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Abstract
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.
© 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
1. Introduction
Photovoltaic devices convert solar energy directly into electricity and have been widely used in various fields with outstanding features, such as long life, safety, and reliability [1]. Compared to non-concentrated photovoltaic devices, CPV can undertake a higher solar power density and generate more electricity per unit area [2]. Furthermore, unlike ordinary commercial silicon photovoltaic cells, CPV has some key advantages, such as a smaller active cell area and higher transmission efficiency [3,4]. Despite the latest reported conversion efficiency of the CPV cells reaching 47.1%, more than half of the energy is dissipated in the environment by heat during photovoltaic conversion [5]. This dissipated heat causes a temperature rise in the photovoltaic cells and reduces the conversion efficiency [6,7]. Therefore, effective thermal management of CPV systems is essential to improve their conversion efficiency and increase their life span [8,9]. In particular, the utilization of dissipated heat is an effective method to improve the overall efficiency of the CPV system [10,11].
Thermoelectric devices can directly achieve bidirectional and reversible conversion of heat and electricity [12,13]. Their advantages include solid-state operation [14], gas-free emission, vast scalability, maintenance-free operation, clean energy production, long lifespan, and high reliability [15]. A thermoelectric generator (TEG) can convert heat energy into electric power through the Seebeck effect, and conversely, transform electrical energy into thermal energy through the Peltier effect. The constituent materials of the TEG are determined by a dimensionless figure of merit, defined as $ZT = ({{S^2}/\rho k} )T$, where S is the Seebeck coefficient, $\rho $ is the electrical resistivity, k is the thermal conductivity, and T is the absolute temperature. Researchers have worked to combine TEG with different types of photovoltaics, including non-concentrating and concentrating, to improve the output performance and energy conversion efficiency for optimal thermal management.
A considerable amount of work has been done to improve the performance of hybrid CPV-TE systems [16], including the use of different cooling techniques [17,18], optimization of the TEG geometry parameters [19,20], and the study of transient and steady-state system behavior [21,22]. Vorobiev et al. [23] discussed two CPV-TE hybrid systems. They proved that the hybrid system can achieve a total efficiency of approximately 25-30% and 30-40% for direct and indirect couplings, respectively, when a GaAs single-junction photovoltaic cell is used. Hajji et al. [24] pointed out that an indirect coupling system can increase the electric efficiency from approximately 8% to 28% when the optical concentration ratio is 100. Other researchers have applied numerical simulations to CPV-TE systems, which help in saving cost and time while providing high-accuracy models [25–28]. Lamba and Kaushik [29] developed a one-dimensional thermodynamic model based on MATLAB to consider the output characteristics of a hybrid CPV-TE system. The results show that the efficiency is improved by 13.37% compared to the photovoltaic-only system. Shittu et al. [30] developed a three-dimensional finite element analysis model to analyze the contact thermal resistance between different interfaces of a CPV-TE system (Table 1).
Table 1. Symbol definition
With the rapid development of semiconductor lasers and fiber optic technologies, power-by-light (PBL) has been used in various fields, such as optically powered remote antenna units [31–33] and remote sensors in hazardous environments [34–39]. Photovoltaic laser power converters (PVLPCs) are key parts of PBL systems, and their light-to-electricity conversion efficiency under laser radiation directly affects the application of the system [40–42]. Thermal management of PVLPCs under laser radiation is essential to avoid their efficiency drop due to overheating. CPV-TE can be used in PBL systems to convert the waste heat of PVLPVs to electricity and improve the conversion efficiency. However, most current CPV-TE studies fused on sunlight conditions. CPV-TE under laser radiation, which is suitable for PBL applications, has not been studied based on our knowledge.
In this research, a three-dimensional simulation model for a 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. In the numerical study, multiple parameters of the laser-concentrated CPV-TE hybrid system, including the optical concentration ratio, the TEG thickness, and the optimal temperature, were discussed. In the experiments, the overall power output and the conversion efficiency were tested using the integrated CPV-TE device. Both numerical study and experimental results show the contact thermal resistance is reduced and the output power, as well as the conversion efficiency, is increased by incorporating a suitable TEG to harvest waste heat of the CPV converter. To the best of our knowledge, this is the first study to investigate a laser-concentrated CPV-TE hybrid system.
