residential house with a daily energy load of 10 kWh. It was found that an unconventional PV system of 3.2 kWp and a storage battery block of 19.2 kWh will be able to cover the total daily energy demands of the house including the outlined electricity cutoff hours. The design of this system and specifics of its components are presented in this paper. The system was simulated by Matlab software, where the daily load curve, grid cutoff hours, and the monthly solar radiation are considered. The obtained simulation results show that the produced PV energy exceeds the load demands during nine months of the year, and thereby, a high battery state of charge (SOC) in the range of 73-84% is achieved. During the three months of the lowest solar radiation (Dec.-Feb.), the produced PV energy is equal to the load demand while the battery state of charge varies in the range of 40-49% which verifies the appropriateness of the proposed PV system. The daily energy yield of the PV system varies between 2.6 and 5.4 kWh/kWp in January and July, respectively, which corresponds to a performance ratio of 90% and 66.25%, respectively.

Description: Electric vehicles (EVs) powered by lithium batteries, which are a promising type of green transportation, have attracted much attention in recent years. In this study, a thermoelectric generator (TEG) coupled with forced convection (F-C) was designed as an effective and feasible cooling system for a battery thermal management system. A comparison of natural convection cooling, F-C cooling, and TEG cooling reveals that the TEG is the best cooling system. Specifically, this system can decrease the temperature by 16.44% at the discharge rate of 3C. The coupled TEG and F-C cooling system can significantly control temperature at a relatively high discharge rate. This system not only can decrease the temperature of the battery module promptly but also can reduce the energy consumption compared with the two other TEG-based cooling systems. These results are expected to supply an effective basis of the design and optimization of battery thermal management systems to improve the reliability and safety performance of EVs.

Description: We investigated broadband-sensitive upconversion (UC) processes in a series of Tm- and Ni-sensitized ABO3 (A = Ca/Sr/Ba and B = Ti/Zr/Hf) perovskites. We have designed combinations of the sensitizers and host cations such that super broad solar radiation ranging from 900 nm to nearly 2000 nm can be efficiently upconverted to 800 nm and shorter wavelengths. The Ni2+ ions located at the center of O2− octahedra absorbed photons in the 900–1500 nm range and transferred those energies to the nearby Tm3+ ions. The Tm3+ ions upconverted those energies at 800 nm, along with the energies absorbed by themselves in the 1100–1250 and 1550–2000 nm ranges, exhibiting super broadband sensitivity. Among the ABO3:Tm, Ni (A = Ca/Sr/Ba and B = Ti/Zr/Hf) upconverters, CaTiO3:Tm, Ni exhibited the best performance due to its most distorted crystal structure, which intensified the emission and absorption extents by increasing the optical transition probabilities of Tm3+ and Ni2+ ions. Introduction of alkali ions at the Ca2+ sites and Nb5+ ions at the Ti4+ sites intensified the UC emission by many folds, mainly due to a charge balance mechanism. At the same time, bigger and smaller codoped alkali ions created an asymmetric crystal field around the active ions and further enhanced the UC emission. Importantly, the upconverted photons are within the absorption edges of GaAs, Cu2ZnSnS4, and dye-sensitized solar cells making wider applications of these upconverters besides crystalline Si solar cells.

Description: Dye-sensitized solid-state solar cells (DSSCs) replacing the liquid electrolyte with a p-type semiconductor have been extensively examined to solve the practical problems associated with wet-type solar cells. Here, we report the fabrication of a solid-state solar cell using copper iodide (CuI) as the hole conductor and alkyl-functionalized carbazole dye (MK-2) as the sensitizer. A DSSC sensitized with MK-2 showed a solar-to-electrical power conversion efficiency of 3.33% with a of 496 mV and a of 16.14 mA cm-2 under AM 1.5 simulated sunlight. The long alkyl chains act as a barrier for charge recombination, and the strong accepting and donating abilities of the cyanoacrylic and carbazole groups, respectively, enhance the absorption of light at a longer wavelength, increasing the short-circuit current density. The efficiency recorded in this work is higher than similar DSSCs based on other hole collectors.

Description: Purpose. The practice of physical activities is considered a primary factor for the maintenance of good health status. However, exhaustive or unusual physical activities can lead to muscle injuries. Several treatments are used to recover muscle injuries; however, systemic NSAIDs often result in serious adverse events. In this study, we aimed to investigate the association of laser therapy (LLLT) and topical diclofenac, evaluating the kinetics of the drug and its pharmacodynamic effect in stretching-induced muscle injury in rats. Methods. Male Wistar rats weighing 200 g were randomized and divided into groups of 6 animals. Plasma concentrations of diclofenac were quantified by mass spectrometry at different times (15 min to 24 hours) in all animals. The laser energy used was 3 Joules (830 nm; 100 mW, 30s). Treated groups received diclofenac at the dose of 1 mg/kg IM or topically applied with or without laser therapy. The electric stimulation was used to study the functional status of the muscles. Results. After topical administration of diclofenac, the peak plasma concentration (t max) occurred for 30 minutes in the irradiated group and 4 hours in the nonirradiated group. The AUC (0-24 hs) was 442 (ng/h/mL-1) in the nonirradiated group and 712 (ng/h/mL-1) in the irradiated group. Conclusion. LLLT was effective to provide a significant improvement in functional patterns. Taken together, our results demonstrate the synergistic effect between LLLT and topical diclofenac in muscle injury induced by stretching in rats.

Description: This paper presents a single-phase standalone photovoltaic (PV) system with two stages of converters. The aim of this work is to track the maximum power point (MPP) so as to transfer the maximum available power to the load and to control the output current in order to feed the AC load by a sinusoidal current. These goals are attained by using the sliding mode to design control laws in order to command the boost DC-DC and the inverter switches. Thus, a maximum power point tracking (MPPT) and an output current controller based on the sliding mode are proposed. The innovative aspect of this work is to propose a standalone PV system with the controllers based only on the sliding mode control approach. The proposed system is modeled and simulated under MATLAB Simulink under fast variations of irradiance and temperature. Then, the obtained results using the suggested MPPT are compared to those using the incremental conductance (IC) method. These results demonstrate the superiority of the sliding mode MPPT in terms of the tracking speed, the efficiency, and the time of response. Moreover, the current controller provides an output current of high quality with a THD of 3.47%. Furthermore, for accurate results, these controllers are evaluated under the fluctuations of two daily climatic profiles (sunny and cloudy) and compared those of the IC method. The results illustrate that the sliding mode MPPT has the potential of generating more electrical energy than the IC MPPT with benefits of up to 13.02% for the sunny daily profile and 27.57% for the cloudy one.

Description: By the method of nonreactive high-frequency magnetron sputtering on Upilex polyimide films, transparent and conductive layers of ITO were obtained. These layers, after high-temperature annealing, at temperatures typical for the solar cell formation, had a resistance of 11 ohm/ and a transmittance of up to 72%. The use of such an ITO layer with the addition of a 100 nm thick layer of undoped zinc oxide, as the front contact, and Cu/ITO composition, as the back contact, made it possible to obtain a flexible solar cell polyimide/ITO/CdS/CdTe/Cu/ITO with an efficiency of 10.4%. With a thickness of the base layer of cadmium telluride 2.5 μm, the average transmittance of the SC in the 850-1100 nm wavelength range is 46.8%. The developed design of a flexible solar cell based on cadmium telluride due to the use of a transparent back contact with a comb metal electrode is easily interfaced with existing designs of flexible solar cells based on copper and indium diselenide, which allow the formation of flexible tandem photoelectric converters CdTe/CuInSe2.

