Concentrator Photovoltaic Systems Research Articles

Preface

Abstract The 2022 International Conference on Electrical, Power and Grid Systems (ICEPGS 2022) was planned to be held on February 25-27, 2022 in Guangzhou, China. Currently, the entire world is struggling against the virulent pandemic COVID-19. Unfortunately, each of us is affected, either overtly or covertly. Our conference, 2022 International Conference on Electrical, Power and Grid Systems (ICEPGS 2022) was not an exception. Nowadays, mass gatherings are not permitted by the government. It is uncertain when the COVID-19 would end, so it remains unclear for postponement time, while many scholars and researchers wanted to attend this long-waited conference and have academic exchanges with their peers. Therefore, in order to actively respond the call of the government, and meet author’s request, the ICEPGS 2022, which was planned to be held in Guangzhou, China from February 25-27, 2022, was changed to be held online through Zoom software. This approach not only reduces people gathering, but also meets their communication needs. ICEPGS 2022 is to bring together innovative academics and industrial experts in the field of energy engineering, electrical engineering, Power Engineering and Grid Systems to a common forum. The primary goal of the conference is to promote research and developmental activities in energy engineering, electrical engineering and materials application and another goal is to promote scientific information interchange between researchers, developers, engineers, students, and practitioners working all around the world. During the conference, the conference model was divided into three sessions, including oral presentations, keynote speeches, and online Q&A discussion. In the first part, some scholars, whose submissions were selected as the excellent papers, were given about 5-10 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches. There were over 90 participants attended the meeting. In the second part, we invited four professors as our keynote speakers. The first keynote speaker, Prof. Chong Kok Keong, Universiti Tunku Abdul Rahman, Malaysia. His research interest including concentrating solar power, concentrator photovoltaic system, photovoltaic, daylighting and solar thermal system. And then we had Prof. Mohammad Dalour Hossen Beg, Universiti Malaysia, Pahang, Malaysia. His major research area is Polymer and Composites. Likewise, his other research area is the production and characterization of nanoparticles, and production of nanocomposites. Prof. Qinghua Liu, University of Science and Technology of China. His current research interests mainly focus on the construction of advanced energy catalytic materials and the in-situ synchrotron radiation characterizations of advanced energy conversion systems. Lastly, we invited A. Prof. Muhammad Jawad Sajid, from Xuzhou University of Technology. He has a strong interest in environmental management research. In particular, he has vast experience with carbon emissions, carbon footprints, and carbon policy. Their insightful speeches had triggered heated discussion in the third session of the conference. Every participant praised this conference for disseminating useful and insightful knowledge. The proceedings are a compilation of the accepted papers and represent an interesting outcome of the conference. Topics include but are not limited to the following areas: Advanced Power Semiconductors, Communication Systems, Electrical Materials and Process, Mechatronics and Robotics, Power System Stability and more related topics. All the papers have been through rigorous review and process to meet the requirements of international publication standard. We would like to acknowledge all of those who supported ICEPGS 2022. The help and contribution of each individual and institution was instrumental in the success of the conference. In particular, we would like to thank the organizing committee for its valuable inputs in shaping the conference program and reviewing the submitted papers. The Committee of ICEPGS 2022 List of Committee member, Conference Chairs, Conference General Chair, Publication Chairs, Program Committee, International Technical Committee, Organize Committee are available in this Pdf.

Enhanced Net Channel Based-Heat Sink Designs for Cooling of High Concentration Photovoltaic (HCPV) Systems in Dammam City

In this study, enhanced net channel based heat sink designs for cooling HCPV systems at geometrical concentration ratios ranging from 500× to 3000× are presented. The effect of increasing the number of layers in the parallel flow net channel, as well as the fraction of the coolant mass flow rate in the counter flow net channel, on the overall performance of the HCPV systems, are investigated. The various configurations of each proposed net channel based-heat sink design are examined, and a comparative analysis between the different proposed designs is performed under the climate weather conditions of Dammam city, Saudi Arabia. On one hand, the double-layered counter flow net channel heat sink outperformed the other designs in terms of electrical efficiency and in keeping the solar cell operating well below the safe operating limits, achieving a reduction in maximum cell temperature relatively compared to the parallel flow net channel with five layers and conventional mini channel of 11.72% and 12.01%, respectively. On the other hand, for effective usability of the heat recovery rate by the cooling mechanism, the parallel flow net channel is the most appropriate design since it has recorded 27.55% higher outlet water temperature than the double-layered counter flow net channel.

