Increase In Electrical Efficiency Research Articles

The influence of using MWCNT/ZnO-Water hybrid nanofluid on the thermal and electrical performance of a Photovoltaic/Thermal system

Rising photovoltaic panel temperatures significantly compromise their performance and lifespan, leading to lower power output and conversion efficiency. Consequently, research on PV panel cooling strategies has gained momentum to address these challenges. This study presents an experimental investigation of a photovoltaic/thermal system's performance using a cooling fluid – a multi-walled carbon nanotube/zinc oxide nanofluid. A comparative analysis is conducted on three PV panels: uncooled, water-cooled, and nanofluid-cooled. Notably, our experiment employed a low mass flow rate (0.156 kg/min), significantly lower than typical values reported in prior literature, and a 0.1 wt% nanofluid concentration. Our primary objective was to evaluate the efficacy of MWCNT/ZnO nanofluid in enhancing the thermal management and overall efficiency of a PVT system. This study focused on the impact of nanofluid on electrical efficiency, thermal efficiency, and exergy performance of the system. The results demonstrate significant improvements. The key findings of this investigation reveal that MWCNT/ZnO nanofluid effectively improves the base fluid's thermal properties, leading to substantial enhancements in both electrical and thermal efficiencies of the PVT system. Compared to the uncooled panel, the nanofluid achieved a maximum temperature reduction of 14.9 °C on the panel surface, a 16.8 % increase in average electrical efficiency, and a maximum thermal efficiency of 51.3 % compared to 45.5 % for water cooling. Moreover, the average overall efficiency of the system with nanofluid cooling reached 58.7 %. Furthermore, the implementation of MWCNT/ZnO nanofluid cooling resulted in a significant boost in maximum overall exergy efficiency, surpassing water cooling and conventional systems by 7 % and 27 %, respectively. Additionally, a 3.5 % reduction in entropy generation and exergy destruction was observed compared to the conventional system.

An experiment-based comparison of different cooling methods for photovoltaic modules

Abstract Temperature effect on the performance of a photovoltaic module represents a major concern for expanding the use of solar energy, especially in hot areas. Cooling the PV module is considered an effective method of increasing efficiency by reducing the module cell temperature. An experimental set-up is developed to investigate the effectiveness of different cooling techniques including air cooling, evaporative cooling and water cooling. A comparative study is made among the cooling techniques by simultaneous recording – for the first time – the performance the modules cooled by the different techniques. Experimental measurements dictated that the reduction of the module cell temperature recorded 5 %, 16 %, 17.25, 39.6 % and 44.8 % for passive air cooling, active air cooling, water cooling, evaporative cooling using sprinkler and nozzles, respectively. The best cooling conditions were achieved by evaporative cooling using film of domestic tap-water from nozzles with flow rate of 90–190 L/h/module. The experimental results showed an increase in electrical efficiency of 1.8 % for continuous- against 1.7 % for intermittent-evaporative cooling using water-film from nozzles. The corresponding increase in electrical efficiency on using evaporative cooling by sprinkler is 1.6 % for continuous- against 1.3 % for intermittent cooling. This means there is no significant difference in efficiency values between continuous and intermittent evaporative cooling. This favors the use of intermittent cooling decreases the cost without sacrificing the efficiency value. This makes it possible to identify the recommended method for cooling modules serving in areas of hot weather and moderate climates.

Active cooling of a photovoltaic module in hot-ambient temperatures: theory versus experiment

