Utilization Rate Of Solar Energy Research Articles

Theoretical study of a novel intermediate temperature photovoltaic/thermal system equipped with heat pipe and evacuated tube

Solar photovoltaic/thermal (PV/T) technology has enormous promise in the field of renewable cogeneration as a key technology to increase the utilization rate of solar energy. The structural restrictions of PV/T and the high power temperature coefficient of solar cells make PV/T mostly used in low-temperature situations. However, the combination of intermediate temperature PV/T and low-grade energy utilization devices can create a wider range of application values, including absorption refrigeration, seawater desalination, and the organic Rankine cycle. To increase the overall efficiency and thermal energy grade of the PV/T system, a novel heat pipe evacuated tube PV/T (HE-PV/T) system is proposed. The heat transfer is modeled using distributed parameters, and the thermoelectric performance and temperature uniformity are computed through numerical simulation. The impacts of different parameters on the thermodynamic performance of the HE-PV/T system are examined. Compared with traditional flat plate PV/T, the system's overall energy utilization efficiency and exergy efficiency have been significantly increased. When the inlet temperature is 80.0 °C, the overall energy and exergy efficiency of the HE-PV/T system can reach 33.55 % and 7.92 %, which is 29.66 % and 21.97 % higher than that of flat plate PV/T. Besides, the temperature distribution of the HE-PV/T is more uniform, which is beneficial for reducing thermal stress and mechanical damage. The property superiority and thermodynamic feasibility of the HE-PV/T system at medium temperature are demonstrated.

Preparation and characteristic of palmitic acid/flower-shaped CuS composite phase change material for effective heat storage and photothermal conversion

Designing and synthesizing the excellent heat storage and photothermal integrated composite phase change materials (PCMs) is an effective strategy for solar energy utilization. This work focuses on two kinds of CuS (cuboidal and 3D flower-shaped) with different morphology were designed as substrates and photothermal materials, and PA/F–CuS and PA/C–CuS composite PCMs have been prepared by melt-blending and vacuum impregnation method. Through SEM and pore structure characterization as well as leakage testing, it is proved that 3D layered flower-shaped CuS not only exposes the large specific surface area and rich adsorption sites, but also 2D thin layers can perform multiple reflections to improve the utilization rate of solar energy. The flower-shaped CuS is more suitable for the supporting material. Noteworthy, the latent heat of PA/F–CuS can reach 226.3 J/g, and the thermal conductivity is 0.3447 W/(m·K). Furthermore, compared with pure PA, the photothermal property of PA/F–CuS increased by 49.22–84.59%, and the photothermal conversion efficiency can reach 70.3%. This work provides an innovative idea for the design and manufacture of composite PCMs related to medium and low temperature solar energy storage, and has broad application potential in the field of thermal energy storage such as solar energy utilization and building insulation materials.

Strategy and capacity optimization of renewable hybrid combined cooling, heating and power system with multiple energy storage

Combined cooling, heating, and power systems offer significant potential for integration with renewable energy sources, such as solar and geothermal energy, alongside energy storage devices. However, the effectiveness and feasibility of these systems depend crucially on the operational strategies and capacity planning for each component. Therefore, an innovative hourly dynamic simulation model that integrates solar energy, geothermal energy, and multiple energy storage devices is established. Using the multi-objective comprehensive evaluation method that combines Technique for Order Preference by Similarity to Ideal Solution methods and non-dominated sorting genetic algorithm-II including elite strategy, establish five dimensions of multi-objective optimization model, including energy-saving, economy, environmental protection, system independence and renewable energy utilization scale. Meanwhile, the system and reference system in a community in Beijing are used as models to analyze the equipment capacity under the three operating strategies. The findings reveal that, compared to the reference system, the new system attains optimal performance when following the electrical load strategy. Its comprehensive index reaches 69%, surpassing the thermal load and hybrid load strategies by 8% and 11%, respectively. When the target is set as “independence-renewable energy-cost,” the utilization rate of solar energy and geothermal energy reaches an impressive 79%, showcasing excellent renewable energy utilization. The presented model holds substantial significance for advancing research in the realms of operating strategies and equipment capacity planning within such systems.

