Photovoltaic Solar Conversion Research Articles

Feasibility study of coffee husk char-derived carbon dots to enhance solar photovoltaic-thermal applications

Coffee is one of the most traded commodities in the world. Coffee husk makes up the majority of the solid debris generated during the dry processing of coffee, which is between 30% and 50%. Pyrolysis is a reliable and feasible technology to valorise the coffee husk. The present study proposes and investigates a novel method for producing carbon dots from coffee husk char through pyrolysis. Nanomaterials are becoming more popular to improve the thermal and optical properties of working fluids used in solar photovoltaic and thermal conversion systems. The coffee husk-char derived carbon dot (CHC-CD) nanofluids are prepared with different char concentrations (1%, 2%, 3% and 4%). The chemical and optical properties of the nanofluid produced from coffee husk char (CHC-CD nanofluid) are investigated. The morphology, size and particle size distribution of the CHC-CD particles were studied using field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The particles were found to have an average size of 5.38 nm. The CHC-CD nanofluid had a basic pH and negative zeta potential, which was found to decrease with an increase in the char concentration and pH. The nanofluid prepared with 2% char was found to have a zeta potential of −61.4 mV. It was evident from the UV–vis transmittance spectra that the CHC-CD nanofluid prepared with a char concentration of 2% had very limited transmittance in the UV region and good transmittance above 735 nm. This transmittance range is found to be favourable for the smooth and efficient operation of silicon-based solar PV cells. The CHC-CD nanofluid also showed a maximum intensity emission wavelength of 522 nm at an excitation wavelength of 450 nm. Characterisation of the carbon phase, surface functional groups, and surface defects was also done using XRD, FTIR, and Raman spectroscopy, respectively. The optical and chemical properties indicate that the developed CHC-CD nanofluid can find application not only in solar photovoltaic and thermal systems but also in applications in biomedical and chemical sensor applications.

The Inclusion of Power Gyrator Topologies as Energy Processing Cells in Photovoltaic Solar Conversion

This paper will provide a classification of high efficiency switching power-gyrator structures and their use as cells for energy processing in photovoltaic solar facilities. Having into account the properties of these topologies presented in the article, their inclusion in solar facilities allows increasing the performance of the whole installation. Therefore, the design, simulation and implementation of a Gtype power gyrator are carried out throughout the text. In addition, in order to obtain the maximum power from the photovoltaic solar panel, a maximum power point tracking (MPPT) is mandatory in the energy processing path. Therefore, the practical implementation carried out includes a control loop of the power gyrator in order to track the aforementioned maximum power point of the photovoltaic solar panel.

Technical achievable potential of photovoltaic conversion of solar radiation for the conditions of Ukraine

This study investigates solar energy photovoltaic conversion processes while exploring new approaches to identify potential areas for the installation of photovoltaic stations. This research aims to enhance existing methodologies of technical-achievable potential calculation, considering the specificity of territories, the possibility of installing rooftop photovoltaic stations, and the current development of photovoltaic technologies. The developed methodology considers the type of stations, urban building specifics during the calculation of suitable areas for photovoltaic station installation, the potential for installing small and medium rooftop stations, and the modern technical characteristics of photovoltaic modules. The refinement of the PV panels and PV station area ratio calculations revealed that its value depends on the type and power of the station, varying from 0 to 1. This approach simplifies the determination of power capacity of a station that can be installed in a designated area. Consideration of the technical characteristics of the latest photoelectric conversion technologies demonstrates a significant potential increase compared to the existing calculation methodologies. Calculations conducted using the developed methodology revealed that the technically achievable potential of solar energy conversion for Ukraine is 369 TWh/year (254 GWp DC). This figure exceeds the estimations of existing calculation methodologies at least twice. The obtained results showed a significantly greater potential for solar energy in Ukraine, which expands the possibilities of using photovoltaic technologies to supply energy to consumers. This is especially important during the war because of the insufficient electricity production by existing power plants, many of which have been destroyed.

