Photovoltaic-thermoelectric Hybrid System Research Articles

Investigating the power and efficiency of the 3D model of the concentrated photovoltaic thermoelectric hybrid system and estimating the power consumption of the water pump for cooling

Solar energy is one of the most useful types of renewable energy. Solar cells are being used to convert solar energy into electricity. By focusing the radiation on the cells, more energy is radiated in a smaller area of the cell which is called concentrated photovoltaic (CPV). Due to the concentration of radiation, the temperature of the cell rises which can be converted into electricity through thermoelectric generators (TEG). The present study is a hybrid system of solar cell, thermoelectric generator, and heat exchanger (CPV-TEG). By this survey being created, it was revealed that the combined power produced by the CPV-TEG reaches its maximum value at concentration ratio of 40. This increase continues with the increase in fluid flow rate. however, according to the power consumption of the pump, it was observed that in all types of heat exchangers, an increase in flow rate of more than 8 liters per hour reduces the output power of the system. The replacement of the secondary heat exchanger with the primary one illustrated that the increase of the channels in the exchanger, despite the increase in the power consumption of the pump, causes a very small increase in the output power and efficiency of the system. Moreover, replacing the tertiary heat exchanger instead of the secondary exchanger showed that changing the direction of fluid output increases the power consumption of the pump in high flow rates.

Experimental optimization of a spectrum-splitting photovoltaic-thermoelectric hybrid system

This paper provides a comprehensive experimental optimization of a spectrum-splitting photovoltaic-thermoelectric hybrid system. A steady-state experimental setup is established. The properties of the coupling system with different splitter cutoff wavelengths and thermoelectric device structures are tested and compared with the single photovoltaic system under the same conditions. The effects of concentration ratio, cooling water temperature, and flow rate on the coupling properties are also experimentally investigated. The results show that among the three cutoff wavelengths tested, 880 nm, 990 nm, and 1100 nm, the coupling system using the 880 nm cutoff wavelength splitter performs best with the highest output power of 1.64 W. The coupling utilization can boost the power by 49.1 % compared to the 1.1 W power of the single photovoltaic system. Effective enhancement in the coupling property can be achieved by increasing the thermoelectric leg height, elevating the concentration ratio, lowering the cooling water temperature, and enhancing the flow rate. The coupling system output power is increased by 24.2 % by raising the thermoelectric leg height from 1.0 mm to 1.5 mm. When increasing the concentration ratio from 55 to 146, the total system power improves by 65 %, and the thermoelectric power ratio of the total power rises from 15.2 % to 37.5 %. The results can be used to guide the subsequent studies and practical applications of the spectrum-splitting photovoltaic-thermoelectric hybrid system.

Feasibility study on radioisotope-powered thermophotovoltaic/thermoelectric hybrid power generation system used in deep-sea: From design to experiment

This study aims to comprehensively examine the feasibility of a hybrid power generation system that integrates solar and thermoelectric technologies, with a focus on utilizing a radioisotope heat source (RHU) for deep-sea applications. The investigation encompasses the whole design process as well as rigorous testing procedures. The self-designed coupling device establishes a connection between the silicon photovoltaic (PV) cell and the bismuth telluride (Bi2Te3) thermoelectric modules (TEMs), therefore creating a photovoltaic-thermoelectric (PV-TE) hybrid system. The measuring platform incorporates the system to investigate the influence of varying light intensity (ranging from 400 to 1600 W/m2) on the electrical properties of the system, specifically focusing on three subgroups of PV cell temperature (20 °C, 25 °C, and 30 °C). The findings suggest that the enhanced performance of the photovoltaic (PV) cell and thermoelectric modules (TEMs) under identical PV cell temperatures may lead to an improvement in the electrical performance of the system due to variations in light intensity. Nevertheless, when the temperature of the photovoltaic (PV) cell increases, there is a gradual decline in the growth rate of the output power. The subsequent research provide evidence that there exist discrete mechanisms responsible for the reduction in intensity between thermoelectric modules (TEMs) and photovoltaic (PV) cells. The processes arise due to the impact of thermal effect on the photovoltaic materials and the increased temperature difference between hot and cold junctions of the thermoelectric modules (TEMs), respectively. Furthermore, a control group is incorporated by calculating the performance of the hybrid system under the same operating conditions as the single thermoelectric (S-TE) system. According to a comparative analysis comparing the Radioisotope Thermal-Photovoltaic-Thermoelectric (RTPV-TE) hybrid power production systems and the S-TE system, it has been shown that the former exhibits a potential increase in output power of up to 271% while operating under identical conditions. This work offers insights and methodologies for the design and measurement of RTPV-TE hybrid power generating systems in engineering application situations.

