Concentrated Photovoltaic Thermal Research Articles

4E assessment of a hybrid RO/MED-TVC desalination plant powered by CPV/T systems

The growing demand for pure water and the challenges of energy transition encourage the use of renewable energies in desalination. This investigation aims to carry out an energy, exergy, economic and environmental analysis of a hybrid RO/MED-TVC desalination powered by CPV/T systems. The electrical and thermal needs of the hybrid desalination unit are supplied by a concentrated photovoltaic solar field. Computational models are elaborated and validated for the CPV/T, RO and MED-TVC units. Three reverse osmosis desalination configurations with two energy recovery strategies are studied: single stage-RO, double stage-RO and three stage-RO. The results showed that the conversion rate increased from 27 to 48 % and from 37 to 62 % and from 49 to 72 % by increasing the feed pressure from 5000 to 8000 kPa for the reverse osmosis units at one, two and three stages, respectively. The exergy destroyed in the whole system was less for Pelton turbine energy recovery than for a pressure heat exchanger. The number of RO membrane modules was minimum for double RO-stage and maximum for triple RO-stage. The results showed that the MED performance improved by 217 % and the specific thermal consumption was reduced by 68.5 % by increasing the number of effects from 4 to 12. The results highlighted that the production of electricity and thermal energy, electricity injected to the grid and the thermal energy storage are high for Sharm-el-Sheikh and low for Tripoli. The levelized costs of water were 0.424, 0.436, 0.448, 0.457, 0.463, 0.466 and 0.468 US$/m3 for Sharm-el-Sheikh, Nouakchott, Benghazi, Tangier, Doha, El Kuwait and Tripoli, respectively. The values of carbon intensity were also 0.67, 0.68, 0.71, 0.78, 0.84, 0.86 and 0.87 kg CO2/m3 for Sharm-el-Sheikh, Nouakchott, Benghazi, Tangier, Doha, El Kuwait and Tripoli, respectively. The overall results demonstrated that the double-stage-RO with energy recovery from the pressure exchanger combined with the ten-effect MED-TVC was the best solution to achieve efficient desalination using the electricity and heat produced by concentrated photovoltaic thermal systems.

Experimental Investigation of a Concentrating Bifacial Photovoltaic/Thermal Heat Pump System with a Triangular Trough

The heat absorbed by the heat transfer fluid for cooling a concentrated photovoltaic thermal (CPVT) solar collector can be used for purposes such as residential heating and cooking. Because of the combined production of heat and power, these systems are proposed for individual or commercial use in rural areas. In this study, a hybrid system was proposed to increase the electrical efficiency of the system. Experiments were conducted in winter conditions. Two operational modes were compared, namely a CPVT system with HP (HP-CPVT) and without HP (CPVT). The evaporator of the heat pump was settled inside the triangular trough receiver. The effects of cooling the PV system with a heat pump in the bifacial CPVT system on the electrical and thermal energy efficiencies were investigated. The electricity and thermal energy efficiencies of the CPVT system were calculated as 12.54% and 38.37% in the HP-CPVT system, respectively, and 10.05% and 81.97% in the CPVT system, respectively. The electrical exergy efficiencies of the CPVT system with and without HP were 14.65% and 10.73%, respectively. The thermal exergy efficiencies of the CPVT system with and without HP were 82.47% and 85.63%, respectively. The thermal heat obtained from the HP-CPVT system can be used for heating needs. Thus, the bifacial HP-CPVT system was an example of the micro-CHP system.

