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Many studies and considerable international efforts have gone into reducing greenhouse gas emissions. This study was carried out to improve the efficiency of flat-plate photovoltaic thermal (PVT) systems, which use solar energy to produce heat and electricity simultaneously. An efficiency analysis was performed with various flow rates of water as the working fluid. The flow rate, which affects the performance of the PVT system, showed the highest efficiency at 3 L/min compared with 1, 2, and 4 L/min. Additionally, the effects of nanofluids (CuO/water, Al2O3/water) and water as working fluids on the efficiency of the PVT system were investigated. The results showed that the thermal and electrical efficiencies of the PVT system using CuO/water as a nanofluid were increased by 21.30% and 0.07% compared to the water-based system, respectively. However, the increase in electrical efficiency was not significant because this increase may be due to measurement errors. The PVT system using Al2O3/water as a nanofluid improved the thermal efficiency by 15.14%, but there was no difference in the electrical efficiency between water and Al2O3/water-based systems.

Solar energy has been one of the accessible and affordable renewable energy technologies for the last few decades. Photovoltaics and solar thermal collectors are mature technologies to harness solar energy. However, the efficiency of photovoltaics decays at increased operating temperatures, and solar thermal collectors suffer from low exergy. Furthermore, along with several financial, structural, technical and socio-cultural barriers, the limited shadow-free space on building rooftops has significantly affected the adoption of solar energy. Thus, Photovoltaic Thermal (PVT) collectors that combine the advantages of photovoltaic cells and solar thermal collector into a single system have been developed. This study gives an extensive review of different PVT systems for residential applications, their performance indicators, progress, limitations and research opportunities. The literature review indicated that PVT systems used air, water, bi-fluids, nanofluids, refrigerants and phase-change material as the cooling medium and are sometimes integrated with heat pumps and seasonal energy storage. The overall efficiency of a PVT system reached up to 81% depending upon the system design and environmental conditions, and there is generally a trade-off between thermal and electrical efficiency. The review also highlights future research prospects in areas such as materials for PVT collector design, long-term reliability experiments, multi-objective design optimisation, techno-exergo-economics and photovoltaic recycling.

The current study assesses several water-based PVT system thermal absorber configurations. The thermal absorber in PVT system plays a vital role in efficiency evaluation as it lowers PV temperature and collects heat energy. The current study aims to discover and analyze advanced thermal absorber design by comparing well-received spiral circular absorbers and non-cooled PV with proposed semi-circular thermal absorbers with varying flow configurations. The proposed thermal absorber maintains surface contact with PV panels and improves heat transfer thereby yielding better thermal and electrical efficiency. Simulated PVT systems have a constant water flow rate and solar radiation. The CFD-FLUENT software was preferred to evaluate the PVT system in steady-state conditions for the investigation. Under constant ambient and inlet water temperatures of 299 K, the PV temperatures at the surface, water discharge temperature, and pressure drop were measured. It was discovered that a thermal absorber could effectively lower PV surface temperature by cooling. A zigzag thermal absorber was the most efficient since it produced the highest water outlet temperature and lowest PV surface temperature while also slightly raising the pressure drop. In comparison with a non-cooled PV system, a zigzag thermal absorber PVT system yields 11.97% more electrical efficiency, with an addition of 76.75% thermal efficiency. It was also noticed that a conventional spiral circular PVT system provides 13.5% electrical efficiency and 54.8% thermal efficiency while an electrical efficiency of 13.61% and thermal efficiency is 76.75% was obtained from a zigzag thermal absorber PVT system. The zigzag thermal absorber PVT system had a high initial investment of INR 38809.00. It showed a simple payback of 4.63 years, a 28% return on investment with a promising 2.1 Debt Service Coverage Ratio. It is advisable to consider incorporating zigzag semi-circular PVT in the prospective improvements of the PVT system.

This study presents a comparative analysis of the annual performances of stationary and dual-axis sun-tracked photovoltaic–thermal (PVT) systems. The experimental research was conducted at a demonstration site in Oświęcim, Poland, where both systems were evaluated in terms of electricity and heat production. The test installation consisted of thirty stationary PVT modules and five dual-axis sun-tracking systems, each equipped with six PV modules. An innovative cooling system was developed for the PVT modules, consisting of a surface-mounted heat sink installed on the rear side of each panel. The system includes embedded tubes through which a cooling fluid circulates, enabling efficient heat recovery. The results indicated that the stationary PVT system outperformed a conventional fixed PV installation, whose expected output was estimated using PVGIS data. Specifically, the stationary PVT system generated 26.1 kWh/m2 more electricity annually, representing a 14.8% increase. The sun-tracked PVT modules yielded even higher gains, producing 42% more electricity than the stationary system, with particularly notable improvements during the autumn and winter seasons. After accounting for the electricity consumed by the tracking mechanisms, the sun-tracked PVT system still delivered a 34% higher net electricity output. Moreover, it enhanced the thermal energy output by 85%. The findings contribute to the ongoing development of high-performance PVT systems and provide valuable insights for their optimal deployment in various climatic conditions, supporting the broader integration of renewable energy technologies in building energy systems.

