Amount Of Solar Radiation Research Articles

Energy Efficiency Enhancement of Photovoltaics by Phase Change Materials through Thermal Energy Recovery

Photovoltaic (PV) panels convert a certain amount of incident solar radiation into electricity, while the rest is converted to heat, leading to a temperature rise in the PV. This elevated temperature deteriorates the power output and induces structural degradation, resulting in reduced PV lifespan. One potential solution entails PV thermal management employing active and passive means. The traditional passive means are found to be largely ineffective, while active means are considered to be energy intensive. A passive thermal management system using phase change materials (PCMs) can effectively limit PV temperature rises. The PCM-based approach however is cost inefficient unless the stored thermal energy is recovered effectively. The current article investigates a way to utilize the thermal energy stored in the PCM behind the PV for domestic water heating applications. The system is evaluated in the winter conditions of UAE to deliver heat during water heating demand periods. The proposed system achieved a ~1.3% increase in PV electrical conversion efficiency, along with the recovery of ~41% of the thermal energy compared to the incident solar radiation.

PV sites suitability analysis in the Eastern region of Morocco

This Paper discusses the possibility of installation of large-scale Photovoltaic (PV) power plants in the Eastern region of Morocco. For this purpose, a large database of land exclusion with “high spatial resolution” has been built. This dataset contains all the information about roads, power grid, vegetation, hydrology, protected areas, etc. The solar irradiation map was created by interpolating the global horizontal irradiation (GHI) measurements of ten meteorological stations distributed on the surface of this region.Furthermore, a simulation of the electrical production, as well as, the performance of a 15MWp Photovoltaic system –similar to the “Lucainena de las Torres” PV project in Almeria, southern Spain– has been conducted under the climate of Oujda city and compared to those calculated under Almeria’s climate.Results show that the Eastern region of Morocco receives a high amount of solar irradiation, with a maximum of 1930kWh.m−2. It also offers a big capability to host PV farms with a surface of 44,863km2, which represents about 75% of its total surface. Moreover, the electrical generation of a PV plant can be considered as high. For instance, the electricity production of a 15MWp – if installed in Oujda city– is about 23,4GWh/a with an annual Performance Ration of 72,3%.

Evaluating the effect of particulate matter pollution on estimation of daily global solar radiation using artificial neural network modeling based on meteorological data

Nowadays, using solar energy as a clean, renewable and available energy resource, has increasingly become crucial due to dwindling of fossil fuel resources and many environmental concerns across the world. Thus, numerous research works have been conducted to study the implementation of this energy source in different industries as a replacement for current, less environmentally-friendly energy sources. Engineering designs and scientific studies for improving the efficiency of solar energy systems and assessing their feasibility require actual data regarding the amount of solar radiation, which cannot easily be measured in some regions. For these locations, empirical relations and theoretical models are common methods of estimating the amount of solar irradiance. Recent studies have illustrated that empirical methods and models are helpful in forecasting the amount of solar radiation and despite their acceptable accuracy, using novel methods such as Artificial Neural Network (ANN) modeling enables researchers to make even more accurate predictions. For estimating daily GSR, importance of key input parameters including Particulate Matter (PM), in addition to widely used modeling parameters in recent studies, such as Relative Humidity, Wind Speed and Daily Temperature has been assessed. Also, based on meteorological data, an ANN modeling approach has been developed for a 1-year period and for Tehran, Iran as a case study location. Some statistical indexes such as Mean Absolute Percentage Error (MAPE), Root Mean Square Error (RMSE) and Absolute Fraction of Variance (R2), which are mainly used for evaluating the efficiency and accuracy of models, have been determined as 1.5%, 0.05 J Cm−2d−1 and 99% respectively. It can be asserted that based on the values of the aforementioned statistical indexes, presented model in this research has relatively higher accuracy and credibility compared to the models that have been presented before. In addition, this paper shows that considering Particulate Matter (PM) as a parameter in estimation of GSR boosts modeling efficiency.

