Amount Of Solar Radiation Research Articles

Solar Radiation Prediction Using Different Machine Learning Algorithms and Implications for Extreme Climate Events

Solar radiation is the Earth’s primary source of energy and has an important role in the surface radiation balance, hydrological cycles, vegetation photosynthesis, and weather and climate extremes. The accurate prediction of solar radiation is therefore very important in both the solar industry and climate research. We constructed 12 machine learning models to predict and compare daily and monthly values of solar radiation and a stacking model using the best of these algorithms were developed to predict solar radiation. The results show that meteorological factors (such as sunshine duration, land surface temperature, and visibility) are crucial in the machine learning models. Trend analysis between extreme land surface temperatures and the amount of solar radiation showed the importance of solar radiation in compound extreme climate events. The gradient boosting regression tree (GBRT), extreme gradient lifting (XGBoost), Gaussian process regression (GPR), and random forest models performed better (poor) prediction capabilities of daily and monthly solar radiation. The stacking model, which included the GBRT, XGBoost, GPR, and random forest models, performed better than the single models in the prediction of daily solar radiation but showed no advantage over the XGBoost model in the prediction of the monthly solar radiation. We conclude that the stacking model and the XGBoost model are the best models to predict solar radiation.

Photovoltaic Placement for Losses Reduction and Voltage Stability Enhancement in the Port Moresby System, Papua New Guinea

The power grid in the capital city of Papua New Guinea, Port Moresby, still experiences problems of voltage stability and power losses due to many factors which is the common problem that most power systems continue to mitigate until today. The factors that give rise to these problems are the imbalance between generation and load and the long-distance of transmission lines. A possible solution to counteract these problems is to integrate photovoltaic systems into the power grid, especially at the load distribution network. This paper presents PV placement for Port Moresby system by using two stages, which are (1) identification of location with good irradiance then (2) determination of PV location by minimizing power losses and improving the voltage profile. This alternative approach is considered because Port Moresby city is situated in a location that is exposed to a significant amount of solar radiation of about 1976 kWh/m2 GHI annually. Therefore, this makes Port Moresby a suitable location to utilize this type of renewable energy technology. This research provides an analysis of the power flow within the Port Moresby grid through simulation using the Newton-Raphson method. The analysis and simulations are performed to identify the most sensitive buses within the system. Based on their high irradiance levels, these specific areas are identified as the best possible areas for integrating the photovoltaic system.

Reduction in autumn precipitation over Southwest China by anthropogenic aerosol emissions from eastern China

Impacts of anthropogenic aerosols in China on autumn precipitation over Southwest China were investigated using version 5.1 of the Community Atmosphere Model. Simulations with and without anthropogenic aerosol emissions were compared to examine the effects of anthropogenic aerosols on surface air temperature and precipitation in East Asia. Our results show that the aerosol increase induces strong cooling over East Asia by aerosols' direct effect on radiation and indirect effect on clouds. Substantial reductions in precipitation are found across eastern China, but the largest decrease is in Southwest China. Anthropogenic aerosols cause a considerable increase in the cloud condensation nuclei number concentration and a decline in the cloud droplet effective radius in East Asia. The reduced cloud droplet sizes suppress the formation of precipitation and increase cloud depth and liquid water path. Consequently, aerosols' direct radiative effect as well as indirect effect on cloud depth and albedo significantly reduce the shortwave radiation for all sky between 20°and 40°N in China. More absorbing aerosols in the lower troposphere increase shortwave radiative heating, which possibly burns off low-level convective clouds and could cause significant reductions in condensational heating in the lower troposphere. The patterns of the shortwave heating increase and condensational heating reduction are generally consistent with significant reductions in the convective precipitation over China. We further investigated other factors governing precipitation and found moderate stability enhancement and moisture transport reductions in most of China, both of which partially contribute to a decrease in the convective precipitation in Southwest China. Aerosols' direct and indirect effects reduce the amount of solar radiation reaching the surface and cool the surface and lower troposphere between 20° and 40°N, causing anomalous subsidence and reductions in the large-scale precipitation over central and eastern China. Both convective and large-scale precipitation are suppressed over Southwest China, leading to a significant decrease in total precipitation over this area.

