Incident Solar Radiation Research Articles

Spatial Models of Solar and Terrestrial Radiation Budgets and Machine Learning: A Review

Currently, spatial modeling is of particular relevance as it enables the understanding of the patterns and spatial variability of an event, the monitoring and prediction of the spatial behavior of a variable, the optimization of resources, and the evaluation of the impacts of a phenomenon of interest. Research carried out recently on variables related to solar energy budgets has been of special relevance due to its applications and developments in machine learning (ML) and deep learning (DL). These algorithms are crucial to improve the efficiency, precision, and applicability of remote sensing, allowing greater decision making with more reliable and timely data. Thus, this work proposes a systematic and rigorous methodology for searching research articles about the latest advances and contributions related to the modeling of radiative energy budgets using novel techniques and algorithms in some of the most relevant international scientific databases (Scopus, ScienceDirect, ResearchGate). Search parameters were applied using tracking methods through various filters, specific classifiers, and Boolean operators. The results allowed for an analysis of search trends and citations in the last 5 years related to the topic of interest and the number of most relevant articles for this research, analyzed through specialized metrics and graphs. Additionally, this methodology was classified into four categories of importance for refined and articulated searches in this evaluation: (i) according to the applied interpolation methods, (ii) according to the remote sensors used, (iii) according to the applications in different fields of knowledge. As a relevant fact and with an essentially prospective purpose, a subchapter of this review was dedicated to the latest advances and developments applied to (iv) spatial modeling of terrestrial radiation through ML, this method being a tool that opens multiple alternatives for data processing and analysis in the development and achievement of objectives in the field of geotechnologies. A quantitative comparison was conducted on the predictive performance results between the classification/regression algorithms found in the studies explored in this review. The evaluation confirmed the existence of a persistent shortage of studies in recent years within the geotechnologies field, particularly concerning the comparison of spatial distribution modeling techniques developed and implemented through ML for incident solar and terrestrial radiation. Therefore, this work provides a synthesis and analysis of the most used and novel techniques in the modeling of solar energy budgets, their limitations, and biggest challenges.

Improving Soybean Gross Primary Productivity Modeling Using Solar-Induced Chlorophyll Fluorescence and the Photochemical Reflectance Index by Accounting for the Clearness Index

Solar-induced chlorophyll fluorescence (SIF) has been widely utilized to track the dynamics of gross primary productivity (GPP). It has been shown that the photochemical reflectance index (PRI), which may be utilized as an indicator of non-photochemical quenching (NPQ), improves SIF-based GPP estimation. However, the influence of weather conditions on GPP estimation using SIF and PRI has not been well explored. In this study, using an open-access dataset, we examined the impact of the clearness index (CI), which is associated with the proportional intensity of solar incident radiation and can represent weather conditions, on soybean GPP estimation using SIF and PRI. The midday PRI (xanthophyll de-epoxidation state) minus the early morning PRI (xanthophyll epoxidation state) yielded the corrected PRI (ΔPRI), which described the amplitude of xanthophyll pigment interconversion during the day. The observed canopy SIF at 760 nm (SIFTOC_760) was downscaled to the broadband photosystem-level SIF for photosystem II (SIFTOT_FULL_PSII). Our results show that GPP can be accurately estimated using a multi-linear model with SIFTOT_FULL_PSII and ΔPRI. The ratio of GPP measured using the eddy covariance (EC) method (GPPEC) to GPP estimated using SIFTOT_FULL_PSII and ΔPRI exhibited a non-linear correlation with the CI along both the half-hourly (R2 = 0.21) and daily scales (R2 = 0.25). The GPP estimates using SIFTOT_FULL_PSII and ΔPRI were significantly improved by the addition of the CI (for the half-hourly data, R2 improved from 0.64 to 0.71 and the RMSE decreased from 8.28 to 7.42 μmol•m−2•s−1; for the daily data, R2 improved from 0.71 to 0.81 and the RMSE decreased from 6.69 to 5.34 μmol•m−2•s−1). This was confirmed by the validation results. In addition, the GPP estimated using the Random Forest method was also largely improved by considering the influences of the CI. Therefore, our findings demonstrate that GPP can be well estimated using SIFTOT_FULL_PSII and ΔPRI, and it can be significantly enhanced by accounting for the CI. These results will be beneficial to vegetation GPP estimation using different remote sensing platforms, especially under various weather conditions.