Performance investigation of solar-assisted supercritical compressed carbon dioxide energy storage systems

Energy storage technology plays a vital role in realizing large-scale grid connection of renewable energy. Compared with compressed air energy storage system, supercritical compressed carbon dioxide energy storage (SC-CCES) system has the advantages of small size and high energy storage density. In this paper, two solar-assisted supercritical compressed carbon dioxide energy storage (SASC-CCES) systems are proposed. One is coupled with simple regenerative compression cycle (SR-SASC-CCES), the other with recompression cycle (RC-SASC-CCES). Thermodynamic and economic analyses are carried out. The results show that the energy efficiency of the system is higher than that of other organic working fluids when the transcritical CO2 is used as the working fluid of the bottom cycle due to the residual heat available in the energy storage system of the recompression cycle. Compared with the baseline SASC-CCES system, the SR-SASC-CCES system and RC-SASC-CCES system are more conducive to improving the solar energy utilization rate, and their photoelectric conversion efficiencies are 23.56 % and 28.77 %, respectively, 2.63 % and 7.84 % higher than that of the baseline SASC-CCES system. Increasing the inlet temperature of turbine 1, energy storage pressure and energy release pressure can effectively increase the energy efficiency, solar-electricity conversion efficiency, exergy efficiency and energy storage per unit volume of these two systems. In addition, the RC-SASC-CCES system has better economic performance, whose dynamic investment recovery period is about 6.8 years. The 20-year net present value (NPV) is 23,456.16 k$, 7956.69 k$ higher than that of the SR-SASC-CCES system.

Optimisation and analysis of an integrated energy system with hydrogen supply using solar spectral beam splitting pre-processing

The application of integrated energy systems (IES) in urban areas is gradually increasing, yet the constraint of limited building space poses a significant challenge to effective system planning. In this paper, to address the issue of area limitation from the perspective of improving solar energy utilization. A novel IES utilizing solar spectral beam splitting (SBS) for hydrogen production is proposed, which introduces SBS technology to make full use of the sun’s full-spectrum energy. Furthermore, the incorporation of photocatalytic hydrogen production introduces an innovative approach to meet the hydrogen needs of hydrogen refuelling stations, facilitating highly efficient co-generation of cooling, heating, electricity, and hydrogen supply. To determine the optimal system configuration, a comparison is made with a stand-alone solar system using a honey badger-simulated annealing optimization algorithm. The results show that the SBS-IES achieves a solar energy utilization rate of 37.72% and reduces equipment footprint by 20.48%. Furthermore, a sensitivity analysis is performed to analyse the impact of changes in floor space on the system. This innovative system is suitable for small-scale IES and serves as an efficient solution for urban energy systems.

Optimal reconfiguration design and HIL validation of hybrid PV-TEG systems via improved firefly algorithm

Partial shading conditions (PSCs) caused by clouds, trees, buildings, and other factors can lead to uneven irradiance on the photovoltaic (PV) panel, resulting in reduced power output and decreased service life of PV systems. To deal with this problem, a reconfiguration method for hybrid photovoltaic-thermoelectric generation (PV-TEG) systems based on an improved firefly algorithm (IFA) is proposed in this paper. Firstly, the method uses PV-TEG hybrid system to make full use of the waste heat of traditional PV systems to improve the utilization rate of solar energy. Secondly, IFA is employed to adjust the electrical connection between the modules to reduce the adverse effects of PSC and increase the total output power of the system. To validate the effectiveness of this method, three different scale PV-TEG hybrid systems of 4 × 4, 9 × 9, and 15 × 9 are reconfigured under practical and standard shading conditions, and the results are compared with those obtained using PSO, GA, BWOA, AO, and ACO. The results demonstrate that the IFA-based reconfiguration enhances the output power by 31.19 %, 21.49 %, and 21.84 % for 4 × 4, 9 × 9, and 15 × 9 arrays compared with that without reconfiguration, respectively. Finally, hardware-in-the-loop (HIL) experiments further verify the hardware feasibility of the proposed method.