Numerical and experimental analysis of the tilt angle’s effects on the characteristics of the melting process of PCM-based as PV cell’s backside heat sink

Changes in the tilt angle technically affect the amount of solar radiation reaching the surface of panels. Specific to PV/PCM system, where PCM is employed as passive cooling methods for the PV cells, these changes could affect the melting performance of the PCM and subsequently the overall performance of the PV cells. This novel study presents a numerical and experimental analysis to access the effect of tilt angle on the characteristics of the melting process of PCM-based as heat sink inside the PV cells backside rectangular container and its potential used for thermal management of the PV cells. While numerous literature on the numerical modeling of this system focused their attention on the vertical angle, four different tilt angles (0°, 30°, 60°, and 90°) are considered in this study. Excellent agreement was seen between the results obtained from experiments and numerical simulations. The results show that as the tilt-angle of PV/PCM system increases from 0° to 90°, the melting process time of PCM decreases which leads to decrease in overall PV cell temperature from −0.4% to −12%. In conclusion, PCM shows minimal cooling performance at a lower tilt angle due to the role of natural convection heat transfer inside PCM container which acts as a passive cooling mechanism.

Development of Solar Energy and Its Place in the Energy Sector of the Republic of Buryatia

Solar energy is one of the priority directions for the development of alternative energy. This is facilitated by climatic characteristics. Buryatia has up to 300 sunny days a year. The amount of solar radiation in Buryatia is 4-5 kWh per m2/day (Fig. 1), and the duration of sunshine is more than 2000 hours per year (Fig. 2). Three investment companies are already operating in Buryatia: LLC “Avelar Solar Technology”, LLC “Complex Industry” and LLC “Green Energy Rus” (Table 2), which in the period of 2017-2019 have already built 5 solar power plants (SPP) with a capacity of 70 MW and a total cost of 8.7 billion rubles (more than $115 mln1). To date, the share of SPP capacity of the total capacity of Buryatia is 4.81%. Until 2022, it is planned to commission another 7 SPPs with a capacity of 155 MW, thus increasing the total capacity to 225 MW (Table 2) and the share to 14%, if the situation with CHPP-2 does not change. All SPP capacities are being introduced into the general energy system of the Southern energy district of the Republic of Buryatia, and will not be isolated energy systems.

Investigation of fly ash soiling effects on solar modules performances

The increase of solar modules installation worldwide has led to an increase in the investigation of the phenomena that may cause adverse effects on the performance of solar modules, such as soiling. Soiling of solar modules surface leads to a reduction in their performance due to reduced quantity of solar radiation reaching solar cells. Having in mind that (in Serbia) solar modules on the roofs are often located near chimneys, and that for heating fossil fuels are mostly used, during the heating season fly ash is accumulated on solar modules reducing their performances. This paper presents results of the outdoor experimental investigation of the impact of accumulated fly ash during the heating season on solar modules surface set at an angle of 0° (horizontal), and at an optimal angle of 32° for the area of ​​Niš on their power. The experiment was carried out for a period of 168 days. The maximum power reduction (greatest reduction of solar modules power due to fly ash soiling) both for the horizontal and optimally installed module due to the fly ash accumulation was measured on the 45th day of the measurement. The maximum power reduction of the horizontal module was 87.2%, and of the optimally set module 30.6%. The morphology of the fuel oil fly ash was analyzed using scanning electron microscopy (SEM). The fly ash particles were generally spherical in shape, of a porous structure and the largest number of particles had diameters of 20 μm to 50 μm.

Biaxial Equatorial Solar Tracker with High Precision and Low Consumption: Modelling and Realization

The solar tracker is a mechanism that helps the photovoltaic panel to maximize its performance, while keeping it oriented towards direct solar radiation. In order to specify tracking, most solar trackers use two axes, one horizontal and the other vertical, which implies an increase of the consumed energy and a decrease in precision, since we have to make both motors operate simultaneously. This paper is a modelling of a biaxial solar tracker, with the principle of an equatorial mount, allowing it to precisely follow the sun via a single axis (equatorial axis), while the second axis (tilt axis) makes a small daily correction of few seconds at sunrise. In this way, our model keeps precision to the maximum, with minimum energy consumption. A detailed simulation clearly shows that the proposed model receives the maximum solar irradiation that a normal surface to solar radiation can receive and may in a certain period of the year receive a gain in the amount of solar irradiation; we have up to 63.47% compared to a fixed installation. The study details the different tracking methods, in order to adapt the concept model to the type of solar panel used. We closed finish the study with the realization of the prototype with a detailed explanation of the concept movement. To validate the simulation, we have made an experience that gives us the same results as given by simulation.