Dependence of the vertical‐tunnel‐junction GaAs solar cell on concentration and temperature

Modelling the current–voltage (I–V) characteristics of photovoltaic (PV) devices is important for understanding their behaviour and potential. Typically, the single exponential model (SEM) is used because of its simplicity and accuracy. In this work, we validate the SEM for a gallium arsenide (GaAs) vertical-tunnel-junction (VTJ) using TCAD software. This cell is the key to overcoming the series resistance limitations of current concentrator solar cells, which can lead to the development of ultra-high concentrator photovoltaic systems (UHCPV) with concentrations (Cratio) greater than 1000 suns. The results indicate that the SEM is a suitable tool to model the I–V characteristics of the VTJ cell with mean errors lower than 1%. Moreover, the solar cell did not show any limitations regarding the Cratio and temperatures under investigation. In addition, the analysis of the temperature coefficients of the cell demonstrates that their dependency on temperature reduces as Cratio increases. The results of this work suggest that VTJ is a promising solution to produce a new generation of high-efficiency and low-cost UHCPV systems.

Simulation of a Low Concentrator Photovoltaic System Using COMSOL

The use of photovoltaic (PV) systems presents a great solution to high energy demand. Many factors limit the output of PV systems. One method of increasing the output of PV systems is to employ concentrators. The function of these concentrators is to increase the amount of solar radiation falling on a PV panel using optical devices. In this work, a simulation of a low concentrated photovoltaic system (LCPV) (V-trough model) will be conducted using COMSOL Multiphysics software package. The ray-tracing technique, based on the finite-element method, was used to study the performance of a V-trough without the incorporation of a tracking system. By investigating the effect of the mirrors’ inclination angles on the performance of the system, the optimum inclination angles were determined. The simulation was done for a non-tilted concentrator photovoltaic (CPV) system if placed in different geographical locations in Saudi Arabia with the inclination of the mirrors being changed every hour of the daylight. It was found that the concentration ratio of the suggested model increased for the city of Jeddah, for example, by 171% and 131% for double and partial coverage cases, respectively. In order to reduce the operation cost, the simulation was repeated with the restriction of the mirrors’ inclination to only three positions during the day. The concentration ratio decreased in this case by not more than 14%. When mirrors were fixed throughout the day, the concentration ratio dropped to about 50%. Such simulations will assist in investigating different designs of PV systems prior to their manufacturing. In addition, it could assist in determining the best geographic location for such CPV systems.

Gamma distribution excess minority carrier concentration model for solar cell performance modeling

Concentrated photovoltaic (PV) technology represents a growing market in the field of terrestrial solar energy production. As the demand for renewable energy technologies increases, further importance is placed on the modeling, design, and simulation of these systems. Given the cultural shift toward energy awareness and conservation, several concentrated PV systems have been installed across the world. This research presents a new model for carrier concentration within a solar cell. The goal of this innovation is to facilitate the determination of the steady-state operating temperature as a function of the concentration factor for the optical part of the concentrated PV system, to calculate the optimum concentration that maximizes power output and efficiency. This model will be shown to produce a more realistic estimate of the current through a solar cell, which will enable further research into dynamic thermal modeling.

A novel variable-height-pinfin isothermal heat sink for densely-packed concentrated photovoltaic systems

A major limitation of liquid cooling is that the temperature of the coolant rises down the stream, which gradually reduces the heat transfer from the heat source to the coolant causing a large temperature gradient (or temperature non-uniformity) along the flow direction. In this study, a technique has been presented to efficiently minimize the temperature non-uniformity of liquid-cooled heat sinks by incorporating simple geometrical modifications. The technique is demonstrated for a densely-packed concentrated photovoltaic module (CPV) by using a heat sink with cylindrical pinfin microstructures. Several cases of the proposed variable height pinfin (VHP) heat sink were investigated by systematically varying the height of pinfin rows to gradually reduce the heat transfer near the inlet zone while keeping the heat transfer near the outlet zone as close as possible to the conventional uniform height pinfin (UHP) heat sink. The heat sinks were designed for a CPV module consisting of an array of 5 × 5 multi-junction photovoltaic cells illuminated under a solar concentration of 1000 suns. The results showed that the best case of the VHP heat sink achieved a variation of merely 1.56 K in the maximum temperature among the cells, which is 84.1% lower than the UHP heat sink (9.82 K). Moreover, the same case exhibited a 33.1% reduction in the pumping power. However, there is a 2.4% increase in the maximum temperature rise among the cells which is an acceptable tradeoff considering the substantial improvement in the temperature uniformity and pumping power.

