High Solar Radiation Research Articles

Integration of electrocoagulation and solar energy for sustainable wastewater treatment: a thermodynamic and life cycle assessment study.

This study presents an innovative approach to sustainable wastewater treatment by integrating electrocoagulation (EC) with solar energy and biogas. The research evaluates the performance of an EC reactor in terms of chemical oxygen demand (COD) removal efficiency under varying current densities, demonstrating enhanced COD removal rates with increased current densities, achieving up to 95.3% at 1500 A/m2. Life cycle assessment (LCA) is employed to compare the environmental impacts of different energy sources for powering the EC system. The findings indicate that biogas derived from domestic waste offers a lower environmental impact compared to natural gas, coal, hydro, solar, and wind. The study further explores the potential of solar energy in Turkey, particularly in Istanbul, where high solar radiation could be harnessed. However, the efficiency of photovoltaic (PV) panels is affected by temperature, with an observed efficiency decrease of approximately 0.5% per degree Celsius increase in temperature. Effective cooling strategies are thus essential for optimizing PV performance. The integration of EC with solar energy, powered by biogas, not only enhances wastewater treatment efficiency but also contributes to reduced greenhouse gas emissions and energy costs. This combined approach presents a viable solution for both domestic and industrial wastewater treatment, especially in remote or off-grid areas.

Multi-Criteria Optimal Operation Strategy for Photovoltaic Systems in Large-Scale Logistics Parks Concerning Climate Impact

Solar power is widely regarded as one of the most promising renewable resources for generating electricity and reducing building energy consumption. Logistics parks, with their low-rise buildings and extensive rooftop areas, offer significant advantages for solar energy utilization via rooftop photovoltaics (PVs). However, limited research has been conducted on the proper operational principles and optimized control strategies for the PV systems of logistics parks, particularly regarding the mismatch between power generation and the loads of various building types under varying climatic conditions. This study proposes four optimal PV operation strategies for large-scale logistics parks across diverse climatic regions, developed using a multi-criteria optimization approach. The strategies optimize the azimuth and tilt angles of PV panels under four adjustment frequencies: annual, semi-annual, seasonal, and monthly. The investigated strategies are validated in a 5500 m2 logistics park, comprising refrigerated storage, warehouses, sorting centers, and other facilities. The results indicate that the proposed strategies outperform conventional fixed-angle approaches, with the monthly adjustment strategy delivering the best performance. Economic costs are reduced by 9.26–17.02%, while self-sufficiency can be improved by 2.00–7.08%. Cold regions with high solar radiation show particularly significant benefits, with self-consumption increasing by 82.44–359.04%. This study provides valuable insights and practical guidelines for optimizing PV system operations in logistics parks, offering enhanced energy efficiency and cost-effectiveness.

Comparative Techno-Economic Analysis of Gray Hydrogen Production Costs: A Case Study

Despite Iran’s considerable renewable energy (RE) potential and excellent wind capacity and high solar radiation levels, these sources contribute only a small fraction of the country’s total energy production. This paper addresses the techno-economic viability of gray hydrogen production by these renewables, with a particular focus on solar energy. Given the considerable potential of solar energy and the strategic location of Shahrekord, it would be an optimal site for a hydrogen generation plant integrated with a solar field. HOMER Pro 3.18.3 software was utilized to model and optimize the levelized cost of hydrogen (LCOH) of steam reforming using different hydrocarbons in various scenarios. The results of this study indicate that natural gas (NG) reforming represents the most cost-effective method of gray hydrogen production in this city, with an LCOH of −0.423 USD/kg. Other hydrocarbons such as diesel, gasoline, propane, methanol, and ethanol have a price per kilogram of produced hydrogen as follows: USD −0.4, USD −0.293, USD 1.17, USD 1.48, and USD 2.15. In addition, integrating RE sources into hydrogen production was found to be viable. Moreover, by implementing RE technologies, CO2 emissions can be significantly reduced, and energy security can be achieved.