Performance analysis and structure optimization for concentrated photovoltaic-phase change material-thermoelectric system in space conditions

High-efficient thermal management is urgently needed for concentrated photovoltaic-thermoelectric hybrid system due to the high heat flux. In present paper, a three-dimensional model for the hybrid system in outer space conditions was established by coupling phase change temperature control and radiation heat sink technologies to find the propriate thermal management scheme. Firstly, the three shortcomings in the typical hybrid system were proposed and their adverse effects on efficiency were elucidated. Then, a heat transfer pillar for temperature control unit and a newly designed circular fins for heat sink were designed. The effects of structure parameters on power generation performance were investigated, and the interaction between temperature control unit and heat sink were discussed. The results show that the hybrid systems with the newly designed heat transfer pillar and circular fins have higher efficiency. After that, a united structure optimization by artificial neural network-multi-objective genetic algorithm was performed to solve the interaction and to balance the electrical efficiency and power density of hybrid system. The comprehensive power generation performance of hybrid system can be further improved after the optimization. The system with PCM thickness dPCM = 6.33 mm, heat transfer pillar width a = 18.19 mm, fin length L = 49.99 mm and fin radius R = 50 mm, has the maximum average total efficiency (31.83%, 2.98% higher than the typical system); the system with dPCM = 3.02 mm, a = 10.05 mm, L = 47.03 mm and R = 25.86 mm, has the maximum average power density (36.97 W/kg, 15.78% higher than the typical system).

Performance investigation of a concentrated photovoltaic-thermoelectric hybrid system for electricity and cooling production

To fully exploit inlet sunlight, a novel hybrid system comprising a concentrated photovoltaic cell, a thermoelectric generator, and a thermoelectric cooler is established. The thermoelectric generator generates electricity by thermally harnessing the solar spectrum energy unavailable to the concentrated photovoltaic cell and then drives the thermoelectric cooler to produce additional cooling. With full consideration of internal and external irreversibility, the numerical model of the hybrid system is developed, where comprehensive heat transfer equations are constructed by the effectiveness-number of transfer units method. Subsequently, the performance characteristics of the system are evaluated by energetic and exergetic analysis. Over the operating range of the thermoelectric unit, when the performance enhancement of the hybrid system is maximized, the associated power density, energy efficiency, and exergy efficiency are, respectively, 42.828 Wm-2, 0.0251, and 0.0255, which are improved by 3.53%, 3.72%, and 3.66% in comparison to the stand-alone concentrated photovoltaic system. Meanwhile, the exergy destruction rate density is reduced by 0.49%. Furthermore, comprehensive sensitivity analyses are undertaken to derive the effects of critical designing parameters and operating conditions on the overall performance. The obtained outcomes may contribute to the design and operation of such a cogeneration system.

Maximizing Electric Power through Spectral-Splitting Photovoltaic-Thermoelectric Hybrid System Integrated with Radiative Cooling.