A Simplified Evaluation Framework for Adaptation Measures to Urban Heat Islands

Adaptation measures to urban heat islands are classified into the following three categories: measures to reduce solar radiation incident on the human body, measures to control and cool ground and wall surface temperature, and measures to control and cool the air and human body temperature. Case studies are conducted to evaluate the effects of the implementation of a cool water circulation sunshade and to examine the adverse effects of cool pavements on the human thermal environment, in addition to the effects of mist sprays on the human body. The effect of the sunshade, watering road, and mist spray, which are typical adaptation measures to urban heat islands, on the human thermal environment was estimated using Wet Bulb Globe Temperature (WBGT) as an indicator for heat stroke prevention and Standard New Effective Temperature (SET*) as an indicator for thermal comfort assessment. The effect of solar radiation shielding on improving the human thermal environment was the most significant, with a large decrease in the amount of solar radiation absorbed by the human body, resulting in a large decrease in SET* and WBGT of 2.7 °C and 1.0 °C, respectively, on fine summer days.

Interdecadal changes and the role of Philippine Sea convection in the intensification of Indian spring heatwaves

Abstract Severe heatwaves have become increasingly frequent over the Indian subcontinent in recent decades. This study found that the increase in extreme heatwaves is related to a significant decadal change in surface temperatures over the Indian subcontinent, and revealed that the increase in convective activity in the Philippine Sea plays a crucial role in this decadal change in surface temperature. Specifically, the surface temperature over the Indian subcontinent in spring has increased significantly by approximately 0.64°C in recent years (1998–2022: post-1998) compared to the past (1959–1997: pre-1998), leading to more intense and frequent heatwaves, particularly in March and April. The difference in atmospheric changes between these two periods shows that the enhancement of convective activity over the Philippine Sea drives an anomalous elongated anticyclonic circulation over the Indian subcontinent. This circulation pattern, marked by clearer skies and increased incident solar radiation, significantly contributes to the heat extremes in the Indian subcontinent. Additionally, stationary wave model experiments demonstrate that local diabatic heating over the Philippine Sea is significantly linked to robust spring Indian heatwaves through the Matsuno-Gill response.

OPTIMIZATION OF INCIDENT FLOWS ON THE WALLS OF A HABITAT FOR A TYPICAL CLIMATE IN THE UPPER REGION IN REPUBLIC OF GUINEA

The aim of this work is to develop a mathematical model of the solar radiation incident on the walls of an inclined roof habitat for a typical climate of Guinea and to highlight the influence of the variation in the angle of inclination of the roof. Thereafter, we set up a program for the determination of all its parameters under the Fortran Language and plot our curves through the Origin software. This work allowed us to know, the amount of solar flux that each wall of a habitat receives, the importance of the orientation of the main facade of the habitat to the south, how often the roof is exposed to radiation solar and the influence of the variation of the angle of inclination of the roof compared to the horizontal. For example, for an angle of 15 ° the maximum value of the solar flux received is 547 W / m2 and for that of 75 ° is 995 W / m2. Thus, the optimal angle obtained from analyzes of the variation of solar radiation with respect to the inclination of the roof through Figure 7 is 60 °.

