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Sky Image-Based Solar Irradiance Prediction Methodologies Using Artificial Neural Networks
摘要： In order to decelerate global warming, it is important to promote renewable energy technologies. Solar energy, which is one of the most promising renewable energy sources, can be converted into electricity by using photovoltaic power generation systems. Whether the photovoltaic power generation systems are connected to an electrical grid or not, predicting near-future global solar radiation is useful to balance electricity supply and demand. In this work, two methodologies utilizing artificial neural networks (ANNs) to predict global horizontal irradiance in 1 to 5 minutes in advance from sky images are proposed. These methodologies do not require cloud detection techniques. Sky photo image data have been used to detect the clouds in the existing techniques, while color information at limited number of sampling points in the images are used in the proposed methodologies. The proposed methodologies are able to capture the trends of fluctuating solar irradiance with minor discrepancies. The minimum root mean square errors of 143 W/m2, which are comparable with the existing prediction techniques, are achieved for both of the methodologies. At the same time, the proposed methodologies require much less image data to be handled compared to the existing techniques.
关键词： Artificial Neural Network,Photovoltaic Power Generation,Solar Energy,Global Horizontal Irradiance Prediction,Sky Image
更新于2025-09-23 15:21:21
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Solar hydrogen production via alkaline water electrolysis
摘要： Electricity generation via direct conversion of solar energy with zero carbon dioxide emission is essential from the aspect of energy supply security as well as from the aspect of environmental protection. Therefore, this paper presents a system for hydrogen production via water electrolysis using a 960 Wp solar power plant. The results obtained from the monitoring of photovoltaic modules mounted in pairs on a fixed, a single-axis and a dual-axis solar tracker were examined to determine if there is a possibility to couple them with an electrolyzer. Energy performance of each photovoltaic system was recorded and analyzed during a period of one year, and the data were monitored on an online software service. Estimated parameters, such as monthly solar irradiance, solar electricity production, optimal angle, monthly ambient temperature, and capacity factor were compared to the observed data. In order to get energy efficiency as high as possible, a novel alkaline electrolyzer of bipolar design was constructed. Its design and operating UI characteristic are described. The operating UI characteristics of photovoltaic modules were tuned to the electrolyzer operating UI characteristic to maximize production. The calculated hydrogen rate of production was 1.138 g per hour. During the study the system produced 1.234 MWh of energy, with calculated of 1.31 MWh, which could power 122 houses, and has offset 906 kg of carbon or an equivalent of 23 trees.
关键词： Solar tracker,Solar energy,Photovoltaic module,Hydrogen,Alkaline electrolyzer,Water electrolysis
更新于2025-09-23 15:21:21
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Local photo-excitation of shift current in noncentrosymmetric systems
摘要： Photocurrent in solids is an important phenomenon with many applications including the solar cells. In conventional photoconductors, the electrons and holes created by light irradiation are separated by the external electric field, resulting in a current flowing into electrodes. Shift current in noncentrosymmetric systems is distinct from this conventional photocurrent in the sense that no external electric field is needed and, more remarkably, is driven by the Berry phase inherent to the Bloch wavefunction. It is analogous to the polarization current in the ground state but is a dc current continuously supported by the nonequilibrium steady state under the pumping by light. Here we show theoretically, by employing Keldysh–Floquet formalism applied to a simple one-dimensional model, that the local photo excitation can induce the shift current which is independent of the position and width of the excited region and also the length of the system. This feature is in stark contrast to the conventional photocurrent, which is suppressed when the sample is excited locally at the middle and increases towards the electrodes. This finding reveals the unconventional nature of shift current and will pave a way to design a highly efficient photovoltaic effect in solids.
关键词： nonequilibrium Green’s function method,shift current,photovoltaic effect
更新于2025-09-23 15:21:21
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Effective solar power harnessing using a few novel solar tree designs and their performance assessment
摘要： Solar irradiance being considered as one of the most important alternative sources of energy can be harnessed in the form of electrical power using photovoltaic panels erected under the sun. Optimum conversion of power from solar panels can be obtained by using Maximum Power Point Tracking (MPPT), which involves continuously adjusting the angle of panels according to the change in the angle of falling irradiance. These trackers, however, use some amount of power for operation of MPPT equipment. Various techniques for arranging the solar panels in three dimensions have been suggested for optimizing the output power from them. The inspiration behind arranging the panels are often drawn from the natural trees where the branches and the leaves follow a particular pattern called phyllotaxy which is directly analogous to the Fibonacci number and Golden ratio. In this research work, the power output from two solar tree models based on 3/8 and 2/5 phyllotaxy pattern and solar conventional panel compared under similar irradiance conditions. There are so many phyllotaxy patterns like 1/3, 2/5, 3/8, etc. When the solar panels aligned in different phyllotaxies, then the orientation direction of solar panels are distinct. Each solar panel connected in solar trees is in a different direction, so that they received the maximum amount of sunlight throughout the day as compared to conventional panels which is oriented unidirectional.