View Factors of Flat Solar Collectors Array in Flat, Inclined, and Step-Like Solar Fields

Solar radiation consists of direct beam, sky diffuse, and reflected radiations from the ground and adjacent surfaces. The amount of diffuse radiation falling on solar collector depends on the view factor of the collector to sky. The reflected radiation striking the collector's surface depends on the reflectivity of the surface, as well as on view factors and the amount of solar radiation reaching the reflecting surfaces. The amount of reflected radiation coming from the ground can be of an appreciable amount, and can be amplified using special reflector surfaces. This study develops general analytical expressions for the sky's view factors as well as factors related to the ground and those between collectors for the deployment of collectors in multiple rows, in three types of solar fields: flat, inclined, and steplike solar fields. All parameters presented in these expressions are measurable (edge-to-edge dimension). The effects of the design parameters such as the tilt of the angle of the collector, the distance between the collectors, the height of the collector, the position of the collector above the ground (as in the case of step-like field), and the inclination of the land of the field (as in the case of an inclined field) on the view factors are numerically demonstrated. The current study also specifies new terms such as the sunny zone and the shadow zone; these zones control the amount of solar radiation reflected onto the collector. As a result, the ground-view factor that depends on the altitude of the solar angle is considered to be a dynamic parameter. The results obtained may be used to estimate the solar radiation incident on all types of solar fields, with the possibility of increasing the incident radiation on a collector by using planar reflectors.

Experimental Analysis of Desalination Unit Coupled with Solar Water Lens Concentrator

The main problem that the world faces in this scenario is shortage of potable water. Hence this research work rivets to increase the yield of desalination system in an economical way. The integration of solar concentrator and desalination unit can project the desired yield, but the commercially available concentrated solar power technologies (CSP) are not economically viable. So this study proposes a novel method to concentrate ample amount of solar radiation in a cost effective way. Water acting as lens is a highlighted technology initiated in this work, which can be a substitute for CSP systems. And water lens can accelerate the desalination process so as to increase the yield economically. The solar irradiance passing through the water will be concentrated at a focal point, and the concentration depends on curvature of water lens. The experimental analysis of water lens makes use of transparent thin sheet, supported on a metallic structure. The Plano convex shape of water lens is developed by varying the volume of water that is being poured on the transparent thin sheet. From the experimental analysis it is inferred that, as the curvature of water lens increases, solar irradiance can be focused more accurately on to the focus and a higher water temperature is obtained inside the solar still.

Sensitivity of modelled sulfate aerosol and its radiative effect on climate to ocean DMS concentration and air–sea flux

Abstract. Dimethylsulfide (DMS) is a well-known marine trace gas that is emitted from the ocean and subsequently oxidizes to sulfate in the atmosphere. Sulfate aerosols in the atmosphere have direct and indirect effects on the amount of solar radiation reaching the Earth's surface. Thus, as a potential source of sulfate, ocean efflux of DMS needs to be accounted for in climate studies. Seawater concentration of DMS is highly variable in space and time, which in turn leads to high spatial and temporal variability in ocean DMS emissions. Because of sparse sampling (in both space and time), large uncertainties remain regarding ocean DMS concentration. In this study, we use an atmospheric general circulation model with explicit aerosol chemistry (CanAM4.1) and several climatologies of surface ocean DMS concentration to assess uncertainties about the climate impact of ocean DMS efflux. Despite substantial variation in the spatial pattern and seasonal evolution of simulated DMS fluxes, the global-mean radiative effect of sulfate is approximately linearly proportional to the global-mean surface flux of DMS; the spatial and temporal distribution of ocean DMS efflux has only a minor effect on the global radiation budget. The effect of the spatial structure, however, generates statistically significant changes in the global-mean concentrations of some aerosol species. The effect of seasonality on the net radiative effect is larger than that of spatial distribution and is significant at global scale.

Seasonal and spatial variation of solar radiation in Nepal Himalayas

Solar radiation data (two-hourly data from 1987 to 1999) observed at high altitude meteorological stations in Nepal Himalayas were analyzed to study seasonal and spatial variation of solar radiation and shed some light on solar energy potential and prospect of vegetation development in the mountainous region of Nepal. Results showed significant similarities and differences on solar radiation with respect to seasons and locations (altitudes). Mean seasonal amount of solar radiation was generally higher in spring than in summer. The significant amount of monsoonal clouds in the summer hindered incoming solar radiation during summer, while less or no clouds during spring allowed more solar radiation to reach the earth’s surface. Absolute extreme values of solar radiation in the mountainous regions during fine weather conditions were close to the solar constant (1367 Wm-2) due to negligible depletion of radiation within the atmosphere. Amount of solar radiation increased with altitude due to smaller optical depth of the atmosphere at higher altitudes. The increasing rate of annual mean solar radiation with altitude is found to be 90 Wm-2km-1 in the mountainous region of Nepal.Journal of Hydrology and Meteorology, Vol. 8(1) p.1-9