Abstract The performance improvement of a PV-module is investigated theoretically and experimentally in a long-term research-plan via module cooling by different approaches including passive, active, and evaporative cooling as well as water cooling for the same module. In the present paper, the investigation is conducted to decide on the suitability of active-cooling of the module in hot-ambient temperatures. A module without cooling is used as a base case for comparison against cooled modules with and without fins attached to the module’s rear-surface and extended down in an air-cooling duct underneath the module. At first, a theoretical study of heat transfer through the module is conducted to investigate how the calculated cell temperature and module output power are influenced by the air velocity from a blower, ambient temperature and solar irradiation. The results showed a decrease of cell temperature by about 7–10 °C with a subsequent increase of electrical efficiency. The cell temperature decreases significantly with the increase of duct height and with the increase of the number and length of fins, the same as in passive cooling. The cell temperature decreases by more than 3 °C at duct height of 0.2 m. The calculated values of cell temperature, open-circuit voltage and short-circuit current of the module with and without active cooling agreed reasonably with the present measured values over the day hours of two successive days in summer season. At air velocity of 1.5 m/s, the increase of electrical efficiency by active cooling was found 0.67–0.80 %. Further increase of air-flow velocity or duct-height in active cooling seeking higher efficiency is not recommended due to increase of consumed electric power by air-blower and limited decrease of cell temperature. This concludes that air cooling is not effective in regions of hot ambient temperatures. For a non-cooled module, the cell temperature is related to the ambient temperature in terms of the solar radiation and NOCT, the datasheet value of normal-operating-cell-temperature. The relationship is modified in the present paper to account for air-flow through the duct seeking its extension for application to air-cooled modules.

A permanent insulator system for hydrometallurgy with a significant increase in electric efficiency and without short circuit

A permanent insulator system for hydrometallurgy has been developed with a significant increase in electric efficiency and without short circuits. The system consists of a double electric contact point for each cathode and anode and a new design of the insulating and contact system of the electrodes. The combination of these technologies provides a more uniform electric density inside each cathode and anode, in each cell, and also for the whole electric circuit in the cellhouse. Keeping a consistent maximum performance necessitates using parts with extreme durability against chemical attacks and short circuits. Hence, a comprehensive research into chemical stoichiometry and the behaviour of different molecules resulted in the development of an outstanding chemical resistance level to sulfuric acid and extremely high temperatures throughout the entire hydrometallurgical process. Field observations show that this formulation has been able to resist up to 19 years of continuous operation without maintenance. The goal of these developments combined with a new contact system was to reduce any type of short circuit by 70 to 80%, which in turn increases the electric current effectiveness by 8 to 10%. As a result, higher contact efficiencies have doubled the lifetime of the cathode and anode with this system. Consequently, the overall electric efficiency in a refinery cellhouse can be improved by 10-12%. Observations from real-world applications over the past decades have proven the efficiency of the earlier versions of this new concept. The system was found to be applicable to any type of contact system and has been used in various hydrometallurgical processes with great success. With the increasing price of energy and CO2 production, it has become more important to operate ecologically and efficiently to maximize profitability and this permanent insulator system can address many challenges which lead to a more efficient and cost-effective process.

Impact of liquid spectrum filter and solar tracker on the overall effectiveness of a photovoltaic thermal system: An experimental investigation

The purpose of this experimental research is to improve the electrical and thermal efficiency of an innovative photovoltaic thermal setup equipped with a Fresnel lens, a nanofluid-based liquid spectrum filter, and a dual-axis solar tracker. The nanofluid, which is a combination of water and ethylene glycol solution with 0.3 wt% of ZnO nanoparticles, was used as a cooling medium. The experiments were conducted on different days that were generally sunny, hazy, and cloudy. The maximum output power of the setup increased by 4.8% and 23.8% from no-lens to single-lens concentration and from a single-stage lens to a two-stage lens concentration system, respectively. The integration of a two-stage system with a solar tracker further enhances the output power by 6.1%. Significant enhancement in the performance of the system was achieved using nanofluid coolant and sun-tracking technologies. The incident solar radiation was efficiently utilized, resulting in an appreciable increase in thermal and electrical efficiency of 6.96% and 28.85%, respectively. Therefore, the proposed system is efficient and suitable for solar photovoltaic thermal applications.

Investigating the effect of employing a 24-hour radiative cooling system on the photovoltaic/thermal systems performance: A case-based research