关键词： three-dimensional phyllotaxy,photovoltaic module,Solar energy,solar tree,Fibonacci number
更新于2025-09-23 15:21:21
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Real-Time MPPT Optimization of PV Systems by Means of DCD-RLS Based Identification
摘要： Maximum power point tracking (MPPT) algorithms continuously change duty cycle of a power converter to extract maximum power from photovoltaic (PV) panels. In all of MPPT methods, two parameters, i.e. perturbation period (Tp) and amplitude (ΔD) have a great effect on speed and accuracy of MPPT. Optimum value of the perturbation period is equal to the system settling time which is the system model-dependent parameter. Since the system model varies according to the change of irradiance level and temperature, the value of Tp has to be determined online. In this paper, the parametric identification method is adopted to identify the online value of Tp. The proposed method is based on the dichotomous coordinate descent-recursive least squares (DCD-RLS) algorithm and uses an infinite impulse response (IIR) adaptive filter as the system model. Computation of this algorithm is based on an efficient, fixed-point, and iterative approach with no explicit division operations; these features are highly suitable for online applications. As a result, the proposed method compared to previous works leads to more accurate and faster identification of the system settling time. In order to test and validate the proposed method, it has been simulated and implemented to be further validated with experimental data.
关键词： Photovoltaic Systems,Perturbation Period,Recursive Least Squares (RLS),Dichotomous Coordinate Descent (DCD),Maximum Power Point Tracking (MPPT),System Identification
更新于2025-09-23 15:21:21
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[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Techno-Economic Potential of Large-Scale Solar Deployment in the US
摘要： PV system generates electricity with minimum environmental impact reduces than conventional greenhouse gas emission and consequently reduces the effects of global warming. In late of 2014, the Indian government announced an ambitious target of 100 GW installation capacity of solar PV systems by 2022. Since then, India has achieved notable progress towards this goal and has installed 20 GW cumulative solar capacity with 9.6 GW in 2017 alone. Based on the 2015 MIT Energy Initiative, by 2050, a major fraction of the world’s electric power will come from solar sources. However, this poses many technical and economic challenges on the electrical infrastructure. In this chapter, we focus on the US case, by studying the technical and economic potentials of large-scale deployment of the most commonly recognized types of solar; photovoltiac (PV) and concentrated solar power (CSP) at different locations in the US. The technical potential is assessed based on grid interconnection topologies, and solar system performance. The economic potential is evaluated based on several metrics such as the levelized avoided cost of energy (LACE) and levelized cost of electricity (LCOE), and the possibility of integration into the electricity markets. The economic potential also covers the subsidies, taxes, policies, and incentives for large-scale solar deployment. Two simulation case studies are implemented on two large-scale solar PV and CSP projects at different locations in the US to evaluate their techno-economic potentials.
关键词： Concentrated solar power,Heat transfer fluid,NPV,LCOE,Thermal energy storage,Photovoltaic system,LACE,Payback period,Mounting system
更新于2025-09-23 15:21:21
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Role of Graphene-Doped Organic/Polymer Nanocomposites on the Electronic Properties of Schottky Junction Structures for Photocell Applications
摘要： In this study, the current–voltage characteristics of non-doped and distinct graphene (Gr)-doped polyvinyl alcohol (PVA) interlayers in metal/organic polymer semiconductor type Schottky junction structures (SJSs) were investigated on both forward and reverse biases under distinct levels of illumination. The distinct doping concentration ratios (1%, 3% and 7%) of the Gr added to the PVA interlayers were compared by taking into account the basic electrical parameters, such as saturation current (Io), ideality factor (n), barrier height (UBo), series (Rs) and shunt resistance (Rsh). The 7% Gr-doped structure displayed the lowest Io values at zero bias. Moreover, the results indicated that the 7% Gr-doped PVA decreased the n value but increased the UBo value compared with values associated with structures that have different doping concentrations. In terms of quality and reliability, the Rs and Rsh values of the SJSs were obtained using Ohm’s law and Cheung’s functions, and the 7% Gr-doped structure eventually displayed more uniformly distributed and lower Rs values and the highest Rsh values. Consequently, the 7% Gr-doped structure had better overall quality because of its superior electrical properties compared with structures that have other doping concentrations. Therefore, the 7% Gr-doped structure can be used as a photodiode in electronic devices.