Thermal and exergy analysis of Pin-finned heatsinks for nanofluid cooled high concentrated photovoltaic thermal (HCPV/T) hybrid systems

• Cooling performance of HCPV/T is systematically investigated. • Different shaped pin-finned heat sinks (inline and staggered) are examined. • Thermal performance is determined for MWCNT nanofluids. • Exergy efficiencies of pin-fin heat sinks in HCPV/T are evaluated. • 2% MWCNT nanoparticle concentration is found to be the optimum. Cooling of High Concentrated Photovoltaic (HCPV) cells is a major concern among researchers due to higher heat generation in the cells from highly concentrated solar radiation. In the present investigation, a numerical study of the High Concentrated Photovoltaic Thermal (HCPV/T) system is conducted for the combined effect of nanofluids and pin-finned heatsinks on the cooling performance. The investigation is carried out for AZUR SPACE solar cell (Model: 3C44C) for 1000 Concentration Ratio (CR) and the Reynolds number ( Re ) varies within the laminar range (600 ≤ R e ≤ 2200). Different shapes of pin-fins and their orientations are systematically investigated for the effect of Multi-walled Carbon Nanotube (MWCNT) nanoparticles in a base fluid. The results show a significant reduction in the temperature (up to 18K) of the solar cells for the MWCNT nanofluid compared to its base fluid counterpart. A higher heat transfer characteristics (Nusselt numbers) and lower average temperature of top surface of HCPV cells are found to occur for the staggered arrangements of pin-fins. It is also noticed that the volume concentration of MWCNT in water affects heat transfer characteristics and reduction in temperature takes place up to the volume concentration of 2%. About 1.3% reduction in temperature is predicted for adding MWCNT nanoparticle concentration from 0.5% to 2%. However, in terms of exergy efficiency, maximum overall exergy (about 67% for water flow rate of 0.00167 kg/s) is found for square pin-fins with inline arrangements. The average increase in Nusselt number from inline to staggered arrangement are around 11%, 74%, and 22% respectively for circular, square and triangular fins. The maximum electrical efficiency reaches to 42.2% for both 2% and 4% MWCNT with staggered circular pin-fins for a mass flow rate of 0.0058kg/s. Finally, it appears that a combination of nanofluids and pin-finned heatsinks gives a better cooling rate in the HCPV/T system and could be a promising alternative along with other cooling techniques.

Optical performance investigation on flat receiver for parabolic trough solar collector based on the MCRT method

Parabolic trough solar collector (PTC) system with a flat receiver is widely used in concentrating photovoltaic/thermal (CPV/T) systems, where the flat receiver and PTC are the key components to exchange the solar radiation into heat or electricity. The optimal design and geometric structure of PTC using a flat receiver are essential to achieve high efficiency and energy yield for CPV/T systems. In this paper, a mathematical model of PTC with the flat receiver was developed to investigate and evaluate optical properties based on Monte Carlo Ray Tracing method, whose feasibility and reasonability was verified by the comparison between the model and published literature's results. An innovative method was proposed to calculate the minimum width by vectoring. The optimal geometric design for the same geometrical focusing ratio was derived through simulations based on MATLAB. The influence of geometric parameters and errors were discussed, which showed that the optical performance has large variations in local concentration ratio (LCR) at the center of the flat receiver and is superior at rim angles of 75°–90° under ideal conditions with the same geometric focusing ratio. The errors were found to have a significant effect on the optical performance, especially on the peak LCR.

Performance evaluation of a MED-MVC desalination plant driven by a concentrated photovoltaic thermal system and an organic Rankine cycle

In this work, a novel integration of a multi-effect distillation (MED) desalination plant driven by mechanical vapor compression and powered by a concentrated photovoltaic thermal system and an organic Rankine cycle is presented. The combined system is designed to produce fresh water at a capacity of 2500 m3/day. Three desalination configurations are studied, forward, backward and parallel cross feed. Mass, energy and exergy balances for different component of the desalination plant are elaborated and validated. The results showed that the specific electricity consumption of MED increased by 69 %, 68 % and 40 % by increasing the steam temperature from 80 to 100 °C, for the forward, backward and parallel cross feed configurations, respectively. The performance ratio decreased by 40 %, 21 % and 28 % by increasing the seawater salinity from 32,000 ppm to 47,000 ppm, for the forward, backward and parallel cross feed configurations, respectively. The results also showed that the solution for optimizing the energy consumption of the compressor by using staged compression equipped with intermediate cooling has enabled a saving of approximately 12 % in terms of electricity consumption. The levelized cost of water desalinated for optimized MED configurations ranged from 0.4 to 1.965 US$/m3. The overall results showed that the parallel cross-feed is the best configuration for desalination driven by a concentrated photovoltaic thermal system and an organic Rankine cycle. The performance of the current desalination unit has been improved compared to that of other MED technologies integrated with renewable energy sources.