This study explores the integration of porous fins with phase-change materials (PCM) to enhance the thermal regulation of photovoltaic-thermal (PVT) systems. Computational simulations are conducted to evaluate the impacts of different porous fin configurations on PCM melting dynamics, PV cell temperatures, and overall PVT system effectiveness. The results demonstrate that incorporating optimized porous fin arrays into the PCM region can significantly improve heat dissipation away from the PV cells, enabling more effective thermal control. Specifically, the optimized staggered porous fin design reduces the total PCM melting time and decreases peak cell temperatures by about 5°C . This is achieved by creating efficient heat transfer pathways that accelerate the onset of natural convection during the PCM melting process. Further comparisons with traditional solid metallic fins indicate that while solid fins enable 12.2% faster initial melting, they provide inferior long-term temperature regulation capabilities compared to the optimized porous fins. Additionally, inclining the PV module from 0° to 90° orientation can further decrease the total PCM melting time by 13 minutes by harnessing buoyancy-driven convection. Overall, the lightweight porous fin structures create highly efficient heat transfer pathways to passively regulate temperatures in PVT systems, leading to quantifiable improvements in thermal efficiency of 16% and electricity output of 2.9% over PVT systems without fins.

Increasing the thermal performance of PVT systems through cooling channels is a crucial concern to improve the efficiency of the PV panels by lowering their temperature. Recent studies on PVT systems’ cooling channels demonstrate notable improvements in both the design and number of the cooling channels. However, research on dimensional optimization of cooling channels to enhance flow and heat transfer characteristics with various subchannel dimensions and Re numbers is still lacking. In this study, PVT system models with four novel cooling subchannels are generated to investigate how subchannel dimensions affect the temperature distribution and the average temperature of the PV module, velocity distribution in the subchannels, pressure drop through the channels, and the figure of merit of the cooling channels with respect to varying Re numbers. Temperature distribution results indicate that the average temperature of the PV module decreases with increasing subchannel dimensions and increasing Re number. Therefore, the lowest average PV module temperature is obtained as 32.63 °C for the subchannel dimension of 20 × 20 mm 2 as Case (4) which is 8% lower than the literature value indicating higher thermal performance for the PV modules. As a result, subchannel dimensions of the PVT system are optimized at 20 × 20 mm 2 for Re number of 2275 in terms of the lowest PV module temperature and the lowest pressure drop.

A new geometry of photovoltaic/thermal (PVT) system is introduced in this study, and the application of Al2O3/water nanofluid as the coolant on the electrical and thermal behavior of a solar system is experimentally evaluated. To intensify the thermal ability of the solar collector, a serpentine half‐pipe cooling system is designed and fabricated behind the solar panel for better cooling. The cells of the panel are assembly on a 3‐mm‐thick aluminum plate, and the Tedlar removes from the system to maximize the heat transfer in the cooling section. A special layer arrangement for the composite panel is used to minimize thermal resistance of the system. Different concentrations of nanofluid samples (0.05–0.5 wt.%) prepared. To increase the stability of prepared nanofluids, suitable surfactants are also used. Based on the obtained results, adding the nanoparticles to the pure water can remarkably raise the efficiency of the PVT apparatus. The best behavior of the solar collector is observed for 0.5 wt.% of nanofluid samples. 126.71% and 7.38% enhancement in terms of thermal and electrical efficiency can be gained by the application of nanofluid in the system compared with pure water, respectively. The best obtained value of the overall efficiency is around 93.73% for the studied system. The maximum temperature rise for water and nanofluid is around 5.5 and 9.1°C, respectively, which confirms the better cooling ability of PVT system by nanofluid compared with water. Layer arrangement of proposed model and overall efficiency of photovoltaic/thermal system versus flow rate and different concentrations of nanofluids.

By using a NAURA Advanced Physical Vapor Transport (PVT) System, the character ofthe synthesized SiC powder were studied. Mainly from the aspects of purity and particle size, and relevant experiments were designed to understand the influence of the powder source on the synthesized SiC powder. The results showed that the selection of Si powder source with appropriate particle size was conducive to increase the proportion of large particle size of SiC powder. In addition, the purification of material source in the early stage of the process was beneficial to improve the purity of SiC powder. The results showed successful preparation of optimized SiC powder and thus high-quality SiC wafers were made.

Solar photovoltaic (PV) has many environmental benefits and it is considered to be a practical alternative to traditional energy generation. The electrical conversion efficiency of such systems is inherently limited due to the relatively high thermal resistance of the PV components. An approach for intensifying electrical and thermal production of air-type photovoltaic thermal (PVT) systems via applying a combination of fins and surface zigzags was proposed in this paper. This research study aims to apply three performance enhancers: case B, including internal fins; case C, back surface zigzags; and case D, combinations of fins and surface zigzags; whereas the baseline smooth duct represents case A. A 2D, steady-state simulation model that took into account the impact of the convective flow of air circulating inside the PVT system in addition to radiative and convective heat losses from the front PV surface was developed and validated via previous tests. The results revealed that, under the same volume requirements, the application of surface zigzags is preferred for airflow rates of 0.06 kg/s or less, whereas the introduction of fins is preferred for higher airflow rates. The results also revealed that, of the three cases considered, the introduction of the fin–surface zigzag combination is the most effective and has the potential to improve the electrical and thermal efficiency by ~26% and 3%, respectively.

A study on carbon particle inclusions during 4H-SiC bulk growth is presented. Special attentions were paid to design of graphite growth compartment, size of SiC source materials, and process of seed crystal handling. It was found that common carbon inclusions with size of 30μm or less were attributed to carbon particles from graphitized SiC source. Less common carbon inclusions with size of over 100μm were also found and were attributed to poor seed crystal mounting process. In order to reduce carbon inclusions, several experiments were designed by using a NAURA Advanced Physical Vapor Transport (PVT) System APS130G. A graphite plate separator was inserted into the growth compartment to prevent the carbon particles from transporting to the growth surface. SiC powder materials with larger diameters were selected to reduce source graphitization. Additional clean process was performed to remove carbon particle residuals on graphite parts during seed mounting. The results showed significant improvement of carbon inclusion problems in SiC ingots and thus high-quality SiC wafers were made successfully.