Experimental evaluation of factors affecting performance of concentrating photovoltaic/thermal system integrated with phase‐change materials(PV/T‐CPCM)

The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system performance.The results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV modules.When the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,respectively.Higher solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy consumption.When the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.

Numerical Assessment of the Thermal Efficiency of a Concentrated Photovoltaic/Thermal (CPV/T) Hybrid System Using Air as Heat Transfer Fluid

In this paper, we propose a thermal model of a hybrid photovoltaic/thermal concentration system. Starting from the thermal balance of the model, the equation is solved and simulated with a MATLAB code, considering air as the cooling fluid. This enabled us to evaluate some of the parameters influencing the electrical and thermal performance of this device. The results showed that the temperature, thermal efficiency and electrical efficiency delivered depend on the air mass flow rate. The electrical and thermal efficiencies for different values of air mass flow are encouraging, and demonstrate the benefits of cooling photovoltaic cells. The results show that thermal efficiency decreases air flow rate greater than 0.7 kg/s, whatever the value of the light concentration used. The thermal efficiency of the solar cell increases as the light concentration increases, whatever the air flow rate used. For a concentration equal to 30 sun, the thermal efficiency is 0.16 with an air flow rate equal to 0.005 kg/s;the thermal efficiency increases to 0.19 with an air flow rate equal to 0.1 kg/s at the same concentration. An interesting and useful finding was that the proposed numerical model allows the determination of the electrical as well as thermal efficiency of the hybrid CPV/T with air flow as cooling fluid.

Polymer Fiber Rigid Network with High Glass Transition Temperature Reinforces Stability of Organic Photovoltaics

Organic photovoltaics(OPVs)need to overcome limitations such as insufficient thermal stability to be commercialized.The reported approaches to improve stability either rely on the development of new materials or on tailoring the donor/acceptor morphology,however,exhibiting limited applicability.Therefore,it is timely to develop an easy method to enhance thermal stability without having to develop new donor/acceptor materials or donor–acceptor compatibilizers,or by introducing another third component.Herein,a unique approach is presented,based on constructing a polymer fiber rigid network with a high glass transition temperature(T_(g))to impede the movement of acceptor and donor molecules,to immobilize the active layer morphology,and thereby to improve thermal stability.A high-T_(g) one-dimensional aramid nanofiber(ANF)is utilized for network construction.Inverted OPVs with ANF network yield superior thermal stability compared to the ANF-free counterpart.The ANF network-incorporated active layer demonstrates significantly more stable morphology than the ANF-free counterpart,thereby leaving fundamental processes such as charge separation,transport,and collection,determining the device efficiency,largely unaltered.This strategy is also successfully applied to other photovoltaic systems.The strategy of incorporating a polymer fiber rigid network with high T_(g) offers a distinct perspective addressing the challenge of thermal instability with simplicity and universality.

Research progress on protective coatings against molten nitrate salts for thermal energy storage in concentrating solar power plants

Concentrating solar power(CSP) has garnered considerable global attention as a reliable means of generating bulk electricity, effectively addressing the intermittent nature of solar resources.The integration of molten salt technology for thermal energy storage(TES) has further contributed to the growth of CSP plants;however, the corrosive nature of molten salts poses challenges to the durability of container materials, necessitating innovative corrosion mitigation strategies.This review summarizes scientific advancements in high-temperature anticorrosion coatings for molten nitrate salts, highlighting the key challenges and future trends.It also explores various coating types, including metallic, ceramic, and carbon-based coatings, and compares different coating deposition methods.This review emphasizes the need for durable coatings that meet long-term performance requirements and regulatory limitations, with an emphasis on carbon-based coatings and emerging nanomaterials.A combination of multiple coatings is required to achieve desirable anticorrosion properties while addressing material compatibility and cost considerations.The overall goal is to advance the manufacturing, assembly, and performance of CSP systems for increased efficiency, reliability, and durability in various applications.

