Concentrated Photovoltaic Thermal Research Articles

Comparison with Carnot battery of an alternate thermal electricity storage charged by concentrated photovoltaic thermal system and resistance heater

In Carnot Batteries (pumped thermal electricity storage), which is known as a low-cost electricity storage method, electrical energy is stored as thermal energy and then converted back into electrical energy using a heat pump and a heat engine, respectively. In the studies carried out to date, different heat source scenarios, heat storage methods, and methods to improve heat pump and heat engine cycles have been applied to increase efficiency and reduce the cost of the Carnot Battery. This study’s novelty was using a concentrated photovoltaic thermal system and resistance heaters instead of a heat pump for the charge cycle in thermal electricity storage. This novel thermal electricity storage design aimed to reduce the levelized cost of storage of the system by eliminating the need for a heat pump and reducing the volume of the water storage tank. First, parametric analyses were performed for the specific variables of both energy storage systems. Afterward, the Carnot Battery and the proposed system were compared for the same electricity storage capacity. For charge/discharge times ranging from 4 h to 8 h and electricity storage capacities ranging from 0.5 MW to 2 MW, a 31.8 % to 58 % increase in round-trip efficiency and a 7.13 % to 20.67 % decrease in levelized cost of energy storage were achieved with the novel design.

Cooling of highly concentrated photovoltaic cells with confined jet impingement by introducing channel configurations

Appropriate cooling techniques are required to be integrated into highly concentrated photovoltaic cells to maintain the surface of the photovoltaic cell at a uniform temperature. This study focuses on cooling photovoltaic cells with confined jet impingement to reduce non-uniform temperature distribution and thermal and bending stresses to avoid hotspots and current mismatching problems, thereby improving the cell electrical efficiency. Channels are formed in an aluminium heat sink on the backside of solar cell layers such that the coolant strikes the heat sink surface at the centre and exits at the four corners of the module. Different designs of confined jet channel configurations are studied. The effect of the coolant mass flow rate on the hydrothermal performance of the concentrated photovoltaic thermal (CPV-T) system is examined for all channel configurations. The electrothermal performance of the CPV-T system is at its maximum with a quadrant mini-channel with a single inlet. The net electrical power generated by the PV cell is at its maximum of 30.5 W for a mass flow rate of 50 g/min with this channel configuration. Further, the pressure loss is minimal at 163 Pa at 25 g/min, and the temperature uniformity is also maximum, with a temperature difference over the cell surface of 6.3 °C at 50 g/min. The present study will be useful in the thermal management of highly concentrated photovoltaic thermal systems and high-temperature applications.

Performance investigation of a building-integrated collector based on spectrum splitting technology

Based on solar spectrum splitting technology, a novel concentrating photovoltaic/thermal (CPV/T) solar collector is proposed, which primarily composed of six Fresnel collector units with separate photovoltaic and photothermal modules. The compact overall structure is optimally designed that can be effectively integrated with ordinary buildings while supply both electrical and thermal energy. The proposed collector achieves the maximum annual average optical efficiency when installed north–south axially with a tilt angle approximately equal to the installation latitude, as a 64.97 % in Nanjing (32°N). Simulation analysis shows that the main influencing factors of the system performance are direct solar irradiance, working medium mass flow, and optical efficiency, the theoretical outlet working medium temperature can reach 150 °C while the photovoltaic and photothermal efficiencies are 12.37 % and 39.74 % when the normalized temperature difference T* is 0.06. Further, to verify the theoretical/simulation analysis results, the outdoor experimental tests are conducted and show that the optimal inlet working medium mass flow is 10.8 kg/h, while the efficiencies are 5.99 % and 27.59 %, respectively, that is, the proposed system comprehensive thermal efficiency can reach 43.35 %. The comparative analysis of theoretical research and experimental tests shows that the proposed system has rationality and practical value, which can provide guidance for practical engineering.