2. Modeling and conditions
2.1 Governing equations
The operation of a TEG is described by its thermal and electrical fields. This follows the Fourier law of heat conduction. When the temperature gradient $\nabla T$ is specified, the electrical field $\vec{E}$ generated in the thermoelectric material is expressed by Eq. (1):
This can be explained by the Seebeck effect and Ohm’s law. Here, $\alpha $, $\rho $, and $\vec{J}$ denote the Seebeck coefficient, resistivity, and current density, respectively. The Peltier effect explains the heat flux $\vec{q}$ in the thermoelements, and k is the thermal conductivity; the heat flux can be expressed as follows:
The second term explains the thermal conduction with thermal conductivity, $\vec{J}$.Eqs. (1) and (2) utilize partial differential equations to explain the thermoelectric effects of thermoelectric materials. Furthermore, Eqs. (3-5) express the energy conservation law, continuity of current, and definition of the electrical potential V, respectively:
The three-dimensional energy equation of the CPV layer is expressed by Eq. (6), where ${C_p}$ is the specific heat capacity, and $\rho $ is the density; T ${Q_{laser}}$, and ${P_{cpv}}$ represent the temperature, volumetric laser energy absorption by layer, and power generation of the photovoltaic volume, respectively.
The volumetric laser energy absorption in each layer was calculated using Eqs. (7) and (8), as follows:
${V_i}$, ${\beta _i}$, and ${\rho _i}$ are the volume, absorptivity, and reflectivity of the $i$th layer, respectively. ${A_i}$ and ${Q_{laser,i}}\; $ are the area and volumetric laser energy at each layer, respectively. In this study, the value of ${G_{laser,0}}$, used throughout, was 100 kW/m2.In the GaAs-doped photoelectric conversion unit, power generation is considered as an internal heat sink and the conversion efficiency ${\eta _{cpv}}$ as well as the output power ${P_{cpv}}$ are expressed as follows:
For further analysis of TEGs, the power output and efficiency of a TEG are expressed by
where S is the Seebeck coefficient, ${V_{oc}}$ is the open-circuit voltage, and $\nabla T$ is the temperature difference between the hot and cold sides of the TEG. Deriving Ohm's law for a TEG, it is known that where ${R_{in}}$ is defined as the TEG internal resistance, ${V_{load}}$ is the output load voltage, and I is the TEG current; the TEG power output is expressed as,The performance of the hybrid PV-TE system was measured in terms of its total electrical output and efficiency. The overall power output of the PV-TE system ${P_{cpv - te}}$ is the sum of the photovoltaic and thermoelectric individual powers. This can be expressed as follows:
There are different calculation methods for the overall conversion efficiency of a CPV-TE system. This study employed the algorithm in Eq. (1)2. The conversion efficiency of the CPV-TE system is defined as ${\eta _{cpv - te}}$.
2.2 Simulation conditions
The schematic diagram of the CPV-TE system is shown in Fig. 1. The CPV is on top of the TEG, and a high-power laser irradiates the CPV, completing photoelectric conversion and heat generation synchronously. This heat energy exchange with the TEG to produce a certain temperature difference in the TEG. Owing to the nature of the material, the TEG converts the temperature difference into electrical output. Therefore, electricity is generated from both CPV and TEG in the CPV-TE system. The CPV-TE system has a series of different materials and contact interfaces, where the heat flows through the thermoelectric material, creating a temperature difference to achieve the conversion between waste heat and electrical energy.
The three-dimensional model of a gallium arsenide photovoltaic cell consists of five distinct layers, including glass, ethyl vinyl acetate, gallium arsenide, and TPT (Tedlar/PET/Tedlar) back sheet layer from top to bottom, respectively. Therefore, the laser has different heat fluxes when it passes through the photoelectric mounting and thermoelectric conversion after irradiation of the CPV surface. Compared to the pure CPV system, the CPV-TE system with TEG has a higher photovoltaic operating temperature. Therefore, the inclusion of a TEG in the CPV-TE system is a parameter that requires to be optimized. The comprehensive three-dimensional numerical model is investigated to study the effect of contact resistance on the performance of the CPV-TE system using COMSOL 5.5 Multiphysics software. The boundary conditions considered in the hybrid CPV-TE model are as follows:
- (a) The thermophysical parameters of all photovoltaic materials are presumed to be isotropic and independent of temperature.