Assessment of High Concentrated Photovoltaic/Thermal Collector in Hot Climate

This work investigates the performance of combined hybrid high concentrated photovoltaic/thermal collector (HCPV/T) in Kuwait harsh climate. The proposed system consists of triple junction solar cells (InGaP/InGaAs/Ge) attached to heat source to discharge thermal energy to cooling media. Published HCPV/T models do not consider the effect of shunt resistance which greatly affects the system performance. So, a single diode model employing five parameters including the effect of shunt resistance is adapted to analyze the proposed system. To analyze the thermal performance of the proposed system, a two-dimensional thermal model based on the technique of finite difference is introduced to determine the efficiency of the hybrid HCPV/T system. The present developed subroutines are integrated with other involved codes in TRNSYS software to calculate HCPV/T system efficiency. Electrical and thermal as well as the whole system efficiency at different weather circumstances are evaluated and assessed. The effect of different weather conditions, cell temperature, concentration ratio and the temperatures of the coolant fluid on system performance are studied. Current results indicate that the model of single diode is a reliable one rather than using the two-diode complex model. Compared to measurements provided by high concentrated PV manufacturer, the current results revealed a total root mean square error of approximately 1.94%. Present predictions show that PV cell temperature has logarithmic increase with the rise in concentration ratio but with low values till concentration ratio of 400 suns after that the rise is faster at higher concentration values up to 1500 suns. Results also revealed that hybrid HCPV/T system works effectively specially in severe hot climate where thermal efficiency increases with high surrounding temperature for higher values of concentration ratio. In addition, an increase of approximately 15% in thermal efficiency and 10% in total efficiency can be achieved by utilizing active cooling device in HCPV/T system.

Performance Improving of a Concentrating Photovoltaic System by Using a New Optical Adhesive

The objective of this present study is to manufacture a new silicone-based adhesive which is used for gluing and bonding the second optical elements (SOE) with Concentrating Photovoltaic solar cell (CPV) in order to guarantee a thickness that can provide a good silicone adherence to obtain long term stability and keeping a good solar transmittance performance, too. This new adhesive is made up of a mixture of silicone and transparent glass balls. The experimental part consists of the choice of the best size of glass balls with the suitable proportion of the glass balls weight in the mixture. For this purpose, ten samples were manufactured for every category of glass balls and weight ratio. Glass ball sizes between 100 and 1100 μm, and weight ratios between 1 and 10% were analyzed. For each category of glass balls, four proportions were mixed with the silicone. The thicknesses and transmittance of every sample were measured with appropriate instruments. The experimental results illustrate that the mixture containing balls with sizes inferior to 106 μm, is the best mixture which assures adhesive minimum thickness value necessary for an efficient mechanical bond and preserves also a good transmittance of solar irradiance.

Design of Reflective Concentrator Model with Application for Concentrator Photovoltaic System

The nonuniform irradiation in the standard photovoltaic（PV） cells causes their relatively high series resistance,which results in a considerably lowered efficiency of PV cells.Currently the concentrator of uniform irradiation designed for concentrator photovoltaic is rare in China and lack sufficient theoretical research.In this paper,a systematic research on the solar reflective concentrator is conducted.A novel structure for a solar reflective concentrator is designed with the application of a flat mirror matrix to concentrate the sunlight for concentrator photovoltaic（CPV） systems.Sunlight beams are focused through the reflection of the mirror array on the solar cell to generate electricity.The concentrator is capable of producing much more uniform sunlight with a certain concentration ratio.The design scheme includes laying out the flat mirrors,optimizing the optical pathway and the parameters of each mirror.The prototype of the CPV system was installed at Nanjing,China.In the configuration of the prototype,it is composed of 24 pieces parallelogram flat mirrors,which are arranged into a total reflective array of 5 rows and 5 columns.In comparison with the parabolic trough concentrator,the experimental measurements verify such design has high efficiency.The concentrator model of a flat mirror matrix and the proposed new design method will lay a solid foundation for designing the concentrator of uniform irradiation.

Full scale experimental study of a small natural draft dry cooling tower for concentrating solar thermal power plant

Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.

Capacity-operation collaborative optimization of the system integrated with wind power/photovoltaic/concentrating solar power with S-CO_(2) Brayton cycle

This paper proposes a new power generating system that combines wind power(WP),photovoltaic(PV),trough concentrating solar power(CSP)with a supercritical carbon dioxide(S-CO_(2))Brayton power cycle,a thermal energy storage(TES),and an electric heater(EH)subsystem.The wind power/photovoltaic/concentrating solar power(WP-PV-CSP)with the S-CO_(2) Brayton cycle system is powered by renewable energy.Then,it constructs a bi-level capacity-operation collaborative optimization model and proposes a non-dominated sorting genetic algorithm-Ⅱ(NSGA-Ⅱ)nested linear programming(LP)algorithm to solve this optimization problem,aiming to obtain a set of optimal capacity configurations that balance carbon emissions,economics,and operation scheduling.Afterwards,using Zhangbei area,a place in China which has significant wind and solar energy resources as a practical application case,it utilizes a bi-level optimization model to improve the capacity and annual load scheduling of the system.Finally,it establishes three reference systems to compare the annual operating characteristics of the WP-PV-CSP(S-CO_(2))system,highlighting the benefits of adopting the S-CO_(2) Brayton cycle and equipping the system with EH.After capacity-operation collaborative optimization,the levelized cost of energy(LCOE)and carbon emissions of the WP-PV-CSP(S-CO_(2))system are decreased by 3.43%and 92.13%,respectively,compared to the reference system without optimization.