As zero-emission technologies, a daytime radiative cooling (RC) strategy developed recently, and photovoltaic (PV) and thermoelectric (TE) technologies have aroused great interest to reduce fossil fuel consumption and carbon emissions. How to integrate these state-of-the-art technologies to maximise clean electricity from the sun and space remains a huge challenge, and the limit efficiency is still unclear. In this study, a spectral-splitting PV-TE hybrid system integrated with RC is proposed to maximise clean electricity from the sun and space without any emissions. For the sun acting as a typical constant heat-flux heat source, the current thermoelectric theory overestimates the thermoelectric efficiency highly since the theory is based on constant temperature-difference conditions. A new theory based on heat-flux conditions is employed to achieve maximum thermoelectric efficiency. The PV-TE hybrid system with RC is superior to the conventional hybrid system, not only in terms of higher efficiency but also in its 24-h operation capacity. In a system with a single-junction cell, the total efficiency with 30 suns (39.4%) is higher than the theoretical PV efficiency at 500 suns (38.2%). In a hybrid system with four-junction cells, total efficiency is over 65% which is superior to most current photoelectric and thermal power systems.

Parabolic trough photovoltaic thermoelectric hybrid system: Simulation model, parametric analysis, and practical recommendations

Parabolic trough photovoltaic thermoelectric hybrid system: Simulation model, parametric analysis, and practical recommendations

Higher conversion efficiency for combined systems with triple-junction GaAs photovoltaic cell and thermoelectric device

Photovoltaic (PV) and thermoelectric (TE) hybrid systems have the potential to increase solar energy utilization and possess broad development prospects. However, it is critical to select a suitable PV cell to couple with TE device and improve the efficiency of the photovoltaic–thermoelectric (PV-TE) hybrid system. This study used thermal interface materials (TIMs) with different thermal conductivities in triple-junction InGaP/GaAs/GeInG (tj-GaAs) PV-TE hybrid systems to reduce thermal contact resistance (TCR). The performance was investigated using a solar simulator with adjustable irradiation intensity and a liquid cooling device with controllable temperature. A comparative study has also been conducted with mono-crystalline (mc-Si) PV-TE system of the similar structure. The results indicated that the total output power of the direct contact PV-TE hybrid device and the optimized hybrid device using a thermal grease with a conductivity of 5.8 W m−1 K−1 could increase by 5.50% and 16.24%, respectively, compared with that of the pure PV. Moreover, lower cooling water temperatures have improved the performance of both PV cell and TE device. Results also indicated that the output power produced by the PV cell and TE device in the tj-GaAs PV-TE system are 537 mW and 0.76 mW higher than that produced by the PV cell and TE device in mc-Si silicon PV-TE system at 3.5 suns and 20 °C cooling water temperature, respectively. Compared to mc-Si PV cells, GaAs PV cells are more suitable for PV-TE hybrid systems and more adaptable under concentrated light conditions.

Multi-objective optimization of a concentrated spectrum splitting photovoltaic-thermoelectric hybrid system

This paper presents a comprehensive multi-objective optimization process of the concentrated spectrum splitting photovoltaic-thermoelectric hybrid system, including sensitivity analysis, parameter evaluation, and genetic algorithm. The coupling efficiency and the efficiency difference compared to the concentrated photovoltaic system are simultaneously taken as the optimization objectives. Theoretical models of the two systems are established. The key influencing factors are determined, and their effects on the operating temperatures and efficiencies are investigated. The Pareto front and optimal working conditions are acquired, and the impacts of the thermoelectric figure of merit on the optimization results are further studied. The results demonstrate that the photovoltaic bandgap, splitter cutoff wavelength, concentration ratio, cooling performance, and thermoelectric structure factor are the system's key influencing factors. The two optimization objectives are negatively correlated, attributed to the effect of the PV bandgap. The cost and lifetime need to be further considered to identify the optimal solution. For the current thermoelectric devices, the coupling system achieves the highest coupling efficiency at the photovoltaic bandgap of about 1.42 eV and the maximum system efficiency difference near the photovoltaic bandgap of 1.65 eV.