This study aims to investigate the potential of a renewable hybrid system that integrates a nocturnal and diurnal radiative cooling system (RC) and photovoltaic/thermal system (PV/T) as a novel system to supply highly efficient electricity, while also providing a 24-hour radiative cooling system and diurnal preheated water supply. The proposed system comprises a photovoltaic system (PV) fitted with a transparent layer instead of glass, along with two cooling systems. The first cooling system involves water flow within aluminum pipes beneath the photovoltaic panel, while the second cooling system utilizes a silicon dioxide layer as RC. The study employs a novel approach by analyzing the impact of utilizing both nocturnal and diurnal RC on PV/T performance. The results are based on simulations conducted over four days during various months of the year, including January, March, July, and October. The findings of the simulations demonstrate that the utilization of the first cooling method increases the electrical efficiency of PV by 9.1%. Furthermore, the incorporation of RC along with the first method again leads to a 3.7% increase in electrical efficiency. Additionally, the thermal efficiency is estimated to be 37.1% and 20.62% for PV/T and RC-PV/T, respectively. The cooling power of RC during the night reached 287.13 W/m2 in July. A sensitivity analysis of the input parameters reveals that variations in solar radiation and inlet water temperature have the greatest impact on the system's electrical efficiency.

Year-round experimental analysis of a water-based PVT-PCM hybrid system: Comprehensive 4E assessments

In this year-long study conducted in Cairo, Egypt, an innovative water-based photovoltaic-thermal (PVT) system coupled with phase change material (PCM) was evaluated for its ability to enhance building energy efficiency. The system utilizes 22 copper capsules filled with RT35 paraffin wax and a water-cooling duct to ensure optimal electricity generation and heat storage. The proposed system underwent detailed 4E (energy, exergy, economic, and environmental) assessments to compare its performance against traditional uncooled PV panels. The results indicated significant improvements: a reduction in cell temperature by up to 8.3 °C, an increase in electrical efficiency by 4.0–13.3%, and a boost in power output by 4.1–15.9%. Overall, the system demonstrated efficiencies between 27.23 and 67.33%, along with an exergy efficiency peak at 74.64% in July, substantially outperforming the uncooled panel. Economically, the PVT-PCM system achieved a 1.58-year payback period, and carbon emissions were reduced by 32%, highlighting its viability and environmental benefits. The potential of the PVT-PCM system to advance sustainable building energy management was strengthened by this study, providing a significant step forward in integrating renewable energy within architectural designs.

Conceptual design and preliminary experimental study on curved PV ventilated facade assisted heat pump system (CPVF-HP)

Integrating photovoltaic PV with curved architecture boosts renewable energy use and reduces carbon emissions in building applications. This paper proposes a curved PV ventilated facade assisted heat pump system (CPVF-HP), utilizing curved PV ventilation facade as carrier for the application of PV in curved buildings, and enhancing overall energy efficiency through synergistic operation with heat pumps. In the cooling mode, the system employs the heat pump evaporator to pre-cool the air entering the curved PV ventilated facade, thereby reducing the temperature of the PV cells and the air conditioning load of the building. In the heating mode, the CPVF-HP system preheats the air entering the heat pump evaporator using the curved PV ventilated facade, elevating the evaporation temperature of the heat pump. The experimental setup of CPVF-HP is established, and the dynamic performance of the CPVF under various ventilation conditions and its synergistic operational performance with the heat pump have been investigated. The results indicate that CPVF displays considerable difference in irradiance and temperature across its east–west orientation, especially noticeable during morning and afternoon hours, affecting the system's electrical performance. Notably, isotropic scattered radiation improves radiation uniformity and the electrical efficiency of CPVF. The system achieves a notable average electrical efficiency increase of 69.90% on cloudy days compared to sunny conditions. CPVF-HP system effectively manages temperatures by precooling or preheating the air, enhancing the electrical efficiency by 34.43% in cooling mode, and increasing COP by 5.23% in heating mode compared to an independent heat pump operation. The CPVF-HP system demonstrates a synergistic improvement in both thermal and electrical performance, offering an innovative approach to optimizing energy efficiency in curved PV integrated buildings.

Novel SOFC system concept with anode off-gas dual recirculation: A pathway to zero carbon emission and high energy efficiency