Component-based SHGC determination of BIPV glazing for product comparison

Building-integrated photovoltaic (BIPV) systems are intrinsically designed to generate electricity and to provide at least one building-related function. When BIPV modules act as glazing products in windows, skylights or curtain walls, their ability to control the transmission of solar energy into the building must be characterised by a Solar Heat Gain Coefficient (SHGC) or g value (also known as Total Solar Energy Transmittance – TSET – or “solar factor”). For the comparison of BIPV glazing products consisting of one PV laminate and possibly further, conventional glazing layers separated by gas-filled cavities, the procedures documented in international standards for architectural glazing (e.g. ISO 9050 and EN 410) form a suitable starting point. Easily implemented modifications to these procedures are proposed to take both optical inhomogeneity (if relevant) and extraction of electricity from BIPV glazing units into account. Geometrically complex glazing and shading devices, and light-scattering glazing layers, are outside the scope of the proposed methodology; SHGC determination for obliquely incident solar radiation is also excluded. For these cases, the experimental calorimetric approach documented in [ISO 19467:2017; ISO 19467-2:2021] is recommended.The paper also presents results and conclusions from an implementation exercise and sensitivity study carried out by participants of the IEA-PVPS Task 15 on BIPV. The cell coverage ratio in the PV laminate, the thermal resistance offered by the glazing configuration, the choice of boundary conditions and the effect of extracting electricity were all identified as parameters which significantly affect the SHGC value determined for a given type of BIPV glazing. A practicable approach to accommodate the great variety of dimensions typical for BIPV glazing is also proposed. These findings should pave the way for modifying the existing component-based standards for architectural glazing to take the specific features of BIPV glazing into account.

دراسة التأثير الحراري لعملية تجفيف الطماطم باستخدام نظام الطاقة الشمسي

This study developed a hybrid solar greenhouse dryer (lean-to) incorporated with a solar collector and photovoltaic (PV) system for smallholder processors of tomatoes and evaluated the thermal performance of forced convection mixed-mode solar dryer with two pretreatments of fresh tomatoes (halves and slices) with salt and sugar. Tomatoes dipped in a 40% sucrose solution for 72 hours before drying exhibited a greater initial drying rate than those treated with salt. The hourly average incident solar radiation without a reflector was 673.8 (±214.2) W/m2 outside and 754.6 (±284.5) W/m2 inside the lean-to solar dehydrator during operation. The incident solar radiation in the collector ranged from 390.3 to 1156.0 W/m2, indicating higher levels at the tilt angle. The hourly average air temperatures outside and inside the solar dehydrator and solar collector during the experiment, respectively, were 30.7 (±2.3), 52.7 (±10.1), and 30.7 (±2.3), 79.7 (±26.9)°C for the salt treatment and 31.0 (±2.0), 55.1 (±15.3), and 31.0 (±2.0), 84.8 (±28.0)°C for the sugar treatment. Thus, the solar dehydrator and the solar collector raised the dehydrating air temperatures over the outside for the salt and sugar treatment by an average of 22.0, 49.0, 24.1, and 53.8ºC, respectively. The average hourly air-relative humidity inside the solar dehydrator was 33.5%, while outside was 47.2%. The pretreated tomatoes had an initial moisture content of 93.1% (w.b). The solar dehydrator's thermal efficiency was 72.21%, and its drying efficiency was 56.48%. Consequently, solar energy contributed 84.28 and 71.18% of the generated heating power. The solar dehydrator lost 15.72 and 28.82% of its remaining solar energy due to exhausted air. The solar dehydrator had a daily average energy of 59.375 kWh, and the heating power was 47.473 kWh during the experimental period (29 h).