Artificial photosynthesis: A pathway to solar fuels

Taking inspiration from nature and from the success of photovoltaic solar conversion, scientists are developing foundations for sunlight-driven synthesis of fuels, chemicals, and materials.

Charging characteristics of finned thermal energy storage tube under variable rotation

Solar photovoltaic-thermal (PVT) systems effectively offset the drawbacks of intermittent solar and low photovoltaic conversion efficiency. Thermal energy storage (TES) tanks of PVT systems with high charging efficiency and consistent thermal safety might achieve efficient utilization of solar energy for building. A new variable rotational strategy has been proposed to optimize the charging characteristics for TES tubes, taking into consideration the non-uniformity of melting. A series of simulations based on the volume-averaged model are conducted to investigate the thermal energy storage property of TES tubes under variable rotary mechanism. Qualitative and quantitative comparisons are made between variable rotation (ω = 1.5–0.5, 1.5–1.0, 1.5–2.0 rad·s−1), constant rotation (ω = 1.5 rad·s−1), and stationary systems. The focus of the comparison is melting efficiency, temperature distribution, and natural convection. The results indicate that rotation effectively shortens charging time, with a 57.62% and 15.73% reduction with variable rotary mechanisms of 1.5–1.0 rad·s−1 when compared with stationary and constant rotating tubes. Meanwhile, in the final moment, the greatest medium-temperature (55–65 °C) proportion of 90.58% and less low-temperature (25–55 °C) and high-temperature (65–70 °C) paraffin occupation of 4.67% and 4.75% could be obtained, reflecting the completed latent heat storage and stable thermal safety. The optimal variable rotation achieves improvements of 47.84% and 106.73% in time-integral Grashof number (Gr) and heat storage rate, compared with traditional stationary tubes.

Study of Renewable Potential of the Republic of Armenia for Implementation of Hybrid Autonomous Power Supply System Using Solar Photovoltaic Modules

Introduction. Solar energy is one of the leading renewable energy industries. Solar photovoltaic modules are most widely used to create hybrid autonomous electrification systems, since photovoltaics are not limited to specific limitations and can be applied almost everywhere.Aim. To determine the potential of meteorological and geographical features of the Republic of Armenia for the implementation of autonomous hybrid renewable energy sources systems (AHRESS) using solar photovoltaics (PV). To simulate operating conditions for various AHRESS configurations providing electric power to a cellular communication base station.Materials and methods. Climatic, geographical, social and economic features of the region of the Republic of Armenia are investigated. Regions are evaluated based on the key factors of AHRESS implementation potential and compared with studies performed by the Effergy-Irsolav. The simulations and technical and economic analysis were performed using the HOMER Pro software in Ttsovinar region.Results. The most efficient configuration is found to be B1, with an energy cost of 0.322 $/kW·h. The parameters of winning system: PV array with capacity of 4.5 kW, 12V battery with 100 A·h capacity, diesel generator with 3 kW capacity. The main efficiency criterion is the low economic costs for the implementation and operation of this AHRESS configuration. Ten additional variants of AHRESS were modeled in order to optimize the component base of the configuration.Conclusion. It was found that, depending on the consumer load, solar photovoltaic converters are limited and can only perform as supporting source of electricity. The use of the existing consumption load profile in the form of BSSS made it possible to cover the widest possible range of configurations of the component base, which indicates the high accuracy of the simulated results and, as a result, the technical and economic relevance of the study.