Description: In recent years, the introduction of the photovoltaic generation system (PV system) has been increasing by promoting the use of renewable energy. It has been feared that the reverse current from the PV system may cause an unacceptable level of voltage rise at the interconnection node in the power distribution system. This paper discusses the effects of the reverse current on the voltage rise and fall characteristics of the interconnection node and the voltage profiles along the power distribution line. When the line current on the circuit is small, the voltage on the line monotonically increases from the sending end to the receiving end. When a relatively large current flows, it causes a voltage reduction near the distribution substation. Furthermore, on the basis of the voltage aspects in the power distribution system with a large PV system, the allowable limits of the line current and the output power from PV system are investigated.

Description: The performance and economics of grid-connected photovoltaic (PV) systems are affected by the array spacing. Increasing the array spacing implies reducing the impact of shading, but at the same time, it increases the land purchase/preparation costs and the wiring costs. A number of technical and economic factors are involved when selecting an optimum array spacing. Designers of PV plants often set the row-to-row spacing based on simplified rules, losing the opportunity of improving the profitability of their projects. In this paper, a comprehensive methodology for optimizing the array spacing is proposed. It is based on annual shading energy calculations and incorporates a PV energy yield model together with an economic model focused on investment costs. The method is applied to the climatic conditions in Aguascalientes, Mexico, as a case study. A sensitivity analysis allowed the impact of the technical and economic parameters involved on the optimum interrow distance to be quantified. According to the results, the most relevant technical parameters are the module tilt (often considered by the PV designers), the ratio of plant width to plant length, and the module efficiency. The main economic parameters are the land-related costs and the costs per kWp. The comparison of this methodology to a conventional rule based on the winter solstice condition shows differences in the array spacing for the same location when the multiple technical and economic parameters are considered. Therefore, the proposed method will be useful for PV designers to improve the energetic and economic behavior of their systems.

Description: The aim of this study was to investigate the effect of hydrogen peroxide on the UVC photolysis of diclofenac (DCF) in aqueous solution. The experimental results confirmed very high effectivity of UVC direct photolysis of diclofenac. Moreover, it was found that H2O2/UV only slightly improved photodegradation; however, the addition of hydrogen peroxide into the reaction system affected the mechanism of DCF decomposition. Kinetics of the DCF reaction with ⋅OH radicals in the UV/H2O2 process was determined. For both processes, namely, photolysis and UV/H2O2, an in-depth analysis focused on the formation of phototransformation products of DCF (TPs) was performed. To the best of our knowledge, such comprehensive comparison of diclofenac photodegradation via UVC photolysis and UV/H2O2 has not been presented so far. Although there were no significant differences with regard to the rate of diclofenac degradation by photolysis and UV/H2O2, different oxidation products were found to be associated with the two considered processes. Furthermore, the H2O2/UV treatment increased toxicity towards Vibrio fischeri, while direct UVC photolysis had no significant effect on toxicity. The increase in toxicity can be attributed to the breakdown of DCF and formation of much more toxic TPs in the course of the H2O2/UVC process.

Description: Cascaded multilevel inverter topologies have received a great deal of attention for grid-connected PV systems. In this paper, three-cascaded multilevel inverter configurations are proposed for grid-connected PV applications. These are the three-phase cascaded H-bridge multilevel inverter topology, three-phase cascaded voltage-source inverter topology using inductors, and three-phase cascaded voltage-source inverter topology using coupled transformers. Distributed maximum power point tracking (MPPT) of PV modules using perturbation and observation algorithm is used for all presented topologies. In all presented configurations, each PV module is connected to one DC-DC isolated Ćuk converter for best MPPT achievement. Simulation is achieved by using the SIMULINK environment. The simulation results show that the three proposed topologies function well in improving the grid’s power quality. The grid currents are kept in phase with the grid voltage to ensure unity power factor, and the THD of the grid currents are within the acceptable range. The proposed topologies are experimentally implemented in the lab, and the switching pulses are generated with the help of the MicroLabBox data acquisition system. Comparing the three topologies according to the number of switches, voltage, and current stresses on switches and THD of the generated voltages and grid currents and according to the efficiency has been achieved in this paper, both experimentally and by simulation. The simulation and experimental results and comparisons are presented to verify the proposed topologies’ effectiveness and reliability.

Description: It is prerequisite to predict the behaviour of photovoltaic (PV) modules in a particular geographical area where the system is to be installed for their better performance and increasing lifetime. For that, models are the easiest and acceptable tools to characterise the behaviour of PV modules in any location. The purpose of this study was to develop an empirical model to predict the influence of temperature on the performance of four different PV module technologies, namely, polycrystalline, monocrystalline, amorphous, and thin film in an outdoor environment. The model has been developed by fitting of one year experimental data using the least squares method. The estimated results of the developed model were validated with real-time data (winter and summer season) and a comparison of other existing model estimates using error analysis with 95% confidence interval. The proposed model estimations confirm that the monocrystalline module performs better in winter and polycrystalline in summer as compared to amorphous and thin film in the study area. During analysis, it is revealed that developed model results are more precise and appropriate among other existing model estimations. It is concluded that the proposed model estimations could be used for the prediction of PV module temperature in similar environmental conditions as that of the study area with more accuracy and confidence. It ultimately helps to develop cost-effective and efficient PV systems.

Description: Dust particle accumulation affects outdoor photovoltaic module transmittance of solar cell glazing and thus leads to significant degradation of conversion efficiency owing to lower irradiance reaching the surface. In this study, the sensitivity of the polycrystalline silicon photovoltaic module towards industrial dust deposition was experimentally investigated under the tropical climatic condition of Arusha, Tanzania. Dust involved in the study came from fertilizer, gypsum, aggregate crusher, and coal mine industries. The experimental measurements were outdoor conducted under 720 W/m2, 800 W/m2, and 900 W/m2 solar irradiances. Results indicated that dust accumulation on the polycrystalline silicon photovoltaic module negatively affected output power as well as short-circuit current, however having no significant impact on open-circuit voltage. Maximum module efficiency loss was observed to be 64%, 42%, 30%, and 29% for coal, aggregate, gypsum, and organic fertilizer dust, respectively; hence, coal dust was the most effecting dust among the four. It was also demonstrated that PV module performance deteriorated with temperature rise owing to heat dissipation caused by dust accumulation.

Description: In this work, the stability of unpackaged CdTe solar cells with different configurations was investigated according to the International Electrotechnical Commission IEC 61215-2016. The measurements of thermal cycling from -40°C to +85°C and 24-hour temperature cycling from -40°C to +85°C withstanding the effects of 20-hour penetration of 85°C were carried out in CdS/CdTe solar cells with structures of FTO/CdS/CdTe/Au, FTO/CdS/CdTe/back contact/Au, and FTO/MZO/CdS/CdTe/back contact/Au, respectively. The performances of these cells before and after the thermal aging experiments were investigated by using light and dark together with . The results reveal varied performance degradation before and after thermal aging in the cells with different structures. Among these, the most deteriorated device is the one without back contact (BC), whose efficiency decreased by 25.12% after thermal cycling accompanying an obvious roll-over phenomenon when forward bias was greater than open circuit voltage. On the contrary, the reduction in the efficiency was about 16.80% in the case cells with BC, and the roll-over phenomenon was not so significant. Furthermore, for the devices with optimized front contact of FTO/MZO, the thermal stability was improved obviously. Interestingly, short-circuit current density associated with the carrier concentration of cells remained relatively small variations compared with the change of and fill factor. All the results indicated that an efficient back contact layer and an optimized front electrode were the indispensable structural elements to attain high stabilization in the CdS/CdTe solar cells.