Experimental performance evaluation of air-based photovoltaic–thermal collector with rectangular turbulators and longitudinal fins

An air-based photovoltaic–thermal collector (PVTC) simultaneously generates electricity and heats air using energy from incident solar radiation. Its simple design ensures low initial costs and easier maintenance. However, its thermal efficiency is limited by the low heat conductivity of air. To address this shortcoming, considerable research has focused on enhancing either the heat transfer area or the heat transfer coefficient. However, only one of these two methods has typically been utilized, and information regarding PVTCs that incorporate both technologies is lacking. Thus, a novel air-based PVTC featuring longitudinal fins and rectangular turbulators is proposed herein. In this PVTC, the fins enlarge the heat transfer area, while the turbulators improve the heat transfer coefficient by creating turbulence near the fin surface. The proposed PTVC (PTVC-LFRT) was experimentally evaluated under real-world weather conditions and also compared with two other PVTC configurations: one with a smooth air channel (PTVC-SMAC) and one with only fins (PTVC-LF) to reveal the potential thermal and electrical gains achievable with the proposed design. As a result, PVTC-LFRT achieved an electrical efficiency of 17.06 %, whereas PVTC-SMAC and PTVC-LF recorded corresponding values of 16.55 % and 16.8 %, respectively. Moreover, PVTC-LFRT exhibited a thermal efficiency of 38.93 %, while PVTC-SMAC and PVTC-LF achieved thermal efficiencies of 22.68 % and 33.56 %, respectively. Finally, the total daily energy output of PVTC-LFRT from incident solar radiation was 42.73 % and 11.2 % higher than those of PVTC-SMAC and PVTC-LF, respectively. These findings verify that incorporating fins with turbulators into a PVTC effectively enhances its electrical and thermal efficiency. Consequently, the feasibility of the proposed system could be confirmed, and its promotion is considered worthwhile.

Large-Scale Solar Potential Analysis in a 3D CAD Framework as a Use Case of Urban Digital Twins

Solar radiation impacts diverse aspects of city life, such as harvesting energy with PV panels, passive heating of buildings in winter, cooling the loads of air-conditioning systems in summer, and the urban microclimate. Urban digital twins and 3D city models can support solar studies in the process of urban planning and provide valuable insights for data-driven decision support. This study examines the calculation of solar incident radiation at the city scale in Sofia using remote sensing data for the large shading context in a mountainous region and 3D building data. It aims to explore the methods of geometry optimisation, limitations, and performance issues of a 3D computer-aided design (CAD) tool dedicated to small-scale solar analysis and employed at the city scale. Two cases were considered at the city and district scales, respectively. The total face count of meshes for the simulations constituted approximately 2,000,000 faces. A total of 64,379 roofs for the whole city and 4796 buildings for one district were selected. All calculations were performed in one batch and visualised in a 3D web platform. The use of a 3D CAD environment establishes a seamless process of updating 3D models and simulations, while preprocessing in Geographic Information System (GIS) ensures working with large-scale datasets. The proposed method showed a moderate computation time for both cases and could be extended to include reflected radiation and dense photogrammetric meshes in the future.

Diurnal Variation in Surface Incident Solar Radiation Retrieved by CERES and Himawari-8

The diurnal variation of surface incident solar radiation (Rs) has a significant impact on the Earth’s climate. Satellite-retrieved Rs datasets display good spatial and temporal continuity compared with ground-based observations and, more importantly, have higher accuracy than reanalysis datasets. Facilitated by these advantages, many scholars have evaluated satellite-retrieved Rs, especially based on monthly and annual data. However, there is a lack of evaluation on an hourly scale, which has a profound impact on sea–air interactions, climate change, agriculture, and prognostic models. This study evaluates Himawari-8 and Clouds and the Earth’s Radiant Energy System Synoptic (CERES)-retrieved hourly Rs data covering 60°S–60°N and 80°E–160°W based on ground-based observations from the Baseline Surface Radiation Network (BSRN). Hourly Rs were first standardized to remove the diurnal and seasonal cycles. Furthermore, the sensitivities of satellite-retrieved Rs products to clouds, aerosols, and land cover types were explored. It was found that Himawari-8-retrieved Rs was better than CERES-retrieved Rs at 8:00–16:00 and worse at 7:00 and 17:00. Both satellites performed better at continental sites than at island/coastal sites. The diurnal variations of statistical parameters of Himawari-8 satellite-retrieved Rs were stronger than those of CERES. Relatively larger MABs in the case of stratus and stratocumulus were exhibited for both hourly products. Smaller MAB values were found for CERES covered by deep convection and cumulus clouds and for Himawari-8 covered by deep convection and nimbostratus clouds. Larger MAB values at evergreen broadleaf forest sites and smaller MAB values at open shrubland sites were found for both products. In addition, Rs retrieved by Himawari-8 was more sensitive to AOD at 10:00–16:00, while that retrieved by CERES was more sensitive to COD at 9:00–15:00. The CERES product showed larger sensitivity to COD (at 9:00–15:00) and AOD (at 7:00–10:00) than Himawari-8. This work helps data producers know how to improve their future products and helps data users be aware of the uncertainties that exist in hourly satellite-retrieved Rs data.

