Photovoltaic Thermal Collector Research Articles

The effect of a reversed circular jet impingement on A bifacial module PVT collector energy performance

Photovoltaic thermal (PVT) technologies have a significant downside in addition to their numerous advantages. PVT technologies are constrained by the fact that its photovoltaic module gains heat due to exposure to solar irradiance, which reduces the photovoltaic efficiency. Jet impingement is one of the most effective methods to cool a photovoltaic module. An indoor experiment using a solar simulator was conducted on a bifacial PVT solar collector cooled by a reversed circular flow jet impingement (RCFJI) to evaluate the energy performance of the PVT collector. The study was conducted under a constant solar irradiance of 900W/m2 and flowrate (mass) ranging from 0.01 to 0.14 kg/s. Three bifacial modules with 0.22, 0.33, and 0.66 packing factors were mounted 25 mm above the RCFJI for cooling. The 0.66 packing factor module recorded the highest photovoltaic efficiency of 10.91 % at 0.14 kg/s flowrate (mass). Meanwhile, the 0.22 and 0.33 packing factors recorded a photovoltaic efficiency of 4.50 % and 6.45 %, respectively. The highest thermal efficiency recorded under the same operating condition was 61.43 %, using a 0.66 packing factor. Overall, the highest combined photovoltaic thermal (PVT) efficiency for 0.22, 0.33, and 0.66 was 56.62 %, 61.88 %, and 72.35 %, respectively.

Solar-Powered Adsorption-Based Multi-Generation System Working under the Climate Conditions of GCC Countries: Theoretical Investigation

In this study, transient modelling for a solar-powered adsorption-based multi-generation system working under the climatic conditions of the Gulf Cooperation Council (GCC) countries is conducted. Three cities are selected for this study: Sharjah in the United Arab Emirates, Riyadh in Saudi Arabia, and Kuwait City in Kuwait. The system comprises (i) evacuated tube solar collectors (ETCs), (ii) photovoltaic-thermal (PVT) solar collectors, and (iii) a single-stage double-bed silica gel/water-based adsorption chiller for cooling purposes. A MATLAB code is developed and implemented to theoretically investigate the performance of the proposed system. The main findings of this study indicate that among the selected cities, based on the proposed systems and the operating conditions, Riyadh has the highest cooling capacity of 10.4 kW, followed by Kuwait City, then Sharjah. As for the coefficient of performance (COP), Kuwait City demonstrates the highest value of 0.47. The electricity generated by the proposed system in Riyadh, Kuwait City, and Sharjah is 31.65, 31.3, and 30.24 kWh/day, respectively. Furthermore, the theoretical results show that at 18:00, the overall efficiency of the proposed system reaches about 0.64 because of the inclusion of a storage tank and its feeding for the adsorption chiller. This study analyzes the feasibility of using a combination of ETCs and PVT collectors to drive the adsorption chiller system and produce electricity in challenging weather conditions.

Performance investigation of a hybrid PV/T collector with a novel trapezoidal fluid channel

The photovoltaic-thermal collector (PV/T) is an innovative technology that combines PV cells and solar thermal collectors into a co-generation unit, enabling full-spectrum solar utilization. This research proposes and examines a hybrid PV/T system with novel trapezoidal fluid channels embedded in graphite, arranged in a parallel S-shaped structure under outdoor conditions of Beijing. Parametric discussions and daily performance analysis are conducted to assess its effectiveness and stability. A daily average of 12.7 °C reduction in cell temperature compared to PV modules results in a relative 5.20 % improvement in electrical output under the intensity of solar radiation is 597 W/m2. Similarly, the peak temperature of the water tank reaches 56.9 °C, and thermal efficiency is enhanced by 7.86 % over conventional sheet-tube PV/T collectors. For further optimization, a constrained adaptive particle swarm optimization algorithm (EPF-APSO) is constructed based on the experimental data, implementing a variable water flow rate (VWV) strategy. Compared to a constant water flow rate (CWV), the overall energy collected varies from 2.755 to 2.828 kWh per day, potentially reducing pump energy consumption by 17.93 %. The contribution of this paper provides references on structural and operational parameters optimization of PV/T collectors applying machine learning algorithms for better comprehensive efficiency.