Sensitivity of surface solar radiation to aerosol–radiation and aerosol–cloud interactions over Europe in WRFv3.6.1 climatic runs with fully interactive aerosols

Abstract. The amount of solar radiation reaching the Earth's surface can be highly determined by atmospheric aerosols, which have been pointed to as the most uncertain climate forcing agents through their direct (scattering and absorption), semi-direct (absorption implying a thermodynamic effect on clouds) and indirect (modification of cloud properties when aerosols act as cloud condensation nuclei) effects. Nonetheless, regional climate models hardly ever dynamically model the atmospheric concentration of aerosols and their interactions with radiation (ARIs) and clouds (ACIs). The objective of this work is to evince the role of modeling ARIs and ACIs in Weather Research and Forecast (WRF) model simulations with fully interactive aerosols (online resolved concentrations) with a focus on summer mean surface downward solar radiation (RSDS) over Europe. Under historical conditions (1991–2010), both ARIs and ACIs reduce RSDS by a few percentage points over central and northern regions. This reduction is larger when only ARIs are resolved, while ACIs counteract the effect of the former by up to half. The response of RSDS to the activation of ARIs and ACIs is mainly led by the aerosol effect on cloud coverage, while the aerosol effect on atmospheric optical depth plays a very minor role, which evinces the importance of semi-direct and indirect aerosol effects. In fact, differences in RSDS among experiments with and without aerosols are smaller under clear-sky conditions. In terms of future projections (2031–2050 vs. 1991–2010), the baseline pattern (from an experiment without aerosols) shows positive signals southward and negative signals northward. While ARIs enhance the former and reduce the latter, ACIs work in the opposite direction and provide a flatter RSDS change pattern, further evincing the opposite impact from semi-direct and indirect effects and the nontrivial influence of the latter.

The thermal dependence and molecular basis of physiological color change in Takydromus septentrionalis (Lacertidae).

ABSTRACTOne of the main functions of physiological color change is thermoregulation. This change occurs much more rapidly than morphological color change, but the underlying mechanism remains poorly understood. Here, we studied the thermal dependence and molecular basis of physiological color change in lizards using Takydromus septentrionalis (Lacertidae) as the model system. Body color was thermally sensitive, becoming increasingly light as body temperatures deviated from the level (∼30°C) preferred by this species. We identified 3389 differentially expressed genes (DEGs) between lizards at 24°C and 30°C, and 1,097 DEGs between lizards at 36°C and 30°C. Temperature affected the cAMP signal pathway, motor proteins, cytoskeleton, and the expression of genes related to melanocyte-stimulating hormone (MSH) and melanocyte-concentrating hormone (MCH). Our data suggest that the role of physiological color change in thermoregulation is achieved in T. septentrionalis by altering the arrangement of pigments and thus the amount of solar radiation absorbed and reflected. G protein-coupling system inhibits adenylate cyclase activity to transform ATP into cAMP and thereby causes rapid pigment aggregation. MCH deactivates the G proteins and thereby initiates pigment dispersion. This mechanism differs from that reported for teleost fish where MCH activates the G proteins and thereby causes pigment aggregation.This article has an associated First Person interview with the first author of the paper.