GIS-Based Analysis of Crop Yield Trends in Response to Climate Change Using Data-Driven Analysis Systems (DDAS) Techniques

Climate variability poses significant challenges to crop production, particularly in vulnerable regions like Southeast Nigeria, where changing environmental conditions directly impact agricultural productivity. This study employs GIS-based analysis and Data-Driven Analysis Systems (DDAS) to assess the effects of climate variables on crop yields, focusing on temperature, rainfall, relative humidity, solar radiation, and wind factors. The objectives are to (1) analyze the Relationship Between Climate Variables and Crop Yield Trends, (2) develop Predictive Models Using GIS and DDAS Techniques, and (3) identify Climate-Sensitive Zones for Targeted Agricultural Interventions within Southeast Nigeria. Findings reveal that maximum and minimum temperatures and moderate rainfall positively influence crop yield, while high relative humidity and solar radiation have a negative impact. GIS mapping and DDAS techniques successfully highlight spatial variations and provide robust yield predictions, emphasizing their value in agricultural planning. By identifying high-risk areas, such as Abakaliki, the study provides actionable insights to develop adaptive, region-specific agricultural strategies, thereby enhancing food security and sustainable agricultural practices in Southeast Nigeria.

Understanding and Modeling the Dynamics of Storm‐Time Atmospheric Neutral Density Using Random Forests

AbstractAtmospheric neutral density is a crucial component to accurately predict and track the motion of satellites. During periods of elevated solar and geomagnetic activity atmospheric neutral density becomes highly variable and dynamic. This variability and enhanced dynamics make it difficult to accurately model neutral density leading to increased errors which propagate from neutral density models through to orbit propagation models. In this paper we investigate the dynamics of neutral density during geomagnetic storms. We use a combination of solar and geomagnetic variables to develop three Random Forest machine learning models of neutral density. These models are based on (a) slow solar indices, (b) high cadence solar irradiance, and (c) combined high‐cadence solar irradiance and geomagnetic indices. Each model is validated using an out‐of‐sample data set using analysis of residuals and typical metrics. During quiet‐times, all three models perform well; however, during geomagnetic storms, the combined high cadence solar iradiance/geomagnetic model performs significantly better than the models based solely on solar activity. The combined model capturing an additional 10% in the variability of density and having an error up to six times smaller during geomagnetic storms then the solar models. Overall, this work demonstrates the importance of including geomagnetic activity in the modeling of atmospheric density and serves as a proof of concept for using machine learning algorithms to model, and in the future forecast atmospheric density for operational use.

Navigating climate shifts for an endemic lizard from a semi-arid environment

Ecological niche models (ENMs) are crucial for understanding species distribution and identifying areas maintaining climatic stability over time (i.e., thermal refugia). Human-induced global climate change underscores the importance of such refugia, which directly impacts species distribution, especially for ectothermic species relying on the environmental temperature to keep their metabolism active. Tropidurus cocorobensis is an endemic, heliothermic, and generalist lizard from Caatinga, a heterogeneous semi-arid domain characterized by low and irregular precipitation patterns and high temperature and solar radiation. Despite its endemism, there is no information concerning temporarily stable (refugial) and unstable (recently colonized) regions for its occurrence, nor future predictions of local thermal suitability in different climate change scenarios. Using ENMs, we assessed Caatinga's past, present, and future thermal suitability for T. cocorobensis, identifying potential changes in its thermal refugia over time. Our results indicated Depressão Sertaneja Meridional (DSM) and Campo Maior Complex (CMC) as climatically stable Caatinga Ecoregions, serving as climate refugia for T. cocorobensis. While DSM covers much of the species' current distribution, CMC lacks occurrence data. Contrastingly, the Chapada Diamantina Complex, a known habitat for the species, was not recovered as a climate refugia nor was suitable for future scenarios, therefore representing a climatically unstable area. Future projections indicate a potential expansion of T. cocorobensis' climate refugia, possibly linked to the species' generalist habits. However, the optimistic outlook for this species may not mirror the overall well-being of the Caatinga domain since generalist species often fill niches left by specialists unable to adapt to stressful environments. Future studies should prioritize comparing the climatic refugia of specialist and generalist species envisioning a comprehensive understanding of the ecological dynamics within the Caatinga ecosystem. This approach will be crucial for formulating effective conservation strategies amid the ongoing challenges of climate change in this domain.