Multi-objective optimization of a solar photovoltaic thermal water collector using Grey Wolf Optimizer

Solar photovoltaic thermal (PV-T) collectors offer enhanced overall efficiency owing to reduced heat losses at the aperture plane and the potential for increased irradiance per unit area in comparison to larger prototypes. In spite of its promise, investigations into optimizing PV-T collector performance remain limited. This paper introduces a novel approach: the multi-objective optimization of a hybrid PV-T water system with a channel-type absorber design, utilizing the Grey Wolf Optimizer. The proposed approach employs regression models to depict key performance metrics—average thermal and electrical efficiencies. Optimal parameters, including rate of flow of cooling fluid, temperature at inlet, and slope of the solar panel, are determined and reported. In this paper, Grey Wolf Optimization algorithm, has been used to systematically explore the interaction of various PV-T parameter values. Optimal values, in line with the defined objective function(s) were obtained. This approach enabled the researchers to concurrently ascertain the comprehensive performance of the collector. Remarkably, the optimization process revealed a unique insight. Despite the inherently conflicting nature of thermal and electrical efficiencies as observed in single-objective optimization outcomes, the multi-objective MOGWO approach unveiled a solution where compromise was attained.

A solar-assisted power-to-hydrogen system based on proton-conducting solid oxide electrolyzer cells

Green hydrogen is anticipated to play a major role in a Net-Zero 2050 scenario since it can be produced using sustainable renewable energy sources, resulting in no greenhouse gas emissions. Furthermore, hydrogen has a high energy density and is readily stored and transferred, making it a versatile and convenient fuel for a broad range of applications. In this regard, an attempt has been made to study a solar-assisted power-to-hydrogen system based on proton-conducting solid oxide electrolyzer cells. The article presents a detailed thermo-economic analysis along with genetic algorithm-based optimization studies of the system. The optimum values of energetic efficiency and the cost of hydrogen are found to be 25.15 % and 1.021 $/kg, respectively. Exergy analysis reveals that the highest exergy destruction occurs in solar photovoltaic thermal (67.83 %) and parabolic trough solar collector (13.31 %), respectively. Furthermore, performance results of the solar-assisted power-to-hydrogen system are compared with other hydrogen production technologies.

3D numerical analysis of a photovoltaic thermal using bi-fluid: Al2O3–water nanofluid at various concentrations

This study aims to use a cooling technology for photovoltaic-thermal (PVT) collectors more effective in terms of cooling and enhancing the thermal efficiency of the system in general. This was done by using bi-fluid modes (air and Al2O3–water nanofluid), which are characterized by being more effective in terms of cooling and enhancing the overall thermal efficiency of the system. To achieve this, aluminum dual exchangers were incorporated with an aluminum back surface of the monocrystalline photovoltaic panels. The cooling was achieved using the Al2O3–water nanofluid at various concentrations of 0.0, 0.2, 0.4, 0.6, 0.8, and 1 % with a steady flow of water at 0.01 kg/s and at a simultaneous airflow rate. Also, the effect of different levels of Al2O3 nanoparticle concentrations (0.0, 0.2, 0.4, 0.6, 0.8, and 1 %) was studied to identify the optimal concentration of Al2O3–water nanofluids that achieves the highest rates of cooling and thermal efficiency of PVT collectors. The 3D numerical model was validated using the experimental published data. The results showed that the total thermal efficiency of PVT modules with the bi-fluid modes is equal to 46.63 %, 48.96 %, 52.39 %, 54.13 %, 59.43 %, and 63.28 %, for Al2O3–water nanofluids concentrations of 0.0, 0.2, 0.4, 0.6, 0.8, and 1 %, respectively. The PV module with the bi-fluid modes (air and Al2O3–water nanofluids with 1 % concentration) at a steady flow of water at 0.01 kg/s is the best design for effective cooling of PV panels, which can contribute to more sustainable and energy-efficient solar energy conversion systems.