Description: Different zinc foils as anode current collectors by electrowinning in various electrolytes with additives were prepared, which were evaluated through X-ray diffraction (XRD), scanning electron microscopy (SEM), float charge, and Tafel curve tests. The effect of different cathode current collectors, electrolytes, and the as-prepared zinc foils as the anode on the coulombic efficiency and the cycling performance of aqueous batteries were investigated. The results indicate that the initial coulombic efficiency and discharge capacity of the battery with 1 mol/L ZnSO4 and 2 mol/L Li2SO4 are 94.31% and 105.7 mAh/g using graphite as the current collector, which are much higher than 68.20% and 71.0 mAh/g using conductive polyethylene, respectively, attributed to the smaller polarization and electrochemical transfer impedance (Rct) of the former. However, the capacity retention of the latter is much higher than that of the former, especially using the high-concentration-lithium-based hybrid electrolyte, of which it is up to 74.63% even after 500 cycles. Moreover, the cycling performance of a battery with as-prepared zinc foil adding thiourea and gelatin into electrolyte during electrowinning is much better than that without additives, which is due to the smaller corrosion rate and side reaction.

Description: This study examines the degradation of single junction amorphous silicon (a-Si:H) photovoltaic (PV) modules. It summarises the main results obtained from over 7 years of field investigation of the degradation mechanisms of a-Si:H modules. The investigation was based on performance parameters such as fill factors, parasitic resistances, and ideality factors. The initial efficiencies for these modules were in accordance with the expected values; however, a significant decrease was observed during the monitoring period.

Description: Overall, CdSe:Ag+ quantum dots were prepared by the successive ionic layer absorption and reaction method using two solutions: mixing molar concentrations of 0.003 mM AgNO3 and a Cd(CH3COO)2·2H2O anion to make solution 1 and 2.27 g Se powder and 0.6 M Na2SO3 were dissolved in 100 ml deionized water, solution 2. The FTO was coated with TiO2 nanoparticles and then was dipped in both solutions, which created a FTO/TiO2/CdSe:Ag+ photoanode with a thickness of 1 layer to 4 layers. The layers of the CdSe:Ag+ film show an effect on the morphology, crystalline structure, optical properties, and photovoltaic through optical and photovoltaic measurements. Finally, the performance of the device based on a FTO/TiO2/CdSe:Ag+ photoanode with the different thickness increased significantly to exactly 3.96%. Moreover, in the pattern of an explanation of the optical and photovoltaic properties of materials, we use Tauc’s theory to determine the band gap, the conduction band, and the valence band.

Description: Despite remarkable economic growth and development in recent decades, Rwanda has been still facing energy crises and challenges. Although the country has considerable energy assets, less than 10% is utilized for its local electricity needs. Currently, national installed generation capacity is estimated at 221 MW, for a population around 12 million, and electricity access is estimated at 51% (37% grid and 14% off-grid networks). About half the population is without electricity access while the grid-connected users face high electricity tariffs and frequent power outages (blackouts). The national grid itself is also experiencing high losses. This paper used the HOMER software for modeling the optimal, sustainable, reliable, and affordable photovoltaic solar technologies as energy solutions for all (off-grid and on-grid users) in Rwanda. The selection and recommendation of a suitable photovoltaic (PV) solar technology depend on its annual electricity production capacity, electrical load, renewable energy penetration percentage, economic viability, feasibility, affordability, carbon footprint, and greenhouse gas emission level for climate change considerations towards a clean and greener future. The results show that the least cost of energy (LCOE) for electricity production by each of the solar PV systems with storage, PV-grid-connected household, and PV-grid connection with storage was 67.5%, 56.8%, and 33.9%, respectively, lower than the normal electricity tariff in Rwanda. The PV systems with storage proposed in this paper could be effective in increasing national energy resource exploitation, providing affordable and reliable energy access to all citizens.

Description: Cascade control is one of the most efficient systems for improving the performance of the conventional single-loop control, especially in the case of disturbances. Usually, controller parameters in the inner and the outer loops are identified in a strict sequence. This paper presents a novel cascade control strategy for grid-connected photovoltaic (PV) systems based on fractional-order PID (FOPID). Here, simultaneous tuning of the inner and the outer loop controllers is proposed. Teaching-learning-based optimization (TLBO) algorithm is employed to optimize the parameters of the FOPID controller. The superiority of the proposed TLBO-based FOPID controller has been demonstrated by comparing the results with recently published optimization techniques such as genetic algorithm (GA), particle swarm optimization (PSO), and ant colony optimization (ACO). Simulations are conducted using MATLAB/Simulink software under different operating conditions for the purpose of verifying the effectiveness of the proposed control strategy. Results show that the performance of the proposed approach provides better dynamic responses and it outperforms the other control techniques.

Description: Recently, chlorination disinfection technology applying ultraviolet radiation (Cl/UV) has received attention as an advanced oxidative process (AOP) for the generation of highly oxidant species. Many studies have evaluated its effects on pathogen inactivation, contaminant removal, and formation of disinfection by-products (DBPs). However, the degradation of three endocrine disruptor chemicals (EDCs), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and bisphenol-A (BPA), associated with simultaneous disinfection and estrogenic activity and ecotoxicity assessments has not yet been reported. Compound degradation increased with increasing chlorine concentrations (2 mg·L-1 chlorine), with pseudo-first-order kinetics s-1, s-1, and s-1 for BPA, E2, and EE2, respectively. The degradation kinetics in a WWTP effluent significantly decreased to min-1, min-1, and min-1, for BPA, E2, and EE2, respectively. However, 45% TOC removal and disinfection of E. coli and total coliform bacteria (TCB) were observed in 10 min of treatment. The yeast estrogen screen (YES) revealed that the treatment did not form by-products with estrogenic activity, demonstrating cleavage or mineralization in the phenolic group, common to all assessed compounds. High cell growth inhibition and mortality for Raphidocelis subcapitata and Ceriodaphnia dubia, respectively, were observed during the photodegradation process. Thus, the formed DBPs may be responsible for the observed toxicity and should be taken into account in WWTP treatments in order to monitor the formation of chlorinated by-products.

Description: The continuous growth in the energy demand across the globe due to the booming population, in addition to the harmful effects of the fossil fuels on the environment, has made it essential to harness renewable energy via different technologies and convert it to electricity. The potential of solar energy still remains untapped although it has several advantages particularly that it is a clean source to generate both electricity and heat. Concentrating sunlight is an effective way to generate higher throughput per unit area of the absorber material used. The heat extraction mechanisms and the fluids used in solar thermal systems are key towards unlocking higher efficiencies of solar thermal systems. Nanofluids can play a crucial role in the development of these technologies. This review is aimed at presenting the recent studies dealing with cooling the photovoltaic thermal (PVT), concentrated photovoltaic thermal (CPVT), and other solar systems using nanofluids. In addition, the article considers the definition of nanofluids, nanoparticle types, nanofluid preparation methods, and thermophysical properties of the most common nanoparticles and base fluids. Moreover, the major factors which affect the nanofluid’s thermal conductivity according to the literature will be reviewed.