Scalable Hierarchical‐Colored Passive Cooling Metapaint for Outdoor Facility

ABSTRACTThe temperature of metal‐based facilities rises significantly under high outdoor solar irradiation, leading to serious safety accidents. The application of active cooling technology poses challenges due to its high energy consumption, especially in complex outdoor environments. Passive cooling devices with high solar reflection and thermal emission can continuously cool objects under sunlight. However, the white or silvery passive cooling devices do not meet the need for aesthetics and specific demands. Here, we present a hierarchical metapaint for outdoor facilities that simultaneously achieve vibrant color and passive cooling ability. The top layer selectively absorbs visible wavelengths to display desired colors, while the underlayer boosts the reflection of near‐to‐short wavelength infrared (NSWIR) light to prevent solar heating. The metapaint‐coated metal is resistant to high and low temperatures, acidic and alkaline environments, and simulated seawater. It also has satisfactory anti‐fouling properties. When compared to metal coated without commercial paint, the hierarchical passive cooling paint (metapaint) coated metal can cool up to 9.7°C and 17.1°C. The metapaint has excellent passive cooling performance, attributed to its broad‐spectrum selective regulation function. Our work offers a simple, inexpensive, and scalable approach to reduce cooling energy usage and promote a low‐carbon lifestyle. image

Cooling Performance of TiO2-Based Radiative Cooling Coating in Tropical Conditions.

The cooling power of radiative cooling (RC) coatings depends not only on the radiative properties of the coating but also on environmental variables. In tropical environments, the cooling performance of RC coatings deteriorates due to high humidity and high solar radiation. Previous studies focused on developing high solar-reflective coatings to achieve subambient cooling in tropical environments. However, these coatings have not demonstrated the ability to be used at a large scale, mainly due to their high cost or less durability. Herein, we test an RC paint coating composed of TiO2 and polydimethylsiloxane (PDMS) in three different cities with high and moderate humidity levels. Though a significant reduction in the internal temperature of an RC paint-coated aluminum (Al) box is observed, compared to an uncoated Al box, in both high and moderate humidity environments, subambient cooling is not achieved. A comprehensive analysis is conducted to clarify the reasons behind the inability to attain subambient cooling.

Advanced building envelope by integrating phase change material into a double-pane window at various orientations

Considering building envelope elements in hot locations, windows contribute to about one-third of the building’s total cooling load since heat is transferred effortlessly through transparent elements more than opaque ones. The present work experimentally explores the energy advancements of a phase change material (PCM) loaded in the air gap of a double-pane window. The PCM window was examined under Southern Iraq weather conditions and compared with an identical air–gap double-pane window at various orientations. Numerous energy indicators were analyzed, including the improvement in the average indoor temperature, attenuation coefficient, and time delay to quantify the PCM’s usefulness to the built environment at different orientations. Study outcomes depicted remarkable energy improvements for the PCM in all orientations over the reference window in which the indoor temperature was reduced as much as 23 °C, and shifted by up to 50 min over the reference case. Conclusively, the PCM window could notably shave peak temperature when exposed to high solar radiation for a short period, while it could shift peak temperature mostly if oriented towards longtime solar radiation.

Modeling of Basin Type Single Slope Solar Still Under Local Climate Conditions in Yemen

The economic crises and instability caused by the conflict in Yemen prevents the establishment of medium and large-scale water desalination plants to overcome the sever water scarcity in the high population major cities. This paper investigates small scale solar still water desalination technology as a potential candidate to aid with the production of fresh water to reduce the accelerated depletion of underground water reserves in Yemen. Water stills have the advantage of low capital cost and no operational cost as it utilizes the high solar radiation intensity in the coastal areas to evaporate water. This paper proposes and compares two models to simulate the performance of solar still following steady-state and transient modelling approaches, with in-depth evaluation of the different parameters affecting the performance. The transient model showed better prediction of the temperature profiles of the solar still when compared to other experimental and mathematical modelling studies. The small scale solar still showed water production yield of about 1.9 kg/day, with maximum hourly yield of about 0.27 kg/h.