Optimal design of solar concentrator in multi-energy hybrid systems based on minimum exergy destruction

The paper presents a systematic approach to designing an imaging dish for a concentrator photovoltaic (CPV) system to minimize exergy destruction. The designed CPV system uniformly distributes light rays on the receiver (TPV/multi-junction PV) to enhance the conversion technology efficiency and lifetime. To this end, a parametric dish is designed using imaging optics and the numerical solution of a differential equation. Afterward, a Monte Carlo simulation is used to estimate the output energy and exergy of the CPV system with the parametric dish. Finally, an optimization algorithm finds the optimal design parameters to minimize the system's exergy destruction. The optimal design leads to a CPV with a concentration factor of 100–150 that is fitted to utilize TPV/multi-junction PV as its receiver. Moreover, it can produce a temperature of 1019° C. Finally, the overall system energy and exergy efficiency with conventional commercial components at solar irradiance of 1000 W/m2 are estimated to be 74.07% and 66.36%, respectively.

Design and implementation of an active optimized optical green energy generation system using ultraviolet solar irradiance

This paper proposes a methodology of optimum power point tracking for tandem solar cell technology to generate green energy. It utilizes an active optical solar tracking and concentrating system, employing ultraviolet (UV) parts: UVA and UVB (280–400 nm), from the solar irradiations. Hence, devises a methodology to avoid complex maximum power point tracking hardware and presents a use of UV solar irradiation. It can be used as an alternative to the conventional concentrated photovoltaic system as well. The performance of the proposed system is also optimized for its output power fixed at a required value of the interest with fewer fluctuations and heating effects. Working of the proposed system is based on a solar irradiance, intensity-dependent axial movement of the light funnel with its variable aperture, and the W/m2 created by a Fresnel lens. The proposed system finds its utility for places where the UV index is recorded at its highest ≥ +11 allowing UV radiations to reach the earth at high levels. The proposed approach is validated, to fulfill fixed energy demand of a thermolysis process against its constant output power claim. For the purpose, firstly absorption response of a quadruple junction solar cell is investigated and made sure that it is capable of operating on UVA and UVB. Secondly, to achieve a constant irradiance level on solar panel surface, control systems along three-axes are designed based on the least-squares optimization criterion to minimize the tracking error and keep the irradiation fixed to a reference value of 1000 W/m2.

Waveguide Concentrator Photovoltaic with Spectral Splitting for Dual Land Use

This research presents a highly transparent concentrator photovoltaic system with solar spectral splitting for dual land use applications. The system includes a freeform lens array and a planar waveguide. Sunlight is first concentrated by the lens array and then reaches a flat waveguide. The dichroic mirror with coated prisms is located at each focused area at the bottom of a planar waveguide to split the sunlight spectrum into two spectral bands. The red and blue light, in which photosynthesis occurs at its maximum, passes through the dichroic mirror and is used for agriculture. The remaining spectrums are reflected at the dichroic mirror with coated prisms and collected by the long solar cell attached at one end of the planar waveguide by total internal reflection. Meanwhile, most of the diffused sunlight is transmitted through the system to the ground for agriculture. The system was designed using the commercial optic simulation software LightTools™ (Synopsys Inc., Mountain View, CA, USA). The results show that the proposed system with 200× concentration can achieve optical efficiency above 82.1% for the transmission of blue and red light, 94.5% for diffused sunlight, which is used for agricultural, and 81.5% optical efficiency for planar waveguides used for power generation. This system is suitable for both high Direct Normal Irradiance (DNI) and low DNI areas to provide light for agriculture and electricity generation at the same time on the same land with high efficiency.