The influence of cloudiness and atmospheric circulation on radiation balance and its components

The article contains an analysis of the influence of cloudiness and atmospheric circulation on the components of radiation balance (Q*) using the example of measurements taken in an extra-urban area of Koniczynka near Toruń (Central Poland) in the years 2011–2018. The average annual value of Q* was 1,818.5 MJ·m−2 with a maximum of 352.3 MJ·m−2 in June, and negative values from November to January (December: −27.4 MJ·m−2). The shortwave radiation balance (S*) amounted to 3,129.2 MJ·m−2 and the longwave radiation balance (L*) was ˗1,310.7 MJ·m−2. In June the average solar irradiance (S↓) at midday was 600 W·m−2. The natural annual and diurnal course of Q* components, determined by astronomical factors, is disturbed by changes in cloudiness and inflow of various air masses. It has been found that an increase in cloudiness causes the amount of incoming solar radiation (S↓) to fall, thus decreasing the S* balance. Moreover, clouds restrict longwave radiation balance (L*), in particular, downward atmospheric radiation (L↓) increases. The opposite relationships of S* and L* affect Q* in individual months. The components of Q* are influenced by atmospheric circulation; it has been observed that anticyclonic types, characterised by smaller cloud amounts, favour a greater influx of (S↓) and—at the same time—greater emittance (L↑); however, Q* is then greater than in the case of cyclonic circulation. A statistically significant trend of Q* and its components has not been ascertained. A notable great year-on-year variability of Q*, ranging from 1,640.4 MJ·m−2 (in 2011) to 2,081.6 MJ·m−2 (in 2018), affects the environment. The changes are related to the cloudiness and the frequency of occurrence of different atmospheric circulation types. The role of snow cover is also important as snow reflects solar radiation which leads to the decrease of S* and—as a result—to a negative value of Q* in winter.

A century since the recognition of cyclic climatic change by Milanković

One hundred years ago the Serbian engineer, mathematician and geophysicist Milutin Milanković published the seminal work Mathematical Theory of Thermal Phenomena Caused by Solar Radiation, which laid the foundation for mathematical modelling of climatic cycles. Milanković succeeded in linking major climate change to three known astronomical parameters which controlled the amount of solar radiation on Earth during different seasons and at different latitudes, these are: Earth's orbit eccentricity around the Sun; the tilt or obliquity of Earth's axis of rotation; and the precession of the rotation axis or 'wobblelike' movement. The proposal of periodic fluctuations in Earth's climate (now known as Milanković cycles) was rejected and ridiculed during the 1950s, but received acclaim in the seventies following publication of the outcomes of seminal multidisciplinary research by Hays, Imbrie and Shackleton.

Solar energy efficiency in the city of Samawah and its speed in charging off-grid PV system batteries

The research shows a study of solar energy efficiency in the city of Samawah by using solar cells with some installations to generate electric energy and charge batteries for areas far from electric power plants and areas that are difficult to connect to the national electricity grid (off grid). Solar energy efficiency is calculated based on the average energy consumed within one home during 24 hours without interruption in those areas. Hence, this research focuses on designing a (photovoltaic system) to generate electrical energy consisting of solar cells with a charge regulator with a current inverter with rechargeable storage batteries. This system depends on the average amount of solar radiation falling in those areas and the high temperature of the sun, which is useful for charging and storing batteries faster.

The impact of urban morphology and building's height diversity on energy consumption at urban scale. The case study of Dubai

The indoor air temperature and cooling load are highly affected by the surrounding environment. Enhancing outdoor thermal performance leads to a positive impact on energy consumption for cooling purposes, specifically in hot climate countries such as the UAE. The UAE weather characteristics specified as desert climate, however, it is more humid than the other cities with similar climate conditions. It has been found that a limited number of publications concern with the direct impact of urban morphology on the indoor cooling load within local climate conditions of the UAE. Moreover, the integrated and direct impact of height diversity on the indoor cooling load at an urban scale requires more investigation. This study aims to explore the impact of urban morphology, specifically height diversity on the cooling load within local climate conditions of the UAE. Furthermore, it aims to find an optimized cooling consumption prototype of an urban block to emphasize the study novelty. It adopts urban planning and building morphology to optimize the outdoor thermal performance and reflect this enhancement on indoor energy consumption. The results show that the orientation is the most influential factor in the urban block cooling load and energy consumption. It is significantly and directly control the amount of solar radiation and buildings solar gain. The minimum direct solar gain of the base case configuration concerning the orientation is recorded in the N–S with a reduction of 13% compared to the NE-SW orientation. This has resulted in a reduction in cooling load by 6.4% between these two orientations. Further to that, the reduction in outdoor air temperature and solar gain by implementing the building's height diversity resulted in a reduction in cooling load by 4.6% between the base case and the urban block configuration with the building's height diversity.