Description: Geometrical and electronic properties of the main photosynthetic pigments in higher plants such as chlorophylls and xanthophylls were studied to find potential candidates that were able to participate in an eventual zeolite-dye artificial antenna. CRDFT (chemical reactivity density functional theory) and TD-DFT (time-dependent DFT) methods were employed in ground-state and excited-state calculations, respectively. The evaluated electronic properties at the gas phase included (a) energies such as HOMO-LUMO band gap (-, ranging from 2.168 to 2.504 eV), adiabatic ionization potential (, ranging from 5.964 to 7.207 eV), and adiabatic electronic affinity (, ranging from 2.176 to 2.741 eV); (b) global chemical reactivity indexes such as electronegativity (, ranging from 4.121 to 4.974 eV), hardness (, ranging from 1.812 to 2.233 eV), electrophilicity index (, ranging from 4.365 to 5.541 eV), and electroaccepting-electrodonating powers (, ranging from 1.671 to 2.115 eV, and , ranging from 4.375 to 5.273 eV); (c) electron-hole reorganization energies (, ranging from 0.225 to 0.519 eV and ranging from 0.168 to 0.425 eV, respectively) and electron-hole extraction potentials (EEP, ranging from 2.570 to 2.966 eV, and HEP, ranging from 5.538 to 7.012 eV, respectively); and (d) local chemical reactivity indexes like condensed Fukui functions (), condensed dual descriptor (), and condensed local softness (). These electronic properties allowed the association between molecules and reactivity-selectivity criteria, under the context of charge transfer and electronic transitions. Also, the aforementioned electronic properties were determined for combinations made with the selected molecules (β-cryptoxanthin and zeaxanthin) and 5 solvents (n-hexane, diethyl ether, acetone, ethanol, and methanol) with upward dielectric constants (). From frequency calculations, IR spectra were obtained for combinations. Finally, excited-state computations were carried out to acquire UV-Vis spectra of the combinations. We conclude that the selection of dyes is controlled mainly by geometrical constraints rather than by electronic properties.

Description: In our day, solar energy and wind energy are becoming more and more used as renewable sources by various countries for different uses such as in an isolated home. These energies admit a unique limitation related to the characteristic of energy instability. For this, the objective of this manuscript is to command and synchronize the power flow of a hybrid system using two sources of energy (solar and wind). The first contribution of our work is the utilization of an artificial neural network controller to command, at fixed atmospheric conditions, the maximum power point. The second contribution is the optimization of the system respecting real-time constraints to increase a generating system performance. As a matter of fact, the proposed system and the controller are modeled using MATLAB/Simulink and a Xilinx System Generator is utilized for hardware implementation. The simulation results, compared with other works in the literature, present high performance, efficiency, and precision. The suggested system and its control strategy give the opportunity of optimizing the hybrid power system performance, which is utilized in rural pumping or other smart house applications.

Description: LED filament lamp has the characteristics of nearly 360° lighting angle, high brightness, and low energy consumption, turning it gradually into the best substitute for traditional incandescent lamps. At present, due to the limitations of heat dissipation, the development of high-power LED filament lamp is restricted. Helium is a rare gas with small density and high heat transfer coefficient. It can be used as a cooling and protective gas for LED filament lamp. In this paper, we investigated the effects of helium on the heat dissipation and luminescence performance of the A60 LED filament lamps by detecting the changes of junction temperature, color temperature, and luminous flux of different ratios helium inflating in the different power A60 LED filament lamps. Through the experiment, we found the most cost-effective ratio of helium gas in the A60 LED filament lamps without improving the lamp size and the filament diameter.

Description: Novel nanocomposites have been prepared by intercalating TiO2 nanoparticles into talc. The nanocomposites have been verified by X-ray diffraction (XRD) from the appearance of a characteristic diffraction peak of TiO2. Thermal behavior of the prepared samples is examined by thermogravimetric analyzer (TGA), scanning electron microscope (SEM), and energy dispersive spectrometer (EDS), which have shown no TiO2 particles on the surface of the talc. The TiO2 particles are found in the layers of talc by transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) method, which have shown the increase of specific surface areas and total pore volumes and the decline of average pore diameters. As the strong adsorption ability of talc can intensify the power of photon absorption and capture-recombination carriers, more than 99.5% of 2,4-dichlorophenol can be degraded in 1 h by the nanocomposite under an ultraviolet lamp in neutral solution and room temperature after reaching adsorption equilibrium, and the result of adsorbance is in accord with the first-order kinetic. The degradation rate was maintained at about 99% after 20 times. Therefore, the prepared talc/TiO2 nanocomposite is an efficient, stable, and recyclable material for wastewater treatment.

Description: Cellulose nanopaper (CNP) has attracted much interest during the last decade as a new fascinating renewable and biodegradable substrate for printed electronics and solar cells. Its outstanding optical and mechanical properties make CNP the ideal substrate for the preparation of photovoltaic devices, since its high transparency and haze favour the absorption of light from the active layer of the solar cell. However, some advances need to be done in the direction of increasing CNP stability in humid environment without compromising its remarkable advantages. This review critically points at these aspects, presenting an overview of state-of-art solutions to enhance nanopaper stability in a humid environment.

Description: Dye-Sensitized Solar Cell (DSSC) is a solar cell device that works using electrochemical principles in which sensitive dyes are absorbed in the TiO2 photoelectrode layer. The problem of DSSC-based natural dyes is the lower efficiency than silicon solar cells. This low efficiency is due to the barrier of electron transfer in the TiO2 semiconductor layer. In this study, the addition of clathrin protein to the TiO2 layer was used to increase electron transfer in the semiconductor layer resulting in improved DSSC performance. Clathrin is a protein that plays a role in the formation of transport vesicle membrane in eukaryotic cells. The method used in this study is clathrin protein with a concentration of 0%, 25%, 50%, and 75% added to TiO2 in DSSC structure. Photovoltaic characteristics of DSSC were measured using a data logger to determine the performance of DSSC, layer morphology was analyzed using Scanning Electron Microscopy (SEM), the element content in DSSC was analyzed using Energy-Dispersive X-ray Spectroscopy (EDS), and functional groups in DSSC layers were analyzed using Fourier-Transform Infrared Spectroscopy (FTIR). The result of this study is the addition of clathrin protein can improve DSSC performance, which resulted in the highest performance of DSSC on 75% clathrin protein addition with ,, and . From the results of SEM analysis, it appears that clathrin protein molecules fill the cavities in TiO2 molecules. EDS analysis shows an increase in carbon, oxygen, and phosphorus content in TiO2 layers with increasing clathrin protein concentration. FTIR analysis shows an increasingly sharp absorption in the FTIR spectrum of protein-forming functional groups by increasing clathrin protein concentration in DSSC.

Description: This work proposes a multicarrier energy hub system with the objective of minimizing the economy cost and the CO2 emissions of a residential building without sacrificing the household comfort and increasing the exploitation of renewable energy in daily life. The energy hub combines the electrical grid and natural gas network, a gas boiler, a heat pump, a photovoltaic plant, and a photovoltaic/thermal (PV/T) system. In addition, to increase the overall performance of the system, a battery-based energy storage system is integrated. To evaluate the optimal capacity of each energy hub component, an optimization scheduling process and the optimization problem have been solved with the YALMIP platform in the MATLAB environment. The result showed that this advanced system not only can decrease the economic cost and CO2 emissions but also reduce the impact to electrical grid.

Description: This paper investigates the impacts of dispatchability of Parabolic Trough Concentrated Solar Power (PT-CSP) systems over PV power plants in Palestinian territories. Jericho governorate was taken as a case study. All conditions required for implementing PV and PT-CSP systems are verified. The capacity of each investigated system is 1 MW, and both systems are investigated in terms of technical, economic, and environmental aspects. The parametric analysis is used to identify the most feasible option of each renewable energy system by varying the cost of each option candidate and introducing thermal energy storage (TES) to the technology of PT-CSP systems with different capacities. A software based on the MATLAB environment is programmed to estimate the energy produced from each system with the important technical, financial, and environmental indicators. It is found that the alternative of installing a 1 MW PV system is the installation of 1 MWe PT-CSP systems with 14.5 h or 18.5 h TES. Introducing TES improves the dispatchability of the system and the capacity factor which consequently justifies the PT-CSP system investment. Increasing the degree of dispatchability improves the capacity factor of the PT-CSP system from 21% at 0 h TES to 57% at 18.5 h TES (24 h operation). The capacity factor of the PV system is 18.7% which is mostly similar to PT-CSP with zero dispatchability (0 h TES). The study considers the environmental benefits by estimating the amount of avoided CO2 emissions, and it was found that increasing the capacity factor augments the environmental benefits.