Influence of transient heat flux on boiling flow pattern in a straight microchannel applied in concentrator photovoltaic systems

Concentrated photovoltaic (CPV) overheating due to the high radiation intensity became the critical challenge to preventing its benefits in advancing the photoelectric efficiency. To promote the application of CPV, efficient heat dissipation becomes the key technology. Meanwhile, microchannel flow boiling, as one of the most promising solution to advance cooling of high-flux equipment, has attracted increasing attentions in recent years. However, the fluctuating and non-uniform heat fluxes of CPVs may lead to challenges to microchannel boiling for cooling CPV. Therefore, the transient flow and phase change phenomenon in a microchannel with deionized (DI) water was studied through a numerical modeling on flow boiling. The effects of different sudden heat flux increases on flow boiling two-phase flow pattern were analyzed. It was found that different heat flux increase resulted to different flow pattern evolutions, a much higher sudden increase in heat flux leaded to serious variation of flow pattern, especially the fluctuation of elongated restricted bubbles, which may evolve to annular flow or even dry-out. The vapor phase volume fraction showed a much higher growth rate. When the heat flux increase was raised from 97.96 kW/m2 to 580 kW/m2, the maximum vapor phase volume fraction was increased from 0.104 to 0.8064, and the bubble length increased from smaller than 0.3 mm to 1.5 mm in the dry zone, indicating rapid phase change. Based on analysis on pressure drop and vapor volume fraction variation, the period after receiving sudden heat flux was divided into three stages: initial period, rapid development period, and quasi-stable period. With the rising of heat flux increase from 97.96 to 580 kW/m2, the duration of rapid development period was increased from 0.03 s to 0.066 s, the pressure drop increase was obviously enlarged, from 2.43 kPa to 14.51 kPa, and the vapor phase volume fraction increase in the microchannel was raised by 3.3 times to 25.6 times, indicating more intensive boiling, and deeper effect of higher heat flux increase on the phase change. In addition, the fluctuation intensity of pressure drop in the quasi-stable period was obviously increased from 0.025 to 0.193, demonstrating the advancement in flow boiling instability under higher heat flux increase, which should be controlled.

Maximization of the output power of low concentrating photovoltaic systems by the application of reflecting mirrors

Solar energy is among the most commonly used sources of renewable energy since sun is available for a significant portion of the year in most parts of the world. Energy from sun can be harnessed through several technologies with continuous progress and development. Concentrated solar power systems apply mirrors or lenses as well as solar tracking systems for the concentration of a large solar radiation area into a tiny PV area. Due to high price of solar panels, several efficiency enhancement methods are being evaluated by researchers throughout the world. In this research, a form of solar technology, i.e. photovoltaic system, was applied to present developed low concentrator photovoltaic system (LCPVS) with cooling. This project aimed to determine how solar panel power output was changed by the application of mirrors to concentrate solar radiation; which they had concentration onto panel for increasing power output from 1 to 4 mirrors with the cooling system. In fact, the aim was to increase the output power by enhancing the amount of solar radiation which reaches the same surface area of solar panel via mirrors. Furthermore, application of mirrors saves PV area which is more economical. Also, the results were compared to a reference solar panel for determining how to increase the power output of a single panel (normal panel receiving solar radiation directly). The results showed that the value of the DC current (A) output of the four mirrors reflecting on the panel is three times greater than that of the reference panel, and the DC power (W) is almost three times greater than the reference panel's power.

Techno-economical evaluation of renewable hydrogen production through concentrated solar energy