关键词： photovoltaic,basic electronic properties,organic polymer nanocomposites,Graphene,I–V characteristics
更新于2025-09-23 15:21:21
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Technological development of multi-energy complementary system based on solar PVs and MGT
摘要： The complementary micro-energy network system consisting of solar photovoltaic power generation (solar PVs) and micro-gas turbine (MGT), which not only improves the absorption rate and reliability of photovoltaic power, but also has the advantages of low emission, high efficiency, and good fuel adaptability, has become one of the most promising distributed power systems in the field of micro grid. According to the development of current technology and the demand of actual work, this research described the domestic and foreign development of micro-energy network system based on solar PVs and MGT. Moreover, it analyzed the challenges and future development regarding the micro-energy network system in planning and design, energy utilization optimization and dispatching management, and system maintenance, respectively. Furthermore, it predicted the future development of the key technology of the multi-energy complementary system. These results will be beneficial for the progress of this field both in theory and practice.
关键词： solar photovoltaic power generation,micro gas turbine,micro-energy network,multi-energy complementary system,renewable energy
更新于2025-09-23 15:21:21
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Power Quality Management of PV Power Plant with Transformer Integrated Filtering Method
摘要： This paper presents a new solution of power quality management for the photovoltaic (PV) power plant with the transformer integrated filtering method. The innovation of the PV power plant is that it contains two-stage filtering station, which consists of a box-type transformer with filter and a 110 kV grid-connected transformer based on inductive filtering method. The filtering reactor can be integrated into the box-type transformer as a decoupled winding, so that the modular design of the box-type transformer and the passive filter are realized. Inductive filtering method applied transformer not only improves the power quality at the point of common coupling, but dampens the harmonic resonance between the passive filter and grid. The hierarchical structure of the PV power plant is introduced firstly. Then, the equivalent circuit model and the mathematical model of the primary filtering stations are established, and secondary respectively. Moreover, the influence of the weak coupling of integrated reactor on the filtering performance is analyzed. The antijamming capabilities of the inductive filtering method and the traditional filtering method are compared under the condition of parameter disturbance. At last, the site tests of the PV power plant with transformer integrated filtering method are made, which show that the PV grid-connected system comprised of the two-stage filtering station has the characteristics of low harmonic emission, high power factor and stable operation.
关键词： inductive filtering,Photovoltaic plant,integrated reactor,power quality
更新于2025-09-23 15:21:21
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Vacuum-free, Room-temperature Organic Passivation of Silicon: towards Very Low Recombination of Micro/Nano-Textured Surface Structures
摘要： Crystalline silicon (c-Si) solar cells remain dominant in the photovoltaic (PV) market due to their cost-effective advantages. However, the requirement for expensive vacuum equipment and the power-hungry thermal budget for surface passivation technology, which is one of the key enablers of the high performance of c-Si solar cells, impede further reductions of costs. Thus, the omission of the vacuum and high-temperature process without compromising the passivation effect is highly desirable due to cost concerns. Here, we demonstrate a vacuum-free, room-temperature organic Nafion thin-film passivation scheme with an effective minority carrier lifetime (τeff) exceeding 9 ms on an n-type c-Si wafer with a resistivity of 1-5 Ω·cm, corresponding to an implied open circuit voltage (iVoc) of 724 mV and upper-limit surface recombination velocities (SRV) of 1.46 cm/s, which is a level that is in line with the hydrogenated amorphous Si film-passivation scheme used in the current PV industry. We find that the Nafion film passivation of Si can be enhanced in an O2 atmosphere and that the Nafion/c-Si interface oxidation should be responsible for the passivation mechanism. This highly effective passivation is also achieved on various micro/nano-textured Si surface structures from actual production, including a pyramidal surface and nanopore-pyramid hybrid structure with nanopores on the inclined plane of the pyramid. We develop an organic Nafion-passivated n-type back-junction Si solar cell to examine application in a real device. The open circuit voltage (Voc) of the solar cell with the Nafion passivation layer achieves a clear improvement (30.8 mV) over those without the passivation layer, resulting in an increase (1.5%) in the power conversion efficiency (PCE). These results suggest the potential use of these organic electronics with current Si microelectronics and a new strategy for the development of vacuum-free, low-temperature Si-based PVs at low cost.
关键词： passivation,Silicon,Nafion thin film,Photovoltaic
更新于2025-09-23 15:21:21