High-efficiency photovoltaic-thermoelectric hybrid energy harvesting system based on functionally multiplexed intelligent thermal management

A photovoltaic-thermoelectric hybrid (PV-TEH) system with intelligent thermal management based on the dual functions of thermoelectrics (TEs) is proposed to improve the conversion efficiency of PV cells. The performance of PV cells is highly dependent on the cell temperature, and the temperature gradient can also be used to generate additional electricity. A microcontroller switching circuit is designed using the same thermoelectric module for the functions of thermoelectric generator and thermoelectric cooler (TEG/TEC) to selectively regulate the PV panel temperature according to the heat dissipation requirements. In addition, PWM-based intelligent cooling regulation technology is presented to set up a hybrid energy harvesting and thermal management system with adjustable conversion efficiency. Experimental results show that the conversion efficiency in the proposed hybrid PV-TEH system can reach up to 27.8 % while reducing the temperature of the PV panel by 6℃. Accounting for 23 % of the high-efficiency energy output due to the PV-TEG mode, the time window of the pure power supply is increased to 1.15 h during the 5 h day measurement. In addition, the effective output power of PV is increased from 6 W to 8.1 W in PV-TEC mode. This intelligent energy harvesting and thermal management by employing the TE functionally multiplexed technique can provide a reference for green self-powered electronic equipment.

Design of high-performance photovoltaic-thermoelectric hybrid systems using multi-objective genetic algorithm

Hybrid systems which integrate photovoltaic (PV) and thermoelectric generator (TEG) can improve the utilization of solar energy. In this study, a multi-objective genetic algorithm (MOGA) is adopted to maximize the output power and conversion efficiency for the PV-TEG system, where the CFD model is coupled in the optimization procedure and the penalty function is employed to ensure the appropriate operating temperature. Meanwhile, two geometric parameters along with two boundary conditions are selected as the design variables, while the effects of three cooling conditions are also discussed. Compared with the PV only system, the output power of the PV-TEG system is improved by up to 11.52% with the conversion efficiency also improved by 44.97%. At the same solar concentration condition, the optimal PV-TEG system could increase the output power by 36%. Based on the analysis of optimal solutions, it is demonstrated that the adopted TEG contributes significantly to the output power, while a better cooling condition also has a positive effect on the comprehensive performances. Furthermore, a multiple-criteria decision-making approach is applied to balance output power and conversion efficiency. Compared with the maximum efficiency solution, the best compromise solution increases output power by 120.02% and decreases the efficiency only by 14.83%.

Efficiency improvement of hybrid PV-TEG system based on an energy, exergy, energy-economic and environmental analysis; experimental, mathematical and numerical approaches

Nowadays, Photovoltaic panels are being used as effective devices to utilize solar free energy. However, they lose their efficiency when their temperature increases; consequently, a large portion of the solar energy is wasted. In this study, a hybrid system of polycrystalline Photovoltaic panel equipped with Thermoelectric generator modules and combined with water-cooled heat exchangers has been proposed to extract more power from the Photovoltaic meanwhile producing electricity by Thermoelectric generators and absorbing heat by water. Previous studies have been mostly based on a 24-hour simulation while not considering the long-term analysis of the system. This study includes a 24-hour analysis via experimental build testing, mathematical modelling, and finite element simulation, followed by a finite element simulation carried out for one year. This study considers the influence of varying irradiance and thermal resistance on the Photovoltaic, Thermoelectric hot and cold sides and outlet water temperatures on the daily and annual energy, exergy, environmental, and energy-economic outcomes. It was found that the averaged maximum Photovoltaic temperature for the experiment and simulations of the Photovoltaic-Thermoelectric hybrid system was 44.2°C at maximum irradiation. In comparison, it was 57.1°C for the stand-alone Photovoltaic. The electrical power production of the Photovoltaic-Thermoelectric hybrid system was 9.49W, which is noticeably higher than the 8.48W output of the stand-alone Photovoltaic meaning that the electrical efficiency and the exergy efficiency increased by 1.67%, and 1.72%, respectively. The environmental and energy-economic simulations show that the carbon payback period and the discounted payback period are 1.31 and 12.39 years, respectively.

Numerical and experimental performance evaluation of a laser-concentrated photovoltaic-thermoelectric generator hybrid system.

