Photovoltaic-thermoelectric Hybrid Research Articles

Optimization of the photovoltaic-thermoelectric hybrid system with and without optical concentrator

The photovoltaic-thermoelectric coupled system has drawn widespread attention in recent years due to its potential of utilization of full-spectrum solar energy. The output power of thermoelectric (TE) is usually much less than that of photovoltaic (PV), because the temperature difference of TE module is usually very small. Thus, the optical concentrating method has been used to increase the temperature difference, but it increases complexity of the structure and extra cost for the sunlight tracking system. Another practical way is using the thermal concentrating method to increase the heat flux of the TE module. However, for there two PV-TE coupled systems i.e. optical and thermal concentrating systems, there exists a confrontation between the PV cell and the TE module. The efficiency of PV cell decreases with the increasing temperature, while the performance of the TE module increases with the increasing temperature difference. In some conditions, the total efficiency of the PV-TE coupled system may be even lower than that without TE module. Therefore, it is necessary to investigate the optimal combination mode of PV cell and TE module for the coupled system. In this paper, a thermodynamic model based on energy-balanced equation is established to investigate the structural optimization and efficiency improvement of PV-TE coupled power generation system, which considers the effects of the thermal concentration factor, the length of thermocouples, the loading resistance of TE module and thermal diffusion factor. The influence rules of these factors on power generation efficiency of PV-TE coupled system without and with concentrator are also theoretically analyzed. (1) For the PV-TE coupled system without concentrator, the influences of thermal concentration factor, the length of thermocouples and the ratio of loading resistance to the internal resistance of TE module on the total efficiency of PV-TE coupled system are analyzed under four efficiency temperature coefficients of PV cells ( β ref =0.001, 0.002, 0.003, 0.004 K−1). It is found that, when the figure of merit of TE module Z is 4×10−3 K−1 and β ref is 0.001 K−1, the total efficiency increases initially and then decreases with the increases of the thermal concentration factor, the length of thermocouples and the ratio of loading resistance to the internal resistance of TE module. Therefore, there exist optimal values of thermal concentration factor, length of thermocouples and loading resistance of TE module to maximize the total efficiency. (2) For the PV-TE coupled system with concentrator, the influence of thermal diffusion factor on the total efficiency of PV-TE coupled system under five efficiency temperature coefficients of PV cells ( β ref=0.001, 0.0015, 0.002, 0.0025, 0.003 K−1) is studied for the figure of merit of TE module Z =2.545×10−3 K−1 and Z = 4×10−3 K−1. The results shown that, for the cases of Z =2.545×10−3 K−1, β ref= 0.001 K−1; Z = 4×10−3 K−1, β ref= 0.001 K−1; Z = 4×10−3 K−1, β ref= 0.0015 K−1, the total efficiency decreases as the thermal diffusion factor increases. While for other cases, the total efficiency increases significantly as the thermal diffusion factor increases. It has also shown that the increases of efficiency caused by the increase in thermal diffusion factor becomes small when the thermal diffusion factor is over 5.12. The reason is that the heat transfer becomes fast when the thermal diffusion factor becomes larger, which leads to the increase of temperature of the PV cell and the hot side of the TE becomes small as the thermal diffusion factor is over 5.12. Based on the above results, it is suggested that an optimal thermal diffusion around 3.0 can have a better balance of both cost and total efficiency of the PV-TE coupled system with concentrator.

The electric feature synergy in the photovoltaic - Thermoelectric hybrid system

The thermoelectric (TE) module can be used to convert the heat generated by the photovoltaic (PV) cell to electricity, therefore the photovoltaic-thermoelectric hybrid system (PV-TE) has attracted extensive attention. The energy loss caused by the mismatch between the PV current and the TE current is studied. Two different electrical connection methods of the PV-TE system are studied in this paper. The choice of the electrical connection method depends on the temperature variation. When the PV temperature changes with the solar radiation, it is better to use the series-connection to connect the electrodes of the PV-TE system. However, if the PV temperature does not vary with the solar radiation, the parallel-connection is a better choice for the PV-TE system. According to these phenomena, it can be known that the PV-TE system without the phase change material must choose the serial connection and the parallel connection is a good choice for the PV-TE system incorporated with the phase change material.