Solar Energy Potential in Kathmandu Valley, Nepal

Meteorological data such as solar radiation (1975-1984, and 2002-2010) and sunshine duration (1968-2004) were analyzed to study temporal characteristics of solar energy and investigate solar energy potential in Kathmandu valley. Pre-monsoon and post monsoon seasons have higher mean monthly sunshine duration (about 8 hours/day) than summer (about 5 hours/day) and winter (about 7 hours/day) seasons over Kathmandu. Pre-monsoon and monsoon seasons receive solar energy of about 190 Wm-2 and 170 Wm-2 respectively. The winter season receives the least amount of solar radiation (135 Wm-2). Approximately 220 MW of solar electricity can be produced in Kathmandu that will substantially fulfill current energy demand and reduce environmental pollution in the valley by replacing fossil fuels with clean solar electricity.Journal of Hydrology and Meteorology, Vol. 8(1) 2012, p.77-82

Geospatial modeling of solar radiation to explore solar energy potential in Papua New Guinea

Climatology and meteorology are essentially driven by the incoming solar radiation and the latter’s latitudinal distribution. The total amount of incoming solar radiation, duration or day-length and the seasonal distribution of radiation have also the leading implication in researches in agricultural sciences. With the reality of climate change looming large, with its plausible paraphernalia on the humankind, it is obvious that the rising demand for clean energy sources will swing the needle of research towards ‘the optimum harnessing of solar energy’ regime. In a specified latitudinal expanse, topography is a major factor that determines the spatial distribution of insolation. Spatial variability of topographic elevation, slope, aspect and shadows influence the amount of insolation received at different point locations. At a given atmospheric impediment, the amount of solar insolation received at a particular geographical location is a function of ‘time of the day’ and the ‘season’. It determines the variability of microclimate as emanated from different parameters such as soil temperature, soil moisture, near surface air temperature, evapotranspiration, and direct-sun or sky-light available for photosynthesis (absorbed photosynthetically active radiation). The variation that occurs in incoming solar radiation over space and time for power generation using photovoltaic panels also warrants proper feasibility assessment prior to investment. In this scenario the solar radiation modeling is attempted in this paper to map and analyse the effects of the sun over a geographic area for specific time periods. Different parameters that are mandatory, like atmospheric condition, latitudinal position, elevation, slope and aspect, sun angle, and topographic shadows are taken in account for the modeling purpose. Two types of output are generated at the end of the modeling, (1) point layer and (2) raster representation while inputting monthly average of the ‘daily solar insolation’. For the first type of output, interpolation process is applied to complete the insolation map and compared with surface meteorology and solar energy (SSE 6.0) database. In this case spatial variations of shadows are not prominently indicated, while the latter is taken care of in the second type of output.

The effect of solar radiation on temperature distribution in outdoor human–clothing–environment systems

The present study investigates heat transfer in the human–clothing–environment system under solar radiation. A new thermal model integrating the solar radiation absorption by clothing, as well as heat conduction within the air layer and heat convection on the clothing surface, is presented. The heat transfer in this system is simply explained based on the heat conduction equation; heat transfer relating to solar radiation is added as the source of heat generation at the surface of clothing. The temperature distributions inside clothing are well predicted with variations in the amount of solar radiation, ambient temperature, air gap depth, and radiative properties. Temperatures are increased or decreased linearly with changes in the air gap distance, confirming that the temperature of the air layer inside clothing is governed by conduction. Temperature distributions differ depending on solar radiation and also radiative properties, particularly absorptance, indicating that radiative heat transfer must be included to evaluate clothing heat transfer.