Cloud ‘shrinking’ and ‘optical thinning’ in the ‘dimming’ period and a subsequent recovery in the ‘brightening’ period over China

There was a dramatic increase in aerosol loading in China after the 1960s due to rapid industrialization, followed by a gradual reduction due to improvements in air quality since the early 2000s. They are deemed to be the main cause of ‘dimming’ and ‘brightening’ in China, respectively. China, therefore, provides an ideal testbed to investigate the multi-decadal evolution of clouds under a background of large variations in the amount of atmospheric aerosols. We used a unique combination of long-term in-situ observational records combined with a radiative transfer model to investigate the changes in clouds and aerosols over the last 60 years (1958–2018) over China. We found during the dimming period, the clouds over China shrunk in area steadily, gradually thinned in terms of optical depth, and thereby blocked less and less solar radiation. This situation reversed during the brightening period. The clouds over China showed a quick expansion in extent and thickening in terms of optical depth, and accordingly the amounts of solar radiation blocked by clouds recovered rapidly. It is observationally demonstrated that high levels of pollution and the associated amount of aerosols cause a suppression of cloud growth and a reduction of optical depth.

Experimental and Theoretical Investigation of Performance of a Solar Chimney Model, Part I: Experimental Investigation

This paper presents the experimental data that was collected from small pilot solar chimney. The experimental data together with ambient conditions are used to evaluate the performance and study the behavior of the solar chimney; this data will be used for comparison with theoretical models in another paper [part II). The solar chimney prototype was designed and constructed at the Subrata Faculty of Engineering-Libya. The data were collected over several days of June 2011. The solar chimney system contains two main components; the solar collector and the solar chimney. The solar collector root‘ has a circular area of126 m3, the solar chimney is a PVC tube with internal diameter of 0.2 m and the total height of chimney is 9.3 m. The measurements include the intensity of solar radiation inside/outside the collector, temperature and velocity of air at the entrance of the chimney, temperature and speed of wind outside the collector, temperature of the ground inside collector al1d temperature measurements of air at speci?c points at different levels throughout the collector. Solar irradiance was found to affect the chimney temperature and subsequently affects chimney air velocity. The experimental results showed that temperature differences of (30 - 45°C) were recorded between the ambient temperature and that of air inside the chimney in the middle of the day, where the highest air temperature of 73.4°C was recorded at the entrance of the solar chimney. The maximum air velocity of 3.6 m/s was recorded inside the solar chimney at noon on 9 June. Wind speed outside the collector had a small effect on the speed of the air inside the chimney and tends to change slightly, hence, can neglect influence of wind speed on the performance of the system. Also the experimental results indicate that such type of system can trap a suf?cient amount of solar radiation, which elevates the air temperature to a suf?cient value able to generate enough air ?ow to operate a wind turbine to produce electricity; this means the solar chimney system for electricity production can work in the north-western part of Libya in the summer time at least.

Late-season plastic covering delays the occurrence of severe water stress and improves intrinsic water use efficiency and fruit quality in kiwifruit vines

Kiwifruit is widely recognized as a fruit crop sensitive to water stress due to low stomatal regulation. Unfortunately, many of the most important kiwifruit producing areas have been affected by increasing water scarcity due to climate change. Protected cultivation may be used in kiwifruit vines not only to mitigate water stress and potential reductions in fruit quality but also to increase intrinsic water use efficiency. At the beginning of fruit maturation, two environmental conditions (uncovered and covered with a transparent plastic covering) were assessed in mature kiwifruit plants (Actinidia deliciosa Chev. cv. Hayward) subjected to conventional and deficit irrigation regimes in San Nicolás, Chile, for two consecutive seasons. The results showed that covered plants under deficit irrigation required twice the time to exhibit severe water stress levels (~−1.3 MPa) than plants under open-field conditions. Despite changes in solar radiation quantity and quality due to the transparent plastic covering, differences in rates of water stress occurrence between cover treatments in deficit-irrigated vines were not explained by differences in soil desiccation or stomatal conductance. The delay in severe water stress onset led to considerable water savings and caused no reductions in either yield or fruit quality, which increased water productivity between 21% and 71%. Fruit from covered plants subjected to deficit irrigation exhibited higher firmness at greater maturity (>7.0 Brix). The increase in water productivity in severely water-stressed kiwifruit vines, when using late-season plastic canopy cover, confirms that protected cultivation can be an excellent tool to reduce the impact of limited irrigation in many kiwifruit producing areas affected by water scarcity.