Thermal management of concentrated photovoltaic (CPV) modules is essential to avoid the decrease in conversion efficiency caused by temperature rise during their operation. This is even more important for laser-concentrated CPV hybrid systems where out-of-control temperature rise is more likely to happen. In this research, a three-dimensional simulation model for a concentrated photovoltaic-thermoelectric (CPV-TE) hybrid system was studied to optimize its parameters and improve its conversion efficiency under laser radiation. Based on the simulation results, an integrated CPV-TE device was designed, fabricated, and tested under a high-power laser. The novel integrated CPV-TE system utilizes growing electrodes to encapsulate CPV directly on the TEG. Compared to conventional CPV-TE systems that utilize silicone-filled, the integrated CPV-TE system reduces contact thermal resistance and increases output power as well as conversion efficiency. To the best of our knowledge, this is the first study to discuss and optimize a CPV-TE hybrid system for laser radiation. In addition, this research improves the efficiency of laser energy conversion, increases the reliability and stability of the system, and may facilitate the promotion of optical wireless and fiber power transmission systems in future applications.

Achieving extensive lossless coupling of photovoltaic and thermoelectric devices through parallel connection

Photovoltaic-thermoelectric hybrid systems have received broad attention in recent years owing to the capability of achieving efficient utilization of full-spectrum solar energy. This paper investigates the lossless coupling method of photovoltaic and thermoelectric devices to address the issue of large electrical coupling losses. The properties of the photovoltaic-thermoelectric hybrid systems with three connection modes, which are electrically separated, series, and parallel, are experimentally compared under different incident power densities. The electrical-thermal interaction characteristics of the photovoltaic cell and the thermoelectric device under different connection modes are further investigated with the theoretical method. The mechanism of achieving extensive lossless coupling of photovoltaic and thermoelectric devices under parallel connection is illustrated. The results demonstrate that when the incident power density is less than 15Wcm−2, the photovoltaic and thermoelectric devices can be losslessly coupled by the parallel connection. Both electrically separated and parallel coupling systems achieve the output power of 0.85 W, while the series coupling system power is only 0.41 W under the same incident power density of 15Wcm−2. Compared with the series mode, the parallel lossless coupling method can be achieved over a broader range of operating conditions and is more stable because of the small variation of the photovoltaic maximum power voltage under the practical varying irradiation and the effect of the weakened Peltier effect.

Evaluation of parameters influencing the performance of photovoltaic-thermoelectric (PV-TE) hybrid system

Abstract This study analyzes the feasibility of the photovoltaic-thermoelectric (PV-TE) hybrid system and examines the appropriate parameters to optimize the design of the hybrid system. A new formula that sets a minimal working condition from which the output power of the hybrid system will exceed that of the PV cell alone at 298 K was developed. The experimental results showed that the hybrid system outperformed the PV cell alone at 298 K, once the minimal working condition is attained. Moreover, the results illustrated that we can enhance the performance with a slight change in the cold side temperature of the TE using PV cells with a relatively small temperature coefficient and efficiency. The results indicated also that the model can produce trustworthy predictions, consequently, it may be useful during the design of a hybrid system with optimized performance.

Structural optimization of thermoelectric modules in a concentration photovoltaic–thermoelectric hybrid system

Concentration photovoltaic (CPV) cells can only partially convert solar energy into electricity. The remaining energy is converted into thermal energy. This not only causes the temperature of the photovoltaic cell to rise, but also reduces the generation efficiency of the cell. The excess CPV heat can be recovered using a thermoelectric generator (TEG). The design of the structure of the TEG is important for a CPV-TEG hybrid system because it affects the heat dissipation of the CPV and thus its efficiency. In this study, a mathematical model of a hybrid system was established. The focus was to examine the effect of the structural parameters of the TEG on the system efficiency. The results showed that an optimal structural parameter (the ratio of the cross-sectional ratio to the height) with the value of 0.36 mm−1 existed for the TEG, enabling the system efficiency to reach a maximum of 41.73% under simulated conditions. In addition, the relationship between the optimal structural parameter, CPV temperature coefficient, concentration ratio, and cooling heat transfer coefficient was analyzed. The results can provide guidance for the efficient design of a hybrid system.