Design and ray tracing of a compound parabolic collector with tubular receiver

Ray tracing for solar collectors shows the behavior of light rays which falls on collector surface and reflected to the receiver. Accordingly the solar collectors are designed or modified to enhance thermal performance. Compound parabolic collectors (CPC) are capable of collecting and reflecting a large amount of solar radiation towards the receiver with less tracking effort. With the help of ray tracing technique its performance can be increased by minimizing the optical losses. In this paper, the limiting diameter (LD) of the tubular receiver at the focus of CPC is determined by the geometrical method of ray tracing. The CPC is designed and ray tracing analyses were performed without receiver to differentiate the region of maximum collection and no collection of reflected rays. The region where not a single reflected ray enters from a CPC half follows an elliptical shape which is tangent internally to the LD of the receiver at the focus and its geometrical relation with the acceptance angle is presented. The geometrical relationship between LD and maximum diameter is also determined. The receiver height is obtained on the basis of receiver surface covered and collector surface utilized.

The corrosion rate in reinforced concrete facades exposed to outdoor environment

Outdoor concrete structures such as concrete facade panels and balcony frame panels are subjected to various environmental actions causing reinforcement corrosion problems. Long-term field measurement data on reinforcement corrosion in carbonated concrete on these structures was utilized in the creation of a corrosion rate regression model combining weather parameters such as temperature, relative humidity, wind-driven rain and solar radiation to corrosion rate. A versatile model capable of predicting the effect of varying environmental actions on the corrosion rates of carbonation induced corrosion was produced. Wind-driven rain was found to have the greatest impact on corrosion rate in tandem with the micro climate surrounding the building. Due to changes in air temperature, air relative humidity as well as in the amount of wind-driven rain and solar radiation, the corrosion rate on concrete facades and balconies is constantly changing. Despite the high seasonal and yearly variation, the average level of the modelled corrosion rate was quite steady on a longer 30-year perspective. This information is substantial for the long term service life design of concrete structures.

On the investigation of photovoltaic output power reduction due to dust accumulation and weather conditions

Certain environmental conditions such as accumulation of dust and change in weather conditions affect the amount of solar radiation received by photovoltaic (PV) panel surfaces and thus have a significant effect on panel efficiency. This study conducted an experimental investigation in Surabaya, Indonesia, on the effect of these factors on output PV power reduction from the surface of a PV module. The module was exposed to outside weather conditions and connected to a measurement system developed using a rule-based model to identify different environmental conditions. The rule-based model, a clear sky solar irradiance model that included solar position, and a PV temperature model were then used to estimate the PV output power, and tests were also conducted using an ARM Cortex-M4 microcontroller STM32F407 as a standalone digital controller equipped with voltage, current, temperature, and humidity sensors to measure real time PV output power. In this system, humidity was monitored to identify dusty, cloudy, and rainy conditions. Validated test results demonstrate that the prediction error of PV power output based on the model is 3.6% compared to field measurements under clean surface conditions. The effects of dust accumulation and weather conditions on PV panel power output were then analyzed after one to four weeks of exposure. Results revealed that two weeks of dust accumulation caused a PV power output reduction of 10.8% in an average relative humidity of 52.24%. Results of the experiment under rainy conditions revealed a decrease in PV output power of more than 40% in average relative humidity of 76.32%, and a decrease in output power during cloudy conditions of more than 45% in an average relative humidity of 60.45% was observed. This study reveals that local environmental conditions, i.e., dust, rain, and partial cloud, significantly reduce PV power output.

A shadow-ring device for measuring diffuse solar radiation on a vertical surface in a tropical zone

A shadow-ring device is developed for use with a pyranometer to measure diffuse solar radiation incident on a vertical surface. The shadow-ring device is operated by affixing it and moving the pyranometer horizontally to account for the seasonal variation of the sun’s path. The correction factor for the measured diffuse solar radiation incident on a vertical surface facing different directions under isotropic sky conditions is developed to account for the amount of diffuse solar radiation blocked by the shadow-ring. The effect of the installation location and ground reflectance on the shadow-ring device’s performance are also investigated. The shadow-ring device is specially designed for use at a location in a tropical zone (i.e. Bangkok (latitude 13.73°N)), and is capable of measuring diffuse solar radiation incident on a vertical surface facing in any direction. The constructed shadow-ring device is tested to verify its accuracy. It was found that the shadow-ring device’s performance is quite satisfactory and the difference between the corrected diffuse solar radiation and the referenced diffuse solar radiation (measured global solar radiation (in the morning)) was in the range around 0.8–8.8% on the tested days which were well within the range of the uncertainty of the measured data.