A study on the combination of crystallization-controllable phase change materials and solar-assisted heat pump for electricity demand shifting in space heating

Supercooled phase change materials offer a promising solution for space heating due to their ability to release latent heat upon crystallization initiation, even when stored at ambient temperatures. This unique property makes them ideal for solar-assisted space heating, where external activation enables on-demand heat release, addressing the critical need for energy-efficient heating solutions. In this study, a system promoting demand shifting is proposed, aiming to transfer energy consumption from morning and evening peak periods to daytime and high solar irradiance days, thereby enhancing the efficiency of solar heat pumps and reducing grid stress through the use of supercooled crystallization-controllable phase change materials. A model was developed, consisting of evacuated tube collectors, a buffer tank, heat storage tanks with crystallization-controllable phase change material, and a building heating demand model. The study introduces a novel system control methodology, focusing on an effective operation of tank shifting based on the heating requirement and solar energy availability. Real weather data were used to calculate system performance. With 50 m2 of collectors, a 1000-liter buffer tank, and a heat pump with a maximum output of 7 kW, the heat storage tanks are charged and discharged following the developed operational methodology. The system achieved a weekly coefficient of performance of 3.56 and successfully shifted electricity demand to solar hours, with only 28.5% of the total consumption occurring during domestic morning and evening peak times.

Solar Energy Applications in Protected Agriculture: A Technical and Bibliometric Review of Greenhouse Systems and Solar Technologies

This study addresses solar energy applications in protected agriculture, focusing on greenhouses and related technologies. A bibliometric and technical analysis is developed, covering research published between 1976 and 2024, to identify the main trends and challenges in the use of solar energy in controlled environments. The methodology was based on the PRISMA approach, using the Scopus database to retrieve relevant documents. From an initial total of 221 documents, 216 were selected after a filtering and debugging process, ensuring the relevance of the final set. In the analytical phase, the results showed a moderate growth of 3.68% in the annual publication rate, highlighting the impact of research on solar energy’s application to air conditioning and energy efficiency in greenhouses. Most of the studies reviewed feature hybrid systems that combine solar energy with other resources, and we highlight both advances in climate control through artificial intelligence and the implementation of photovoltaic and thermal technologies to improve the energy efficiency of agricultural systems. The results also underline the importance of tomato cultivation in the selected studies, reflecting its global economic impact. The conclusions highlight the need for the further integration of energy storage and desalination technologies, especially in arid regions with high solar irradiation, to ensure the sustainability of greenhouses. It is proposed that future research should address the wider implementation of hybrid systems and advanced climate control technologies, optimizing both the use of energy resources and the performance of crops under cover. In addition, it is recommended that international collaboration be strengthened to address technical and climatic challenges in protected agriculture and to expand the adoption of innovative solutions in different geographical contexts.

Extended Failure Mode and Effects Analysis for Development of Hot Desert Test Cycle Proposal

ABSTRACTA growing number of gigawatt‐scale photovoltaic (PV) power plants are being established in hot desert regions worldwide, which are favored for their vast available land, high solar irradiance, long sunshine hours, and relatively low maintenance needs. This study combines insights from global PV experts on degradation rates, failure mode and effects analysis (FMEA), and desert weather conditions to develop a hot desert test cycle (HDTC). The average degradation rate for PV modules installed in hot desert regions over the past 10 years is estimated to be around 1.63% per year. Eighteen failure modes were identified and analyzed using FMEA. According to the results, the main degradation mechanisms include UV light‐induced degradation (UVLID), thermomechanical failures in interconnects and fingers, light‐elevated temperature‐induced degradation (LeTID), and abrasion of the glass and antireflection coatings. A radar map comparison shows that desert environments experience UV exposure, ambient, and module temperatures that are more than twice as high as those in moderate climates. The HDTC protocol was developed based on FMEA results and desert‐specific weather conditions. It includes tests for desert UV exposure, temperature cycles, mechanical loads, and sand/brush abrasions. To ensure consistency across countries, there is a plan to establish an internationally recognized standard that complements existing IEC standards. As the industry grows, desert regions are expected to place greater emphasis on adopting desert‐specific testing standards for the qualification and evaluation of PV modules.

Thermal performance of south-facing envelopes in solar enrichment zone of Qinghai–Tibet plateau: Field measurements of multiple dwellings in winter and transition seasons

Utilizing solar energy is essential for achieving zero carbon emissions in buildings, especially in solar enrichment zone, such as the Qinghai-Tibet Plateau. Given a climate characterized by low temperatures and high solar radiation, the thermal performance of south-facing envelopes is crucial for the collection and utilization of solar radiation, necessitating detailed field investigations. This study conducted field measurements on three typical dwellings in Litang County and Ngari Prefecture during winter and transition seasons. Transparent envelopes had heat gains of 20.7 MJ⋅m-2 but lost 26.4 MJ⋅m-2, with indoor temperature fluctuation of 17.2 °C. Opaque envelopes gained 132.3 W⋅m-2 from solar radiation and lost 99.3 W⋅m-2 through convection, storing 2.5 MJ⋅m-2 with over 85 % lost to the outdoor environment. This research revealed the dynamic thermal characteristics of heat collection, storage, and insulation performance of south-facing envelopes in local climate, indicated that the existing thermal performance is not yet sufficient to cope with the low temperature and high radiation climate. This work can provide reference for the development of solar utilization envelopes for the Qinghai-Tibet Plateau.