Evaluation of a nanofluid-based concentrating photovoltaic thermal system integrated with finned PCM heatsink: An experimental study

Concentrating photovoltaic is an efficient system to implement instead of single photovoltaic modules. Nevertheless, the PV performance and life span would decrease by increasing the cell temperature. This article aims to implement PV cooling methods with a novel hybrid configuration. Accordingly, five cooling methods including concentrating photovoltaic thermal (CPV-T) with water circulation, CPV-T with nanofluid circulation, CPV-T with PCM and nanofluid circulation, CPV-T with nanofluid circulation and finned-PCM, and CPV-T with water circulation and finned-PCM have been analyzed experimentally in a warm climate. After analyzing and comparing the outcomes, it was found that the CPV-T with nanofluid circulation and finned-PCM (CPV-T/NF/FPCM) technique had the most efficient cooling performance. It enhanced the daily average electrical and thermal efficiency of the CPV system, which improved to 17.02% and 61.25%, respectively. Also, the average PV module temperature decreased by about 26.6 °C compared to the CPV units’ temperature. Furthermore, the average system output power reached 20.18W, while the output power for the single CPV achieved a difference of about 4 W compared to the CPV-T/NF/FPCM unit. This study obtained the maximum cooling achievable in actual conditions and technical gaps coverage for a CPV system using commercially available PCM, metal fins, and nanofluids simultaneously.

Hybrid nanofluid filtered concentrating photovoltaic/thermal-direct contact membrane distillation system for co-production of electricity and freshwater

The membrane distillation (MD) systems integrated with photovoltaic/thermal (PV/T) collectors can hardly obtain large permeate flux and favorable electrical performance simultaneously. Therefore, an innovative hybrid nanofluid filtered concentrating PV/T (CPV/T)-direct contact membrane distillation (DCMD) system is proposed. The novelty is that Ag/saline water nanofluid acts as a multifunctional fluid capable of absorbing solar spectrum, which cannot be efficiently utilized by solar cells, and converting it into heat to directly produce water in DCMD. Mathematical models of both nanofluid filtered CPV/T and DCMD are established to evaluate the system performance. Results indicated that nearly 70% of solar radiation is converted into useful energy by the nanofluid filtered CPV/T device. Besides, detailed parametric studies are performed to explore how the system performance is affected by the operation and design parameters. It is found that Ag/saline water nanofluid can be heated to 353 K for desalination, at which, the DCMD module can produce 26.4 kg m−2 h−1 of fresh water. Meanwhile, the electrical efficiency of the system is 12.2% and the equivalent system thermal efficiency can reach a maximum of 71.3%. Furthermore, we demonstrate that the use of Ag/saline water nanofluid as feed stream can mitigate the temperature polarization and improve DCMD performance.

4E analysis of a concentrating photovoltaic thermal system (CPVT) with examining the effects of flow regime and concentration ratio

Due primarily to environmental concerns, attention to renewable energy sources has increased significantly in recent years. Of these sources, solar energy and wind energy have received the most study. With the improvement in photovoltaic (PV) panels’ efficiency, photovoltaic (PV) panels have grown significantly in popularity among the various solar energy methods. One hybrid system that uses these panels is the concentrating photovoltaic thermal (CPVT) system. Throughout the present study, an analysis of energy, exergy, environmental, and economic (4E analysis) aspects have been conducted. In addition, the life cycle assessment (LCA) method has been used to evaluate the system’s performance. Moreover, the effects of the working fluid flow type regime and the concentration ratio (CR) have been evaluated. The results indicate that CPVT will have about 63% of the total energy efficiency and 9% of the total exergy efficiency. CO2 emissions for the system could cost as much as 20 cents a year in a worst-case scenario.