Experimental investigations into low concentrating line axis solar concentrators for CPV applications

Solar photovoltaic conversion systems with integrated, low concentration ratio, non-imaging reflective concentrators, could be on south facing building roofs used to generate power at a lower cost than currently available proprietary systems. The experimental investigation presented by this research provides information on the optical and energy conversion characteristics of two geometrically equivalent non-imaging concentrators; a compound parabolic concentrator and a V-trough reflector. The aim was to investigate the assumption of uniform cell illumination when PV cells located on the receiver surface with their central axes are aligned parallel with the focal line of the line-axis concentrator. Solar radiation incident was measured at the aperture and the PV cell surface using respectively a pyranometer and photodiodes at six different collector tilt angles of 0°, 10°, 20°, 30°, 40° and 52°. The analysis of the collected experimental data presented demonstrated that the V-trough system had a more even distribution of solar radiation than the CPC and a higher optical concentration ratio (ratio of solar radiation incident on the aperture cover to that incident on the receiver) though the geometrical concentration ratio of the two collectors was equal to 2.2×. Also, the V-trough concentrator had an electrical power output up to 17.2% higher than the CPC system at a specific tilt angle of 30°. The V-trough had a consistently higher receiver plate temperature as it was reflecting larger quantities of solar radiation than the CPC. Over 17 consecutive typical summer days’ similar performance was observed over the range of tilt angles studied. The development of V-trough concentrators should be preferred due to higher power production, reduced complexity, increased uniformity of illumination and lower manufacturing costs compared to CPCs.

Determination of the Optimal Tilt Angle of Solar Collectors for Different Climates of China

The tilt angle with the horizon (with respect to the ground) of the solar energy system affects the amount of solar radiation received. This paper suggests a simple and universal method to obtain the optimum tilt angles by estimating the monthly mean daily global solar radiation on tilted surfaces facing directly towards the equator, which is based on monthly average daily global solar radiation data produced from Typical Meteorological Year (TMY) data. The monthly, seasonal, and yearly optimum tilt angles for photovoltaic panels are calculated at six stations of different climatic types (Tropical Zone (TZ), Subtropical Zone (SZ), Warm Temperate Zone (WTZ), Mid Temperate Zone (MTZ), Cold Temperate Zone (CTZ) and Tibetan Plateau Zone (TPZ)). The results indicate that changing the monthly, seasonal, and yearly optimum tilt angles causes a significant yearly gain in the solar radiation for the region. In addition, general correlations are generated to estimate the optimum tilt angle of solar collectors at six typical climatic stations of China. The performances of the proposed models are compared using statistical error tests such as the mean absolute bias error (MABE), the root mean square error (RMSE) and the correlation coefficients (R).

Design and cost analysis of 1 kW photovoltaic system based on actual performance in Indian scenario

Summary The exhaustion of conventional resources and its effect on climate requires an urgent call for the substitute power resources to convene up the current power requirement. Solar energy is an endless, unsoiled and prospective energy source among all other nonconventional energy options. As more concentration is being done on focal point for the development of renewable energy capital globally. To ascertain their viability it is necessary to do the economic and technical assessments of these resources. This paper presents designing aspects and assessments of solar PV system based on field and actual performance. The study is based on design of solar PV system and a case study based on cost analysis of 1.0 kW off-grid photovoltaic energy system installed at Jamia Millia Islamia, New Delhi (28.5616° N, 77.2802° E, and about 293 m above sea level) India. Both monthly and weekly costs of energy produced by the 1 kW PV system have been calculated. In addition, the solar PV 1 kW system can give internal rate of return of about 1.714% on investment. Based on assumptions used in this study, solar 1 kW PV system of Rs. 0.9724/kWh is estimated for a project with profitable life of 25 years with no other financial support. This translates to Rs. 80,000 payment over the livelier cost of energy of 1 kWh generated by the system. However, if the financial support is more than 50% of the initial investment cost, no further payment fee is necessary to support this type of system. Basically this system has been designed for small home located at the place of availability of grid power is rare. 1 kW PV solar system is also very useful in rural areas of India. India as a subcontinent receives great amounts of solar radiation annually.