- (b) The CPV-TE model side boundary is considered adiabatic.
- (c) The initial temperature of the CPV-TE system is equal to the ambient temperature.
- (d) The CPV reference efficiency is 40% at a reference temperature of 298.15 K, and the temperature coefficient is 0.00068 K-1.
- (e) The thermoelectric elements are connected in series electrically and in parallel thermally.
- (f) To simulate the actual situation, the laser energy absorption of all materials in the photovoltaic module was considered. The surface area of the CPV cell was irradiated by the full energy of the laser.
3. Results and discussion
3.1 Simulation results and discussion
The complete CPV-TE system was modeled according to the above equations and boundary conditions. The CPV cell was placed separately on the heat sink. The laser irradiates a circular spot with an area of 1 cm2, which is completely projected onto the CPV. The temperature in the middle is higher than that at the edges. The TEG is included between the CPV cell and heat sink, which forms the CPV-TE system. The CPV module is on the top, the TEG is below the CPV module, and the heat sink is at the bottom to dissipate heat from the CPV-TE system.
First, the effect of the incident power on the CPV-TE system is explored. Figure 2 indicates that the system performance is directly affected by the incident power. As the incident power increased, the maximum output power of the CPV-TE system increases gradually. The total output power of the system (${P_{cpv - te}}$) is equal to the sum of the output power of the thermoelectric power (${P_{teg}}$) and centralized photovoltaic power (${P_{cpv}}$) components. In Fig. 2(a), the black, blue, and brown boxed lines represent ${P_{teg}}$, ${P_{cpv}}$, and ${P_{cpv - te}}$, respectively. The red line represents the efficiency of the CPV-TE system. The output power of the CPV decreases as the incident power increases; however, the overall output power of the CPV-TE system shows an increase followed by a decrease. Therefore, for a defined CPV-TE system, there is an optimum incident power that maximizes the total output of both the CPV and TEG. When the incident power is 9 W, the energy utilization performance of the system is at its optimum point, and the energy conversion efficiency of the system is 29.41%. The potential distribution and current-voltage characteristic output of TEG are shown in the supplementary material. When the irradiated optical power of the laser is 6 W, the overall energy conversion efficiency from photovoltaic and thermoelectric is 29.38%. In Fig. 2 (b), controlling the temperature of the heat sink changes the cold location temperature of the thermoelectric devices. This confirms that under different temperatures on the cold surface of the ceramic (${T_{cer,c}}$), the trend of conversion efficiency always increases and then decreases with increasing incident power. However, as the value of ${T_{cer,c}}$ increases, the overall efficiency curve of the CPV-TE system decreases. Figure 2(c) shows the overall temperature distribution within the CPV-TE system when the low-temperature end of the thermoelectric device, ${T_{cer,c}}$ is 5 °C. The temperature on the surface of the CPV ranged from 97.2°C to 171°C, and the temperature on the upper surface of the TEG ranged from 67.4°C to 92.4°C, with a temperature variation of 23°C.
Fig. 2. Relationship between incident power and (a) output power and efficiency, (b) the efficiency change under different cold junction temperature of the TEG ${T_{cer,c}}$ and (c) temperature distribution of the CPV-TE simulation model.