Description: This paper presents the design and implementation of a photovoltaic emulator, based on an accurate mathematical model of a photovoltaic panel, instead of the look-up table method. The latter requires more memory for increasing accuracy and considering all the desired environmental situations. Furthermore, the proposed approach takes into account the incidence solar angle, as an input parameter, to offer the possibility of evaluating daily losses for different values of tilt angle. The validation of the proposed emulator is carried out by comparing in real-time, both the studied panel output and the emulator output, under variable load, temperature, and irradiation levels. The emulator is able to operate online with connected solar radiation and temperature sensors or offline with recorded measurement vectors. The practical tests were performed on a prototype designed using a MATLAB C MEX S-function, dSPACE board 1104, and a controlled DC/DC converter. The results showed that the emulator was able to behave accurately as the studied photovoltaic panel.

Description: Currently, demand-side management (DSM) covers a whole range of technological and policy measures aimed at reducing electricity consumption connected with economic activities. Thus, the development of wind PV and other renewable energy technologies, combined with microgrid technology, offers the remote consumers and prosumers ample opportunities to stabilize long-term costs and increase local energy system security. Apart from that, DSM from microgrid based on renewable sources also has certain social benefits, such as protection of the environment and conservation of natural resources. Due to the advances in photovoltaic material research and solar panel price reduction over the last years, the usage of this alternative energy source in Baltic region countries seems more attractive. The usage of energy storage devices can help use the solar power more efficiently and smarter. This paper deals with the optimization of a proposed solar panel array of a renovated office building’s communal lighting in Riga, using storage devices and demand-side management of the produced power, looking into a way to calculate the needed storage capacity on the basis of potential PV system and existing power consumption for communal space lighting system. The proposed approach will become one of the first basic steps in applying DSM to help reduce the communal space’s illumination power consumption, in turn helping to reduce the needed PV generating power and energy storage.

Description: The main goal of this paper is to review the most important methods previously developed to enhance the efficiency and increase the lifetime of photovoltaic panels. The methods to increase the solar radiation incident on photovoltaic panels, as well as the cooling and the maximum power point tracker methods, are concisely presented in this paper. The pros and cons analysis reveals that the methods to enhance the power generated by the photovoltaic panels are strongly dependent on geographical location, climatic conditions, and the materials used. This review paper is also of interest for engineers who attempt to identify the most adequate solutions to maximize the energy output of photovoltaic systems for each location.

Description: Photovoltaic (PV) panels are used for both standalone applications and grid-connected systems. In the former case, the PV panels used vary in size, from very small, for smart solar garden lamps, to standard, in order to ensure the necessary electric energy for a house. For these cases, it is very important to choose the best solution in terms of photovoltaic cell materials. In this paper, a comparative study of two commercial photovoltaic panels, monocrystalline and amorphous silicon, is presented. The two photovoltaic panels are measured in natural conditions, during two years, in Brasov, Romania. The emphasis is placed upon the maximum power generated by the two panels, but the cost and the lifetime are also taken into consideration. The gain in average maximum power for the monocrystalline silicon panel varies from 1.9 times for low irradiance to 2.4 times higher than the one obtained from the amorphous silicon panel, during the test period. The temperature of the monocrystalline silicon panels is lower than that of the amorphous silicon panel in the majority of measurements. The degradation rate determined in two years is 1.02% for the monocrystalline silicon panel and 1.97% for the amorphous silicon panel.

Description: Layered double hydroxides (LDH) M2+M3+CO32− were synthesized following the sol-gel methodology using Mg-Al, Mg-Fe, and Zn-Al as cation pairs for subsequent use in the preparation of TiO2/LDH materials. The samples were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), and the Brunauer–Emmett–Teller (BET) technique to determine the surface area (SA); the results of which were used to determine the roughness of the samples in terms of surface fractal dimension (). The prepared materials exhibited both adsorption and photocatalytic properties in the removal of phenol in aqueous solution under ultraviolet irradiation. This work studies the relationship between the textural parameters of the materials obtained in relation to their photocatalytic efficiency and adsorption capacity, finding that the surface of the solids, their structural heterogeneity, and roughness condition the photodegradation and adsorption processes, using phenol as reference organic pollutant. The results show that different cation in LDH influences in photocatalytic capacity; the TiO2/ZnAl was the best material in one test, but after 10 times of test, the TiO2/MgFe gave the better photodegradation material. In adsorption capacity, TiO2/ZnAl and TiO2/MgFe have a close rate for phenol adsorption and both were better than TiO2/MgAl. The differences in textural characteristics (surface area, surface roughness, and pore-size distribution) affected phenol adsorption and photodegradation efficiency.

Description: This research work was conducted to investigate the structural, molecular, electronic, and photophysical parameters of the fluorescein dye derivatives using the density functional theory (DFT) and time dependent-density functional theory (TD-DFT) computations. The organic donor-π-acceptor dye used for dye-sensitized solar cells, based on 2-(3-hydroxy-6-oxo-6H-xanthene-9-yl)benzoic acid (fluorescein) and its five derivatives, was investigated. The derivatives were formed by attaching different donor groups at para position. The excited state energies, electron absorption spectra, and oscillator strengths () were calculated using TD-DFT/B3LYP/6-311G basis set calculations on fully DFT-optimized geometries. The HOMO orbital, LUMO orbital, and energy gap values show that fluorescein attached with thiophene (FST) compound has a smaller energy gap compared to others and the fluorescein attached with an amine (FSA) have a larger energy gap than all compounds. The increasing order of the energy gap between HOMO and LUMO for the fluorescein and its derivatives is FST 

Description: Graphite with a single atomic layer known as graphene shows great capability in energy conversion and storage devices. Dye-sensitized solar cells (DSSCs) have attracted intense interests due to offering high photo-to-electric conversion efficiencies. DSSCs are built from a photoelectrode (a dye-sensitized nanocrystalline semiconductor), an electrolyte with redox couples, and a counterelectrode. In this review article, we outline the strategies to enhance the efficiency and reduce the cost by introducing graphene into the DSSCs as the photoelectrode. First, the development of DSSCs and the properties of graphene are briefly described. Then, the applications of graphene-based materials for photoelectrodes (transparent electrode, semiconductor layer, and dye sensitizer) in DSSCs are deeply discussed. Finally, an outlook for graphene materials in DSSCs is provided.

Description: The aim of this study is to examine the technological challenge of the electrochemical formation of zinc oxide and Al-doped ZnO films (ZnO:Al, AZO) as transparent conductive oxide coatings with complex architectures for solar cell photoanode materials. A cathodic electrodeposition of AZO was performed using aqueous nitrate electrolytes at 25°C. A significant positive deviation in aluminum percentage in the films was demonstrated by the LAES, EDX, and XPS methods, which originates from aluminum hydroxide sedimentation. The photoluminescent characteristics of the ZnO films reveal low band intensities related to intrinsic defects, while the samples with 1 at.% of aluminum show a strong and wide PL band at and increase in conductivity.