Defect-regulated charge carrier dynamics in two-dimensional ZnO/MoS2 heterostructure

Van der Waals ZnO/MoS2 heterostructure has been experimentally demonstrated as one of the potential candidates for photocatalyst, however, the charge carrier dynamics upon photoexcitation still remains unclear. By using nonadiabatic molecular dynamics simulations, we mainly focus on the influences of interfacial point defects on photogenerated charge separation in the ZnO/MoS2. The results reveal that oxygen vacancy in ZnO layer can induce a higher hole transfer efficiency compared to the pristine ZnO/MoS2, which attributes to the enhanced nonadiabatic coupling, originating from an out-of-plane vibration mode of S atoms, a decreased energy gap for intralayer hole transfer and stronger energy state oscillation. Alternatively, S vacancy in MoS2 introducing additional energy states in the band gap of ZnO/MoS2, serves as charge carrier recombination channels, and significantly reduces charge carrier lifetime, while doping O atom in S vacancy can compensate this effect. This study provides helpful guidance to design functional devices for solar energy photovoltaic conversion, based on two-dimensional ZnO/MoS2 heterostructures.

First-principles calculation of electronic structure, chemical bonding and optical properties of β-AgBiS2

We investigated the structural, electronic, chemical bonding, and optical properties of β-AgBiS2 crystal by using the Perdew-Burke-Ernzerhof (PBE) functional and the hybrid functional Heyd Scuseria Ernzerhof (HSE) within the DFT formalism. The electronic band structures obtained by both methods indicate that β-AgBiS2 is an indirect band gap semiconductor with band gap of 0.571 and 1.025 eV, respectively. The electron density difference and Mulliken overlap population show that the Ag-S bonds and Bi-S bonds are both ionic bonds. The calculated optical absorption spectrum prove that β-AgBiS2 is a promising material for solar photovoltaic conversion

Comparison of Control Method System by Using Perturbation and Observation Algorithms and Fuzzy Logic for the Maximum Power Point Control in Photovoltaic Systems

Currently, photovoltaic energy conversion has developed tremendously in the global energy industry. The enormous capacity of solar power plants generates electricity all over the world. Hundreds of gigawatts of electrical energy are supplied to the networks of various countries around the globe. In addition, up to hundreds of gigawatts of installed capacity of solar power plants are commissioned every year in all countries of the world. And this has been the trend for the past few decades. The main problem of solar photovoltaic conversion is the instability of the solar radiation flux associated with the climatic conditions in the regions where photovoltaic plants are operated. This problem can be solved by using highly efficient methods to control the generation of solar power plants, in particular, such as the use of information control systems for a particular PV system to increase the final generation of electrical energy supplied to the consumer. The photovoltaic (PV) conversion of solar radiation flux is an important renewable energy source. Due to the varying intensity of the sun, the electricity generated by PV directly from the radiation flux is not constant. The photovoltaic system currently uses maximum power point (PMP) tracking in perturbation and observation (P&O) mode to increase the final output power of the photovoltaic panels. A step-down DC-DC converter allows PMP to change the PV operating voltage and determine the maximum power output of the PV panel. This study proposes a fuzzy logic implementation. The magnitude of the perturbed voltage is determined by the change in power dq and the change in power relative to the change in voltage dq/dv is fuzzy. The performance of fuzzy logic is investigated in this work in order to optimize MPM. Fuzzy logic can simplify maximum power tracking and reduce voltage instability. According to the simulation results, the MPM method based on fuzzy computation performs better than the traditional P&O method. By using the proposed methods, we can significantly improve electric power generation and increase the efficiency of photovoltaic conversion.

Research on route planning for solar UAV based on the intelligent optimization algorithm.

The solar unmanned aerial vehicle (UAV) route planning needs to comprehensively consider the conversion efficiency of solar cells under the influence of solar ground reflection radiation and sky scattering radiation. On the one hand, it is necessary to consider the cost of radar threat, mileage energy consumption, mountain impact and other costs. On the other hand, it is also necessary to consider the influence of high threat, mountain shadow occlusion cost, and cloud shading cost on solar photovoltaic conversion efficiency. The above problem was solved through using the ant colony intelligent optimization algorithm. By constructing ant colony paths rationally, models of mountain impact cost, high threat, mountain shadow shelter cost, and cloud shading cost were established. The constraints such as the maximum action distance, solar irradiation angle and effective action distance of various costs were introduced into the cost model and exploration factor calculation, and the comprehensive optimization problem of solar UAV route was solved. Finally, the simulation results show that the algorithm path structure is reasonable; the target node can be found independently; the convergence speed can meet the requirements of route planning; the generated route cost is small; the algorithm is reasonable and effective.