UV-absorbing mycosporine-like amino acids in the eyes of temperate marine and freshwater fish species

Ultraviolet radiation (UVR) is the photochemically most reactive waveband of incident solar irradiation. Despite high absorption in aquatic environments, UVR causes numerous biochemical, genetic, and cytotoxic effects in aquatic organisms. To counteract UVR stress, many of those species are able to synthesize, accumulate, or acquire UV-sunscreen compounds for photoprotection from their diet. The most abundant UV sunscreens in marine and freshwater organisms are mycosporine-like amino acids (MAAs), which exhibit high molar extinction coefficients in the UVR range along with a strong photo- and heat stability. In this study, we investigated the qualitative and quantitative MAA distribution patterns in the eyes of 39 fish species, mainly from the temperate northern hemisphere (Baltic Sea, Northern Atlantic), using state-of-the-art analytical methods. The fish eyes of the most investigated species (33 taxa) contained MAAs, between one and seven different compounds. The MAAs palythine, asterina-330, palythene, and usujirene were present (as previously reported), and three new compounds, aplysiapalythine A, porphyra-334, and shinorine, were identified. Total MAA concentrations covered a wide range from trace amounts to > 4.2 mg g−1 dry weight, thereby providing the first quantitative data on MAAs in fish eyes. The highest MAA contents were measured in Sprattus sprattus, which are comparable to those of intertidal red seaweeds. The trophic transfer of MAAs from primary producers via zooplankton to the fish is discussed, along with the localization in the fish eye as well as possible additional functions.

Solar global irradiance from actinometric degree data for Filaret Observatory (Bucharest), 1892–1903

Long-term series of solar irradiation measured at ground level are not available in the old times. However, long-term series of actinometric degree data obtained by using the Arago-Davy instrument have been recorded in the second half of the 19th century in several locations of the world. We have developed recently a method to estimate global solar irradiance on horizontal surface from actinometric degree data (doi.org/10.1007/s00704-023-04485-2). This opens a way of finding proxy information about the incident solar irradiance on various areas of the globe before the 20th century. Hourly actinometric degree data for the years 1892–1903 are available at the Filaret Observatory (Bucharest, Romania, South-Eastern Europe). The observed series have a systematic decreasing tendency, which has been removed by using a correction procedure. The proposed method is used here to evaluate solar global irradiance at Filaret Observatory. Solar irradiance data provided by the Twentieth Century Reanalysis Project version 3 (20CRv3) are used as a reference. The expected hourly and daily average solar irradiance values show reasonable qualitative consistency with the 20CRv3 data. This consistency is notably stronger during the warmer months from April to September. Much better agreement is found for the monthly averaged solar global irradiance values. At this level, the proposed method and the procedure of the 20CRv3 project seem to validate each other.