Forming of organic/inorganic material heterojunction: Effectively improve the carrier separation rate and solar energy utilization rate

CdS is a kind of traditional inorganic semiconductor, but its photocatalytic performance is far from satisfactory. In order to improve the photocatalytic performance of CdS. We decided to use organic material C2N-h2D to form organic-inorganic heterojunction, CdS/C2N-h2D heterojunction, to improve the photocatalytic performance of CdS. First of all, the CdS, C2N-h2D and CdS/C2N-h2D heterojunction was studied by using the HSE06 hybrid functional method. The energy band and DOS of CdS/C2N-h2D heterojunction were calculated, and the band gap and band types of CdS/C2N-h2D heterojunction were determined. Next, the interaction between CdS and C2N-h2D is discussed. The results showed that the VBM and CBM of CdS and C2N-h2D changed with the forming of heterojunction. In addition, the light absorption spectra show that CdS/C2N-h2D heterojunction has a higher absorption efficiency for visible light. These results indicate that CdS/C2N-h2D heterojunction has a significant advantage in improving the photocatalytic efficiency under visible light irradiation.

Study on structure design and control of concentrating germanium solar power system

In the solar energy application system, in order to improve the efficiency of solar cells and the utilization of light energy, the paper studies the solar tracking system with concentrating device and using germanium solar cells. This paper compares the differences between germanium cells and silicon cells in terms of photoelectric conversion efficiency and output characteristics, and demonstrates the superiority of germanium solar cells. Several common types of concen-trating devices such as Fresnel lenses, trough concentrators, tower concentrators and disc con-centrators were listed, and the disc concentrator was finally selected considering the concen-trating performance and cost. The paper also analyzes the solar operation law and the charac-teristics of various tracking devices, and on the basis of comprehensive analysis of the ad-vantages and disadvantages of various tracking devices, a hybrid tracking scheme is proposed. After completing the design of the system structure, the efficiency and cost of the traditional fixed solar system and the concentrated germanium solar power generation sunny system are compared and analyzed by SIMULINK modeling, and the results show that the solar energy utilization rate and power generation efficiency of the system designed in this paper are greatly improved, which verifies the effectiveness and economy of the system. The concentrating germanium solar power generation system not only adopts germanium cells with better photo-electric characteristics, but also adds a concentrating device and a sun tracking device, which greatly improves the efficiency of solar power generation. And the volume of the device is not large, which can realize the promotion of small home solar energy systems.

In situ synthesized S-type heterojunction Bi2O2CO3/CuBi2O4 enable efficient NIR light-driven H2O2 activation for water purification

Hydrogen peroxide (H2O2) was the most commonly used oxidant in advanced oxidation processes to degrade emerging organic pollutants. However, photoactivation of H2O2 by catalysts had the problems of narrow pH application range and low solar energy utilization rate. Herein, the Bi2O2CO3/CuBi2O4 heterojunction photocatalyst was in-situ synthesized, which could activate H2O2 under NIR radiation to degrade organic pollutants and complex heavy metal pollutants. Both in-situ irradiation XPS spectra and DFT supported the S-type charge transfer mechanism. Driven by the IEF and bending band, photogenerated electrons were transferred from Bi2O2CO3 to CuBi2O4, which inhibited the recombination of carriers and promoted the activation of H2O2. The activation rate constant of CBO-2/Vis/H2O2 system for H2O2 was 0.0403 min−1, which was 36.6 times that of the original BOC. This work provided new systematic insights into H2O2 activation by S-scheme heterojunction and had implications for wastewater treatment.

A novel thermosyphon cooling applied to concentrated photovoltaic-thermoelectric system for passive and efficient heat dissipation

Concentrated photovoltaic-thermoelectric systems have received extensive research attention as a means of enhancing the utilization rate of solar energy. However, the expedited progress of these systems has been hindered by a myriad of challenges, such as the additional power consumption required for active cooling and the inadequate cooling rates of conventional passive cooling techniques. To overcome these limitations, a novel concentrated photovoltaic-thermoelectric system integrating thermosyphon cooling has been developed and subjected to a comprehensive analysis, encompassing its start-up performance, pipe resistance characteristics, and power generation performance have been analyzed. The results reveal that the buoyancy generated by the thermosyphon is 8.22 N, which effectively drives the speed of cooling water circulation to 0.011 m/s. The start-up time of the thermosyphon effect lengthens gradually with a decrease in inclination angle of heat sink, while the cooling temperature at the final stable state remains relatively consistent. Remarkably, at 240 kW/m2, the concentrated photovoltaic cell exhibits a remarkable heat dissipation power density of 15.26 W/cm2. Meanwhile, the optimal output voltage of concentrated photovoltaic is 1.907 V, at which the concentrated photovoltaic output power is 1.774 W. The optimal output voltage of thermoelectric is 0.528 V, at which the thermoelectric output power is 0.054 W. The results provide guidance for designing high-performance cooling systems for concentrated photovoltaic-thermoelectric systems.