Solar photovoltaic converter controller using opposition-based reinforcement learning with butterfly optimization algorithm under partial shading conditions.

The major use of a power point tracking controller is to maximize or enhance the power generation in photovoltaic systems. These systems are steered to operate and maximize the power point. Under partial shading conditions, the power points may vary or fluctuate between global maxima and local maxima. This fluctuation leads to a decrease in energy or energy loss. Hence, to address the fluctuation issue and its variations, a new hybridized maximum power point tracking technique based on an opposition-based reinforcement learning approach with a butterfly optimization algorithm has been proposed. The proposed methodology has been tested on 6S, 3S2P and 2S3P photo-voltaic configurations under different shading conditions. Performance comparison and analysis have been presented with a butterfly optimization algorithm, grey wolf optimization algorithm, whale optimization algorithm, and particle swarm optimization-based maximum power point tracking techniques. Experimental results show that the proposed method performs better adaptation than the conventional approaches and mitigates the load variation convergence and frequent exploration and exploitation patterns.

Study on the effectiveness of a solar cell with a holographic concentrator

Abstract Solar energy is an important power source. Given this, the development in the direction of converting solar radiation into electrical energy using holographic concentrators is of great importance. The purpose of the study is to determine the electrical characteristics of the solar cell inside the solar cells. To determine the electrical characteristics of the solar cell inside the photovoltaic panel, digital sensors HC-SR04, INA219 and the “Arduino Nano” microprocessor controller were used. The paper presents the results of experimental studies of a solar panel with a holographic concentrator and photovoltaic cells based on gallium arsenide. The high efficiency of converting solar energy into electrical power is shown when dispersing and focusing different wavelengths on a photocell. During elaboration of the obtained volt-ampere characteristics of solar photovoltaic conversion elements, which determine the output power of the photovoltaic panel, the high potential of the developed design of the photovoltaic panel has been revealed. The practical value of the study lies in the fact that with the help of a holographic concentrator it is possible to increase the efficiency of solar energy conversion.

Enhanced near-infrared light-induced photoresponse via transition of monocrystalline phase and surface reconstruction

Rare-earth-doped upconversion (UC) materials are ideal candidates for solar photovoltaic conversion and NIR response devices due to their unique spectral conversion properties. However, their low efficiency remains a tremendous challenge for practical applications. Here, we constructed an efficient NIR light-responsive device by coating a Si-photoresistor with a transparent gel consisting of UC powders and an organic polymer matrix. We show that reasonable introduction of alkali metal ions (Na+, K+, and Cs+) into the lattice of UC crystals results in the improvement of photoelectricity conversion efficiency, due to the high crystallinity and surface reconstruction caused by alkali metal ion doping.

48-Pulse Voltage-Source Converter Based on Three-Level Neutral Point Clamp Converters for Solar Photovoltaic Plant

The demand for high-power converters for use in large-scale solar photovoltaic (PV) plants increases as the plant size continues to grow. The multipulse voltage-source converter (VSC) configurations are the viable option for high-power solar PV converter applications because they improve conversion efficiency due to low switching losses and allow direct integration with a medium-voltage (MV) grid. In this article, a 48-pulse VSC based on the fundamental frequency switching (FFS) three-level neutral point clamp (NPC) converter with a start–delta transformer configuration is used for large-scale solar PV plant application. It is also used as a PV-static synchronous compensator (STATCOM) to provide the required reactive power support to the grid to regulate the voltage. The solar PV plant configuration for a 100-MW capacity is modeled in MATLAB and implemented in the real-time OPAL-RT platform to verify its design and controls. The harmonics, static, and dynamic performances are demonstrated in detail.