In recent years, the potential of Solid oxide fuel cell (SOFC) technologies as energy conversion devices with high efficiency and zero‑carbon emissions has been underestimated, where high fuel utilization plays a crucial role. Although the SOFC system with anode off-gas single recirculation has received much attention as a means to increase fuel utilization, this problem is not thoroughly addressed. To overcome this limitation, this paper proposes a novel SOFC system concept featuring anode off-gas “dual” recirculation, designed to maximize fuel utilization up to the theoretical limit of 100%. This innovative approach inherently eliminates carbon dioxide emissions through an integrated carbon capture process, thereby maintaining systematic carbon balance. A comparative analysis among the novel dual recirculation system, traditional single-pass, and other anode off-gas recirculation systems, reveals that the proposed system outperforms existing configurations. It achieves electrical and overall combined heat and power efficiencies of 49.6% and 85.7%, respectively, even after accounting for the energy required for carbon capture. This represents a 21.5% increase in electric efficiency over the single recirculation system, with a six-fold increase in tail-gas CO2 concentration, reaching 26.3%. The study categorizes the four analyzed systems into “open” or “closed” based on whether the anode off-gas is directly discharged into the environment. Systematic investigations into carbon deposition potential, fuel utilization, flow rate, operating voltage, carbon capture ratio, and condensation temperature disclose distinct patterns between open and closed systems. The closed configurations exhibit superior performance, suggesting they are more suitable for SOFC applications.

Impact of hybrid nano PCM (paraffin wax with Al2O3 and ZnO nanoparticles) on photovoltaic thermal system: Energy, exergy, exergoeconomic and enviroeconomic analysis

Global renewable energy efforts place a significant preference on substantial solar photovoltaic (PV) systems. Photovoltaic thermal (PVT) systems are the upgraded version of PV modules that concurrently produce both electricity and heat. Hybrid nano-particles (2.0 wt % ZnO and 2.0 wt % Al2O3) into the phase change material (PCM) known as HNPCM system has been introduced in this current study for enhancing the electrical and thermal performance of the PVT system by improving the thermophysical properties of paraffin wax as used for passive cooling. Three PV systems were compared in terms of performance: a conventional PV system, a PVT system using paraffin wax as a PCM (PVT/PCM), and a PVT system with 2.0 wt % of Al2O3 and ZnO in PCM (PVT/HNPCM). Upon investigation, the PVT/HNPCM system under outdoor environmental condition shows that the inclusion of different nanoparticles in PCM led to improvements in thermal and overall efficiency of 17.32 % and 13.82 % compared to PVT/PCM, respectively. This results in increase of electrical efficiency of 34.84 % when compared to conventional PV panel and incremental peak exergy efficiency of 36.47 %. Besides, for PVT/HNPCM, cost of electricity production ($/kWh) is almost 16.67 % less than the conventional PV configuration and the payback time is about 2.1 years on the overall exergy basis. Additionally, PVT/HNPCM system exhibits the long-term life cycle conversion efficiency compared to conventional PV panel and maximum sustainability index of 1.21 has been also found. Finally, the conclusion can be drawn positively for PVT/HNPCM as the most effective system from the exergy efficiency, exergy cost, and CO2 avoidance rates point of view.

Artificial Neural Network and Genetic Algorithm-based prediction of photovoltaic panel performance with porous foam gradient and nano-enhanced phase change material

Photovoltaic panels (PV) become less efficient as the temperature rises. The use of porous foam gradient, phase change materials (PCMs), and nanoparticle-PCM (nePCM) can effectively lower the temperature of PV panels. This study employed numerical analysis using the finite volume method to investigate the effects of different types of PCMs (n-octadecane, decanoic acid natural, lauric acid, paraffin wax, and RT-42), mono and hybrid nanoparticles/PCM, and the position of PCM in the design system. The results indicate that the highest electrical efficiency of 9 % is achieved when the PCM is placed under the PV panel and the thickness of the PCM layer is 0.6 times the height of the microchannel. Furthermore, the use of a porous medium with a variable porosity coefficient that increases along the y-direction can significantly improve thermal and electrical efficiency (approximately 5–42 % and 5–48 % respectively). Additionally, incorporating PCM and hybrid nanoparticles-PCM enhances PV performance compared to the absence of nanoparticles. For TiO2, Ag, Al2O3, GO, and MWCNT nanoparticles, the thermal efficiency, electrical efficiency, and exergetic efficiency increase by approximately 24.18 %, 26.15 %, 26.28 %, 26.30 %, and 26.33 % respectively. Similarly, for hybrid nanoparticles such as GO-Al2O3, GO-Al2O3-MWCNT, MWCNT-GO, and MWCNT-Al2O3, these values increase by approximately 26.32 %, 26.3419 %, 26.3432 %, and 26.335 % respectively for thermal efficiency, and 5.16 %, 5.1702 %, 5.1704 %, and 5.1689 % respectively for electrical efficiency. Moreover, n-octadecane exhibits the highest melting fraction, while paraffin wax has the lowest melting fraction. Lastly, the genetic algorithm-neural network method was employed to estimate the PV electrical efficiency.