A direct Z-scheme GeS/GeSe van der Waals heterojunction as a promising photocatalyst with high optical absorption, solar-to-hydrogen efficiency and catalytic activity for overall water splitting: First-principles prediction

Seeking an efficient photocatalyst is the key to solve the problem of energy shortage and environmental pollution. We construct a GeS/GeSe heterojunction and explore its structural stability, electronic property, charge transfer, optical property and solar-to-hydrogen energy conversion efficiency by first-principles calculations. The results show that the GeS/GeSe heterojunction has high thermal and kinetic stability and is a direct Z-scheme photocatalyst with a smaller indirect band gap (1.73 eV) than two monolayers GeS (3.28 eV) and GeSe (3.00 eV), which can not only avoid the backward reaction and light-shielding effect caused by the carrier transfer mediators in traditional and all-solid-state Z-scheme photocatalysts, but also increase the light-harvesting ability, suppress recombination of the photoexcited charge carriers, promote surface catalytic reaction by preserving the strong redox capacity of photoexcited charge carriers with respect to the traditional type-II and p-n heterojunction photocatalyst. The charge transfer analysis shows that the electron accumulates on the GeS side and the hole accumulates on the GeSe side, forming a built-in electric field from GeSe to GeS, which can effectively restrain the recombination of photogenerated carriers. Besides, its band edge positions support overall water splitting reactions in acid and alkaline environments. The optical absorption of the heterojunction is higher than that of its monolayer materials and the solar-to-hydrogen energy conversion efficiency reaches up to 31.21%, which effectively improves the absorption and utilization rate of solar energy. We have good reasons to believe that the GeS/GeSe heterojunction provides an effective strategy for the research and development of efficient photocatalysts.

CeVO4 nanoparticle coupled with Ag/AgBr as an efficient plasmonic photocatalyst for degradation of rhodamine B: Construction, characterization, and mechanism insight

The unique characteristics of the surface plasmon resonance effect significantly improve the utilization rate of solar energy and charge separation of narrow band-gap semiconductor materials. In this work, Ag/AgBr/CeVO4 plasmonic photocatalyst was synthesized by the microwave-assisted hydrothermal method, followed by in-situ precipitation and photoreduction process. The as-prepared Ag/AgBr/CeVO4-2.0 composite showed superior photocatalytic efficiency for degradation of rhodamine B (84.2% in 10 min), which was 1.45 and 84.2 times higher than that of Ag/AgBr and pristine CeVO4 nanoparticles (NPS, size 30–50 nm), respectively. Photoluminescence and photocurrent tests indicated the rapid transfer and separation of electron–hole pairs in this plasmonic system, which can be attributed to the localized surface plasmon resonance effect of Ag NPs. In investigations on band structure and radical quenching experiments, a Z-scheme photocatalytic system bridged by the Ag NPs was proposed. This research offers revealing insight into the design and fabrication of the CeVO4 plasmonic photocatalytic system for application in environment purification and remediation.

Dual-Layer Starch-based Biological Hydrogel Durable Evaporator for Efficient Solar Steam Generation

Solar-powered desalination is an effective means to address the global freshwater shortage and combat water pollution. However, the light absorption capacity, thermal insulation performance, and water transmission efficiency of most current solar evaporators cannot be effectively combined, resulting in a relatively low utilization rate of solar energy. In this study, a double-layer solar evaporator was reported by using starch as the biological hydrogel matrix and carbon nanotubes as an efficient light-absorbing material, which greatly improved the solar energy utilization rate of the evaporator and the steam generation efficiency was as high as 2.21 kgm−2h−1 under 1.0 sun.