MXene incorporated nanofluids for energy conversion performance augmentation of a concentrated photovoltaic/thermal solar collector

This research work introduces emerging two-dimensional (2D) MXene (Ti3C2) and Therminol55 oil-based mono and hybrid nanofluids for concentrated photovoltaic/thermal (CPV/T) solar systems. This study focuses on the experimental formulation, characterization of properties, and performance evaluation of the nanofluid-based CPV/T system. Thermo-physical (conductivity, viscosity, and rheology), optical (UV-vis and FT-IR), and stability (Zeta potential and TGA) properties of the formulated nanofluids are characterized at 0.025 wt.% to 0.125 wt.% concentrations of dispersed particles using experimental analysis. By suspending the nanomaterials, photo-thermal energy conversion is improved considerably, up to 85.98%. The thermal conductivity of pure oil is increased by adding Ti3C2 and CuO nanomaterials. The highest enhancements of up to 84.55% and 80.03% are observed for the TH-55/Ti3C2 and TH-55/Ti3C2 + CuO nanofluids, respectively. Furthermore, dynamic viscosity decreased dramatically over the temperature range investigated (25°C-105°C), and the nanofluid exhibited dominant Newtonian flow behavior as viscosity remained nearly constant up to a shear rate of 100 s−1. Numerical simulations of the experimentally evaluated nanofluids are performed to evaluate the effect on a CPV/T collector using a three-dimensional transient model. The numerical analysis revealed significant improvements in thermal and electrical energy conversion performance, as well as cooling effects. At a concentrated solar irradiance of 5000 W/m2 and an optimal flow rate of 3 L/min, the highest thermal and electrical energy conversion efficiency enhancements are found to be 12.8% and 2%, respectively.

Insight into the Investigation of Diamond Nanoparticles Suspended Therminol®55 Nanofluids on Concentrated Photovoltaic/Thermal Solar Collector.

Nanofluids are identified as advanced working fluids in the solar energy conversion field with superior heat transfer characteristics. This research work introduces carbon-based diamond nanomaterial and Therminol®55 oil-based nanofluids for implementation in a concentrated photovoltaic/thermal (CPV/T) solar collector. This study focuses on the experimental formulation, characterization of properties, and performance evaluation of the nanofluid-based CPV/T system. Thermo-physical (thermal conductivity, viscosity, and rheology), optical (UV-vis and FT-IR), and stability (Zeta potential) properties of the formulated nanofluids are characterized at 0.001–0.1 wt.% concentrations of dispersed particles using experimental assessment. The maximum photo-thermal energy conversion efficiency of the base fluid is improved by 120.80% at 0.1 wt.%. The thermal conductivity of pure oil is increased by adding the nanomaterial. The highest enhancement of 73.39% is observed for the TH-55/DP nanofluid. Furthermore, dynamic viscosity decreased dramatically across the temperature range studied (20–100 °C), and the nanofluid exhibited dominant Newtonian flow behavior, with viscosity remaining nearly constant up to a shear rate of 100 s−1. Numerical simulations of the nanofluid-operated CPV/T collector have disclosed substantial improvements. At a concentrated solar irradiance of 5000 W/m2 and an optimal flow rate of 3 L/min, the highest thermal and electrical energy conversion efficiency enhancements are found to be 11 and 1.8%, respectively.