Experimental study on energy and exergy assessments of a new PV system with a concave cover for active cooling and self-cleaning

Sandstorms and the spread of dust are problems in semi-arid and arid desert regions. The performance of the photovoltaic cells is lowered as a result of dust buildup on their front side and overheating. Through the use of a combined cooling and self-cleaning technique, the overall performance of a solar panel is improved in this experimental study. As a result, the solar panel receives four upgrades: a concave cover, mirrors, constant flow water cooling, and natural flow air cooling. For this purpose, a transparent concave cover is applied to the front side of the photovoltaic cells to allow the greatest amount of solar radiation to pass through while preventing the accumulation of dust on this face. The front face is cooled with water at a constant flow of 0.0042 kg/s and cooled by air to pass between the front face of the solar cell and the concave cover with a natural flow. Mirrors are positioned on the right and left sides to increase solar radiation. The modified PV solar panel module (PV-M) and conventional solar panel module (PV-C) are contrasted in terms of their operating temperature, current, and output voltage. According to the experimental findings, PV-M had a 24.11% increase in electrical efficiency over PV-C under the same operating conditions and at maximum solar radiation. With a 76.51% improvement, the overall average energy efficiency of PV-C and PV-M was calculated to be 23.63 and 41.71%, respectively. in comparison, the average exergy efficiency was about 25.04%.

The Performance Evaluation of Photovoltaic Integrated Organic Phase Change Material in a Single Container using Indoor Solar Simulator

Photovoltaic panels convert sunlight, a renewable energy source, into electrical energy. The abundant irradiance will heat the photovoltaic panel, reducing the panel's efficiency. This study proposes using PCM 36 as a cooling technique to reduce the temperature of the photovoltaic panel, which is low-cost and has higher latent heat capacity. The indoor solar simulator study is performed to meet the IEC 60904-9 standard. The research process starts with validating PCM 36, sun simulator testing, validating the photovoltaic panel, and fabricating a container to place the PCM 36 at the rear side of the photovoltaic panel to cool down the temperature. The final experiments are conducted indoors, using three different irradiance levels and a one-hour photovoltaic panel operation under the sun simulator. The optimal results reveal a 31.67% reduction in temperature and a 6.83% increase in electrical efficiency at a maximum of 40 minutes, 500 W/m2 irradiance, with a 9 mm thickness of PCM 36. Throughout this study, the efficiency of the photovoltaic system is enhanced by effectively reducing the temperature within the optimal range by incorporating phase change material.

Performance Evaluation of Photovoltaic Thermal using MgO Nanofluid

This study investigated the performance and efficiency of a photovoltaic thermal (PV/T) system utilizing a metal-based nanofluid, specifically MgO nanofluid. This research proposes MgO as nanoparticle to mix with base fluid because it demonstrated to have superior features with the highest thermal conductivity and lowest viscosity among the metal oxide. The nanofluid offered improved thermophysical properties that enhanced the PV/T system performance. The study focused on formulating a stable nanofluid, determining its thermophysical properties, and analysing the overall system performance. 0.2wt% MgO nanofluid were successfully developed and demonstrated excellent stability over a 14-day period by using a two-step method which 20 minutes of homogenization at 1000rpm and 30 minutes of ultrasonication. Tests were conducted to determine the thermal conductivity and viscosity of the nanofluid at various concentrations and temperatures. Results showed that increasing the concentration and temperature enhanced thermal conductivity, while viscosity increased with concentration but decreased with temperature. The thermal and electrical efficiencies of the PV/T system at various irradiances (200W/m2, 500W/m2 and 800W/m2), and flow rates (10L/h, 20L/h, 30L/h) were examined, calculated and compared between water and the MgO nanofluid as working fluids. At 10L/h, it was observed that nanofluid had the highest 74% of thermal efficiency increment compared to the water at 500W/m2 followed by 71% at 200w/m2 and 55% at 800W/m2. Also, Nanofluid demonstrated a 5% increase in electrical efficiency at 200W/m2, 2.1% increase at 500W/m2, and 1.9% increase at 800W/m2 compared to water. The nanofluid exhibited superior thermal and electrical efficiency compared to water, indicating its potential for improving system performance hence, surpassing the performance of a standalone PV system.