The Effect of the Temperature Difference on the Performance of Photovoltaic-Thermoelectric Hybrid Systems

The performance of the photovoltaic-thermoelectric (PV-TE) hybrid system was examined using three types of PV cells and a thermoelectric generator (TEG) based on bismuth telluride. The investigated PV cells are amorphous silicon (a-Si), monocrystalline silicon (mono-Si), and cadmium telluride (CdTe). The results showed that the TEG contribution can overcome the degradation of the PV cell efficiency with increasing temperature at the minimal working condition. This condition corresponds to the critical temperature difference across the TEG that guarantees the same efficiency of the hybrid system as that of the PV cell alone at 298 K. The obtained results showed that the critical temperature difference is 13.3 K, 44.1 K, and 105 K for the a-Si, CdTe, and mono-Si PV cell, respectively. In addition, the general expression of the temperature difference across the TEG needed for an efficiency enhancement by a ratio of r compared with a PV cell alone at 298 K was given. For an efficiency enhancement by 5 % (r = 1.05), the temperature difference required is 30.2 K, 61.3 K, and 116.1 K for the a-Si, CdTe, and mono-Si PV cells, respectively. These values cannot be achieved practically only in the case of the a-Si PV cell. Moreover, a TE material with a high power factor can reduce this temperature difference and improve the performance of the hybrid system. This work provides a tool that may be useful during the selection of the PV cell and the TE material for the hybrid system.

Experimental optimization of operating conditions for concentrating photovoltaic-thermoelectric hybrid system

This paper provides a comprehensive experimental optimization process of the concentrating photovoltaic-thermoelectric hybrid system, considering the total input energy, the output characteristics of coupling devices, the system structure and the electrical connection modes. An experimental system with an adjustable light source is established. The concentrating photovoltaic-thermoelectric hybrid system is firstly compared with the concentrating photovoltaic system at varying optical concentration ratios to verify the feasibility of hybrid utilization and to illustrate the effect of optical concentration ratio on the hybrid performance. Then, the effects of the photovoltaic output voltage and the thermoelectric load resistance on the temperature and output power of the hybrid system are investigated to obtain the optimum output characteristics. Subsequently, the influence of the thermoelectric thermal resistance determined by its number and structure on the hybrid performance is studied. Finally, two electrical connection modes (series and parallel) of the thermoelectric modules are compared considering the same thermoelectric thermal resistance. The results demonstrate the superiority of the concentrating photovoltaic-thermoelectric hybrid system and the importance of optimizing the operating conditions. The obtained results can provide some useful guidance for the design and operation optimization of the practical concentrating photovoltaic-thermoelectric hybrid system.

High-Performance Monolithic Photovoltaic–Thermoelectric Hybrid Power Generator Using an Exothermic Reactive Interlayer

A high-performance monolithic photovoltaic–thermoelectric hybrid generator with a photothermal conversion layer is introduced. The layer, a thin acrylic film dyed with black colored AZO dye, effectively absorbs photons in the near-infrared region. The AZO dye supports an exothermic reaction through nonradiative relaxation. The hybrid generator was fabricated through monolithic integration. A thermoelectric (TE) module was fabricated directly on the back surface of the photovoltaic (PV) module without using the ceramic substrate typically employed in conventional TE modules, so that thermal resistance between the PV module and TE module could be minimized. The 51.35 cm2 fabricated hybrid generator showed a power conversion efficiency of about 22.5% with an open-circuit voltage of 0.94 V and a maximum power of 1.15 W under standard AM 1.5G illumination. The hybrid power generator with the photothermal conversion layer showed about 40% higher output power compared to the control PV only, about 16% higher tha...

Modelling of an Improved Hybrid Cooler Used in Sustainable Buildings

Sustainable buildings are resource-efficient and environmentally friendly in terms of structure and energy consumption. It is not enough for a green building to have only greener structure and envelope; the meaning is extended to all its equipment and applications used, too. The purpose is to reduce the consumption of the conventional energy, to efficiently use energy resources and to reduce pollution and environmental degradation. Due to all these aspects, sustainable buildings use renewable and other different types of alternative energies. Among these are the photovoltaic (PV) and the thermoelectric (TE) energies. In most cases, a highperformance building uses the electric energy provided by PV panels included in a more complex system. In attempt to reduce the complexity of the photovoltaic system and its investment costs, modelling an improved photovoltaic-thermoelectric hybrid cooler was a proper option (a cooler can be found in almost every existing building, especially in houses). The choice of this combination was determined by the use of the direct (DC) current delivered by the PV system by the thermoelectric cooling (TEC) modules embedded on the cooler. An improved variant of the PV-TEC cooler was investigated. The modelling analysis comprises i) an appropriate volume for the day-to-day use, ii) new materials comparing to those already used in the structure of other hybrid coolers, iii) different numbers and positions of the TEC modules on the surface of the cooler’s sides. All the results are discussed to establish the proper behaviour and variant of the photovoltaic-thermoelectric cooler and to further realize a prototype to see if the theoretical results confirm.