Electrical power output potential of different solar photovoltaic systems in Tanzania

This study examines the photovoltaic (PV) energy output and levelized cost of energy (LCOE) in seven regions of Tanzania across five different tilt adjustments of 1 MW PV systems. The one-diode model equations and the PVsyst 7.2 software were used in the simulation. The results reveal variations in energy output and LCOE among the regions and tilt adjustments indicating a strong correlation between PV energy output and solar irradiance incident on the PV panel. For horizontal mounting, the annual energy output ranges from 1229 MWh/year in Kilimanjaro to 1977 MWh/year in Iringa. Among the three optimal tilt adjustments, annually, monthly and seasonal, the last two are predicted to yield larger energy outputs, whereas the two axis tracking configuration consistently provides the maximal energy output in all regions, ranging from 1533 MWh/year in Kilimanjaro to 2762 MWh/year in Iringa. The LCOE analysis demonstrates the cost-effectiveness of solar PV systems compared to grid-connected and isolated mini-grid tariffs. The LCOE values across the regions and tilt adjustments range from $0.07/kWh to $0.16/kWh. In comparison, the tariff for grid-connected solar PV is $0.165/kWh, while for isolated mini-grids; it is $0.181/kWh. The monthly optimal tilt configuration proves to be the most cost-effective option for energy generation in multiple regions, as it consistently exhibits the lowest energy cost compared to the other four configurations. The results provide valuable insights into the performance and economic feasibility of various system setups. Through meticulous simulation and data analysis, we have gained a comprehensive understanding of the factors influencing energy generation and costs in the context of solar photovoltaic systems.

Electrical and thermal performance of bifacial photovoltaics under varying albedo conditions at temperate climate (UK)

Bifacial photovoltaics (bPV) provide an advantage over their traditional monofacial counterparts as they can utilise solar radiation incident on both the front and rear side of the module, allowing for increased energy production. While this is an advantage on the side of bPV, the amount of energy produced by the rear side of the bPV panel can vary greatly depending on the inclination and azimuth of the panel as well as external climatic and ground albedo conditions. This paper aims to analyse the electrical and thermal performance of bPV under varying albedo conditions, using two different materials: grass, and a reflective material. It also contains an example of bifaciality testing under real-world conditions. Several experiments were conducted to evaluate the electrical performance and the temperature distribution of the bPV panel under different weather conditions at the UK location and then the results were compared with the single diode model of bPV. Furthermore, a bPV panel temperature model has been developed for the temperate climate condition of UK. The results show that the open circuit voltage of the system increases with irradiance up to around 800 W/m2, at which point it decreased due to the increased PV system temperature. The normalised efficiency for the PV system under different conditions were also evaluated, which showed that the bPV module was most efficient under diffuse irradiance conditions, encouraging the use of the bPV technology in the UK.

Experimental study of a PV-PCM window under hot summer and warm winter climate

An energy-efficient PV-PCM (Photovoltaic-Phase change material) window is proposed in this study. During the day, a portion of the incident solar radiation is converted into electricity, while excessive heat from internal sources and solar radiation is stored within the PCM infill. At night, the stored heat can be released from the PCM. Unlike existing PV windows with PCM infill, the PCM is sealed in separate modules, allowing for easy adjustment or removal to better adapt to different weather conditions. In this study, the light, thermal and electrical performance of the PV-PCM window was tested in comparison with common clear glazing window, PV window and PCM-infill window under hot summer and warm winter climate.The experiment results demonstrated the ability of PV-PCM window in delaying and reducing the peak indoor temperature in hot summer. Compared with common clear glazing window, the peak temperature reduced by 8.67, 5.35 and 10.70 °C in the three days. Correspondingly, the indoor heat gains were reduced by 364.97, 265.96 and 301.10 kJ. SHGC of the proposed PV-PCM window was reduced to <0.30, whereas the U-value was reduced to <2.50 W/(m2·K). Compared with the PV window, more power generation were observed by PV-PCM window because of the cooling effect brought by the PCM module nearby. Whilst balancing thermal regulation, the daily power generations of the 0.36 m2 semi-transparent CdTe PV-PCM window were 548.33, 316.55 and 58.85 kJ.