Design and analysis of passively cooled floating photovoltaic systems

Floating photovoltaic systems deployable on ponds, lakes and water bodies are an attractive solution in photovoltaic cell technology with several advantages with respect to land-based installations, including a reduced expensive land investment required, reduced water evaporation, and suppression of algae growth. Moreover, the water body can be exploited as a heat sink for the thermal management of the photovoltaic cells, thereby decreasing the operating temperature and increasing efficiency. High operating temperatures are in fact one of the major problems in photovoltaic cells, which can degrade photovoltaic panels' electrical efficiency and service life. Recent research has demonstrated the potential of natural convection cooling loops for the thermal management of floating photovoltaic systems. Using numerical simulations combined with experiments, we show how sensitive is the performance of the natural convection cooling loop to the height of the coolant reservoir, which can then be used as a design parameter to maximise the cooling effectiveness of the photovoltaic module, with a consequent increase in electrical efficiency of 17.84% with respect to the base design without cooling.

The effects of coolant mass flow rate and atmospheric indicators in a PV/T system with experimental and ANN’s models

In this study, the effects of the mass flow rate of coolant and other atmospheric and positional variables on the performance and efficiency of a PV/T system have been experimentally researched and modeled with ANN’s models. Mass flow rate, irradiance, ambient temperature, wind speed, wind direction, relative humidity and coolant water inlet temperature have been measured while solar azimuth angle and solar elevation angle have been calculated. These parameters have been selected as the input parameters (independent variables), mainly having the preliminary focus on the mass flow rate of the coolant. The performance parameters namely, electrical power production, thermal energy production, total energy production, temperature decrease on the PV module, electrical efficiency increase, surface temperature of the PV module and water outlet temperature for the PV modules have been experimentally measured. They were also computed by ANN models, as the output variables (dependent variables) with the most robust estimation of FBPANN based models depending on the real measurement data set from the experimental works. The relevance of the dependability of each targeted variables were revealed by statistical indicators in order to maintain the sensitivity of the ANN calculations. Among all the dependent parameters that were predicted by the ANN models, the strictest predictions were found for electrical power production by the FFANN1 model with the R value of 99.985% and the R2 value of 99.971%. Also, all of the performance parameters have robustly been predicted by the FFANN models. Besides, the order of importance of the predictors that effects dependent variables has been found. The mass flow rate has been determined to be highly effective on electrical efficiency increase, surface temperature of the PV module, electrical power production, thermal energy production and total energy production. The benefit of the present work is that the effects of daily working parameters such as mass flow rate of coolant with respect to the other atmospheric indicators on instantaneous electrical and thermal performance of a PV or PV/T system can be robustly predicted with their order of importance with the developed ANN models. It will make the investors to easily manage their systems.

Evaporative cooling of photovoltaic panels in dry and hot climatic conditions

ABSTRACT Solar photovoltaic (PV) technology is a popular choice among other renewable energy sources, but its electrical efficiency decreases with a rise in PV panel temperature. Previous studies on passive cooling with phase change material (PCM) based approach face limitations of temperature drop and leakage issues. To address this issue, an evaporative cooling method that can enhance panel efficiency is investigated. The present study demonstrated a simple, optimized, and cost-effective evaporative cooling for hot and dry climate conditions. The system consists of jute cloth attached directly to the PV panel backside and water flowing from the top header to the jute cloth under gravity has been experimentally investigated in outdoor conditions during summer. The electrical and thermal characteristics (with and without cooling) of the panel were measured. The finding shows that the jute cooling in PV panels leads to a substantial reduction in average temperature by 18°C and a corresponding increase in electrical efficiency by 10.31%. The jute-cooled panel shows an average and maximum output power improvement of 4.33 and 7.10 W, respectively, compared to the referent panel, while consuming only 0.55 l of water per hour. The study also investigated the effect of water failure on jute cooling and water ingress to the junction box. In the event of water cooling system failure, the panel’s temperature increases by an average of 6°C in comparison to the referent panel. Furthermore, the proposed evaporative cooling system shows a cost-incurred payback period of 7 years against the referent system of 5 years.