Higher-efficiency for combined photovoltaic-thermoelectric solar power generation

ABSTRACTSolar energy application in a large spectrum has the potential for high-efficiency energy conversion. Though, solar cells can only absorb photon energy of the solar spectrum near their band-gap energy, and the remaining energy will be converted into thermal energy. The use of the thermoelectric generator becomes a necessity for convert this thermal energy dissipated so as to increase efficiency conversion.This paper analyses the feasibility of photovoltaic-thermoelectric hybrid system and reviews their performance in order to optimize harvested energy. Regarding the thermoelectric effect, a new method of the ambient energy harvesting is presented. This method combines thermoelectric generators and the effects of heat sensitive materials associated to photovoltaic cells in phase change for generating both energy day and night. Experimental measures have been conducted primarily in laboratory conditions for a greater understanding of hybridization phenomena under real conditions and to test the actual performance of devices made. Results show that the hybrid system can generate more power than the simple PV and TEG in environmental conditions. This hybrid technology will highlight the use of renewable energies in the service of the energy production.

Feasibility analysis of a concentrating photovoltaic-thermoelectric-thermal cogeneration

This paper provides a novel solar energy utilization system that firstly achieves the cogeneration of photovoltaic, thermoelectric and high-grade heat. The novel concentrating photovoltaic-thermoelectric-thermal cogeneration system can overcome almost all of the disadvantages of the existing systems and provide a better way for solar energy utilization. The operating temperature, energy and exergy efficiency of the new system and the existing systems in different weather and seasons are first compared to demonstrate the superiority of the new structure. The new system is then optimized by investigating the effect of controlled temperature and thermoelectric structure on the hybrid performance to improve the solar energy utilization. Finally, the system array is proposed to reduce the system cost, and the economic analysis of the systems is conducted. The results indicate that when the solar irradiance is high, the new structure can well mitigate the temperature fluctuation caused by the varying solar irradiance and keep the photovoltaic cell operating at a safe temperature. The new system provides more exergy output than the existing systems because it produces both electricity and high-grade thermal output. When the solar irradiance is low, the new system behaviors similar to the concentrating photovoltaic-thermoelectric hybrid system, but it also provides more exergy output. All of the results demonstrate the significant advantages of the new system: efficient, stable and secure.

Experimental investigation on effects of thermal resistances on a photovoltaic-thermoelectric system integrated with phase change materials

Phase change materials have been introduced into the concentrated photovoltaic-thermoelectric hybrid system to control its operating temperature. As the poor thermal conductivity of phase change materials (paraffin in this paper), the expanded graphite and copper foam are respectively added into the paraffin to decrease its thermal resistance. An experimental platform containing three concentrated photovoltaic-phase change material-thermoelectric hybrid subsystems is established. Experimental comparisons of performances among the concentrated photovoltaic system, the conventional concentrated photovoltaic-thermoelectric hybrid system, and the concentrated photovoltaic-phase change material-thermoelectric hybrid system are firstly carried out. Then, a series of comparative experiments are conducted to reveal the effects of thermal resistances on the hybrid system performance. The results demonstrate that the improved phase change material can well maintain the photovoltaic-thermoelectric hybrid system at the desired temperature and generate more electricity. The temperature of the photovoltaic cell in the concentrated photovoltaic-phase change material-thermoelectric hybrid system is nearly 50 °C while the one in the concentrated photovoltaic-thermoelectric hybrid system reaches about 80 °C. The average output power of the concentrated photovoltaic-phase change material-thermoelectric hybrid system increases by 23.52% compared with the concentrated photovoltaic-thermoelectric coupling system. The expanded graphite and copper foam both can decrease the thermal resistance of paraffin, and the expanded graphite has a better effect. The thermal resistance of the cooling system has little effect on the operating conditions of the photovoltaic cell and phase change material but greatly affects the performance of the thermoelectric generator.