Exergo-economic analyzes of a combined CPVT solar dish/Kalina Cycle/HDH desalination system; intelligent forecasting using artificial neural network (ANN) and improved particle swarm optimization (IPSO)

Power and freshwater are two energy-intensive products, which consume a huge amount of fossil fuels. It is important to supply the aforementioned products using renewable energy sources due to the depletion of fossil fuel resources and environmental issues. This paper investigates the exergy and exergy-economic analysis of water and power production using a small-scale combined cycle encompasses the concentrated photovoltaic thermal (CPVT) solar collectors, a Kalina cycle (KC), and a humidification-dehumidification (HDH) desalination unit. An exergo-economic parametric analysis was first investigated to determine the influence of some pertinent parameters on the exergy efficiency, and specific unit cost of the products. In the second stage, two intelligent forecasting approaches based on the artificial neural network (ANN) and improved particle swarm optimization (PSO) algorithms were utilized for predicting the performance metrics of the studied system. The system was supposed to work at half of the year's hour. The results demonstrated that the shares of CPVT, generator, humidifier, dehumidifier, and condenser in exergy destruction are 84 %, 6 %, 3 %, 2.5 %, and 2 %, respectively. Moreover, the exergy efficiency, and specific unit cost of the products, unit cost of electricity, and unit cost of the fresh water at the design condition were obtained as 23.23 %, 0.0806 $/kWh, 5.44 $/m3, and 31.15 $/GJ, respectively. Besides, the most effective parameter on the exergy efficiency and the specific unit cost of the products was the solar beam radiation, the increment in which from 300 W/m2 to 1000 W/m2 improved the exergy efficiency by 15.21 % and reduced the specific unit cost of the products by 63.16 %. In addition, the increase in the condenser pressure from 15 bar to 22 bar and the generator pinch point temperature difference from 5 °C to 15 °C reduced the exergy efficiency by 8.13 % and 4.03 %, respectively, leading to increasing the specific unit cost of the products by 1.30 % and 4.30 %. The results of modeling showed that hybrid ANN-IPSO models provide the most accurate prediction, highest tendency, and agreement to observation as compared to ANN in terms of (R2| exergy efficiency = 0.9903 and R2| specific unit cost of products = 0.9948) and (RMSE| exergy efficiency = 0.0010 and RMSE| specific unit cost of products = 0.9684).

Critical analysis of enhanced photovoltaic thermal systems: a comparative experimental study of PCM, TEG, and nanofluid applications

Phase change materials (PCM), thermoelectric generators (TEG), and nanofluids are popular methods investigated for improving conventional photovoltaic thermal (PVT) systems. These methods are particularly used in warm climates where high temperatures negatively impact photovoltaic (PV) power output and energy efficiency. This experimental study evaluated the effects of 32 °C melting point PCM and TEG integration on PVT units, as well as 42 °C melting point PCM and nanofluid incorporation on concentrated PVT (CPVT) units. Technical, exergetic, and economic performance were compared using a small-scale PVT module. Low-cost commercially available materials were used to construct all PVT units. Industrial metal waste was introduced to enhance the thermal conductivity of paraffin wax and salt hydrate PCMs. The results indicated that applying PCMs, porous media, and concentrator plates increased energy generation, potentially offsetting their higher initial cost and achieving an energy cost of approximately $0.135/kWh. However, TEG and nanofluid implementation remained uneconomical, leading to a 15–35 % increase in energy cost. The water-based CPVT unit, enhanced with paraffin wax and copper fins, demonstrated the best technical performance. This unit achieved electrical, thermal, and exergy efficiencies of approximately 15.5 %, 37.4 %, and 16.7 %, respectively, with more than a 20 % reduction in cell temperature. The study also revealed that severe structural changes caused by corrosion of metallic materials in hydrated PCMs could alter the melting point by more than 30 %. This change negatively impacts heat storage capacity. Conversely, incorporating metal chips in non-hydrated PCMs improved the time to reach the melting point state by 30–60 minutes.

Influence of vortex generator on performance of concentrated solar photovoltaic module in existence of heat sink

New configuration of concentrated photovoltaic thermal (CPVT) with the implementation of parabolic concentrator and heat sink combined with the vortex generator (VG) were presented in current work. The testing fluid is water and temperature-dependent features were utilized. The regime of water flow in absence and presence of VG are laminar and turbulent, respectively. Numerical simulations were done for different values of angle of VG (θ = 30°, and 60°), pitch ratio (S = 0.025, 0.0375, and 0.05), and volumetric flow rate (Q = 0.5, to 2 Lit/min). Four values for width of reflector have been applied and radiation model was utilized to derive the absorbed heat flux. The accuracy of modeling has been examined for three cases and good accommodations have been reported. The maximum values of thermal (ηth) and electrical (ηel) performance are 63.75 % and 13.96 % which happens when θ = 30°, S = 0.025, Q = 2 Lit/min. Installing VG leads to increments of ηth and ηel about 1.42 % and 2.74 %. Increase of S and θ cause performance to decrease while this function increases with rise of Q. Increase of Q causes ηth and ηel to increase about 1.17 % and 2.55 % for the best case.