Description: The interest in TiO2 nanotubes has resulted in a lot of studies including the effects of various parameters on the properties and performance for different applications. This study investigated the effect of anodization at a low temperature on the properties and photoelectrochemical performance. The effects of varied anodization settings on morphology, crystallinity, and PEC response were studied. Low-temperature anodization resulted in smaller pore diameter and shorter tube length. Annealing temperature affected the presence of varied phases of TiO2 such as the prominence of anatase and amounts of rutile and amorphous TiO2 at 125°C. To observe photoelectrochemical response, annealing at 450°C is necessary. However, a cathodic response was observed for TiO2 nanotubes synthesized with low voltage at low temperature. Hence, amorphous titania nanotubes annealed at 125°C with thickness achieved in the anodization can be a potential material used for photocatalytic applications due to its determined cathodic photoelectrochemical response.

Description: The main objective of this work is to create a daily updated database that includes all components of solar radiation, either energetic or spectral radiation. This will lead us to quantify the Moroccan solar potential and to determine the dimensions of all types of solar thermal and photovoltaic systems. Consequently, the obtained database will be the fundamental support for engineers, designers, and all organizations interested in developing solar systems, in different regions throughout Morocco. It will also be a basic tool for researchers in modelling and simulating the new solar systems. Firstly, we used one year’s worth of measurements of the different components of the solar radiation, provided by the National Meteorological Department, to establish the extrapolation equations between the global radiation at the reference site and the global radiation of twenty-eight other sites. As well as with the same measurements, we developed the correlation equations between the global solar radiation and the other solar radiation components. Secondly, from ten years of Fez station’s daily global radiation measurements and through the extrapolation equations, we were able to estimate the global radiation of all Moroccan cities. Then, by using the obtained global radiation data and the correlation equations, we predicted the other components of solar radiation. Subsequently, with a new measurement campaign carried out on several sites, we validated the estimation models by using the usual statistical indicators. In addition, we compared our results with those obtained by other estimation models. The resulting differences for each solar component display the advantage of our model with errors under 6%. To facilitate the use of our results, we compiled them into maps representing the spread of solar radiation across Morocco.

Description: Silver nanoparticles (Ag-NPs) possess excellent antibacterial properties and are considered to be an alternative material for treating antibiotic-resistant bacteria. The present study was aimed at enhancing the antibacterial efficiency of Ag-NPs using visible laser light against Escherichia coli and Staphylococcus aureus in vitro. Four concentrations of Ag-NPs (12.5, 25, 50, and 100 μg/ml), synthesized by the chemical reduction method, were utilized to conduct the antibacterial activity of prepared Ag-NPs. The antibacterial efficiencies of photoactivated Ag-NPs against both bacteria were determined by survival assay after exposure to laser irradiation. The mechanism of interactions between Ag-NPs and the bacterial cell membranes was then evaluated via scanning electron microscopy (SEM) and reactive oxygen species analysis to study the cytotoxic action of photoactivated Ag-NPs against both bacterial species. Results showed that the laser-activated Ag-NP treatment reduced the surviving population to 14% of the control in the E. coli population, while the survival in the S. aureus population was reduced to 28% of the control upon 10 min exposure time at the concentration of 50 μg/ml. However, S. aureus showed lower sensitivity after photoactivation compared to E. coli. Moreover, the effects depended on the concentration of Ag-NPs and exposure time to laser light. SEM images of treated bacterial cells indicated that substantial morphological changes occurred in cell membranes after treatment. The results suggested that Ag-NPs in the presence of visible light exhibit strong antibacterial activity which could be used to inactivate harmful and pathogenic microorganisms.

Description: Photocatalytic water splitting represents an emerging technology well positioned to satisfy the growing need for low-energy, low CO2, economically viable hydrogen gas production. As such, stable, high-surface-area electrodes are increasingly being investigated as electrodes for the photochemical conversion of solar energy into hydrogen fuel. We present a titanium dioxide (TiO2)/zinc oxide (ZnO) nanowire array using a hybrid hydrothermal/atomic layer deposition (ALD) for use as a solar-powered photoelectrochemical device. The nanowire array consists of single crystalline, wurtzite ZnO nanowires with a 40 nm ALD TiO2 coating. By using a TiO2 nanocoating on the high surface area-ZnO array, three advancements have been accomplished in this work: (1) high aspect ratio nanowires with TiO2 for water splitting (over 8 μm), (2) improved stability over bare ZnO nanowires during photocatalysis, and (3) excellent onset voltage. As such, this process opens up new class of the micro/nanofabrication process for making efficient photocatalytic gas harvesting systems.

Description: This paper develops the photovoltaic bidirectional inverter (BI) operated in dual mode for the seamless power transfer to DC and AC loads. Normal photovoltaic (PV) output voltage is fed to boost converter, but in space application, boost converter is not so preferable. To overcome this, buck and boost converters are proposed in this paper. Duty cycle to this converter is provided with the help of the outcome of the maximum power point tracking (MPPT) controller. This can be implemented by using perturbation and observation method. The MPPT will operate the switch between buck and boost modes. When the output voltage of a PV array is close to the dc bus voltage, then the bidirectional inverter can fulfill both rectification and grid connected mode. To control the power flow between dc bus and ac grid, a dc distribution system is used to regulate the dc bus voltage to a convinced level. Moreover, the bidirectional inverter must fulfill grid connection (sell power) and rectification (buy power) with power factor correction (PFC) to control the power flow between dc bus and ac grid. The simulations and hardware experimental results of a 2.5 kVA circuit are presented to validate the performance of the proposed dual-mode seamless power transfer.

Description: Solar Charge Controller (SCC) with Maximum Power Point Tracking (MPPT) is needed to extract maximum energy from photovoltaic. However, a SCC device with MPPT technology feature is expensive on the market due to the requirements for a high-power system. On the other hand, in lower power applications such as IoT sensors, solar street lights, and wireless communication nodes, these types of controllers can be produced at a lower cost. In this study, the design of a low-cost SCC was conducted using the MPPT technology for low-power solar applications. The SCC is designed based on the Arduino microcontroller, which has the role of controlling the circuit and producing PWM signals to regulate the DC-DC converter. Several tests were conducted to validate the efficiency of the MPPT algorithm. The SCC device succeeded in increasing efficiency up to 52% on the low irradiance level.

Description: In order to explore the influence of vibration that the vehicles are often subjected on water management of PEMFC, the dynamic characteristics of vibrating droplet on gas diffusion layer (GDL) surface were investigated through a high-speed image technology. The operating condition of vertical and horizontal excitations separately or coupled with air flow under different frequencies and amplitudes are applied on the substrate, so that the laws for the transition from Wenzel-Cassie regime to Cassie regime and the contact angle, the deformation rate for the width and height are obtained. It is observed that the wetting diameter of the droplet is smaller than the initial value under vertical vibration, making it easier for the gas to discharge the water droplets from the PEMFC. For the horizontal excitation, the droplet is pulled apart when the applied energy exceeded the cohesive energy at elevated frequency and amplitude. Moreover, as to the interaction of vibration and air flow, the droplet was more likely to move forward under the gas-driven force.

Description: Accurate and reliable measurements of the 3D flame temperature profile are highly desirable to achieve in-depth understanding of the combustion and pollutant formation processes. In this paper, a measurement method for reconstruction of a 3D flame temperature profile was proposed by using a light field camera. It combines the convolution imaging model and radiative transfer equation and takes into account the characteristics of emission, absorption, and scattering of a semitransparent flame. According to the point spread function characteristics of the imaging system, the number and positions of the refocus planes were set by comprehensive consideration of the reconstruction accuracy and efficiency. The feasibility of the present method was proved by numerical simulation and an experiment of a candle flame. This method achieves the reconstruction of a 3D asymmetric flame profile through a single exposure of a single camera, which overcomes the problem of complexity of a multicamera system and the time delay of a conventional scanning camera system.