Thermal and Electrical Analysis of N-PVT-FPC Hybrid Active Heating of Biogas Plant

Abstract In order to increase biogas production during winter months/cold climatic conditions, a self-sustained N-photovoltaic thermal and flat plate collector (PVT-FPC) hybrid active heating biogas plant has been analyzed in terms of thermal energy and electrical energy. A general analytical expression for thermal and electrical energy of the biogas plant has been derived as a function of climatic and design parameters from one order coupled differential equations. Various photovoltaic thermal and flat plate collector (N-PVT-FPC) configurations have been considered for optimizing maximum electrical and thermal energy gain for a given total number of N-PVT-FPC collectors. Based on mathematical computation for Indian cold climatic conditions, it has been found that the N-PVT-FPC combination is always better than the flat plate collector-photovoltaic thermal (N-FPC-PVT) collector for maximum electrical and thermal energy. Overall exergy analysis of hybrid active heating of biogas plants has also been carried out.

An advanced Photovoltaic Thermal Collector Storage Solar Water Heating based on planar liquid vapour thermal diode: Model-based design approach for the optimal energy performance assessment

The building sector is responsible for the highest portion of energy consumption and carbon dioxide emissions. To partly address this issue, the scientific community is placing greater emphasis on the utilization of Building Integrated Solar Systems (BISS) as a means of improving building thermophysics and decreasing primary energy demand. Within this framework, Integrated Collector Storage Solar Water Heaters (ICSSWH) have the potential to significantly decrease the costs associated with the installation and maintenance of building-integrated solar systems (BISS), all while optimizing the utilization of solar power. Nevertheless, ICSSWHs exhibit certain limitations in their capacity to retain thermal energy, particularly during nocturnal periods. One potential approach for enhancing the efficiency of ICSSWH collectors involves the integration of Thermal Diodes (TD), which have the capability to optimize heat absorption while minimizing heat retention. In this context, to advance the state-of-the-art in the field, this paper presents a novel dynamic simulation tool conceived to assess the performance of an innovative Hybrid Photovoltaic Thermal ICSSWH (the HyPVT), incorporating a cutting-edge Planar Liquid Vapour Thermal Diode (PLVTD), and purposely designed to be integrated into buildings’ envelope. By using the developed simulation tool, the performance of the proposed HyPVT collector concept is investigated with the aim of assessing its collection and retention efficiencies under different boundary and operating conditions. Furthermore, to show the effect of the Planar Liquid Vapour Thermal Diode (PLVTD) adoption, a comparative analysis is conducted between the proposed ICSSWH and a conventional one (without a thermal diode). Finally, the developed tool will be utilized in forthcoming research to determine the optimal device configuration through the utilization of a model-based design methodology.

Photovoltaic Thermal Technology Collectors, Systems, and Applications

Photovoltaic thermal (PVT) technology has been drawing attention recently. Electrification of the heating sector with heat pumps run by carbon‐free electricity sources like photovoltaics is setting the ground for the interest. This article gives insight into PVT technologies and collector designs according to application and operating temperatures. For most conventional designs, examples like prototypes from Research & Development projects are presented. In addition, commercial products are listed along these categories, and the influence on the gross thermal and electrical yield is depicted based on Solar Keymark certification data. The process of certification is presented in a comprehensive way, showing current limitations, giving an outlook on the most recent approach for enhanced procedures and specifications. Finally, different system layouts are presented, and examples from installations combined with a heat pump are given with their specific performances. Real performance data of several PVT installations are compared to conventional heat pump systems. The identified seasonal performance factors are in a range from 3.4 to 4.2 and in between air source and ground source heat pumps. Continuous monitoring and derived data are enablers to discover the decisive influence of the system layout and dimensioning on performance indicators like, for example, operating temperatures over the year.

Optimizing Photovoltaic Thermal Collector Temperature with Varying Number of Collectors: A CFD Simulation Study

Optimizing Photovoltaic Thermal Collector Temperature with Varying Number of Collectors: A CFD Simulation Study

Air Bubble Effect on Heat Transfer Enhancement in 90° Ribbed Parallel Channels Based on Photovoltaic-Thermal Collector Cooling

The effect of entrained air bubbles on heat transfer enhancement inside 90° ribbed parallel channels has been experimentally studied to improve electrical efficiency inside future solar panels. In this work, the Reynolds number was measured from 200 to 600. The essential ratios of channel aspect, rib height, and rib pitch were all set to 0.4, 0.18, and 10, respectively. The volumetric flow fraction for all test conditions varied from 0.0 to 0.5. The overall heat transfer distributions on the surface were captured using an infrared thermography camera. The main finding showed that the average heat transfer rate and the thermal performance gained beyond 25–81% and 7–82% compared with the smooth wall. In addition, the volumetric flow fraction of 0.5 at the Reynolds number of 200 became the best.