Spectrum-Splitting Diffractive Optical Element of High Concentration Factor and High Optical Efficiency for Three-Junction Photovoltaics

A spectrum-splitting and beam-concentrating （SSBC） diffractive optical element （DOE） for three-junction pho- tovoltaics （PV） system is designed and fabricated by five-circ/e micro-fabrication. The incident solar light is efficiently split into three sub-spectrum ranges and strongly concentrated on the focal plane, which can be di- rectly utilized by suitable spectrum-matching solar cells. The system concentration factor reaches 12x. Moreover, the designed wavelengths （450nm, 550nm and 65Onto） are spatially distributed on the focal plane, in good agree- ment with the theoretical results. The average optical effic/ency of all the cells over the three designed wavelengths is 60.07%. The SSBC DOE with a high concentration factor and a high optical efficiency provides a cost-effective approach to achieve higher PV conversion efficieneies.

Energy and Life Cycle Assessment of Zinc/Water Nanofluid Based Photovoltaic Thermal System

Cooling the PV surface in a Photovoltaic Thermal system is a pivotal operational aspect to be taken into account to achieve optimized values of performance parameters in a Photovoltaic Thermal System.The experimental design used in this study facilitates the flow of varying concentrations of Zn-water nanofluid in serpentine copper tubing installed at the rear of the PV panel thereby preventing the PV surface temperature from increasing beyond the threshold value at which a decrease in electrical efficiency starts to occur.This fusion of solar thermal with PV devices leads to better electrical and thermal efficiency values resulting in decreased cell degradation over time and maximization of the lifespan of the PV module and the energy output from the PV system.Due to the superior thermal heat properties of nanofluids,their usage in such systems has become increasingly widespread.Life cycle metrics which include Energy Payback period,Energy Production Factor and life cycle conversion efficiency were evaluated for the PVT system by exhaustively chalking fundamental parameters such as embodied energy of the PVT setup and the total energy output from the PVT system.This research aims to be a major milestone in the evolutionary journey of Photovoltaic Thermal modules by guiding the engineers working on the theory,design and implementation of PVT systems towards its economic feasibility,environmental impact and energy sustainability.

Environmental Impacts of Grid Connected High Concentrated Photovoltaic Systems Adapted for Peak Load Minimization in Hot Climate

High concentrated PV multi-junction solar cells (HCPV) likely present a favorable alternative to achieve low cost of energy. However, multi-junction solar cell has different characteristics which should be settled before they can be adapted for large scale energy generation. Peak energy consumption in Kuwait usually occurs in periods of utilizing air conditioning systems which are essentially used in almost all year around in harsh climate like Kuwait. Power consumed at peak times is more costly than power needed to satisfy loads at regular consumption times. The main goal of the present research is to increase HCPV solar cells’ efficiency, to decrease maximum power cost in Kuwait. Multi-junction solar cells performance in weather conditions of Kuwait is investigated employing a single diode equivalent circuit model. The model developed considers the impacts of concentration ratio as well as temperature. Most research in literature review usually neglects shunt resistance of the diode, however this resistance is taken into consideration in current developed theoretical model. To calibrate the present model, current predictions are compared with corresponding measured data provided by multi-junction solar cell manufacturer. The total root mean square errors in the present model predictions are about 1.8%. This means that current developed model of single diode model which takes into account shunt resistance impacts gives precise and reliable data. HCP electrical efficiency is noticed to rise as concentration increases but to a certain concentration value, then it begins to decrease. In addition, utilizing HCPV linked to grid satisfies great decrease in maximum load. Power produced from HCPV modules is utilized to provide energy needs to a family in normal Kuwaiti family home to evaluate HCPV environmental effects. HCPV modules slopes and areas are changed to accomplish peak energy production all over the year. Present results reveal that optimum power production corresponds to HCPV modules directed to south and having latitude of 25°. In addition, employing HCPV modules can avoid approximately 1.55 ton of emitted CO2 per year. In conclusion, current work reveals the advantage impacts of grid connected HCPV in Kuwait weather.