A Review on Heat Extraction Devices for CPVT Systems with Active Liquid Cooling

Numerous numerical and experimental studies have been conducted regarding the Concentrated Photovoltaic Thermal (CPVT) system because of its significant potential for efficient conversion of solar energy. The overall efficiency of the CPVT system is strongly dependent on the device, which extracts excess heat from photovoltaic cells. The most efficient cooling technology involves active cooling, which means that heat is collected from the PV cell via the forced flow of heat transfer fluid. This research paper provides an extensive discussion on devices dedicated to active-cooling CPVT systems, taking into account the latest solutions. First, a short introduction regarding CPVT systems and their main components is presented. The second part of this study presents state-of-the-art solutions in the field of heat extraction devices for the active cooling of photovoltaic cells. The available solutions are classified into two main groups depending on the scale of internal channels: macro- and micro-. Each geometry of the heat receiver is juxtaposed with the corresponding concentrating element, photovoltaic cell, concentration ratio, heat transfer fluid, and operating parameters of the specified system. In addition, this paper discusses the advantages and disadvantages of various devices for heat extraction and provides a comparative study of these devices. Finally, a set of recommendations for CPVT cooling devices is provided.

Performance investigation of SUNTRAP module for different locations: An energy and exergy analysis

Concentrating Photovoltaic/Thermal (CPV/T) systems can harness the freely available solar energy to simultaneously generate electricity and sensible heat. Using the principles of optical concentration, they can generate more electrical energy per unit area of solar cells and provide a better quality of thermal energy. In this work, we have developed an analytical model to simulate and predict the performance of a dense array hybrid CPV/T collector called “SUNTRAP.” The concentration of incident radiation is achieved using a reflective type three-dimensional cross-compound parabolic concentrator (3DCCPC) with a geometric concentration ratio of 3.6 × . The extraction of heat from the solar cells is achieved by allowing water to flow through the copper cooling duct on which the solar cells with CCPC are bonded. Using previously developed algorithms, the optical efficiency of the CCPC is calculated as a function of solar azimuth and altitude angle. The obtained optical efficiency is coupled to the thermal model to obtain the temperature distribution in the collector. The numerical results are in good agreement with the experimental measurements obtained at the outdoor solar laboratory at Penryn Campus, Cornwall. The average deviation in outlet water temperature between the numerical and experimental ones is 1.9%. The total electrical and thermal energy obtained from the CCPC-PV/T module on an experimental day is 1.21 kWh/m2 and 46.46 kWh/m2. A parametric study was done to obtain the effect of flow rate and external wind velocity on the performance of the collector. The solar cell temperature is found to decrease with an increasing flow rate. The performance prediction of the CCPC-PV/T module at Penryn shows that the module produced maximum energy in August, producing 7.51 kWh/m2 of useful energy. An economic analysis was performed to obtain the Levelized cost of electricity (LCOE) that the CCPC-PV/T module can deliver, and the LCOE was found to be £1.08/kWh. The coupled model is also utilised to predict the performance of the system for five different geographical locations, including Chennai, Rome, Alice Springs, Montreal, and Barrow. The model considers optimum panel tilt and time-dependent optical efficiency of the concentrator while estimating the energy output. Based on the results, the overall performance of the collector was found to be good in Chennai, with an annual electrical energy gain of 51.95 kWh/m2 and an annual thermal energy gain of 1164 kWh/m2.

Novel design of concentrating photovoltaic thermal collector – A comparative analysis with existing configurations