PVT integrated hydrogen production with small-scale transcritical power cycle

The objective of the present research is to examine the performance of an integrated hydrogen generation system based on solar power. The system is comprised of photovoltaic-thermal (PVT) panels, a transcritical Rankine cycle (tRC), and a hydrogen generation unit, namely proton exchange membrane electrolysis (PEME) process. Carbon dioxide (CO2), which is an environmentally friendly fluid, is used as the working fluid of tRC, where it is directly heated up in the PVT collector. To perform the performance assessment of the system, first, a dynamic simulation of the PVT is conducted based on data from August 17 of Izmir. After, energy and exergy analyses of the integrated system are carried out, followed by parametric analyses. According to the results, the maximum power obtained from the PVT is found to be 2.6 kW, the net energy generated from tRC is calculated as 0.8 kW, while the maximum H2 generation rate is 16 g/h.

Performance of a solar hybrid desalination plant integrated with photovoltaic-thermal collectors for remote regions: Experimental and modeling investigation

Energy and freshwater are the most prioritized needs for any nation nowadays, especially for arid areas. Giving attention to renewable energy sources like solar energy is a must towards a cleaner environment and a world with no need of temporary sources like fossil fuels. Also, a solution to lower the power requirements and costs of desalination hybrid systems should be investigated to overcome the water problem. The present study aims to design and build a novel hybrid desalination plant working with the highest productivity and lowest power consumption. This was done by incorporating a reverse osmosis desalination unit with the conventional solar distiller. The photovoltaic/thermal collectors were utilized to produce electricity as well as a heating unit in addition to the evacuated tube solar collectors, to preheat the hybrid desalination plant feed water. The results presented that the use of photovoltaic/thermal panels and evacuated tube solar collectors as preheating units improved water recovery by 46% and reduced power consumption by 38.34% for the small reverse osmosis unit but the salt rejection decreased by 4%. Cooling the photovoltaic panel increased its electricity production by 24.1% on average. Moreover, the combination of the solar distiller with the reverse osmosis unit on the feed line represents the best configuration which improves the solar distiller’s productivity by 98.32% as compared to separate solar distillers. The cost of freshwater produced is 0.719 $/m3 which is cost competitive compared to previous solar desalination systems.

Analytical and experimental study of hybrid photovoltaic–thermal–thermoelectric systems in sustainable energy generation

A new hybrid system, known as photovoltaic–thermal–thermoelectric (PVT-TE), has been proposed to enhance the conversion efficiency of PV cells by incorporating an intelligent thermal management system, which leverages the dual functions of thermoelectric (TE). This study aims to explore the potential for creating a hybrid system that is more efficient and offers improved performance than standalone photovoltaic thermal (PVT) systems. The key parameters for the creation of a hybrid system were analysed, and the theoretical and experimental results were compared to validate the model. The performance of the PVT-TE collector was evaluated through a steady-state analysis using a one dimensional (1D) mathematical model. Energy balance equations were solved using Microsoft Excel and inverse matrix method. Experiments on PVT and PVT-TE collectors were examined at a solar radiation intensity of 593.16 W/m2. The air mass flow rate was set at 0.009, 0.021, 0.039, 0.069 and 0.095 kg/s for specific radiation intensity. The thermal and electrical performance of the hybrid system was higher than that of the conventional PVT system. The PVT-TE system combines photovoltaic and thermoelectric components, including a thermoelectric module and an air collector. The integration improves system efficiency and performance, surpassing previous research efforts. The PVT-TE system with an air collector has innovative features including efficient thermal-electric conversion, integrated component utilisation, and air collector integration. The overall efficiency of the hybrid system was 7.05%–31.13% higher than the theoretical values and 9.64%–34.83% higher than the experimental values. The increase in the output power of the hybrid system was also higher by 32.59%–55.93%. The findings indicate that the integration thermoelectric (TE) with PV cells has the potential to enhance solar thermal systems' performance. This study provides the basis for further analysis and optimisation of PVT-TE hybrid systems.