Power-to-X system utilizing an advanced solar system integrated with a thermally regenerative electrochemical cycle

This article discusses power-to-X technology by proposing an advanced system to generate green electricity and hydrogen. The proposed system is powered by an advanced concentrated parabolic photovoltaic thermal (CPV/T) hybrid system. A proton exchange membrane (PEM) water electrolyzer system is used for the hydrogen production process, with a multistage compression system to increase hydrogen pressure and regulate hydrogen temperature. Additionally, a heat recovery system is employed through the thermally regenerative electrochemical cycle (TREC). A parametric analysis was performed based on thermal resistance to investigate the effect of solar radiation, Reynolds number, lengths of both the receiver side and tube and ambient temperature. A mathematical model was developed and validated to investigate the integrated system performance. CPV/T achieved a maximum system efficiency of 85.4% at 1000 W/m2 and a side length of 0.2 m, with electrical and thermal contributions of 21.1% and 64.3%, respectively. With a tube length of 20 m, the maximum hydrogen flow rate reached 280 kg/h, requiring 2.5 TJ/h for production under a pressure of 750 bar. The TREC system showed a maximum electrical production contribution of about 25.4% at a Reynolds number equal to 3000 compared to the contribution of CPV/T cells.

Seasonal thermo-enviro-economic performance analyses of concentrated PV/T integrated with humidification-dehumidification water desalination system

Concentrated solar photovoltaic thermal offers a great opportunity for water desalination by applying some thermally driven techniques. Humidification–dehumidification water desalination is appropriate for moderate installations and runs on low temperatures matching the attainable output of low concentrated photovoltaic thermal systems. So, in this paper, thermo-enviro-economic performance analyses of an integrated system consisting of compound parabolic collectors partially covered with photovoltaic cells powering humidification dehumidification water desalination system is theoretically introduced. The system performance is conducted at a seasonal scale using MATLAB throughout the whole year under the weather of New Borg El-Arab city-Alexandria-Egypt. The results indicate that raising the flow rate of the working fluid of the system increases the desalination output, reduces the PV cell temperature, and enhances PV efficiency. At a fluid flow rate of 0.02 kg/s suitable for PV safety temperature, the cell maximum and minimum temperature are 79 and 42.5 °C, maximum and output power is 6 and 3.8 kW, and maximum and minimum efficiency is 17.2 and 14.2 % respectively. The output water temperature is 73 and 36.9 °C in summer and winter, respectively. The desalination system produces maximally 4.7, 6.2, and 3.8 L/h at water to air mass flow rate ratios of 1.5, 2, and 3, respectively. The maximum achieved average monthly desalination system gain output ratio is 3.15 with an overall system efficiency of 41 %. The average annual system thermal energy and exergy yield is approximately 176 and 0.2 kWh, respectively. The annual freshwater cost is $0.0351/Liter. The system mitigates an annual average of 7.2 tons of CO2 emissions.

A 3D symmetry-preserving simulation of a concentrated photovoltaic thermal (CPVT) solar collector

In this work, a general collocated and unconditionally stable framework on unstructured meshes for solving Conjugate Heat Transfer (CHT) problems is presented by means of preserving the underlying symmetries of the continuous differential operators, thus not introducing uncontrolled artificial numerical dissipation to our system. Then, this framework is applied to solve a Concentrated PhotoVoltaic Thermal (CPVT) Solar Collector. Furthermore, a new boundary condition is implemented to consider the heat transfer between enclosed elements, including radiation. The model is validated using experimental data.

Optical, electrical, and thermal performance of low-concentrating photovoltaic/thermal system using microencapsulated phase change material suspension as a coolant

Concentrated photovoltaic/thermal (C-PV/T) systems exhibit superior output compared to common PV/T collectors. To address potential issues caused by excessive concentration of conventional parabolic concentrators and enhance the electro-thermal co-generation capability, this work proposes a low-concentrating PV/T (LC-PV/T) system that integrates two improved concentrator designs and a coolant of microencapsulated phase change material suspension (MPCMS). A numerical model is established to investigate the effects of working conditions and meteorological conditions on the optical, electrical and thermal performances. The results indicate that the improved concentrator designs effectively prevent over-concentration of sunlight while maintaining a comparable concentration ratio (CR). The electrical output increases with an increase in mass fraction, inlet mass flow rate and solar irradiance, but decreases with an increase in ambient temperature and inlet temperature. Conversely, thermal output increases with an increase in all of these parameters except for the inlet temperature. This system can achieve 17 % electrical efficiency and 72 % thermal efficiency due to the high-efficiency solar cells, optimized concentrator design, and unique MPCMS coolant. The system can produce a maximum electrical power of 4.76 kW/m2 and a maximum thermal power of 19.53 kW/m2. Throughout the day, total electrical and thermal energies are approximately 4.1 kWh and 58.8 MJ.