Performance on Power,Hot and Cold Water Generation of a Hybrid Photovoltaic Thermal Module

This paper proposed a new function of photovoltaic thermal(PVT)module to produce nocturnal cool water not just only generating electrical power and hot water during daytime.Experimental tests were carried out under Chiang Mai tropical climate with a 200 Wp monocrystalline PVT module having dimensions of 1.601 m×0.828 m connected with two water tanks each of 60 L taken for hot and cool water storages.The module was facing south with 18o inclination.The electrical load was a 200 W halogen lamp.From experiments,by taking the module as a nocturnal radiative cooling surface,the cool water temperature in the cool storage tank could be reduced 2℃–3℃each night and the temperature could be reduced from 31.5℃to 22.1℃within 4 consecutive days.The cool water at approximately 23℃was also used to cool down the PVT module from noon when the PVT module temperature was rather high,and then the module temperature immediately dropped around 5℃and approximately 10%increase of electrical power could be achieved.A set of mathematical models was also developed to predict the PVT module temperature and the hot water temperature including the cool water temperature in the storage tanks during daytime and nighttime.The simulated results agreed well with the experimental data.

Comprehensive Examination of Solar Panel Design: A Focus on Thermal Dynamics

In the 21st century, the deployment of ground-based Solar Photovoltaic (PV) Modules has seen exponential growth, driven by increasing demands for green, clean, and renewable energy sources. However, their usage is constrained by certain limitations. Notably, the efficiency of solar PV modules on the ground peaks at a maximum of 25%, and there are concerns regarding their long-term reliability, with an expected lifespan of approximately 25 years without failures. This study focuses on analyzing the thermal efficiency of PV Modules. We have investigated the temperature profile of PV Modules under varying environmental conditions, such as air velocity and ambient temperature, utilizing Computational Fluid Dynamics (CFD). This analysis is crucial as the efficiency of PV Modules is significantly impacted by changes in the temperature differential relative to the environment. Furthermore, the study highlights the effect of airflow over solar panels on their temperature. It is found that a decrease in the temperature of the PV Module increases Open Circuit Voltage, underlining the importance of thermal management in optimizing solar panel performance.

Thin Film Photovoltaic/Thermal Solar Panels

A solar panel is described,in which thin films of semiconductor are deposited onto a metal substrate.The semiconductor-metal combination forms a thin film photovoltaic cell,and also acts as a reflector-absorber tandem,which acts as a solar selective surface,thus enhancing the solar thermal performance of the collector plate.The use of thin films reduces the distance heat is required to flow from the absorbing surface to the metal plate and heat exchange conduits.Computer modelling demonstrated that,by suitable choice of materials,photovoltaic efficiency can be maintained,with thermal performance slightly reduced,compared to that for thermal-only panels.By grading the absorber layer-to reduce the band gap in the lower region-the thermal performance can be improved,approaching that for a thermal-only solar panel.

Contrastive Observation of Solar Thermal and Photovoltaic Resource

Solar thermal and photovoltaic applications are the most w idely used and the most successful w ay of commercial development in solar energy applications. Observation and assessment of solar thermal and photovoltaic resources are the basis and key of their large-scale development and utilization. Using the observational data carried out from Beijing southern suburbs observation station of China M eteorological Administration in summer of 2009,preliminary solar thermal and photovoltaic resources characteristics for different w eather conditions,different angle and different directions are analyzed. The results show that:(1) In sunny,cloudy or rainy w eather conditions,both of solar thermal and photovoltaic sensors daily irradiance have consistent change in trend. Solar thermal irradiance is larger than photovoltaic. Under sunny conditions,solar thermal global radiation has about 2.7%higher than the photovoltaic global radiation. Under cloudy w eather conditions,solar thermal global radiation has about 3. 9%higher than the photovoltaic. Under rainy w eather conditions,solar thermal global radiation has about 20% higher than the photovoltaic.(2) For different inclined plane daily global radiation,southern latitude-15 °incline is the maximum and southern vertical surface is the minimum. The order from large to small is southern latitude-15 ° incline,southern latitude incline,southern latitude+15 °incline,horizontal surface and southern vertical surface. Southern latitude-15 °incline global radiation has about 41% higher than the southern vertical surface.(3) For different orientation vertical surface daily global radiation,southern vertical surface is the maximum and w estern vertical surface is the minimum,w hich eastern vertical surface is in the middle. Southern vertical surface global radiation has about 20% higher than the w estern vertical surface.