Towards resilient operation of photovoltaic-thermal collector with incorporated organic phase change material: Numerical and experimental investigation

The resilient operation of the novel free-standing photovoltaic-thermal (PVT) collector with an integrated phase change material (PCM) in variable weather conditions was examined by developing the computational fluid dynamics (CFD) 3D model to perform numerical analysis of heat transfer. The developed transient multi-parameter numerical model was directly compared with experimental measurements for the case of variable cloudiness, unstable ambient temperature, and fluctuating wind. Due to volatile weather conditions, the numerical analysis included variable time-dependent boundary conditions implemented using user-defined functions (UDF). The investigation considered a novel multi-parameter numerical approach, together with novel experimental data for unconventional organic PCM. Specifically, the thermal characteristics of unconventional organic PCM, i.e., pork fat, were experimentally determined with the differential scanning calorimetry (DSC) method and embedded in the numerical model. It was found that melting of the crystal phase of pork fat PCM starts at 8.3 °C and ends at 45.2 °C with a latent heat of melting being 45.4 Jg−1. The numerical model was successfully validated with experimental data. The mean absolute percentage deviation of the operating temperature numerical forecast compared with the experiment was from about 2.9% to 4.9%, depending on the considered domain. The findings of this investigation can be used to improve the existing designs of PVT-PCM collectors. Furthermore, a validated numerical model can be used to investigate the impact of various operating parameters on the system performance to enhance the resilience aspect in the early development phase of novel designs.

Numerical investigation of PV module cooling process by developing single-pass and doublepass PVT collectors

In this study, single-pass and double-pass photovoltaic thermal collectors were designed and analyzed numerically. Energy efficiency and heat transfer coefficients of the PV module were calculated in the study. For case studies two different meteorological conditions (winter and summer) choosed. Case studies were performed with three different Reynolds number (15059, 17805, 22061). Avarage thermal efficiencies obtained for single and double-pass PV-T calculated in winter 65.15% and 67.88% ; summer 56.09%, and 58.46% conditions, respectively. For double- as PV-T, these values are It has been determined that the temperature of the PV module decreases with the increase in flow rate. Avarage electrical efficiency for single pass PVT in winter condition determined as 13.68% where for summer it was calculated as 13.24%. For double pass PVT these values obtained as 14.40% and 13.94%, respectively.

A solar spectral splitting-based PVT collector with packed transparent tube receiver for co-generation of heat and electricity

Combined heating and power (CHP) systems co-generating electrical energy as well as thermal energy is indispensable for modern-day distributed applications. Photovoltaic thermal (PVT) systems are such hybrid co-generation systems. However, in a conventional PVT system, the PV module/cell temperature restricts the thermal output, making these systems unsuitable for various applications. This study offers a novel and resilient design for a spectral beam splitting-powered compound parabolic collector-based PVT system that employs a nanofluid optical filter within borosilicate glass tubes for volumetric absorption. By maximizing the “splitting effect”, the goal of this work is to disrupt the long-standing relationship between the thermal and electrical yield from a PVT collector, i.e., obtaining a higher heat transfer fluid temperature than the PV cell temperature. Several configurations with varying array width-to-receiver tube diameter ratios, i.e. bdo ratios (ranging from 3 to 8) and one, two, and three rows/layers of receiver tubes were evaluated and compared. The optical and thermal performance of the collector designs are compared using metrics such as heat flux distribution, optical efficiency, temperature distribution, receiver efficiency, and splitting ratio. This work determines how the splitting effect dictates the performances of the collector. Through the ray-tracing routine and thermal analysis, it is demonstrated that for certain bdo ratios, the developed collector attained a maximum cumulative temperature rise of >100∘ C using ZnO–water–ethylene glycol nanofluid as the optical filter. Also, the receiver and electrical efficiency of 51.81% and 18.77%, respectively, are achieved. Moreover, the packed borosilicate glass receiver tubes with a bdo ratio of 8 and two receiver rows/layers achieved the so-called “splitting ratio” (ratio of filter fluid temperature to cell temperature; THTFTcell) of >1.6. The studied configurations find their application depending on the extent of the achieved splitting ratio. Based on these findings, it is concluded that the analyzed packed glass tube receiver designs provide a viable new route towards cost-effective and dependable robust PVT collectors for distributed and other applications.