Electrical and Financial Impacts of Inverter Clipping on Oversized Bifacial Photovoltaic Systems

This paper studies the impacts of inverter clipping on bifacial PV modules under different weather and ground reflectivity. A 5 kW bifacial array was connected to a 3.8 kW grid-tied inverter, a 10 kWh Li-ion battery, and an EV charger. A PV output calculation model was developed to compare the estimated output of the modules with the actual measurements to evaluate the relation between ground reflectivity and clipping loss. The results showed that clipping potentially occurs on sunny days in summer from 10:00 to 15:00 during the period with the highest solar irradiance. Three colors of ground cover were also examined to compare the performance of bifacial modules under different albedo reflective properties. The results indicated that the white ground in winter leads to the highest bifacial gain (13.1%) and daily DC efficiency (22.2%) due to the combination of high reflectivity with low solar angle giving maximum upward reflection of direct sunlight. This same combination shows a minimal advantage in summer due to the clipping. The proposed model is evaluated, demonstrating 98.2% agreement between modeled and actual data for all conditions. Furthermore, simulation models based on the actual system with different system sizes and ground reflectivities have been studied to evaluate the impacts of the clipping in terms of technical losses and financial returns. The analysis shows that a high reflective ground condition can provide the best financial benefit, and the clipping loss does not have a great effect on the finance of the project since the loss is less than 4% of the annual production even in an extreme case.

A Methodological Approach to the Study of Retroreflective Pavements

Climate change, principally driven by human activities, has led to an increase in global temperature, which is predicted to continue rising in the coming years. This temperature increase is even more pronounced in urban areas due to the heat island effect. This phenomenon is highly influenced by the presence of paved streets made with bituminous mixtures, which are characterised by their high solar radiation absorption capacity. Bituminous mixtures retain and re-emit a large amount of heat that intensifies the urban heat island effect. The novelty of this work is to measure retroreflective properties of bituminous mixtures that present a highly textured surface. In this context, the aim of this study is to evaluate the retroreflectance of different bituminous mixtures for use as pavement surfaces, focusing on the influence of colour and different types of aggregates. For this, total and directional reflectance measurements were conducted to determine the retroreflectance of these mixtures, with the purpose of mitigating the heat island effect in urban environments without affecting users through reflected solar radiation. The results show the retroreflective capacity of the designed mixtures within the visible spectrum, especially those manufactured with light-coloured aggregates and synthetic binders pigmented with titanium dioxide. Thus, the retroreflectance of the lighter mixtures range from 37.9% at a 0° entrance angle to 68.9% at 60°, while the black mixtures exhibit values between 5.1% and 8.4%.

Study of Photodegradation of Organic Solar Cells Under Brazilian Climate Conditions

The increasing technical and economic viability of photovoltaic solar energy technologies includes modules with organic photovoltaic (OPV) cells, which have shown significant efficiency increases, reaching 20% for research devices. This study investigated the photodegradation and associated loss mechanisms in OPV devices under tropical conditions in Brazil. The electrical and optical characteristics of the modules were correlated with chemical and structural changes when exposed to sunlight. Electrical parameters were monitored over time on external test benches and measured in solar simulators, while changes in the optical transmission and absorption of the films were analyzed. Scanning electron microscopy, energy-dispersive spectroscopy, and Fourier-transform infrared spectroscopy were used to study the physical and chemical properties of the materials. We found that photodegradation causes bound breakage in the active layer, altering the carbon structure and consequently reducing the module’s output power. The primary reasons for the activation and progression of this mechanism are high temperature and elevated solar irradiance. Therefore, we demonstrate that understanding these mechanisms is essential for the development of more sustainable OPVs in tropical climates.

Extraction, characterization and antioxidative potentials of UV-screening compound, mycosporine-like amino acids from epilithic cyanobacterium Lyngbya sp. HKAR - 15.