This paper analyses renewable hydrogen production using concentrated solar energy considering a hypothetical production plant located in Guamaré, Brazil. The solar resource and the solar field performance for a typical meteorological year (TMY) were evaluated for this location.The thermochemical metal oxides cycle and the high-temperature electrolysis (HTE) were selected as hydrogen production paths due to their high development potential. For the HTE was proposed, a novel arrangement for a high-efficiency operation and the hydrogen production was carried out in a Solid Oxide Electrolysis Cell (SOEC) in thermo-neutral operation, driven by the electricity generated in a concentrated photovoltaic (CPV) system and heat obtained from the solar field, this arrangement uses tubular and closed volumetric receivers for the steam production and superheating, and a heat exchange network for heat recovery at SOEC outlet. In the thermochemical metal oxides case, a commercial CFD code was used to perform the reactor's thermal simulation, and the hydrogen production rate was calculated using different scenarios for the oxygen uptake capacity. In addition, an operation strategy was proposed to increase the hydrogen yield. Maximum year averaged sun to hydrogen efficiencies of 31.8% and 10.2% were obtained for the HTE system and the thermochemical metal oxide cycle, respectively.The hydrogen production cost was estimated for different production capacities and scenarios, leading to a hydrogen production cost of 4.55 US$/kg for HTE and 4.32 US$/kg for the metal oxide cycle for a long-term scenario and a production capacity of 2500 tonnes per year. Finally, a novel approach of hydrogen-production is proposed and evaluated, using HTE coupled with CPV and concentrated thermal energy. This approach has high development potential due to its high sun to hydrogen efficiency and the use of known technologies.

Design and experimental study of a Fresnel lens-based concentrated photovoltaic thermal system integrated with nanofluid spectral splitter

Minimizing optical losses during light focusing and preparing an appropriate nanofluid for spectral splitting is crucial for the performance of a concentrated photovoltaic thermal system. A Fresnel lens-based solar concentrator integrated with a nanofluid spectral splitting photovoltaic thermal system was designed and validated in this study. The design posited solar irradiation being appropriately concentrated by a linear Fresnel lens on a series of tubes through which the nanofluid flowed, allowing a large beam of limited spectra to be transmitted to the PV below, with the rest absorbed and converted to thermal energy is introduced. The optical loss was minimized by increasing the surface area and decreasing the optical path length. The synthesized nanofluid's spectral transmittance was measured experimentally. Dynamic modeling energy balance equation for the concentrated solar energy conversion system was developed and computed by MATLAB programming. Since the photovoltaic module was decoupled from the filtering channel and integrated with the water cooling, its surface temperature was much lower than the nanofluid and output water temperature. The combined efficiency of the system was 50.35%, 65.2%, 72.70%, 74.7%, and 85% for ZnO nanofluids with volume concentration ratios of 0.00036%, 0.00089%, 0.0017%, 0.0036%, and 0.0089%, respectively. A nanofluid with a concentration ratio of 0.00089 vol% provides the closest spectral match with a silicon solar cell, as verified by a reasonable electrical and thermal efficiency. We used this as a representative concentration ratio of ZnO nanoparticles to validate the prototype. The maximum deviation between simulated and experimentally determined overall performance was less than 3.7% which shows the two results are in good agreement. The findings highlight the potentials of employing a low-cost ZnO nanofluid in a concentrated photovoltaic thermal system for full spectrum utilization.

Performance Optimization of Solar Photovoltaic System using Parabolic Trough and Fresnel Mirror Solar Concentrator

An attempt has been taken to design parabolic trough and Fresnel mirror solar concentrator with the purpose of optimizing the output power of a photovoltaic system for both bright sunny day and cloudy day by using a 72-cell 5W photovoltaic solar panel. The PV system's efficiency has been analyzed in terms of output voltage, current, and power of the solar panel. Accordingly, to our expectation, we observed that on a bright sunny day, the output power improvement of the solar panel is 26.81% for the parabolic trough and 17.89% for the Fresnel mirror concentrator. On a cloudy day, both concentrators improve output power by 22.3% and 14.1%, respectively. In terms of power optimization of a photovoltaic system, the following has been discerned: a solar photovoltaic concentrator system with a parabolic trough is much more effective than one with a Fresnel mirror.

Development and Accuracy Assessment of a High-Precision Dual-Axis Pre-Commercial Solar Tracker for Concentrating Photovoltaic Modules