Performance analysis of a multi-source renewable energy system for temperature control in buildings of varied thermal transmittance and climate zone

The current paper presents a numerical analysis of a multi-source renewable energy system for building air conditioning aiming at decarbonising the building envelope. The thermal management of the building is pursued through a radiant floor fed by a heat pump and integrated with phase change materials for thermal inertia enhancement. A fan coil is foreseen for humidity control. The heat pump can be fed through three parallel circuits involving different thermal sources: air with an ordinary air-to-water heat exchanger, sun through photovoltaic thermal solar collectors, and ground using shallow ground flat-panel heat exchangers. At need, the ground can be exploited for thermal energy storage when the heat pump is idle. A set of dedicated control rules chooses the optimal source or mix of sources to exploit at any time. Simulations of a reference building, namely a large single-room snack bar, are performed for various plant configurations, hypothesising the building as located in distinct climate zones and characterised by different thermal transmittance. The thermal performance of the building is given in terms of primary energy needs per year and compared to that of an analogous single-source plant. Results show that the proposed system can lead to primary energy savings of up to 16% compared to the corresponding state-of-the-art single-source plant, being more effective if the geothermal field is large enough and the building heating and cooling needs are comparable. The relevance of a proper control algorithm for plant performance optimisation is highlighted: a thermal power-based approach is proposed and successfully tested.

High vacuum flat plate photovoltaic-thermal (HV PV-T) collectors: Efficiency analysis

Through a numerical model developed in MATLAB, we investigate the performance of a novel hybrid flat plate photovoltaic-thermal collector under high-vacuum (HV PV-T) to optimize the solar-to-thermal energy conversion and efficiently meet the thermal loads of industrial processes up to 150 °C along with additional production of electrical energy. In the proposed design, the photovoltaic (PV) cell is positioned directly above the Selective Solar Absorber (SSA) in a multi-layered PV-SSA structure.The performance analysis of the system has been first carried out by considering the theoretical Shockley-Queisser limit of the electrical efficiency, different values of energy bandgap (0.66 eV ≤Eg≤3.00eV), emittance (0.1≤ɛ≤1), and working temperature (25°C ≤TPV≤175°C) of the PV layer, and secondly by focusing on a wide variety of actual semiconductive materials. We analyzed the specific case of high bandgap materials, such as CdTe, CdS, and GaAs reported in previous publications. The analysis performed shows that full exploitation of the incident solar radiation with HV-PVT collectors can produce about 12.2% of electrical efficiency while 76.4% of the incident power remains available for thermal conversion at 100 °C. Moreover, obtaining the same annual energy using stand-alone solutions (i.e., a combination of the best PV and solar thermal collectors commercially available) would require up to 50% of the collector area more than the proposed HV PV-T collector.

The effects of using twisted tape, ferrofluid, and external magnetic field on hydrothermal performance and entropy generation of the building integrated photovoltaic thermal collectors

The numerical analysis of the present study was performed to evaluate the usefulness of twisted tape insert inside a building integrated photovoltaic thermal (BIPVT) system in the presence of an external Magnetic Field (MF) aimed to reducing the system size. The results demonstrated that the MF reduces PV plate temperature (TPV) by 1.13%-0.89%, 2.21%-1.96%, 1.61%-1.36%, and 1.38%-1.04% in the plain tube and twisted tubes with pitch distances (Pd) of 50 mm, 75 mm, and 150 mm, respectively, at Res of 400–600. In addition, the pressure drop (ΔP) escalates by 30.87%-27.36% in the presence of the MF for the plain tube. However, in the twisted tubes, ΔP under the MF effect has an increasing or decreasing trend. ΔP at Pds of 50 mm, 75 mm, and 150 mm, is 87% (or 83%), 82% (or 78%), and 76% (or 71%) higher than that in the plain tube, respectively, in the absence (or presence) of the MF effect. In addition, the increase in Re from 400 to 600 improves the electrical efficiency by 1.89–1.47% for the plain tube and 2.24–1.41% using three turbulators in the tube, respectively, for the without-with scenarios of MF effect. In addition, the increase in Re from 400 to 600 leads to escalating the frictional entropy generation rate by 52–62%.