The aim of this paper is to propose a novel concentrating photovoltaic thermal (CPVT) collector based on parabolic trough concentrator with a semi-cylindrical receiver, and provide a comprehensive comparative analysis of the proposed configuration with the main existing CPVT collectors. To this end, a thermal model of the considered solar collectors is developed to investigate the impact of the receiver’s design on the collector’s performance in terms of their thermal, electrical, primary energy and exergy efficiencies. A residential building, located in the Moroccan city of Ouarzazate, characterized by its hot semi-arid climate, is considered as a case study to investigate the integration of solar collectors in air-conditioning application. A performance, economic and environmental analyses of CPVT driven cooling system are conducted by means of key indicators such as, solar coefficient of performance (SCOP), discounted payback period (DPP), levelized cost of cooling (LCOC), savings-to-investment ratio (SIR) and saved greenhouse gases (GHG) emissions.The results revealed that the proposed CPVT collector exhibited the highest primary energy efficiency with a value of 0.798. The performance outcomes of the solar cooling systems proved that a SCOP of 0.488 was achieved by the proposed CPVT collector followed by those based on the triangular, tubular and rectangular receivers with a value of 0.436, 0.406 and 0.367 respectively. Furthermore, from an economic perspective, the novel CPVT configuration has been proven to be the most cost-effective one with a LCOC, DPP and SIR of 0.129 $/kWh, 12.3 years and 1.488, respectively. Moreover, this configuration was found to be the most eco-friendly one with the lowest greenhouse gases emissions. This study could contribute to the promotion of the sustainable CPVT technology and is expected to be a guideline to select the most suitable configuration of CPVT collectors for solar cooling purposes.

Recent progresses and challenges in cooling techniques of concentrated photovoltaic thermal system: A review with special treatment on phase change materials (PCMs) based cooling

Concentrated Photovoltaic (CPV) system is one of the efficient and economical photovoltaics (PV) technologies. The fundamental principle of using CPV system is a substitution of expensive cell area with inexpensive optics. Concentrating the solar radiation on small areas enhances the power output. However, operating at high temperatures can potentially impair their life span and performance. Thus, cooling medium plays a crucial role in refining the CPV system's efficiency. The integration of the CPV system with Phase change materials (PCMs) provides a state-of-the-art hybrid design for both thermal and electrical outputs, suggesting a better utilization of solar energy. Nano-enhanced Phase Change Materials (NePCMs) were demonstrated to be the best combination for optimal behavior, such as storing and releasing energy quicker during the phase transition process without help from external systems. Key objective of this review article is to present the latest works and technical challenges on the application of PCMs and NePCMs in Concentrated Photovoltaic Thermal (CPVT) as cooling and thermal energy storage mediums to improve PV cell efficiency. This review leads to the current gaps in the research and recommends future work on developing new PCMs, and NePCMs integrated CPV systems for improved performance, life span and economic feasibility. • Different active and passive cooling techniques of CPVT systems are presented. • Thermal regulation of PCM integrated with CPVT system are extensively analyzed. • Thermal regulation of NePCMs integrated CPVT systems are discussed. • Technical challenges associated with PCM integrated CPVT systems are discussed.

Experimental and Theoretical Modelling of Concentrating Photovoltaic Thermal System with Ge-Based Multi-Junction Solar Cells

Climate change is one of the biggest environmental, political, economic, technological, and social challenges of the 21st century. Due to ever-increasing fossil fuels costs. The world energy system should be transitioned to renewable energy sources to mitigate greenhouse gas emissions. Solar energy is one of the suitable alternatives to fossil fuel usage. Currently, the most widely available solar technologies are solar photovoltaic (PV) and solar thermal. The integration of these two techniques enables the exploitation of the most significant amount of solar radiation. This combination has led to a hybrid photovoltaic/thermal system (PV/T). Concentrated solar radiation on PV cells, known as concentrated photovoltaic (CPV), effectively decreases PV receivers’ area and harnesses the same quantity of solar radiation. However, the main problem with CPV is the elevated PV surface temperature, which often requires active cooling. This issue can be solved by introducing a Concentrating Photovoltaic Thermal (CPVT) system. In this article, a new CPVT hybrid system based on Point Focus Fresnel Lens (PFFL) and embedded Multi Junction Photovoltaic (MJPV) (GaInP/InGaAs/Ge) cells has been experimentally investigated and numerically modelled under indoor conditions. Experiments and simulations were carried out at different heat transfer fluid (HTF) flow rates and under constant irradiation emitted from a sun simulator. The results indicate that the thermal and electrical performance of the CPVT system improves under the testing conditions, where the total efficiency was 68.7% and 73.5% for the experimental and CFD models, respectively. At the same time, the highest thermal efficiency of the experimental and CFD models was 49.5% and 55.4%, respectively. In contrast, the highest electrical efficiency was 36.5% and 37.1%. Therefore, the CPVT system has an excellent possibility of being competitive with conventional power generation systems.