Description: Exploring a novel and efficient photocatalyst is the key research goal to relieve energy and environmental issues. Herein, Z-scheme heterojunction composites were successfully fabricated by loading g-C3N4 nanosheets (CN) on the surface of Mg1.2Ti1.8O5 nanoflakes (MT) through a simple sol-gel method followed by the calcination method. The crystalline phase, morphologies, specific surface area, and optical and electrochemical performance of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-disperse X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET), diffuse reflectance spectroscopy (DRS), and electrochemical measurements. Considering the suitable band structures of the components, the photocatalytic performance was evaluated by photocatalytic H2O splitting and photocatalytic inactivation of Escherichia coli (E. coli). Among the samples, MT/CN-10 (the molar percentage of melamine to as-obtained Mg-Ti gel was 10%) shows superior photocatalytic performance, which the average H2 production rate was 3.57 and 7.24 times higher than those of MT and CN alone. Additionally, the efficiency of inactivating Escherichia coli (E. coli) over MT/CN-10 was 1.95 and 2.06 times higher as compared to pure MT and CN, respectively. The enhancement of the photocatalytic performance was attributed to the advantages of the extremely negative conduction band (CB) of CN and the extremely positive valence band (VB) of MT, the enhanced light absorption, and more efficient photogenerated charge carrier separation.

Description: This paper presents an implementation of real-time energy management systems (EMS) to maximize the efficiency of the electricity distribution in an isolated hybrid microgrid system (HMGS) containing photovoltaic modules, wind turbine, battery energy storage system, and diesel generator (DG) which is used as a backup source. These systems are making progress worldwide thanks to their respect for the environment. However, hybridization of several sources requires power flow control (PFC). For this reason, in this work, a proper energy management system is developed using LabVIEW software and embedded in a suitable platform for the real-time management of the hybrid energy system. The developed EMS is tested and validated through a small-scale application which accurately represents the case study of an isolated mosque located in a remote area of Morocco. The aim of this paper is to (i) propose a novel modelling method and real-time monitoring interface under the LabVIEW software based on the real data obtained by an optimal sizing previously made using Homer-pro software and (ii) implement the power control system on a low-consumption embedded platform that is the Raspberry-pi3.

Description: This study examines the degradation of single junction amorphous silicon (a-Si:H) photovoltaic (PV) modules. It summarises the main results obtained from over 7 years of field investigation of the degradation mechanisms of a-Si:H modules. The investigation was based on performance parameters such as fill factors, parasitic resistances, and ideality factors. The initial efficiencies for these modules were in accordance with the expected values; however, a significant decrease was observed during the monitoring period.

Description: In this study, a dynamic system has been modeled to efficiently use a photovoltaic generation and control system (PVGCS) for driving of a medium power off-grid electric machine. The measures have been taken to respond to three different disturbing factors in this system. First, the photovoltaic panels selected for energy generation have a variable solar radiation effect. Second, the DC motor load at the system output is assumed to have a variable torque. Third, a variable reference voltage, which is determined even in the case of time-varying energy generation and consumption of the system, is followed with minimum error. For this purpose, a push-pull converter has been chosen as a highly flexible structure since it is predicted that it can provide stable and effective variable DC voltage at increasing and decreasing level required for DC motor. The control of the DC voltage at different levels to be provided by the push-pull converter is performed by PI, fuzzy logic, fuzzy-tuned PI, 2-DOF PI, and fractional PID logic whose coefficients are selected by appropriate methods, respectively. The system efficiency and stability under the influence of these five different advanced controllers are compared. In the case of two disturbing factors affecting the system, the difference values (errors) of the voltage generated by each selected controller with the reference voltage are determined comparatively. The studies were carried out by using dynamic system modeling in MATLAB-SIMULINK software. In addition, the results of this study proved which type of controllers is more successful in controlling systems with the second order and more instability factors and which of them responds to sudden changes in errors more quickly.

Description: In this work, the effect of DIM on the PCE and photostability of PCDTBT:PC71BM PSCs was investigated. DIM is an effective additive in a BHJ PCDTBT:PC71BM solar cell since it fulfills the requirement of a selective PC71BM dissolution. PCE of the device based on PCDTBT:PC71BM processed with DIM is higher than that of the reference device. In terms of the device stability, the PSCs processed with DIM showed poor stability at longer light exposure time. For the device without DIM especially as the light exposure time was increased, the device stability was better because the PCDTBT could be shielded from air by an aggregated PC71BM layer. For the PCDTBT:PC71BM device processed with DIM, the results obtained from measurement indicates that it has a lower recombination rate. The result from IS measurement shows that for pristine PCDTBT:PC71BM devices with 3% DIM, the active layer resistance is lower compared to the device without DIM. However, after irradiating the device for 5 hr, the resistance of the device processed with DIM is higher and it is consistent with decreased PCE of the aged device.

Description: Overall, CdSe:Ag+ quantum dots were prepared by the successive ionic layer absorption and reaction method using two solutions: mixing molar concentrations of 0.003 mM AgNO3 and a Cd(CH3COO)2·2H2O anion to make solution 1 and 2.27 g Se powder and 0.6 M Na2SO3 were dissolved in 100 ml deionized water, solution 2. The FTO was coated with TiO2 nanoparticles and then was dipped in both solutions, which created a FTO/TiO2/CdSe:Ag+ photoanode with a thickness of 1 layer to 4 layers. The layers of the CdSe:Ag+ film show an effect on the morphology, crystalline structure, optical properties, and photovoltaic through optical and photovoltaic measurements. Finally, the performance of the device based on a FTO/TiO2/CdSe:Ag+ photoanode with the different thickness increased significantly to exactly 3.96%. Moreover, in the pattern of an explanation of the optical and photovoltaic properties of materials, we use Tauc’s theory to determine the band gap, the conduction band, and the valence band.

Description: In this work, the stability of unpackaged CdTe solar cells with different configurations was investigated according to the International Electrotechnical Commission IEC 61215-2016. The measurements of thermal cycling from -40°C to +85°C and 24-hour temperature cycling from -40°C to +85°C withstanding the effects of 20-hour penetration of 85°C were carried out in CdS/CdTe solar cells with structures of FTO/CdS/CdTe/Au, FTO/CdS/CdTe/back contact/Au, and FTO/MZO/CdS/CdTe/back contact/Au, respectively. The performances of these cells before and after the thermal aging experiments were investigated by using light and dark together with . The results reveal varied performance degradation before and after thermal aging in the cells with different structures. Among these, the most deteriorated device is the one without back contact (BC), whose efficiency decreased by 25.12% after thermal cycling accompanying an obvious roll-over phenomenon when forward bias was greater than open circuit voltage. On the contrary, the reduction in the efficiency was about 16.80% in the case cells with BC, and the roll-over phenomenon was not so significant. Furthermore, for the devices with optimized front contact of FTO/MZO, the thermal stability was improved obviously. Interestingly, short-circuit current density associated with the carrier concentration of cells remained relatively small variations compared with the change of and fill factor. All the results indicated that an efficient back contact layer and an optimized front electrode were the indispensable structural elements to attain high stabilization in the CdS/CdTe solar cells.

Description: Different zinc foils as anode current collectors by electrowinning in various electrolytes with additives were prepared, which were evaluated through X-ray diffraction (XRD), scanning electron microscopy (SEM), float charge, and Tafel curve tests. The effect of different cathode current collectors, electrolytes, and the as-prepared zinc foils as the anode on the coulombic efficiency and the cycling performance of aqueous batteries were investigated. The results indicate that the initial coulombic efficiency and discharge capacity of the battery with 1 mol/L ZnSO4 and 2 mol/L Li2SO4 are 94.31% and 105.7 mAh/g using graphite as the current collector, which are much higher than 68.20% and 71.0 mAh/g using conductive polyethylene, respectively, attributed to the smaller polarization and electrochemical transfer impedance (Rct) of the former. However, the capacity retention of the latter is much higher than that of the former, especially using the high-concentration-lithium-based hybrid electrolyte, of which it is up to 74.63% even after 500 cycles. Moreover, the cycling performance of a battery with as-prepared zinc foil adding thiourea and gelatin into electrolyte during electrowinning is much better than that without additives, which is due to the smaller corrosion rate and side reaction.