Performance research and multi-objective optimization of concentrating photovoltaic/thermal coupled air source heat pump heating system

In this paper, TRNSYS is used to simulate the heating systems of air-cooling concentrating photovoltaic/thermal (CPVT) coupled air source heat pump and water-cooling CPVT coupled air source heat pump. Besides, Grasshopper is adopted for multi-objective optimization of air-cooling system. This study not only proposed two hybrid systems and enriched the research of CPVT coupled air source heat pump, but also proposed a multi-objective optimization method, which uses Grasshopper to invoke TRNSYS. Compared with the air source heat pump system, the annual average COP of heat pump in the air-cooling system increases by 22.8%, and that of the water-cooling system decreases by 6%. The primary energy saving rate of the air-cooling system is 1.06 times and 6.67 times that of the water-cooling system and the air source heat pump system. The optimized air-cooling system reduces the annual total cost by 2.83%, and increases the energy utilization coefficient by 4.76%. The proposed air-cooling system has obvious advantages in energy saving and improving COP of heat pump. This study is useful for the cost savings and energy conservation of air-cooling concentrating photovoltaic/thermal (CPVT) coupled air source heat pump systems based on urban public buildings.

Recent techniques for cooling of concentrated photovoltaic thermal systems

Recent techniques for cooling of concentrated photovoltaic thermal systems

Energy management of a concentrated photovoltaic−thermal unit utilizing nanofluid jet impingement in existence of thermoelectric module

To generate a concentrated photovoltaic–thermal (CPVT) unit system, linear Fresnel concentrators have been attached to a PV unit and a thermoelectric generator (TEG) has been combined in this work to boost productivity. In the presence of concentrators, the temperature of the silicon layer increases. While electrical output is enhanced for the CPVT unit, the non-uniform isotherms can decrease the lifetime of the panel, so confined jets of alumina–water nanofluid have been applied for cooling. To validate the numerical code, previous papers were examined and good accommodations were reported. Various values of the inlet temperature (T in) and velocity (V in) of jets have been analysed. The impacts of installing concentrators on overall performance and CO2 mitigation have been investigated. An increase in V in leads to an incremental increase in thermal performance of about 4.2% and thermal uniformity is enhanced by about 13.91%. The thermal power of the system is enhanced by about 2.19 times as a result of adding concentrators. Also, the PV power is enhanced by 86.22% in the presence of the reflectors. With the increase in T in, the thermal and electrical performance decrease by about 19.95% and 5.24%, respectively. Installing concentrators enhances the overall performance by about 6.55%. After 10 years, the amount of CO2 mitigation for the CPVT-TEG system reaches 148.28 ton.

Mathematical model to optimize solar spectrum allocation for a Stirling engine-based concentrated photovoltaic thermal system

Incorporating a Stirling engine into a concentrated photovoltaic thermal system (CPVT) with spectral beam splitting converts wasted photovoltaic panel energy into electricity, boosting efficiency. However, complex Stirling engine development slows system performance estimation, which explains the scarce studies on the Stirling engine-based CPVT spectrum allocation range. Furthermore, the literature shows inconsistent remarks on low or high-energy photon allocation to a thermal system and uncertainty of solar irradiance variation effect on spectrum allocation. A generic methodology is presented for determining optimal spectrum allocation for a Stirling engine-based CPVT system with a dichroic filter. The analysis in this work shows that considering non-absorption and thermalization losses improves performance by 13.2 % compared to solely accounting for non-absorption loss in beam splitting. Additionally, a shift of up to 40 nm in the optimal spectrum allocation range is observed with a daily spectral irradiance source compared to the AM1.5D source. The PV mathematical model is validated with an average error of 8.9 %, and the Stirling engine model with an error of 5.2 %. Through this study, future researchers can determine an optimal spectrum allocation range for Stirling engine-based CPVT that maximizes PV performance based on a specified location with the proposed generalized CPVT model.