A parametric assessing and intelligent forecasting of the energy and exergy performances of a dish concentrating photovoltaic/thermal collector considering six different nanofluids and applying two meticulous soft computing paradigms

In the present study, the application of six engine oil-based Nano fluids (NFs) in a solar concentrating photovoltaic thermal (CPVT) collector is investigated. The calculations were performed for different values of nanoparticle volume concentration, receiver tube diameter, concentrator surface area, receiver length, receiver actual to the maximum number of channels ratio, beam radiation, and a constant volumetric flow rate. Besides, two novel soft computing paradigms namely, the cascaded forward neural network (CFNN) and Multi-gene genetic programming (MGGP) were adopted to predict the first law efficiency (ηI) and second law efficiency (ηII) of the system based on the influential parameters, as the input features. It was found that the increase of nanoparticle concentration leads to an increase in ηI and a decrease in ηII. Moreover, the rise of both the concentrator surface area (from 5 m2 to 20 m2) and beam irradiance (from 150 W/m2 to 1000 W/m2) entails an increase in both the ηI (by 39% and 261%) and ηII (by 55% and 438%). Furthermore, it was reported that the pattern of changes in both ηI and ηII with serpentine tube diameter, receiver plate length, and absorber tube length is increasing-decreasing. The results of modeling demonstrated that the CFNN had superior performance than the MGGP model.

Design and field testing of a sunflower hybrid concentrator photovoltaic-thermal receiver

Hybrid concentrator photovoltaic-thermal (CPV/T) systems generate both electricity and process heat by splitting concentrated sunlight onto CPV cells and a thermal receiver utilizing a heat-transfer fluid. Such energy co-generation increases total conversion efficiency and reduces system costs to compete with more widely used electricity and heat-generation methods in target markets. Here, we design and prototype a sunflower-like CPV/T system that collects a portion of the incoming sunlight using triple-junction CPV cells operating with an average temperature of <85°C. In the same receiver, thermal output >245°C may be generated from both waste heat from the CPV cells and a spatially separated fraction of the incoming concentrated light illuminating a heat-exchanger coil. In total, >65% of incident sunlight is converted to electricity or process heat. On-sun field tests validate this model and guide future development, and a techno-economic model demonstrates a US average levelized cost of heat of 2.5 ¢/kW t h. • Solar co-generation of heat and electricity with >65% efficiency • Process heat output of >245°C with CPV cells <85°C • US average levelized cost of heat of 2.5 ¢/kW t h Process heat makes up approximately 36% of the energy usage within the US manufacturing sector, with many applications requiring medium temperature. Here, Skelton et al. design, build, and test a hybrid concentrator photovoltaic system that generates both electricity and medium- to high-temperature process heat at >65% efficiency.

Thermal conductivity, reliability, and stability assessment of phase change material (PCM) doped with functionalized multi-wall carbon nanotubes (FMWCNTs)