A switchable concentrating photovoltaic/concentrating solar power(CPV/CSP)hybrid system for flexible electricity/thermal generation

Due to the intermittency and indeterminacy of solar irradiance,balancing energy supply and load demand remains a challenge.This paper proposed a switchable hybrid system that combines concentrating photovoltaic/concentrating solar power(CPV/CSP)technology with thermal energy storage(TES)to achieve flexible electricity and thermal generation by adjusting the incident solar flux of photovoltaic(PV).The hybrid system can directly transfer surplus solar energy into high-quality heat for storage using a rotatable PV/heat receiver.The simulated results demonstrated that the hybrid system effectively improves power generation,optimally utilizes TES capacity,and reduces the levelized cost of electricity(LCOE).Over a selected seven-day period,the single-junction(1J)Ga As solar cells used in the hybrid system sustainably satisfied the load demand for more than five days without grid supplement,outperforming the CSP plant by an additional two days.The hybrid system utilizing the 1J Ga As with the base configuration of solar multiple(SM)of 1.26 and TES capacity of 5 h improved the annual power production and renewable penetration(RP)by 20.8%and 24.8%compared with the conventional CSP plant,respectively.The hybrid plant with monosilicon and a configuration of SM(1.8),PV ratio(1),and TES capacity(6 h)achieved an optimal LCOE of11.52$ct/k Wh and RP of 75.5%,which is 8.8%lower and 12.1%higher than the CSP plant,respectively.

Performance analysis of a photovoltaic/thermal system with lunar regolith-based thermal storage for the lunar base

Powering a moon base,especially keeping it warm during the long lunar night,is a big challenge.This paper introduces a photovoltaic/thermal(PV/T)system incorporating regolith thermal storage to solve the challenge of power and heat provision for the lunar base simultaneously.The vacuum of space around the moon helps this system by reducing heat loss.During the moon's daytime,the system not only generates electricity but also captures heat.This stored heat in the regolith is then used at night,reducing the amount of equipment we need to send from Earth.The spectrally selective PV/T panels are designed to absorb a wide range of sunlight(0.3–2.5μm)while minimizing heat loss in the infrared range(3–30μm).Simulation results of the hybrid solar energy system indicate the average value of the overall efficiency is 45.9%,which relatively elevates 56.1%compared to the PV system.The launch mass of the proposed PV/T system is only 8.4%of a traditional photovoltaic-lithium battery system with the same amount of energy storage.And the total specific energy of the proposed system is 7.3 kWh kg^(-1),while that of the photovoltaic-lithium battery system is about 0.3 kWh kg^(-1).In summary,this study proposes an alternative combined heat and electricity supply system for the lunar base,which can greatly reduce the launch mass and free up load for other scientific research equipment.

Spectral Selectivity of CdTe Cells with Substrate Configuration for Photovoltaic/Thermal Applications

Existing photovoltaic cells with high infrared emissivity generate huge radiative heat loss in photovoltaic/thermal applications and degrade the photothermal performance.The purpose of this work is to evaluate the full spectral absorptivity of CdTe cells to find a spectrally selective photovoltaic cell for photovoltaic/thermal applications.To this end,the solar absorptivity and mid-infrared thermal emissivity of CdTe cells were tested by ellipsometry,UV-Vis-NIR spectrophotometer,and Fourier transform infrared spectrometer.The experimental results show that the AM 1.5 solar spectrum weighted absorptivity of the substrate configuration CdTe cell reaches 0.91,and the mid-infrared emissivity is only 0.29,while the superstrate configuration cell emissivity is as high as 0.9.Further research shows that substrate configuration with a transparent conductive layer on top can be flexibly grown on metal foils and has spectral selectivity with high solar absorptivity and low mid-infrared emissivity should be considered in the future for photovoltaic/thermal applications.

Performance Assessment and Improvement of Photovoltaic-Thermal System based on Energy, Exergy, Economic and Environment Analysis

A photovoltaic thermal(PV/T)system with parallel cooling channels was designed in this work to decrease the PV panel temperature and improve its photoelectric conversion efficiency.A 4E analysis method(includes energy,exergy,economic,and environmental aspects)was formulated to comprehensively evaluate the performances of the PV/T system,combining experimental and simulation studies.Firstly,the experiment was performed using water as the cooling medium.Results show that the PV/T system can reduce daily CO_(2) emissions by 1682.47-1705.98 g,and compared to the PV system,the added cooling module can increase electrical efficiency and environmental performance by 12.19%and 6.2%,respectively.When the mass flow of water rose from 0.017 kg/s to 0.023 kg/s,the electrical,thermal,and overall efficiencies were improved by 3.82%,11.36%,and 8.27%,respectively.Secondly,a numerical simulation model was constructed based on the experimental results to predict operations of the presented PV/T system using nanofluids as the cooling medium,including Ag,Al_(2)O_(3),and SiO_(2).Simulation results show that the Al_(2)O_(3)-nanofluid-based PV/T system has a higher application value,enabling an electrical efficiency of up to 15.13%.Its thermal efficiency can be enhanced by 5.43%when the volume fraction of Al_(2)O_(3);increases from 1%to 5%.