Mycosporine-like amino acids (MAAs) are a unique class of UV-screening bioactive molecules with potent antioxidants and photoprotective properties, synthesized by various species of cyanobacteria in different habitats. The cyanobacterial biofilms play a crucial driver in the development of ecological communities. The current study examined the existence of the photoprotective MAAs in a novel epilithic cyanobacterium Lyngbya sp. strain HKAR-15 isolated from cyanobacterial biofilms on the rock surface. The isolated MAAs were identified, purified and characterized using UV-Vis spectroscopy, HPLC (High-Performance Liquid Chromatography), ESI-MS (Electrospray Ionization-Mass Spectrometry), FTIR (Fourier Transform Infrared Spectroscopy) and NMR (Nuclear Magnetic Resonance). The compounds were recognized as palythine (retention time (RT): 2.7min; UV λmax: 320nm; m/z: 245.02) and porphyra-334 (RT: 3.6min; UV λmax: 334nm; m/z: 347.1). FTIR spectroscopy analyses also revealed the presence of functional groups of both compounds. NMR spectroscopy analyses confirmed the presence of both palythine and porphyra-334. The UV-induced production of both MAAs was visualized under ultraviolet radiation (UVR) in contrast to the photosynthetically active radiation (PAR). The MAAs (palythine and porphyra-334) had a significant dose-dependent free radical scavenging capacity. The findings show that MAAs perform a dynamic role in the survival and photoprotection of cyanobacteria in hostile environments under high solar UV irradiances. These photoprotective compounds may have various biotechnological applications as well as role in the development of natural sunscreens.

Innovations and Challenges in Semi-Transparent Perovskite Solar Cells: A Mini Review of Advancements Toward Sustainable Energy Solutions

Amid the shift away from fossil fuels, third-generation perovskite solar cells (PSCs) have become pivotal due to their high efficiency and low production costs. This review concentrates on semi-transparent perovskite solar cells (ST-PSCs), highlighting their power conversion efficiency (PCE) and average visible transmittance (AVT). We address strategies to optimize ST-PSC performance, tackling inherent challenges, such as optical losses from reflection, parasitic absorption, and thermalization loss, which impact the operational efficiency under variable environmental conditions. ST-PSCs are distinguished by their lightweight, flexible, and translucent properties, allowing for diverse applications in urban building integration, agricultural greenhouses, and wearable technology. These cells integrate seamlessly into various settings, enhancing energy harnessing without compromising on aesthetic or structural elements. However, the scalability of ST-PSCs involves challenges related to stability and efficiency in large-scale deployments. The tropical urban landscape of Singapore provides a unique case study for ST-PSC application, blending architectural aesthetics with high solar irradiance to optimize energy efficiency. While the potential for ST-PSCs to contribute to sustainable urban development is immense, significant technological hurdles must be overcome to realize their full potential. Continued advancements in material science and engineering are essential to address these challenges, ensuring the scalability and long-term deployment of ST-PSCs in global energy solutions.

Experimental investigation of enhanced thermal performance of solar air collectors through optimized selection of manufacturing materials: Energy, exergy, economic, and environmental analysis

AbstractThe current study aims to experimentally investigate the thermal performance of three identical solar air collectors manufactured from three different metals: aluminum, zinc, and steel. The study conducted environmental and economic analyses of the three proposed solar air collectors over a month. The aluminum solar air collector demonstrated superior performance, achieving a maximum thermal efficiency of 24.46%, while the steel and zinc solar air collectors recorded thermal efficiencies of 21.57% and 18.16%, respectively. The exergy efficiency ranges for aluminum from 0.95% to 13.54%, zinc absorber plate exhibits from 0.63% to 11.89%, and steel from 0.6% to 9.98%. The aluminum solar air collector revealed high monthly cost savings of about $1429.6/month, followed by zinc ($1203.8) and steel ($963.4) solar air collectors. Environmental analysis to showed savings entering the atmosphere per month showed that the aluminum reduced about 19,795 kg CO2/month, Zinc solar air heat 16,668 kg CO2/month, and the steel solar air collector recorded 13,339 kg CO2/month. In this study, the absorber plate made of aluminum was the most efficient material, followed by zinc and steel. That confirms its suitability for designing efficient solar air heating systems in areas with high solar radiation intensity, such as Tunisia, and provides a clear direction for future research and development in manufacturing solar air collectors.