Effects of climate variables and nanofluid-based cooling on the efficiency of a liquid spectrum filter-based concentrated photovoltaic thermal system

Effects of climate variables and nanofluid-based cooling on the efficiency of a liquid spectrum filter-based concentrated photovoltaic thermal system

Reducing the cost of electricity storage with a novel solar thermal support scenario in pumped thermal energy storage (PTES)

Pumped Thermal Electricity Storage (PTES) is a system that allows the conversion of electrical energy into thermal energy and its more cost-effective storage. Thermal integration is one of the methods applied to increase the round-trip efficiency (ηrt) of PTES. The disadvantage of TI-PTES systems that use solar energy as a heat source is the need to store hot water with an additional heat storage system due to fluctuations in solar energy. Additional heat storage system significantly increases the cost of energy storage. In this study, a novel solar thermal integration scenario was presented. The novelty in the study has been utilizing the same water tanks for both the thermal storage of electricity and thermal support. Thermal support for PTES was provided by a concentration photovoltaic thermal (CPVT) system. Thus, it was aimed to reduce additional heat storage costs. With the proposed design (STI(CPVT)-PTES), the power supplied to the compressor (ẆCOMP) and round-trip efficiency varied in the range of 0.52–2.6 MW and 41.1–128.3 %, respectively. The overall exergy efficiency of the system varied between 19 % and 42 % depending on solar energy, sunshine duration, and parameter values. The parameter that most economically affected the system was the mass flow rate of the heat source (ṁhs), and the lowest levelized cost of storage (LCOS) was obtained as 0.227 $kWh−1 at a ṁhs of 250 kg/s. With STI(CPVT)-PTES, a reduction in LCOS ranging from 1.3 % to 33.2 % was achieved compared to other thermal integration scenarios. Analysis results revealed that the proposed system has a high potential to be an alternative to other thermally integrated PTES systems.

Numerical Assessment of the Thermal Efficiency of a Concentrated Photovoltaic/Thermal (CPV/T) Hybrid System Using Air as Heat Transfer Fluid

Numerical Assessment of the Thermal Efficiency of a Concentrated Photovoltaic/Thermal (CPV/T) Hybrid System Using Air as Heat Transfer Fluid

Simulation for impact of nanofluid spectral splitter on efficiency of concentrated solar photovoltaic thermal system

Nanofluid filter has been applied in current research to boost the efficiency of a concentrated photovoltaic thermal (CPVT) module. Owing to tunable optical features of nanofluid and its greater thermal characteristics, it was utilized as spectral filter and cooling fluid in the present proposed solar system. The mixture of silver and water has been utilized as working fluid and its concentration within the filter and cooling duct are 0.005 and 0.05, respectively. Three dimensional models have been proposed involving spectral distribution of solar irradiation. Also, transmissivity of nanofluid filter has been derived according to empirical models. Two structures have been applied for cooling duct: 1) straight bottom wall; 2) wall with triangular obstacles (semi-wavy wall). As velocity of nanofluid within the filter (Vf) section enhances, the electrical performance increases about 3.4 %. For case 4, with augment of concentration ratio (CR) from 3 to 30, the electrical performance reduces about 13.57 % while thermal performance augments about 5.68 %. When CR=10, utilizing case 4 makes electrical and thermal performance to enhance about 25.09 % and 22.36 % in comparison to case 1. Also, cell temperature decreases about 47.82 % with applying the filter within the second structure of the cooling duct.

Concentrated Photovoltaic Thermal System (CPVT): Dust Effect and Solution for Enhancing Efficiency in Photovoltaic Technology

Concentrated Photovoltaic Thermal System (CPVT): Dust Effect and Solution for Enhancing Efficiency in Photovoltaic Technology

Effects of partial shading on thermal stress and exergetic efficiency for a high concentrator photovoltaic

Highly concentrated photovoltaic systems can produce higher energy yields than conventional photovoltaic panels but have yet to reach widespread deployment, partly because of lower lifetime and hence cost effectiveness. One limiting factor in the lifetime is the excessive generation of thermal stress. This study takes a multi-objective approach to the calibration of a highly concentrated photovoltaic thermal hybrid system. Novelty is found by exploring the relationship and trade-off between thermal stress and exergetic efficiency. A variety of optical configurations are compared by partially shading the input aperture of the primary optics. Similarly, adjustments to the receiver are made by changing the angle of the solar cell by 45°. To minimise light spillage. The primary and secondary optic positions stay the same throughout all calibrations.By experimentally validating a COMSOL model of the concentrator photovoltaic system (including irradiance distribution) a thorough analysis is conducted. It was found that the maximum thermal stress within the solar cell in this study could drop by almost 10 % with small losses (<3.5 %) to total exergetic efficiency after only small changes to receiver position. Further investigations into other specialised concentrator photovoltaics are required to understand the range of impact on thermal stress.