Heat and Mass Transfer within Unsteady Nanofluid Movement in the Presence of Sustained Solar Radiation

The unsteady movement of nanofluid on porous inclined media is essential for absorbing and transferring heat from solar radiation. From renewable energy sources, solar is limitless, sustainable and universally accessible without creating conflict. In this study, heat and mass transfer have been explored by unsteadily moving nanofluid with the occurrence of Sun rays and viscous dissipation. Tiwari-Das and Darcy-Forchheimer models are encompassed with convective heat transfer and mass suction/injection. Then, the non-linear higher-order set of ordinary differential equations was obtained from fundamental non-linear partial differential equations by using similarity transformation. Both semi-analytical and numerical strategies have been adopted. Comparisons with published articles have detected and observed similar outcomes. Accordingly, thermal Grashof number elevates nanofluid motion while postponing drag force creation. Permeability and Darcy’s number have publicized a contradictory trend in the nanofluid’s movement and temperature. Nanofluid’s temperature expands by incident solar radiation and Eckert number but not by absorption. There is less heat transfer rate by convective than conductive through magnifying magnetic field and nanoparticles’ concentration. Nanofluid constructed by Cu–H2O produces more drag force and less heat transfer rate than that of Cu–C3H8O2. Heat transfer from solar energy is applicable for cooking, heating water and producing electricity.

Breathing space in a compact city: Impacts of urban re-densification on Mumbai's low-income housing environment

Redevelopment of low-income settlements by re-densifying cities is a common approach in the Global South to improve living conditions and tackle the housing shortage. However, the effectiveness of the housing design in redevelopment schemes remains to be questioned. This study evaluates a proposed design of a slum redevelopment project in Mumbai, India, by comparing the environmental performance of three design schemes: the existing low-income housing, the redevelopment scheme proposed by the local government and a hypothetical design (modified scheme) that aligns with positive environmental outcomes identified in the current literature. The environmental factors such as the natural airflow, incident solar radiation and daylighting parameters were assessed by computational simulations and validated by a wind tunnel experiment. These factors were associated with direct and indirect density metrics of the three design schemes to inform better policymaking for slum redevelopment projects that seek to re-densify housing for the urban poor. The results indicated that the design performance of the redeveloped scheme is less preferable due to the unclean indoor air and inadequate daylighting conditions requiring large-scale demolition of the existing buildings. The modified plan requires minimal demolishment and demonstrates relatively better environmental performance. The study revealed that indirect density measures - building geometry factors and urban form parameters - are essential in affecting the ecological performance of housing. Considering these factors in design standards and policymaking for high-density redevelopment schemes can enable the “Goldilocks density” that significantly improves the quality of living while densifying the cities.

Performance improvement of building-integrated photovoltaic panels using a composite phase change material-carbon foam heat sink: An experimental study

Building-integrated photovoltaic (BIPV) panels are important for enhancing building self-power generation, promoting sustainable energy practices, and reducing dependence on the grid. Nevertheless, the efficiency and output power of these panels are negatively affected by the temperature increase caused by incident solar radiation. Thus, the present study introduces an innovative paraffin/carbon foam composite phase change material for efficient thermal management of building-integrated photovoltaic panels. Through indoor and outdoor experimental tests, the study evaluated and compared the performance of the proposed system. This system integrates a PV panel with an RT-55 phase change material and carbon foam structure (BIPV-PCM-CF) and was compared to three other cases, including a naturally cooled free PV panel, a building wall integrated PV panel to simulate conventional building-integrated photovoltaic system (BIPV), and a PV panel integrated with only RT-55 paraffin wax as the phase change material (BIPV-PCM). The study found that integrating the PV cell into building walls (BIVP) increased its temperature by 9.61 °C and decreased generated power and efficiency by 5.11 % and 10.95 %, respectively, compared to the free PV panel. On the other hand, the BIPV-PCM panel reduced module temperature by 18.1 °C but could not solidify the needed amount of PCM during the nighttime. The BIPV-PCM-CF panel, which incorporated carbon foam with PCM, outperformed the other systems, producing a cooling performance of 22.94 °C and increasing electricity generation and system efficiency by an average of 12.64 % and 27.35 %, respectively, compared to the free PV panel. These findings highlight effective strategies to promote sustainable energy practices, improve the electric performance of BIPV panels, and reduce dependence on non-renewable energy sources in buildings.