A hybrid DDAO-RBFNN strategy for fault tolerant operation in fifteen-level cascaded H-bridge (15L-CHB) inverter with solar photovoltaic (SPV) system

This paper proposes a hybrid approach for fault-tolerant operation in fifteen-level cascaded H-Bridge (15LCHB) inverter with solar photovoltaic system (SPV). Fault-tolerant operation performs two tasks: detection (classification of normal or abnormal) and identification (identification of faults). The proposed intelligent controller is the combination of Differential Annealing Dynamic Optimization (DDAO) and Radial Basis Function Neural Network (RBFNN) named DDAO-RBFNN approach. The major intention of the DDAO-RBFNN approach is separated into fault detection with lessening of complete photovoltaic solar energy conversion system. The proposed system takes into account the failure of the entire autonomous photovoltaic solar conversion process and manages the output voltage (OV) owing to the conditions of partial shading (PS). The collected data set (normal, abnormal) is stored at workstation. RBFNN is utilized to compute the CMI switching pattern that changes the PWM carrier signal. DDAO get the voltage values from RBFNN and evaluates them with the data set, if there is a rate of change of voltage. Any deviation find in the rate of voltage change, it makes a decision based on standard or fault conditions. The proposed system is activated on MATLAB/Simulink working platform, then the efficiency is compared with existing approaches.

Solar-Driven Soil Remediation along with the Generation of Water Vapor and Electricity.

As a renewable energy source, solar energy has become an important part of human energy use. However, facilities utilizing solar energy are often complex and technically difficult, and preparation equipment and materials are expensive, while these equipment and materials often cause new environmental pollution. Soil, which exists in large quantities on the earth’s surface, is an inexhaustible natural material with loose and stable properties. Due to the specificity of its composition and microscopic form, the soil has an inherent advantage as a medium for solar thermal and photovoltaic conversion. Here, we built an integrated solar energy utilization system, the Integrated Soil Utilization Module (ISUM), integrating multi-functions into one hybrid system, which enables solar-driven water vapor and electricity generation and soil remediation. The evaporation rate of the soil represented by the rocky land was 1.2 kg·m−2·h−1 under 1-sun irradiation with evaporation induced voltage of 0.3 V. With only seven days of continuous exposure to sunlight, the removal of heavy metal ions from the soil reached 90%, while the pH was raised to near neutral. The combined application of readily available natural soil with solar energy not only demonstrates the potential of a soil for solar desalination and power generation, but in addition, solar-driven interfacial evaporation provides an energy-efficient, environmentally friendly, and sustainable method for purifying heavy metal and acid-contaminated soil.

Which thermochemical water-splitting cycle is more suitable for high-temperature concentrated solar energy?

The manuscript reviews the thermochemical water-splitting cycles not in general (many other works have covered this topic) but specifically for producing hydrogen coupled with high temperature concentrated solar energy which is available at temperatures of 1000 to 1100 °C. This is important to benefit from synergies with near future dispatchable concentrated solar power, simply replacing the power cycle with the thermochemical hydrogen production plant. The review shows as three-step cycles are those benefiting the most from the synergy with higher solar flux dispatchable concentrated solar power with thermal energy storage, also profiting in terms of technology readiness level from past experiences in thermochemical water-splitting cycles for nuclear power plants, and the affordable complexity of the cycle. From preliminary evaluations, three-step cycles may permit CO2-free hydrogen production within a decade at a competitive cost with green hydrogen as well as the current prevailing production of hydrogen from hydrocarbons at less than $1 per 1 kg. The thermochemical pathway has the same minimum energy requirement as electrolysis, despite the conversion efficiencies achieved so far have been much less because of the reduced development. Since the collection of solar thermal energy is much easier and more efficient than solar photovoltaic conversion, the thermochemical pathway has the potential to deliver a cost of hydrogen smaller than green hydrogen from solar photovoltaic electricity and electrolyzers.