Design of a gravity spin-driven adsorption-based desalination device

Based on the adsorption property of porous materials and the gravitational spin principle, an innovative design of an adsorption desalination device based on gravitational spin-driven phase change materials for heat storage and exotherm was developed. The power required for the conversion of the device compartment is provided by the gravity difference, and the position fixation of the heat insulation baffle is controlled by the magnetic clasp. The source of thermal energy required by the device follows the green and low-carbon principle, relying on sunlight to irradiate the selective coating and convert it into thermal energy, and then transfer the absorbed thermal energy to the phase change material for storage, which increases the solar energy utilization rate by about 80%. The use of phase change materials can maintain the temperature inside the hot chamber at about 70 °C, allowing water molecules to desorb from the silica gel material and water vapor to rise to the top conical roof to condense into fresh water and collect to the mezzanine water storage chamber. The cylindrical chamber is divided into two chambers, hot and cold, and the adsorption and desorption work is carried out simultaneously, with heat loss within 3%. The initial position where the heat insulation baffle is located is equipped with a magnetic buckle, which can precisely control the angle of baffle rotation. The daily water production of a single device is 8.02 kg, and the carbon emission saving is 0.1518 kg. This work is of great significance to the field of energy saving and emission reduction, and the whole can realize self-operation without an electric power drive, which is a novel way of desalination, considering the concept of energy saving and emission reduction and the full utilization of renewable energy.

Performance analysis and optimization study of a new supercritical CO2 solar tower power generation system integrated with steam Rankine cycle

Currently, the supercritical CO2 solar tower power generation (S-CO2 STPG) has become a research hotspot, but due to S-CO2 Brayton cycle characteristics, the solar energy utilization rate of the system is low. Therefore, a new S-CO2 STPG system integrated with steam Rankine (SR) cycle is first proposed. The SR cycle absorbs the waste heat of the S-CO2 Brayton cycle, and the introduction of the SR cycle can increase the solar energy utilization rate. The research is based on the simulation results, the system model is developed by Ebsilon, and system operation calculation is developed by MATLAB. The daily and monthly performances of the new S-CO2 STPG system integrated with SR cycle are compared with those of conventional S-CO2 STPG system in detail. The system location is Bakersfield. The comparative analysis results show that compared with the conventional system, the monthly power output for the new system rises significantly, especially in summer. The new system can effectively improve the solar energy utilization rate. The effect of SR cycle power output on new system performance is studied. Increasing SR cycle power output can improve the thermal energy storage subsystem and solar field subsystem performances. The optimal SR cycle power output is related to the solar radiation level. The Fargo, Bakersfield and Phoenix are selected as three places representing low-direct normal irradiance (DNI), medium-DNI and high-DNI districts, respectively. For the medium-DNI and high-DNI districts, the SR cycle power outputs corresponding to the optimal thermal performance and optimal economic performance are 20 MW and 15 MW, respectively; for the low-DNI district, those are 15 MW and 5 MW, respectively.

Construction of photocatalyst by modification of argentum noble metal and hydrogen doping into WO3 nanoparticles: Enhancing the solar energy utilization

Solar energy is considered sustainable green energy to prevent environmental pollution. Tungsten trioxide (WO3) is one of the attractive solar energy-driven photocatalysts and photocatalytic supports. Besides, Hydrogen (H) has a small size and can move into many inorganic compounds, and occupy the sites in microstructure as well, with little space structure expansion. H doping in semiconductors attracts more and more attention due to its effect of providing free carriers, resulting in localized surface plasmon resonances which can improve the utilization efficiency of solar energy. In our research, we developed a new method to prepare the H-doped WO3 whose color turned green, and to prepare Ag/HxWO3, which could extend the solar light response range to near-infrared. Furthermore, the photocatalytic activity to degrade RhB solution under UV light and visible light was both improved. The density of free electrons is based on the Drude model to discuss the mechanism of photocatalysis upon the visible. The contact of noble metal Ag and HxWO3 can play a vital effect in the separation of photogenerated electron-hole pairs. The localized surface plasmon resonances and green coloration bring the tungsten trioxide more remarkable performance together. Results showed that constructed photocatalysis of this work greatly enhanced the utilization rate of solar energy. Photocatalytic for the Degradation of liquid organic pollutants with HxWO3 is believed to have a bright feature.