Optimization and experimentation of concentrating photovoltaic/cascaded thermoelectric generators hybrid system using spectral beam splitting technology

The concentrating photovoltaic-thermoelectric (PV-TE) hybrid system by using spectrum splitting technology had been considered to be a promising system. The IR-wavelength light, which can’t generally be converted by solar cells, can be separated from the full solar spectrum in this system and then be appropriately converted by thermoelectric generators based on Seebeck effect. The overall system efficiency might be improved due to the additional contribution of thermoelectric generation. In this paper, a prototype PV-TE hybrid system and a numerical model for the evaluation of the whole system are presented. In order to convert IR-wavelength light into electricity sufficiently, we proposed the cascaded thermoelectric module for thermoelectric generation, which consists of two individual TE stages. These are middle-temperature thermoelectric materials, CoSb3 and low-temperature thermoelectric materials, Bi2Te3 which are configured in tandem. The numerical model was established to optimize thermoelectric module geometries and the optical concentration ratio. In addition, such a novel PV/cascaded TE generators hybrid system had been constructed and experimentally researched in practical conditions. Meanwhile, the effects of the direct normal irradiation (DNI) on the temperature of the thermoelectric module and the overall output power of the hybrid system are experimentally investigated. The optimized results showed that the DNI, optical concentration ratio and the height ratio of two TE stages could significantly affect the performances of this hybrid system. The TE subsystem efficiency ηTE can reach to 8%, the PV subsystem efficiency ηPV can reach to 44%, and total hybrid system efficiency ηPV-TE can reach to 35% under the conditions that DNI = 1000 W/m2, optical concentration ratio CF = 1000, optimized height ratio of two TE stages τ = 0.6. The experimental research results revealed that output power of PV and TE subsystem could reach to 22 W and 1.9 W respectively.

An integrated design of the photovoltaic-thermoelectric hybrid system

The photovoltaic-thermoelectric hybrid system (PV-TE) has attracted much attention due to its ability of utilizing solar energy in full spectra. This paper uses the concept of the integrated design to improve the PV-TE system. To enhance the heat transfer, the ceramic plates of the commercial TE modules are eliminated from the PV-TE system in order to reduce the thermal resistance. To enhance the absorption of the solar energy, a V-type groove which can keep each PV cell perpendicular to its adjacent PV cells is used in the PV-TE system. An experimental setup is established to demonstrate the feasibility of the structural improvement. The results indicate that the simplified TE structure can lead to an increase in both PV efficiency and TE efficiency by enhancing the heat transfer. An obvious increase in the PV-TE efficiency caused by the V-type groove is observed in the experiment.

Numerical simulation of a photovoltaic thermoelectric hybrid power generation system

In this study, three dimensional numerical models for a PV module and a TEG device are developed. The objective is to investigate the performance of hybrid PV + TEG power generation systems composed of thermoelectric generators attached to the backside of a PV module. The proposed numerical model ignores the inner structural complexities and considers the device as a homogeneous medium. The electric power output is modeled as an internal energy sink. The governing energy equations are solved by finite volume method. User defined functions are developed to account for the electrical behavior of PV and TEG. Results show that the hybrid system can generate more power than the simple PV in certain environmental conditions. However, the increase is marginal due to the insufficient temperature difference for the TEG device. Also, the presence of TEG may have undesirable effects on cooling of PV module. Simulations are performed for different number of TEG modules and also various optical concentration ratios. It is revealed that the maximum power generation occurs at a certain concentration ratio which depends on the heat sink characteristics.

A novel optimal design method for concentration spectrum splitting photovoltaic–thermoelectric hybrid system

In this paper, a novel optimal design method for the concentration spectrum splitting photovoltaic-thermoelectric hybrid system is proposed. The newly provided optimal design method tries to optimize the solar energy distribution of the concentration spectrum splitting photovoltaic-thermoelectric hybrid system while maintaining the optimal operating states of the subsystems, which has never been mentioned before. For the optimal design, the optimum operating temperature of the hybrid system is firstly determined. Then, a series of cutoff wavelengths of the spectral splitter is given, and the efficiencies of the coupling systems with all different cutoff wavelengths are calculated. The highest efficiency and the optimal cutoff wavelength will be obtained by comparing the performances of the concentration spectrum splitting photovoltaic-thermoelectric hybrid systems with different cutoff wavelengths. The optimal thermoelectric thermal resistance and structure factor related to the optimum operating temperature of the thermoelectric subsystems are finally acquired. The effects of the thermoelectric figure of merit and the convective heat transfer coefficient of the cooling system on the optimal design are also discussed. The results show that the optimal temperature distribution of the thermoelectric subsystem can be obtained by regulating the thermoelectric structure factor. Although the solar energy transferred to the thermoelectric subsystem decreases, as the cutoff wavelength increases, the thermoelectric efficiency can be increased through optimization. The optimal cutoff wavelength of the spectral splitter decreases with the increase of the thermoelectric figure of merit, and a thermoelectric module with smaller thermal resistance should be used to maintain its optimum operating temperature.