In recent decades, advances in the development of solar tracking systems (STSs) have led to concentrating solar technologies to increase their energy conversion efficiency. These systems, however, still have areas of opportunity or improving their performance and reducing their manufacturing costs. This paper presents the design, construction and evaluation of a high-precision dual-axis solar tracking system with a technology readiness level of 7–8. The system is controlled by a low-cost Arduino board in a closed-loop control using a micro-electromechanical solar sensor. Real-time tracking experiments were performed under a clear sky as well as during partly and mostly cloudy days. Solar tracking accuracy was evaluated in an operational environment using test procedures adapted from the International Electrotechnical Commission (IEC) 62817 standard. The total mean instantaneous solar tracking error on a clear day measured with a calibrated digital solar sensor was 0.37° and 0.52° with a developed pinhole projection system. Similarly, the total mean reported solar tracking accuracy achieved was 0.390° on a sunny day and 0.536° on a partially cloudy day. An annual power generation analysis considering a conventional photovoltaic (PV) panel system and a typical concentrator photovoltaic (CPV) module as payloads was also presented. Simulations showed an increase in the generation of up to 37.5% for a flat panel with dual-axis tracking versus a fixed panel. In the case of the CPV system, first, a ray tracing study was implemented to determine the misalignment coefficient, then the annual power generation was estimated. The developed STS allowed the CPV modules to reach at least 90% of their nominal energy conversion efficiency.

Energy and economic comparison of three optical systems adopted in a point-focus CPV system

The concentrating photovoltaic (CPV) systems allow good results for generation of clean energy at competitive costs, but a careful selection of the optical system is essential to obtain energy and economic advantages. Hence, three different point-focus optics (parabolic mirror, spherical mirror and a commonly used Fresnel lens) characterized by same dimensions are compared in this paper from energy and economic point of view in order to identify the most convenient in terms of unit cost of electrical power. The optical concentration factor, the maximum values of triple-junction (TJ) cell electrical power and temperature are experimentally measured for each optical system, and successively, the unit cost of electrical power is calculated. The parabolic mirror results the least convenient because it guarantees almost the same performances of a spherical optics but with costs of about 2.7 times higher than it. The Fresnel lens presents a value of the unit cost of electrical power near to the spherical mirror, but its much lower optical efficiency implies a necessary area for the CPV plant about three times larger. Moreover, a forecast of the increase in the CPV plant power capacity in Italy and the consequent decrease in the unit cost of electrical power in two possible scenarios, optimistic and pessimistic, is realized. A reduction of the unit cost of electrical power, between 13 and 30%, is expected for the CPV systems.

Cylindrical Fresnel lens: An innovative path toward a tracking-less concentrating photovoltaics system

We here invent an implicitly new optical device - cylindrical Fresnel lenses historically used in the decades-old lighthouse concentrator to find application in the field of concentrator photovoltaic, with numerous demonstrations of exotic features in optics. The precious attribute of such a solar concentrator is its ability to grant a focal point sequence, essentially distributed over an arc at any light incidence. The other striking merit of this design is its high acceptance angle, about 60°, at hand and even up to 90°, ideally. We have applied this approach to a simplified principle-of-concept model that closely depicts the octagonal cylindrical Fresnel lens in essence. This convergence feature was evidenced in a mock-up model through optical simulation and further consolidated by electrical characteristics analysis. Specifically, the simulation affirmed that an optimal structure can attain a concentration ratio of ∼23 and an optical efficiency of ∼70%. We indeed confirmed through an outdoor experiment a 16-fold improvement of current gain, which was close to the simulation result. Of further exceptional interest in such a design is its compatibility with two mature common tracking mechanisms: daily or yearly single-axis tracking, leaving room for design compromises. This design leaves ample margins for simple and low-cost light couplers, which are advantageous in affordable concentrator photovoltaic systems. In addition, the quantitative assessment unravelled that the generated power can be enhanced 1.3× in comparison with the flat Silic panel. We describe the potential realization of the large-scale of the model, making this solar concentrator amenable to commercialization.

Performance analysis and optimization of a trilateral organic Rankine powered by a concentrated photovoltaic thermal system

The growing demand for energy encourages the use of organic Rankine cycles powered by renewable energies. This work introduces the novel renewable system combining a high performance concentrated photovoltaic thermal and a trilateral organic Rankine cycle for power generation. The high performance concentrated photovoltaic thermal system is sized to meet the heat requirements of a trilateral organic Rankine cycle at high evaporation temperatures of the working organic fluid. Mathematical models are developed for different components of the combined system. The differences between current and previous work models did not exceed 3%. The results showed that the electric power generated by the combined system varied between 70 and 273 kW and the overall efficiency ranged from 29 to 38.55%. Effect of some parameters such as the incidence angle, the aperture area and the condensing temperature of the working organic fluid on the system efficiency are investigated. The results demonstrated that production performance decreased as the incidence angle and the condensing temperature of the working fluid increased. The results also showed that the levelized cost of electricity of the combined system ranged from 0.047 to 0.099U$/kWh. The overall results highlighted that the production performance of the renewable system was very high compared to other solar technologies presented in the literature review.