ANSYS investigation of solar photovoltaic temperature distribution for improved efficiency

<p>A computational analysis of the influence of varying solar module material properties on operating temperature is presented and related to electrical conversion efficiency through the devised method. By varying the properties of density, specific heat capacity, and isotropic thermal conductivity for each material that comprises a solar module, density, and specific heat capacity were found to have the greatest influence on decreasing the operating temperature when increased by a factor of 50% for the glass layer, resulting in a decrease in temperature of 5.33 °C. Utilizing the devised method, which is based on the work of Palumbo, this temperature decrease was correlated to an electrical efficiency increase of 3.08%.</p>

High-efficiency bio-inspired hybrid multi-generation photovoltaic leaf

Most solar energy incident (>70%) upon commercial photovoltaic panels is dissipated as heat, increasing their operating temperature, and leading to significant deterioration in electrical performance. The solar utilisation efficiency of commercial photovoltaic panels is typically below 25%. Here, we demonstrate a hybrid multi-generation photovoltaic leaf concept that employs a biomimetic transpiration structure made of eco-friendly, low-cost and widely-available materials for effective passive thermal management and multi-generation. We demonstrate experimentally that bio-inspired transpiration can remove ~590 W/m2 of heat from a photovoltaic cell, reducing the cell temperature by ~26 °C under an irradiance of 1000 W/m2, and resulting in a relatively 13.6% increase in electrical efficiency. Furthermore, the photovoltaic leaf is capable of synergistically utilising the recovered heat to co-generate additional thermal energy and freshwater simultaneously within the same component, significantly elevating the overall solar utilisation efficiency from 13.2% to over 74.5%, along with over 1.1 L/h/m2 of clean water.

Effect of Different Preparation Parameters on the Stability and Thermal Conductivity of MWCNT-Based Nanofluid Used for Photovoltaic/Thermal Cooling

The thermal conductivity and stability of any nanofluid are essential thermophysical properties. These properties are affected by many parameters, such as the nanoparticles, the base fluid, the surfactant, and the sonication time used for mixing. In this study, multi-walled carbon nanotubes (MWCNTs) were selected as additive particles, and the remaining variables were tested to reach the most suitable nanofluid that can be used to cool photovoltaic/thermal (PVT) systems operating in the harsh summer conditions of the city of Baghdad. Among the tested base fluids, water was chosen, although ethylene glycol (EG), propylene glycol (PG), and heat transfer oil (HTO) were available. The novelty of the current study contains the optimization of nanofluid preparation time to improve MWCNTs’ PVT performance with different surfactants (CTAB, SDS, and SDBS) and base fluids (water, EG, PG, and oil). When 1% MWCNT mass fraction was added, the thermal conductivity (TC) of all tested fluids increased, and the water + nano-MWCNT advanced all TC (EG, PG, and oil) by 119.5%, 308%, and 210%, respectively. The aqueous nanofluids’ stability also exceeded the EG, PG, and oil at the mass fraction of 0.5% MWCNTs by 11.6%, 20.3%, and 16.66%, respectively. A nanofluid consisting of 0.5% MWCNTs, water (base fluid), and CTAB (surfactant) was selected with a sonication time of three and quarter hours, considering that these preparation conditions were practically the best. This fluid was circulated in an installed outdoor, weather-exposed PVT system. Experiments were carried out in the harsh weather conditions of Baghdad, Iraq, to test the effectiveness of the PVT system and the nanofluid. The nanofluid-cooled system achieved an electrical efficiency increase of 88.85% and 44% compared to standalone PV and water-cooled PVT systems, respectively. Additionally, its thermal efficiency was about 20% higher than that of a water-cooled PVT system. With the effect of the high temperature of the PV panel (at noon), the electrical efficiency of the systems was decreased, and the least affected was the nanofluid-cooled PVT system. The thermal efficiency of the nanofluid-cooled PVT system was also increased under these conditions. This success confirms that the prepared nanofluid cooling of the PVT system approach can be used in the severe weather of the city of Baghdad.