Figure 3 shows the performance of the CPV-TE system under different TEG thicknesses. The output power of the system with an increase in the TEG thickness is shown in Fig. 3(a). The purple, orange and green boxes represent ${P_{teg}}$, $\textrm{ }{P_{cpv}}$, and ${P_{cpv - te}}$, respectively. Figure 3(a) shows that the maximum output of the centralized photovoltaic cells continues to decrease with the increase in the TEG thickness, which is owing to the increase in the temperature of the system itself during operation. The factor that affects the temperature is the increased thickness of the thermoelectric unit, which causes a reduction in the total heat flux between the system and the surrounding environment. Figure 3(a) also shows that the output power of the thermoelectric device first increases and then decreases with the increase in the TEG thickness. This is because the internal resistance of the TEG affects the output power. Figure 3(a) shows that the output power of the CPV-TE system has a maximum value. The overall output power of the system is increased by the thermoelectric equipment more than reduced by the CPV modules until it reaches a maximum point. Thereafter, the power loss in the CPV cell accounts for the main impact of the system. In Fig. 3(b), the black line shows the output power of the TEG in the CPV-TE system and the red line shows the ratio of the CPV-TE output power to that of the CPV only. When the thickness of the thermoelectric device is 6 mm, ${P_{teg}}$ of the CPV-TE system reaches a maximum, as shown in Fig. 3(b). ${P_{cpv - te}}$ of the CPV-TE decreases when the TEG output power is optimally attained. The optimal performances of the CPV-TE system and TEG are not synchronized. Compared to pure CPV power, the CPV-TE hybrid power has an optimized state of increase in a certain TEG thickness range. As the TEG thickness continues to increase, the heat exchange between the CPV-TE and the environment is limited by the TEG, which will cause temperature rise significantly, in that the output performance of the CPV-TE hybrid system is inferior to that of a pure CPV cell system. Figure 3(c) presents the relationship between the temperature of each part of the system and the thickness of the thermoelectric device. It shows that the temperature of the photovoltaic module in the CPV-TE hybrid system is higher than that of a pure CPV system. In the CPV-TE hybrid systems, when the temperature of the CPV and the TEG increases, the temperature difference between them also increases. This proves that the thickness increase causes a degradation in the heat exchange performance between the system and the outside. Thus, the thickness needs to be optimized to maximize the system performance.
Fig. 3. Relationship between the thickness of TEG and (a) output power, (b) TEG output power and value of CPV-TE hybrid power divided by pure CPV power, and (c) temperature of each part.
Even with the same CPV, CPV-TE systems with different TEG thicknesses have different output performances. TEG-71 and TEG-127 represent 71 and 127 pairs of $\pi $-type thermoelectric p-n junctions in a thermoelectric device, respectively. Figure 4(a) displays the out-put power at different TEG thicknesses for TEG-71 and TEG-127. The maximum output power of TEG-127 is slightly larger than that of TEG-71, which indicates that more heat is collected by TEG-127. However, the optimal TEG performance does not indicate CPV at maximum power. In contrast, in the CPV-TE hybrid system, the output power of the CPV decreased gradually with increasing TEG thickness, as shown in Fig. 4(b). The output power of the CPV cell (TEG-71) in the CPV-TE hybrid system (blue line) is lower than that of the CPV cell (TEG-127) (pink line). Figure 4(c) shows that the total output power of the CPV-TE (TEG-71) is slightly higher than that of CPV-TE (TEG-127). The optimal thickness of the TEG-71 of the CPV-TE hybrid system is shorter than that of the TEG-127 of the CPV-TE system.
Fig. 4. Relationship between the thickness of TEG and models of TEG-71 and TEG-127; (a) TEG output power, (b) CPV output power, (c) CPV and CPV-TE output power, and (d) CPV and TEG temperature difference.
As shown in Fig. 4(d), the CPV-TE hybrid system consisting of TEG-71 establishes a wider temperature difference than the CPV-TE hybrid system consisting of TEG-127. The number of various thermoelectric legs changes the heat flow of the system and affects its overall performance. Figure 4 provides an exhaustive comparison of the output power and temperature of each component of the CPV-TE system, further demonstrating that several parameters in the CPV and TEG need to be optimized to achieve the best overall performance of the CPV-TE.