Design and dynamic performance of a concentrated photovoltaic system with vapor chambers cooling

• A dynamic model of CPV system with vapor chambers cooling established and validated. • Ray tracing analysis shows concentrator has optical efficiency of 74% at 30 suns. • Vapor space thickness of 3.5 mm and vapor chamber width of 250 mm are the optimum. • CPV cells temperature with vapor chambers is 17.5 K lower than that without them. • Max. instantaneous PV temperature with vapor chambers cooling at 30 suns is 323.8 K. One of the challenges faced by concentrated photovoltaic (CPV) system is the thermal management of the CPV module because it can seriously degrade and even shorten the lifetime of the CPV cells. Vapor chamber as a two-dimensional heat pipe has drawn attention for use in cooling electronic devices. In this research, vapor chambers cooling is proposed for a CPV system based on multi-segment mirror concentrator to ensure the operation of CPV module at low and uniform temperature. Ray tracing analysis shows that the developed concentrator exhibits optical efficiency of 74% at concentration ratio of 30 suns and the concentrated solar flux intensity distribution on the CPV module surface is quite uniform. To maximize the electrical energy output, the dynamic performance of the linear CPV system with vapor chambers cooling by varying the thickness of the vapor space, the vapor chamber width and the concentration ratio is analyzed. The results indicate that the vapor space thickness of 3.5 mm and the vapor chamber width of 250 mm are the optimum to achieve the best system performance. Further, it is found that the temperature of CPV cells with vapor chambers is 17.5 K lower than that without them, resulting in improvement in the system electrical performance. The maximum instantaneous CPV cells temperature of the system with the designed vapor chambers cooling under 30 suns concentration can be maintained as low as 323.8 K in a typical day and the minimum electrical efficiency and the average electrical efficiency for the whole day are 13.9% and 14.4%, respectively.

Modeling of a novel nanofluid-based concentrated photovoltaic thermal system coupled with a heat pump cycle (CPVT-HP)

• A nanofluid-based CPVT system coupled with a domestic heat pump is proposed. • An acceptable agreement between CFD and optical analysis results and experimental data. • The effects of CPVT parameters on performance of the proposed system is studied. • The optimal nanofluid mass flow rate of 0.01382 kg/s is obtained. • A significant improvement in performance of the proposed CPVT-HP system is obtained. The concentrated photovoltaic thermal (CPVT) system is one of the heat and power generation systems that have received special attention in recent decades. In this paper, a novel CPVT system with Al 2 O 3 nanofluid flow into porous channel coupled with a domestic heat pump (CPVT-HP) is evaluated from energy, exergy and economics viewpoints. In addition, mass flow rate of the nanofluid through the CPVT is thermo-economically optimized. The study is divided into three parts of Computational fluid dynamics (CFD) analysis of the CPVT, optical analysis of parabolic trough concentrator (PTC) and thermo-economic analysis of the proposed CPVT-HP system. The continuity, Brinkman momentum and energy equations are employed as governing equations for CFD analysis considering the average solar flux using optical calculations. Then, energy-exergy-economic optimization is performed on the proposed domestic CPVT-HP system in Mashhad city of Iran during November to February. The validation results show that the numerical simulation obtained for the proposed model has an acceptable agreement with the experimental data. Results show that with increasing the nanofluid mass flow rate, the PV cell temperature and nanofluid outlet temperature decease which lead to increases in PV cell efficiency and CPVT energy efficiency while the exergy efficiency of the CPVT system decreases. It is also found that the maximum performance of the porous channel collector is obtained for the pore diameter and the porosity of 0.9 mm and 95%, respectively. Finally, based on energy-exergy-economic analysis and Pareto method, the optimal nanofluid mass flow rate of the integrated CPVT-HP system is achieved equal to 0.01382 kg/s.