THEORETICAL PERFORMANCE ASSESSMENT OF A PARABOLIC TROUGH HUMIDIFYING SOLAR COLLECTOR-BASED SOLAR STILL

In this paper, a parabolic trough humidifying solar collector-based solar still (PHSC-SS) is proposed. Its purpose is to apply some important performance improvement techniques to the flat plate humidifying solar collector-based solar still (flat plate HSC-SS), to significantly improve overall system performance. These included the use of parabolic trough solar concentrators and the design of humidifying solar collectors from evacuated tube collectors. The results reveal that, unlike flat plate HSC-SS, which must operate with a turbulent airflow regime to achieve optimum overall performance, PHSC-SS must operate with a laminar airflow regime and high inlet and outlet temperatures of air (at least 55 °C and less than 100 °C, at atmospheric pressure) in the heat collector element. For 900 W/m2 of incident solar irradiance, 2 m2 of solar collector area, and 0,00042 kg/s of air flow rate, the maximum energy efficiency, exergy efficiency and daily freshwater productivity of PHSC-SS were found to be 68,12%, 14,87% and 1,697 kg/h, respectively. Whereas for the same incident solar irradiance and solar collector area, and 0,1 kg/s of air flow rate, those of the flat plat HSC-SS were 72,9%, 1,12%, and between 1,07 – 2,923 kg/h (for inlet and outlet temperatures of air less than 30 °C, at atmospheric pressure), respectively. Although in some extreme cases freshwater productivity of flat plate HSC-SS can be higher than that of PHSC-SS, it should be noted that laminar airflow regime confers great advantages to PHSC-SS. These are higher air temperatures at condenser inlet (which ease water condensation process), no need of an auxiliary cooling device (needed in the flat plate HSC-SS), less mechanical vibrations of system, reduced condenser size, and less energy consumed by air blowers. Furthermore, the upper limit of the PHSC-SS is a PHSC-SS that operates without air flow, but rather by vaporization of water droplets at boiling point from absorber, followed by their suction to condenser, similarly to a flash evaporation.

Energy- and exergy-based economical and environmental (4E) evaluation of the influence of natural pollutants on PV array performance

In the present investigation, thermodynamic/eco/environmental analysis of the relationship between time-dependent particle deposition and thermal-based losses and incident solar radiation intensity on the PV front cover glass during the months with the least precipitation in the city of Samsun (Turkey) was performed. To evaluate the effect of dust accumulation, controlled experiments were carried out where the surface of one set of PV panels was periodically cleaned with water and the other one was left to natural contamination. The results showed that over three months, the difference in energy loss rates between cleaned and uncleaned PV arrays ranged from 2.53% to 8.1%, with the exergy efficiency difference measured at 1.3%–2.44%. According to the energy-based analyzes, August was the most effective month, with cleaned PV arrays reducing CO2 emissions by 401.5 kg and saving $6.02, compared to uncleaned PV arrays which reduced emissions by 362.21 kg and cost $5.43, respectively. Similarly, in the exergy-based evaluation, August was the most efficient month, with cleaned PV arrays decreasing CO2 emissions by 401.5 kg and saving $6.02, compared to uncleaned PV arrays, which dropped CO2 emissions by 362.21 kg and costing $5.43, respectively. While the cleaned surfaces were initially positive, a decrease was observed over time. However, the efficiency of PV decreased with increasing panel temperature. The study concludes that PV surfaces need to be cleaned at certain intervals, depending on the location’s weather conditions.