Optimal solar energy on thermoelectric cooler of water generator in case study on flood crisis

The purpose of this research is to study the drinking water production using a photovoltaic-thermoelectric hybrid system. The methodology used in this study was simulated by using a psychrometric chart and MATLAB/Simulink software to validate the operating conditions (temperature and humidity). We construct a portable drinking water system, consisting of a TEC-12706 array which is powered by a photovoltaic hybrid system. The system comprises a 50 W solar cell and an 80 AH battery. The thermoelectric module is mainly used to recover waste heat from the heat exchanger (hot side). On the basis of the principle of latent heat, molecules of water vapor can be converted into water droplets from the heat exchanger (cold side). The prototype has been tested at the Rajamangala University of Technology Lanna (Doi Saket campus), Chiang Mai, Thailand. The preliminary results showed that drinking water can be produced approximately 1 L per day at a temperature of 10–30 °C and a humidity of 60–80%. Hence, such a portable drinking water module may serve 1–2 persons per day under a flood crisis.

Optimal design method for concentrating photovoltaic-thermoelectric hybrid system

Utilizing the dissipated thermal energy by photovoltaic cells working as the heat source of thermoelectric module to generate extra electricity is an optional way to further improve the photoelectric conversion efficiency of concentrating photovoltaic system. However, there exists a confrontation between the efficiency temperature characteristics of the photovoltaic cell and the thermoelectric module. The photovoltaic efficiency decreases with the rise of its temperature while the thermoelectric efficiency increases with its temperature difference augmenting, which makes the design of the concentrating photovoltaic-thermoelectric hybrid system crucial. In this paper, the selection principle of the coupling devices and a novel optimal design method for the concentrating photovoltaic-thermoelectric coupling system are proposed. The minimum figure of merit of the thermoelectric generator that enables the efficiency of the concentrating photovoltaic-thermoelectric hybrid system to be larger than that of the concentrating photovoltaic system is calculated and regarded as the reference of evaluating the feasibility and selecting the coupling devices. For the optimal designs, the temperature distribution where the concentrating photovoltaic-thermoelectric hybrid system has the highest electric efficiency is firstly calculated. Then, the optimum thermal resistance of the thermoelectric generator, which keeps the photovoltaic-thermoelectric hybrid system operating at the optimal temperature distribution, is calculated. Once the thermoelectric thermal resistance is obtained, the optimal structure of the thermoelectric generator can be determined. The effects of reference efficiency, the efficiency temperature coefficient of the photovoltaic cell, the figure of merit of the thermoelectric module and the convective heat transfer coefficient of the cooling system on optimal designs of the concentrating photovoltaic-thermoelectric hybrid system are also discussed.

Solar driven concentrated photovoltaic-thermoelectric hybrid system: Numerical analysis and optimization

In this study, a theoretical model of a concentrated photovoltaic-thermoelectric hybrid system has been developed based on first and second laws of thermodynamics and analysed in MATALB. A numerical method has been exploited to determine the temperatures of photovoltaic module (PV) and hot and cold side of thermoelectric generator (TEG) by iteratively solving the energy balance equations. The proposed study takes into account the effects of hot and cold side thermal resistances, thermoelectric properties, fill factor, geometry of thermoelectric module, load resistance and electrical current on the performance of the hybrid system. The results show that the optimum value of ratio of TEG load resistance to TEG internal resistance, m for maximum power output and efficiency of thermoelectric module is higher than unity. The concentration ratio should also be optimized to achieve maximum PV power output. For the fixed leg length of 5 mm and CG value of 1 kW/m2, the optimum m corresponding to maximum power output and maximum efficiency of the hybrid system is 0.5. The maximum power output and efficiency of the hybrid system increase by 5% as compared to the corresponding values of concentrated PV system. Moreover, at higher concentration ratios, the contribution of thermoelectric power to the power output of hybrid system is higher. Further, for other parameters fixed, the optimum value of CG for maximum power output of the hybrid system is 5.5 kW/m2 and it is 14% higher than the corresponding power output of CPV system alone. This improvement in the performance of hybrid system is added by the thermoelectric generator module. The results of this analysis incorporating the electrical and thermal contact resistances of thermoelectric device, may be helpful to envisage the design of a real photovoltaic-thermoelectric hybrid system.