The thermal properties of Phase Change Material (PCM) can be altered by introducing nanoparticles, and composite formed from the addition of nanoparticles are termed Nano-Enhanced Phase Change Materials (NEPCM). In the present study, the enhancement of thermal conductivity and feasibility study of dispersing multi-walled carbon nano tubes (MWCNTs) and functionalized MWCNT (FMWCNTs) in various mass fractions (AFMW-0.1, AFMW-0.3, AFMW-0.5, AFMW-0.7, AFMW-1.0) into the Plusice A70 PCM were examined. Differential scanning calorimetry (DSC) and TEMPOS thermal analyzer measured the latent heat storage, melting temperature, and thermal conductivity of the nano PCM composite. The thermal conductivity measured for the prepared nanocomposite showed a 109.5% enhancement for 1.0 wt% of non-functionalized MWCNT and 150.7% enhancement for 1.0 wt% of functionalized MWCNT compared to pristine PCM's thermal conductivity. This statement concluded that 50% enhancement for a 1.0 wt% of functionalized MWCNT compared to non-functionalize MWCNT immersed in A70 PCM. The nano composite PCM was thermally stable up to 200 °C and no chemical reaction takes place between the base PCM and nanoparticles. The result shows that the microscopic structure remained stable for the nanocomposite while the optical transmittance reduced noticeably for the nanocomposite relative to pristine A70 PCM. It can be concluded, the prepared nano composite PCM may be useful for solar thermal, photovoltaic thermal system, and low concentrated photovoltaic thermal system applications.

Comprehensive energy, exergy, and economic analysis of the scenario of supplementing pumped thermal energy storage (PTES) with a concentrated photovoltaic thermal system

The pumped thermal energy storage (PTES), which is designed to store electricity more cheaply, is one of the issues that have been discussed in recent years. In the PTES system, electrical energy is stored as hot water employing a heat pump, and when needed, it is converted back into electrical energy by using a heat engine. As a result of supporting the PTES system with a heat source, the performance coefficient of the heat pump is increased, thereby increasing the round-trip efficiency of the system. These systems are called thermally integrated PTES (TI-PTES). The novelty in this study was the thermal integration method applied to the PTES system. In the thermal integration scenarios were given in the literature, solar collectors, geothermal sources, district heating, and industrial waste gas were used as heat sources. In the presented study, the part of photovoltaic modules in the system where the electricity to be stored was produced, was designed as a photovoltaic thermal system (CPV/T), and the hot water obtained from the CPV/T units was used to support the PTES system thermally. The proposed PTES system (TI(CPV/T)-PTES) was extensively evaluated in terms of thermodynamics and economics, and thermodynamic analyzes were carried out for different values of the design parameters of the CPV/T and PTES system. Depending on the change in parameter values, the electricity storage capacity of the system changed between 0.85 MW and 9.1 MW, and the round-trip efficiency changed between 48% and 81%. As a result of thermo-economic calculations, the lowest levelized cost of storage (LCOS) for the TI(CPV/T)-PTES system was obtained as 0.278 $kWh−1. The results of the thermo-economic analysis revealed that lower LCOS values can be obtained in regions with higher solar radiation values. In addition, the TI(CPV/T)-PTES system was compared with other energy storage systems economically and a lower LCOS value was obtained for certain parameter values compared to Li-ion and VRF battery technologies.

Design and performance validation on a solar louver with concentrating-photovoltaic-thermal modules

Traditional building integrated photovoltaic (BIPV) windows face the problems of low efficiency and unsatisfactory daylighting. Given this, this paper proposes a solar louver to harvest solar energy in the vertical building space for on-site electricity and heat generation. The solar louver is composed of concentrating photovoltaic-thermal (CPV-T) modules and allows users to adjust interior daylight according to individual demand. The design scheme of the CPV-T module and the solar louver is introduced. The CPV-T module's optical characteristics are revealed by optical simulations. The results illustrate that the CPV-T module can concentrate sunlight at the incident angle between 5° and 75° and holds the maximum concentration ratio of 3.14. Moreover, its concentration ratio can exceed 2.5 over the range of light incident angles between 15° and 45°. A prototype of the solar louver is manufactured and experimentally studied under actual weather conditions to illustrate its electricity and thermal collection performance. The results show that within the light incident angle of 20°–50°, the solar louver can maintain electrical efficiency above 4.18% and thermal collection efficiency above 55.6%. Additionally, the effective working hour is greater than 6 h, which provides a possibility to be used on buildings.