Investigation of the P-doped lead-free glass frit based on the principle of low-temperature phosphorus diffusion for multicrystalline silicon solar cells

For P-doped glass frits, the doping efficiency of phosphorus is low because of the volatility of phosphorus at high temperatures. A lead-free 5% P-doped glass frit was prepared using low-temperature phosphorus diffusion. The network structure formed by the glass was mainly composed of [BiO6] octahedron, [SiO4] tetrahedron, and [BO4] tetrahedron. The pore size of the glass frit was distributed in the mesopore range. High-temperature microscopy confirmed that the glass frit began to soften at 620 °C. The glass frit was prepared into a front silver paste for multicrystalline silicon solar cells. The high efficiency of P2O5 doping helped resolve problematic defects caused by the typically poor doping efficiency of P-doping while forming the n-type emitter and p-n junction of solar cell. Finally, the solar cell photovoltaic conversion efficiency improved to 18.3%.

Augmentation of dye-sensitized solar cell photovoltaic conversion efficiency via incorporation of terpolymer Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) based gel polymer electrolytes

A dye-sensitized solar cell (DSSC) is the alternative photovoltaic technology for the replacement of the standard photovoltaic liquid electrolyte-dependent cell. Gel polymer electrolyte (GPE) was used in this research to replace the volatile liquid electrolyte. This GPE has been developed using terpolymer type Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) P(VB-co-VA-co-VAc), iodine (I2), sodium iodide (NaI), and ethanol. The findings from X-ray diffraction (XRD) showed the effect of NaI on the crystalline content of the electrolyte systems. Samples showed higher conductivity with a lower degree of crystallinity. Differential scanning calorimetry (DSC) analysis revealed the slight decrease in melting temperature (Tm) upon addition of NaI salts. The thermogravimetric analysis (TGA) showed that GPE ′s thermal stability decreases as NaI salt content increases. Fourier-transform infrared (FTIR) results indicated that P(VB-co-VA-co-VAc) interacted with NaI. The highest room temperature ionic conductivity of 3.22 × 10−3 S cm−1 by the sample with 30 wt % NaI. Temperature-dependent findings showed that all GPE samples adhere to the Arrhenius equation in the temperature range from 303 K to 373K and found the lowest activation energy obtained by the sample with 30 wt % NaI as 0.066 eV. Dielectric and modulus properties of all samples have been studied. DSSC fabricated using the electrolyte containing 30 wt% NaI has achieved the highest conversion efficiency of 4.01% with maximum JSC value of 12.52 mA cm−2, VOC of 0.61 V, and fill factor (FF) of 51.8%.

Performance improvement of solar PV power conversion system through low duty cycle DC‐DC converter

AbstractCharacteristics like reliability and modularity of solar photovoltaic (SPV) units makes them one of the apt options for generating electric power. However, the input intermittency is their major lacuna, and power electronic circuits are being used to nullify this effect. A solar photovoltaic power conversion process includes a DC‐DC converter in the plant side to deliver a fixed DC voltage and a DC‐AC converter in the grid side for converting DC voltage in to grid compatible AC voltage. The high duty ratio of typical DC‐DC boost converters limits the switching frequency and efficiency. In this article, a way to enhance the performance of a SPV unit using an improved quadratic boost converter (IQBC) is analysed. It can deliver a higher output voltage at lower duty ratio with Perturb and Observe (P&O) algorithm‐based Maximum Power Point Tracking (MPPT). A 250 W prototype of IQBC‐based Solar PV power conversion system (SPVPCS) is developed, and its performance is compared against conventional and quadratic boost converters and found that the IQBC‐based solar power conversion system is efficient and the results are presented.