Photovoltaic-thermoelectric (PV-TE) hybrid system for thermal energy harvesting in low-power sensors

Nowadays, population growth and increasing urbanization imply a growing demand for energy, which must be achieved while limiting polluting emissions. To meet this dual challenge, the use of renewable energy resources and energy generators is essential. Thermoelectric generators (TEGs) have demonstrated their ability to directly transform thermal energy into electrical energy through the Seebeck effect. Due to their unique advantages, thermoelectric systems have emerged in the last decade as a promising alternative among other green energy generation technologies. In this regard, the study focuses on a design of a Photovoltaic-Thermo-Electric (PV-TE) Hybrid System for thermal energy harvesting in low power collectors. The power harvested by TEG increases with the temperature and an interesting value close to 7mW is achieved with a maximum temperature of 52 °C of the hot face the thermoelectric system.

Design and Implementation of Hybrid Photovoltaic-thermoelectric System with Intelligent Power Supply Management

A photovoltaic thermoelectric hybrid (PV-TEH) system with intelligent power supply management is proposed in this paper. Combining the advantages of the thermoelectric generator (TEG) and the thermoelectric cooler (TEC), the TE intelligent switching circuit and the water speed regulation circuit are presented in this system. Due to the energy harvesting of the TE devices, the high conversion efficiency can be realized in the PV-TEG mode. The experimental results show that the output power of the PV cell in our work is increased by 14.4% on average compared with that in a PV system without TE. Since the proposed system overcomes the disadvantage of power consumption for TEC throughout the whole process, the electrical energy generated by the TEG is effectively harvested, achieving 57.9% improvement of the overall energy conversion efficiency over the PV-TEC system. This intelligent energy harvesting and thermal management by employing TE as generator and cooller with the multiplexed technique can provide a reference for self-power electronic equipment.

Device performance matching and optimization of photovoltaic-thermoelectric hybrid system

• The effects of various factors on the device selection of the hybrid system are studied. • A device selection method of the hybrid system with broad suitability is established. • A multi-objective genetic algorithm is adopted to optimize the coupling efficiency and efficiency difference. • The two optimization objectives are proved to be negatively correlated. This paper focuses on the two critical issues of device selection and performance optimization for the photovoltaic-thermoelectric hybrid system. Theoretical models of concentrating photovoltaic-thermoelectric hybrid system and concentrating photovoltaic system are established. The impacts of varying factors on system device selection are investigated. The device performance matching mechanism of the coupling system is revealed, and a device selection method of broad suitability is proposed. The optimization of the hybrid system is conducted by adopting a multi-objective genetic algorithm with the highest coupling efficiency and the maximum efficiency difference relative to a single photovoltaic system as the optimization objectives. The results show that the minimum thermoelectric figure of merit of the hybrid system is determined only by the concentration ratio and the photovoltaic device capability when the cooling condition is fine, the thermal contact resistance is low, and the thermoelectric structure is appropriate. The proposed device selection method on the basis of these results can be well employed to select coupling devices and evaluate the system feasibility. The multi-objective optimization results reveal that the two optimization objectives are negatively correlated. Further consideration of the system economy is required to determine the compromise between the highest coupling efficiency and the maximum efficiency difference for the optimum design of the coupling system.

Hybrid photovoltaic-thermoelectric system using a novel spectral splitting solar concentrator

A hybrid photovoltaic-thermoelectric (PV-TE) system employing a novel solar concentrator is designed and constructed to demonstrate the feasibility of improving the overall efficiency of light-to-electricity conversion based on spectral splitting strategy. The concentrator consists of four rectangular dichroic mirrors arranged in a crossed V-trough configuration that reflects and concentrates the visible spectrum onto a photovoltaic cell in the centre while passes the infrared spectrum onto a thermal absorber to produce heat for a thermoelectric generator. The experimental results show that the overall efficiency of the hybrid PV-TE system is 16.9% compared to 15.9% of the same configuration except for using specular aluminium mirrors. An increase in the overall efficiency by 6.3% was achieved due to thermoelectric harvesting of the light energy in infrared spectrum. The results also show that a significant increase in the power output from 12.41 mW in the bare cell to 62.04 mW of the same cell in the concentrated system, indicating the advantages of using concentration system, particularly beneficial to high-cost solar cells, such as GaAs and GaInP.