Sulfate Aerosols from Non-Explosive Volcanoes: Chemical-Radiative Effects in the Troposphere and Lower Stratosphere

SO2 and H2S are the two most important gas-phase sulfur species emitted by volcanoes, with a global amount from non-explosive emissions of the order 10 Tg-S/yr. These gases are readily oxidized forming SO42− aerosols, which effectively scatter the incoming solar radiation and cool the surface. They also perturb atmospheric chemistry by enhancing the NOx to HNO3 heterogeneous conversion via hydrolysis on the aerosol surface of N2O5 and Br-Cl nitrates. This reduces formation of tropospheric O3 and the OH to HO2 ratio, thus limiting the oxidation of CH4 and increasing its lifetime. In addition to this tropospheric chemistry perturbation, there is also an impact on the NOx heterogeneous chemistry in the lower stratosphere, due to vertical transport of volcanic SO2 up to the tropical tropopause layer. Furthermore, the stratospheric O3 formation and loss, as well as the NOx budget, may be slightly affected by the additional amount of upward diffused solar radiation and consequent increase of photolysis rates. Two multi-decadal time-slice runs of a climate-chemistry-aerosol model have been designed for studying these chemical-radiative effects. A tropopause mean global net radiative flux change (RF) of −0.23 W·m−2 is calculated (including direct and indirect aerosol effects) with a 14% increase of the global mean sulfate aerosol optical depth. A 5–15 ppt NOx decrease is found in the mid-troposphere subtropics and mid-latitudes and also from pole to pole in the lower stratosphere. The tropospheric NOx perturbation triggers a column O3 decrease of 0.5–1.5 DU and a 1.1% increase of the CH4 lifetime. The surface cooling induced by solar radiation scattering by the volcanic aerosols induces a tropospheric stabilization with reduced updraft velocities that produce ice supersaturation conditions in the upper troposphere. A global mean 0.9% decrease of the cirrus ice optical depth is calculated with an indirect RF of −0.08 W·m−2.

Effect of 1.5 Years of Space Exposure on Tensile Properties of Teflon

Materials on the exterior of spacecraft in low Earth orbit are subject to extremely harsh environmental conditions, including exposure to various forms of radiation, temperature extremes, thermal cycling, and atomic oxygen. These environmental exposures can result in erosion and optical and mechanical property degradation of susceptible materials, threatening spacecraft performance and durability. In an effort to better understand the effect of space exposure on the mechanical property degradation of Teflon insulation, 19 tensile samples were exposed to the space environment for 1.5 years on the exterior of the International Space Station. The samples were flown in ram, wake, zenith, or nadir orientations as part of three Materials International Space Station Experiment 7 mission experiments. This paper provides an overview of the flight mission, an introduction to the experiments, and compares the Teflon property degradation in the various orientations. The reduction in ductility of the samples correlates with the amount of solar radiation. Samples with high solar exposure (zenith orientation) experienced a 76% reduction in elongation relative to controls, whereas samples in the shadowed nadir orientation only experienced a 4% reduction. Additionally, thickness loss measurements show that erosion is significant in the ram orientation, but negligible in other orientations.

Experimental energy and exergy analysis of a flat plate solar air heater with a new design of integrated sensible heat storage

This paper presents an experimental energy and exergy analysis of a novel flat plate solar air heater (SAH). It has a specially designed absorber plate made up of copper strips (copper tubes with extended copper fins on both sides), welded longitudinal to one another. This structure acts as an integrated absorber-cum-storage unit, where a high quality synthetic oil (Therminol-55) is filled within those copper tubes as a sensible heat storage (SHS) medium. To study the impact of this novel design and the sensible heat storage over the performance of the SAH, the results were compared with the output of a conventional SAH of similar dimensions. For the precise comparison of their performances, the experiments were conducted on both the SAHs at same location, simultaneously. It ensures identical testing conditions such as the amount of solar radiation received and surrounding environment of the experimental setup. Exergy analysis is a powerful thermodynamic tool and it helps in computing the actual output of a system, theoretically. It helps the researchers to optimize the system design to compensate the present and also the future needs. Experiments were conducted for two different mass flow rates (0.018 kg/s, and 0.026 kg/s). The results showed that the maximum energy and exergy efficiency obtained was in the range of 49.4–59.2% and 18.25–37.53% respectively, for the SAH with sensible storage at m˙ = 0.026 kg/s. Besides, the SAH with sensible heat storage was observed to perform better than the conventional flat plate SAH without storage.