The Influence of Air Quality on Solar irradiances in most air polluted months in China

Solar energy, as a kind of clean and sustainable energy, is widely used in most countries, and the number of PV generators is increasing year by year in China. The solar energy generation directly depends on the amount of solar irradiance, which is easily affected by atmosphere situation. With the rapid development of urbanization and industrialization, the atmosphere situation in China become worse and worse, and the air is always heavily polluted in recent years, which will reduce the irradiance getting to the ground. In order to analyze the effect of air quality on the solar irradiance, we analyze three kinds of solar irradiance Direct Normal Irradiance (DNI), Global Horizontal Irradiance (GHI), and Diffuse Irradiance (DIF). The influence of the Air Quality Index (AQI) on DNI, GHI, DIF are analyzed from November to February in the most air polluted months in recent four years for Beijing, Harbin, Shanghai and Guangzhou. The date when the AQI was the local maximum(minimum), DNI and GHI were the local minimum(maximum), and DIF was also the local maximum(minimum) are selected. The results shows that DNI and GHI decrease, and DIF increases with the increase of AQI,. The six-order polynomial is used to fit the difference of the three irradiance and the difference of AQI. The average fitting coefficient R2 for GHI is 0.8855, DNI is 0.8529 and DIF is 0.8466, and the highest R2 for GHI is 0.9748, DNI is 0.9794 and DIF is 0.9820.

Experimental Investigation of Phase Change Material as an Insulator in Hollow Brick Wall

In this paper, an experimental study has been conducted for using a PCM as a thermal insulation material in a south wall of a room. Two identical cubic rooms were fabricated from sandwich panels except for the south wall (test wall) was built as an Iraqi domestic wall. South wall orientation was chosen as the test wall due to the significant amount of solar radiation falling on it so that the study compared two test walls, a wall without PCM or not treated wall (NTW) and a wall embedded with PCM or treated wall (TW). The results show that using PCM in TW will increase the time lag by 1 hour and decrease the inner surface wall and room temperature by about 2.7 °C compared with NTW.

Optimization of Photovoltaic Array Orientation and Performance Evaluation of Solar Tracking Systems

In recent years, solar energy has received tremendous attention in accordance with the global efforts in moving towards clean energy generation. A solar tracking system shifts the position of solar panel following the Sun's movement, allowing more energy to be harvested. This paper aims to evaluate the performance of solar tracking system in Malaysia, including the east-west single-axis tracking system, north-south single-axis tracking system, vertical axis tracking system, and dual-axis tracking system. The periodical tilt angle adjustment of fixed-tilt photovoltaic system is also investigated to optimize its performance. A mathematical model is formulated to compute the amount of solar radiation collected in a photovoltaic system and the optimization model is solved using genetic algorithm to determine the optimal tilt and azimuth angles for maximum solar radiation yield. Based on the results, PV system with dual-axis solar tracker has 22.14 % more solar radiation collected compared to the fixed-tilt system, while monthly tilt angle adjustment improves the yield by 2.15 %.

The Optimum PV Panels Slope Angle for Standalone System: Case Study in Duhok, Iraq

Due to the high operation and maintenance charges of the photovoltaic (PV) tracking systems, it is better to install the PV panels at a stationary angle which is considered as an optimum slope angle. Usually the optimum annually slop angle equals to latitude. However, Duhok site (latitude 36°50’40.6” N, longitude 43°01’05.3” E) has a special case because it’s located in valley between two mountains where the eastern sides of these mountains block the sunlight at the early morning. This paper aims at finding the optimum annually slop angle that makes the solar panels in this site generate the highest possible amount of electrical energy by capturing largest amount of solar radiation at this period when the sun appears from behind the mountain. HOMER software is used to simulate the suggested standalone PV system at the study site. The optimization outcomes present that the optimum annually slope angle for the PV panels should be equal to 25 °.