3.2 Experiment results and discussion
According to the simulation results of the CPV-TE system, the CPV-TE devices were developed based on the TEG-127 model. A single-junction GaAs photovoltaic cell with a copper-clad ceramic plate was combined with a TEG and filled with thermally conductive silicone grease in the interface gap to obtain the CPV-TE system used in the experiment. The TEG thicknesses of the integrated CPV-TE devices are 3.5 mm, 4 mm, and 5 mm, respectively. The cross-sectional area of the thermoelectric semiconductor contained in the devices is 1 mm2. To test the performance of the integrated CPV-TE device, a laser with a wavelength of 808 nm
(FC-808, Changchun New Industry Optoelectronics) was used as the incident light source. Multimode fiber with a core diameter of 400 µm with a length of 2 m was used to transfer the laser light. The laser is output from the terminal side of a SMA905 connector and shines vertically on the surface of the CPV. The output power of the CPV-TE system was tested using a source meter (model 2461, Keithley). The output power of the multimode fiber is 10 W. The laser spot has a Gaussian distribution and the scattering angle at the output side of the fiber is about 9°. Carefully adjust the vertical distance between CPV and laser exit, and test the I-V curve of the photovoltaic device with a digital source meter, so that the CPV is the optimal output. By the output characteristics of the CPV can be approximated that the photovoltaic output is optimal when the laser radiation circular spot the irradiation range controlled in a circular spot of area 1 cm2. Figure 5 presents the power of TEG, CPV, and CPV-TE at different TEG thicknesses. It shows that the overall output power is largest when the TEG thickness is 4 mm. Compared to the simulated results, the maximum power is slightly lower. This is due to multiple contact thermal resistances at different interfaces between the photovoltaic and TEG devices, which reduces the conversion efficiency.
In conventional CPV-TEG systems, the thermal resistance consists of three parts: intrinsic thermal resistance of the CPV, intrinsic thermal resistance of the TEG, and interfacial thermal resistance of the adhesion of the CPV and the TEG. The thermal contact resistance between the photovoltaic-thermoelectric interface is the most important contact resistance in the hybrid system that needs to be reduced [30]. However, most of the photovoltaic devices and thermoelectric elements are combined using thermally conductive silicone adhesion [18,19,21]. Therefore, there are certain air holes between the CPV and TEG interfaces, which affect the heat transfer process of the system.
To further reduce the impact of the copper-clad ceramic plate and interface thermal resistance on the overall performance, a triple-junction GaAs-doped chip without substrate was selected to develop an all-in-one integrated CPV-TE hybrid device. To start, TEGs and ceramic wafers were cleaned with alcohol and acetone to remove surface dust. The treated surface was covered with electrodes according to the size of the optoelectronic chip and the areas that did not need to be grown were covered with a polyimide tape film. Then, the electrodes were unfolded on the ceramic plate of the thermoelectric device, followed by sputtering chromium, copper, and gold as electrodes. As shown in Fig. 6(a), the integrated CPV-TE device has a positive pole on one side and three negative poles on the other side. The back of the triple-junction CPV cell was pasted with conductive silver paste on the positive electrode. One end of the platinum wire was glued to the negative electrode of the chip, and the other end was glued to the negative electrode of the ceramic plate. The ceramic plate sputtered with electrodes served as both the hot-end substrate of the TEG and the photovoltaic heat sink substrate. Figure 6 shows the output power and conversion efficiency of the CPV under different conditions and the total output power and conversion efficiency of the integrated CPV-TE system (${P_{itg - cpv - te}}$, $Ef{f_{itg - cpv - te}}$).
Fig. 6. (a) Designed integrated CPV-TE hybrid device, (b) stability test results of CPV-TE system. The relationship between incident power and (c) output power, (d) efficiency.
As shown in Fig. 6(b), the initial degradation of the performance of the photovoltaic cell performance in less than 1 min is caused by changes in the substrate temperature. It also indicates that the prepared integrated CPV-TE devices have good stability in practical applications within 30 min. Figures 6(c) and (d) display the output power and the conversion efficiency of the CPV-TE system at different incident powers. When the incident power is 6 W, the TEG output power is 5.2% of the PV output power. The conversion efficiency of the CPV- TE system is maintained at 35%. The overall system performance is approximately 2% higher than that of the CPV cell alone. The results show that the conversion efficiency of the CPV-TE system is higher than that of the CPV-only system at all incident power conditions.