Description: Ternary nickel-cobalt lithium aluminate LiNiCoAlO2 (NCA, ) is an essential cathode material with many vital advantages, such as lower cost and higher specific capacity compared with lithium cobaltate and lithium iron phosphate materials. However, the noticeably irreversible capacity and reduced cycle performance of NCA cathode materials have restricted their further development. To solve these problems and further improve the electrochemical performance, numerous research studies on material modification have been conducted, achieving promising results in recent years. In this work, the progress of NCA cathode materials is examined from the aspects of surface coating and bulk doping. Furthermore, future research directions for NCA cathode materials are proposed.

Description: This paper develops the photovoltaic bidirectional inverter (BI) operated in dual mode for the seamless power transfer to DC and AC loads. Normal photovoltaic (PV) output voltage is fed to boost converter, but in space application, boost converter is not so preferable. To overcome this, buck and boost converters are proposed in this paper. Duty cycle to this converter is provided with the help of the outcome of the maximum power point tracking (MPPT) controller. This can be implemented by using perturbation and observation method. The MPPT will operate the switch between buck and boost modes. When the output voltage of a PV array is close to the dc bus voltage, then the bidirectional inverter can fulfill both rectification and grid connected mode. To control the power flow between dc bus and ac grid, a dc distribution system is used to regulate the dc bus voltage to a convinced level. Moreover, the bidirectional inverter must fulfill grid connection (sell power) and rectification (buy power) with power factor correction (PFC) to control the power flow between dc bus and ac grid. The simulations and hardware experimental results of a 2.5 kVA circuit are presented to validate the performance of the proposed dual-mode seamless power transfer.

Description: In order to explore the influence of vibration that the vehicles are often subjected on water management of PEMFC, the dynamic characteristics of vibrating droplet on gas diffusion layer (GDL) surface were investigated through a high-speed image technology. The operating condition of vertical and horizontal excitations separately or coupled with air flow under different frequencies and amplitudes are applied on the substrate, so that the laws for the transition from Wenzel-Cassie regime to Cassie regime and the contact angle, the deformation rate for the width and height are obtained. It is observed that the wetting diameter of the droplet is smaller than the initial value under vertical vibration, making it easier for the gas to discharge the water droplets from the PEMFC. For the horizontal excitation, the droplet is pulled apart when the applied energy exceeded the cohesive energy at elevated frequency and amplitude. Moreover, as to the interaction of vibration and air flow, the droplet was more likely to move forward under the gas-driven force.

Description: In this study, a dynamic system has been modeled to efficiently use a photovoltaic generation and control system (PVGCS) for driving of a medium power off-grid electric machine. The measures have been taken to respond to three different disturbing factors in this system. First, the photovoltaic panels selected for energy generation have a variable solar radiation effect. Second, the DC motor load at the system output is assumed to have a variable torque. Third, a variable reference voltage, which is determined even in the case of time-varying energy generation and consumption of the system, is followed with minimum error. For this purpose, a push-pull converter has been chosen as a highly flexible structure since it is predicted that it can provide stable and effective variable DC voltage at increasing and decreasing level required for DC motor. The control of the DC voltage at different levels to be provided by the push-pull converter is performed by PI, fuzzy logic, fuzzy-tuned PI, 2-DOF PI, and fractional PID logic whose coefficients are selected by appropriate methods, respectively. The system efficiency and stability under the influence of these five different advanced controllers are compared. In the case of two disturbing factors affecting the system, the difference values (errors) of the voltage generated by each selected controller with the reference voltage are determined comparatively. The studies were carried out by using dynamic system modeling in MATLAB-SIMULINK software. In addition, the results of this study proved which type of controllers is more successful in controlling systems with the second order and more instability factors and which of them responds to sudden changes in errors more quickly.

Description: The aim of this work is to study the behaviour of a silicon solar cell under the irradiation of different fluences of high-energy proton radiation (10 MeV) and under constant multispectral illumination. Many theoretical et experimental studies of the effect of irradiation (proton, gamma, electron, etc.) on solar cells have been carried out. These studies point out the effect of irradiation on the behaviour of the solar cell electrical parameters but do not explain the causes of these effects. In our study, we explain fundamentally the causes of the effects of the irradiation on the solar cells. Taking into account the empirical formula of diffusion length under the effect of high-energy particle irradiation, we established new expressions of continuity equation, photocurrent density, photovoltage, and dynamic junction velocity. Based on these equations, we studied the behaviour of some electronic and electrical parameters under proton radiation. Theoretical results showed that the defects created by the irradiation change the carrier distribution and the carrier dynamic in the bulk of the base and then influence the solar cell electrical parameters (short-circuit current, open-circuit voltage, conversion efficiency). It appears also in this study that, at low fluence, junction dynamic velocity decreases due to the presence of tunnel defects. Obtained results could lead to improve the quality of the junction of a silicon solar cell.

Description: Despite remarkable economic growth and development in recent decades, Rwanda has been still facing energy crises and challenges. Although the country has considerable energy assets, less than 10% is utilized for its local electricity needs. Currently, national installed generation capacity is estimated at 221 MW, for a population around 12 million, and electricity access is estimated at 51% (37% grid and 14% off-grid networks). About half the population is without electricity access while the grid-connected users face high electricity tariffs and frequent power outages (blackouts). The national grid itself is also experiencing high losses. This paper used the HOMER software for modeling the optimal, sustainable, reliable, and affordable photovoltaic solar technologies as energy solutions for all (off-grid and on-grid users) in Rwanda. The selection and recommendation of a suitable photovoltaic (PV) solar technology depend on its annual electricity production capacity, electrical load, renewable energy penetration percentage, economic viability, feasibility, affordability, carbon footprint, and greenhouse gas emission level for climate change considerations towards a clean and greener future. The results show that the least cost of energy (LCOE) for electricity production by each of the solar PV systems with storage, PV-grid-connected household, and PV-grid connection with storage was 67.5%, 56.8%, and 33.9%, respectively, lower than the normal electricity tariff in Rwanda. The PV systems with storage proposed in this paper could be effective in increasing national energy resource exploitation, providing affordable and reliable energy access to all citizens.

Description: Dust particle accumulation affects outdoor photovoltaic module transmittance of solar cell glazing and thus leads to significant degradation of conversion efficiency owing to lower irradiance reaching the surface. In this study, the sensitivity of the polycrystalline silicon photovoltaic module towards industrial dust deposition was experimentally investigated under the tropical climatic condition of Arusha, Tanzania. Dust involved in the study came from fertilizer, gypsum, aggregate crusher, and coal mine industries. The experimental measurements were outdoor conducted under 720 W/m2, 800 W/m2, and 900 W/m2 solar irradiances. Results indicated that dust accumulation on the polycrystalline silicon photovoltaic module negatively affected output power as well as short-circuit current, however having no significant impact on open-circuit voltage. Maximum module efficiency loss was observed to be 64%, 42%, 30%, and 29% for coal, aggregate, gypsum, and organic fertilizer dust, respectively; hence, coal dust was the most effecting dust among the four. It was also demonstrated that PV module performance deteriorated with temperature rise owing to heat dissipation caused by dust accumulation.