Research and application of park multi-source synergistic and complementary heating system and its coordinated control method

The integration of solar thermal collectors (STC) and air source heat pump (ASHP) heating systems has been widely used for building heating. However, these systems have the problems that the STC cannot fully utilize the solar energy at weak radiation, and the ASHP has insufficient output as well as low coefficient of performance (COP) under extreme cold conditions. In this study, a multi-source synergistic and complementary heating system (MSSCHS) with a heating mode selection model based on belief rule base and evidential reasoning (BRB-ER) method is designed. First, the MSSCHS composed of the STC and the ASHP as the main heat sources, and the water source heat pump as the auxiliary heat source, along with its three heating modes under different operating conditions were proposed. Then, a system heating mode selection model based on the BRB-ER method was establish to achieve mode switching. Finally, the MSSCHS with BRB-ER heating mode selection model was tested experimentally. The results show that compared with the conventional ASHP + STC heating system, the solar energy utilization rate of the MSSCHS had increased by 19.3 %, 16.6 % and 8.2 % respectively in three typical days, and the ASHP's COP had increased by 37.7 %- 55.6 % under extreme cold conditions. The high efficiency and stability of the MSSCHS were verified through operational tests during the heating period. Furthermore, by applying in different types of buildings, it is verified that the MSSCHS can meet different heating requirements and has a good applicability. It was demonstrated that the proposed MSSCHS has more efficient heating mode and more accurate mode selection method, which can provide a new research idea for building heating.

Critical Review of Ca(OH)2/CaO Thermochemical Energy Storage Materials

Thermal energy storage is an essential technology for improving the utilization rate of solar energy and the energy efficiency of industrial processes. Heat storage and release by the dehydration and rehydration of Ca(OH)2 are hot topics in thermochemical heat storage. Previous studies have described different methods for improving the thermodynamic, kinetic, and structural stability of Ca(OH)2 to improve energy storage density, energy storage rate, and cycle stability, respectively. Here, the mechanisms and effects of different techniques on the performance improvement of Ca(OH)2 and some common problems were reviewed. Specific problems were also clarified based on the characteristics of different technologies. Finally, suggestions for the future development of Ca(OH)2 heat storage materials were provided.

A new perspective of solar hot water system operation optimization: Supply and demand matching

Solar hot water (SHW) systems have been widely used in residential buildings for energy conservation and emission reduction. The system operation control from the supply side and the occupant's hot water behavior on the demand side both affect the energy performance of the SHW system. However, there is a lack of synergistic optimization analysis of the supply-demand matching process. Therefore, in this study, quantitative methods for describing the supply- and demand-side equivalent profiles of SHW systems were proposed. Based on the two equivalent profiles, commonly used regulation measures on the supply and demand sides were analyzed from the perspective of time and intensity modification by proposing simplified estimation methods for the adjustment effect. Five supply side adjustment strategies are investigated. Through a questionnaire, three specific demand-side guidance strategies were obtained to guide the user's hot water behavior, and it was found that the performance of these strategies differed in different user groups. Integrated supply and demand matching regulation processes were established and verified. The results showed that the proposed supply-demand matching optimization process can increase the annual solar energy utilization rate by 9.6%, which meant that one household could save 136.19 kWh of reheating energy and reducing 121.51 kg CO2 in a year.

Research on Intelligent Regulation System of Solar Panels Driven By Low-Voltage Electric Energy

This paper proposes a design method for tracking solar panel light tracking control system based on microcontroller. The main structure of the system includes light intensity detection module, automatic control module, intelligent information processing module, human-computer interaction module, computer control module and interface circuit module. In this paper, the photoelectric method is used to track the position of the sun, the control process is modeled and simulated in the system. The system is optimally controlled by adding a Kalman filter to the output of the classic PID control. Actual tests show that the input voltage of the circuit is 1.2~5.5V, the maximum charging current is 1.2A, the minimum conversion efficiency of the circuit is not less than 72%, and the maximum conversion efficiency is more than 92%, and the power energy output of the solar panel can be collected and charged even under very weak lighting conditions. Solar energy utilization rate is high.