Conversion efficiency gain for concentrated triple-junction solar cell system through thermal management

Abstract The application of the thermoelectric (TE) modules can provide extra power in PV cell systems, but the increased thermal resistance leads to an increase in the temperature of the PV cells. In this paper, the phase change materials (PCMs) attached to the back side of the PV cell is used to control the temperature of the PV cells. The PCMs transfers the heat absorbed from the PV cell to the TE modules. A comprehensive experimental study is carried out to investigate the performance of the photovoltaic-thermoelectric hybrid system with PCMs. The outdoor tests are performed to reveal the influence of the cooling methods, the sunlight intensity, and the uniformity of the concentrated light spot on the conversion efficiency of the system. The results indicate that the conversion efficiency of the PV-TE hybrid system with PCMs is 0.56% more than solo PV cell system due to a decrease of the PV cell temperature and the efficiency contribution of the TE modules. This work investigates the factors that affect the full spectrum utilization of solar energy in PV cell systems.

A Hybrid Electric and Thermal Solar Receiver

Summary Solar energy offers a promising renewable energy source; however, it is expensive to store electricity from photovoltaics (PV), the most widely deployed solar electricity technology. Solar thermal energy technologies can be paired with inexpensive thermal storage, but are more expensive overall. We have developed a solar receiver that combines PV and solar thermal systems to efficiently convert solar radiation to electricity (to be used immediately) and thermal energy (to be stored and converted to electricity on demand). This paper describes the Hybrid Electric And Thermal Solar (HEATS) receiver and models its performance. An idealized model predicts high solar-to-electricity efficiency (35.2%) with high dispatchability (44.2% of electricity from thermal energy) at an operating temperature of 775 K. Modeling using measured performance values for HEATS subcomponents predicts 26.8% efficiency and 81% dispatchability with silicon PV and 28.5% efficiency and 76% dispatchability with gallium arsenide PV, both operating at 700 K.

The effect of the full-spectrum characteristics of nanostructure on the PV-TE hybrid system performances within multi-physics coupling process

Nanostructured surface is an important way to improve the efficiency of solar energy by absorbing more solar irradiance. However, due the bandgap of semiconductor material, more absorbed irradiance results in more waste heat. As for photovoltaic-thermoelectric (PV-TE) hybrid system, more waste heat reduces the efficiency of PV module due to the increased temperature, but is beneficial for TE module. There are complex and coupling physical processes (near-field optics, photovoltaic conversion, thermoelectric effects, and heat transfer) in the PV-TE hybrid system. Therefore, a multi-physics coupling mathematic model is developed for investigating the effect of full-spectrum characteristics of nanostructure on the PV-TE hybrid system performances. At first, the full-spectrum characteristics of nanostructure is found and summed up. As an example, the II set of the cone nanostructures have two cone nanostructure (Ⅱ-1 cone nanostructure and Ⅱ-2 cone nanostructure) with different dimensions. They have the same average reflectance of the wavelength range from 0.35 μm to 1.1 μm (0.05), however the average reflectance of the wavelength range from 1.1 μm to 2.5 μm (Ra,1.1-2.5) of the Ⅱ-1 cone nanostructure is 74.8% lower than that of the Ⅱ-2 cone nanostructure, which results in that the output power density of the PV-TE hybrid system with the II-2 cone nanostructure being 8.4 W/m2 more than that with the II-1 cone nanostructure when the concentration ratio is 10. Thus, the cone nanostructures with as high Ra,1.1-2.5 as possible are more beneficial for the hybrid system. Then, by optimizing the heat transfer structure of the PV-TE hybrid system, the output power density is increased by 9.1%. At last, through dynamic analysis, it is found that the annual power generation per square meter of the PV-TE hybrid system with II-2 cone nanostructure is about 17 kW·h/m2 greater than that with the II-1 cone nanostructure. As a result, combined with the structural analysis of the cone nanostructure, the bottom diameter should be as short as possible for the cone nanostructure.

Transient Model of Hybrid Concentrated Photovoltaic with Thermoelectric Generator

Transient performance of a concentrated photovoltaic thermoelectric (CPV-TEG) hybrid system is modeled and investigated. A heat sink with water, as the working fluid has been implemented as the cold reservoir of the hybrid system to harvest the heat loss from CPV cell and to increase the efficiency and performance of the hybrid module. This investigation is carried out by using a numerical simulation approach with MATLAB software. The governing equations for CPV-TEG hybrid system in transient state is derived and discretized. The results are consisting of the variation of the temperatures, power generation and efficiency of the CPV and TEG with the time in the transient condition.