In addition, compared to the conventional CPV-TE systems, the new integrated CPV-TE devices developed in this research use TEG ceramic plates to directly replace the original encapsulated copper laminate of the CPV. This method simplifies the heat transfer path and optimizes the heat transfer efficiency of the system. The new devices have no mechanical movement inside and are more stable. They also have less contact thermal resistance than systems with thermally conductive silicone grease-filled CPV-TE. TEGs of the same size and material were used to form two different CPV-TE systems. The first one uses the conventional method of coating the TEG devices with an appropriate amount of thermally conductive silicone grease and bonding the photovoltaic cells with copper-clad plates. The schematic diagram of the physical device is shown in the supplementary material. The second uses a new type of integration, growing electrodes on the TEG and directly encapsulating the optoelectronic chip. Experiments were conducted to study effect of the interfacial thermal resistance between the newly prepared integrated CPV-TE system and the conventional CPV-
TE system. When both systems were stabilized for a few minutes, output IV curves and output power characteristics of the PV and TEG were tested. Laser with an output power of 6 W was irradiated on the surface of the CPV, and data were collected from the CPV and TEG after 5 min irradiation. Figure 7(a) and (b) show the open-circuit voltage of the integrated CPV system is less than that of the conventional system, while its short-circuit current is greater than that in the conventional system. This phenomenon indicates that the temperature of the integrated CPV system is higher than that of the conventional system. The CPV output power of the integrated CPV-TE system (1.589 W maximum output power) is slightly higher than that of the conventional CPV-TE system (1.539 W maximum output power). This is likely due to larger heat flux and higher rapid heat flow in the integrated CPV system. Results in Fig. 7(c) and (d) also prove this point. When other conditions remain unchanged, the open-circuit voltage and output power of TEG in the integrated CPV-TE system are 0.70 V and 115 mW, while they are 0.34 V and 29 mW for the conventional CPV-TE system. Based on the material properties of TEG, it is clear that the temperature difference of TEG increases in the new integrated CPV-TE system. Since the material magnetron sputtered on the upper surface of the TEG is gold, the heat absorption of the TEG can be neglected. Therefore, the increase of temperature difference of TEG is caused by the decrease of thermal resistance between CPV-TE and the increase of heat flux in the new integrated CPV-TEG system. In the integrated CPV-TE system, the maximum output power is 1.704W, representing an 8% increase in total output power compared to the 1.568W in the conventional system.
Fig. 7. Output characteristics of the integrated CPV-TE system and the conventional CPV-TE system. In integrated and conventional CPV-TE kind of systems, (a) IV characteristic curve of CPV, (b) output power curve of CPV, (c) IV characteristic curve of TEG, (b) output power curve of TEG.
4. Conclusion
To conclude, 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.
In the simulation, the maximum conversion efficiency of the system is optimized by considering both the effect of the incident optical power and ambient temperature. When the total energy output of the CPV-TE system is at its optimal state, the output of each part of the TEG and CPV is not at its maximum power state. This is because the addition of TEG increases the PV temperature while collecting waste heat to generate electricity. Therefore, it is necessary to properly optimize the TEG to control the temperature increase. The optimized simulation results show that the total energy conversion efficiency of the system is 29.4%.
In the experiments, the overall power output and the conversion efficiency were tested using the integrated CPV-TE device. The developed CPV-TE equipment reduces the contact thermal resistance between the photovoltaic and the TEG interface, increases the heat flux of the system, and improves the conversion efficiency. The overall maximum conversion efficiency reaches 35.3%, and the stable efficiency is 28.9% after continuous operation. Under similar conditions, the output power of the newly integrated CPV-TE system is increased by 8%.
Both numerical study and experimental results show the conversion efficiency is increased by incorporating a suitable TEG to harvest waste heat of the CPV converter under laser radiation. To the best of our knowledge, this is the first study to investigate a laser-concentrated CPV-TE hybrid system. We believe that studies on laser-concentrated CPV-TE may play a key role in improving the light-to-electricity conversion efficiency of the PBL system.
Funding
National Natural Science Foundation of China (62075017); State Key Laboratory of Information Photonics and Optical Communications (IPOC2021ZR01).
Acknowledgments
The research project was carried out with the help of the NSFC. The authors thank Jiangxi Power Supply Company and Dalian Institute of Chemical Physics for their support.
Disclosures
The authors declare no conflicts of interest.
Data availability
The data underlying the results presented in this paper are not publicly available at this time, but may be obtained from the authors upon reasonable request.
Supplemental document
See Supplement 1 for supporting content.
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