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Revised optical air mass tables and approximation formula

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... The impact of each process is quantified by its optical depth, which is related to the composition of the local atmosphere, in combination with the relative air mass (AM) [22]. The AM corresponds to the path length through the atmosphere at an arbitrary place and time relative to the path at solar zenith, i.e. when the sun is directly overhead and perpendicular to the ground [23]. Hence, the transmission of sunlight at a given location and time can be characterized by the AM, the PW and O3 content, the aerosol optical depth (AOD) typically defined at 500 nm and the atmospheric pressure (Patm) [22]. ...
... The remaining scattered light corresponds to the diffuse irradiance. In practice, a pyrheliometer with a ±2.5º aperture mounted on a dual-axis tracker is used to measure DNI [27,28], whereas a pyranometer also mounted on the tracked plane is used 3.1 Solar radiation 23 to measure global normal irradiance (GNI) [28]. In this way, the amount of diffuse irradiance on the front (DIF) can be calculated as, DIF = GNI -DNI. ...
Thesis
In this cumulative thesis, a novel hybrid photovoltaic module combining the concentrator and flat plate approach (CPV/PV), named EyeCon, is developed and characterized. Conventional concentrator photovoltaic (CPV) modules use highest efficiency III-V multi-junction solar cells and convert up to 38.9% of the direct sunlight. Nevertheless, the use of concentrating optics prevents them from absorbing the diffuse part of the solar spectrum. On the other hand, flat plate silicon (Si) photovoltaic (PV) modules convert light from all angles of incidence with efficiencies around 20%. This work focuses on the enhancement of a multi-junction CPV module by the integration of bifacial Si PV cells to obtain the highest power output per unit area through the conversion of direct, diffuse and rear side irradiance. The development and manufacturing of the EyeCon module consisted of the design of the 4-terminal circuit of the CPV and flat plate PV cells, the optimization of the metallization grid of the bifacial Si PV cells under partial illumination, the thermal validation of using the Si PV cells as heat spreaders for the CPV cells and the development of a seamless process that integrates the flat plate PV cells into a CPV module with minimum additional steps and materials. The main optical, thermal and electrical characterizations include the quantification of the effective amount of irradiance absorbed by the Si PV cells under the concentrating optics, the effect of tracker misalignment on power output when the focal spot moves from the CPV receivers onto the flat plate PV cells, the definition of hybrid reference standard conditions and filtering criteria and the development of a power rating procedure for hybrid CPV/PV bifacial modules. The analysis of the EyeCon module performance under different meteorological and spectral conditions comprises the power output under a hypothetical voltage-matched interconnection between the CPV and the bifacial PV cells, the extensive worldwide energy yield modeling and the techno-economic comparison with CPV and single-junction flat plate PV modules. Under the scope of this research, a world record efficiency of 34.2% and a bifacial power output beyond 350 W/m2 at standard test conditions were reached using III-V four-junction CPV and flat plate bifacial Si PV cells. Furthermore, hybrid CPV/PV technology is expected to generate up to 1150 kWh/m2 in subtropical arid regions, whereas in places like Europe, China, central Africa and Latin America a 25 - 35% higher yield than its closest contender is expected. Thus, hybridization is a promising path towards increasing the competitiveness of conventional CPV technology.
... (2), it is necessary to make the azimuth negative before solar noon (Ham, 2005). The sea level air mass (m a ) is given by (Kasten and Young, 1989) as where φ is the solar zenith angle in degrees. ...
... Here SW ↓ h is the total shortwave incoming radiation. R a is the extraterrestrial radiation calculated according to Ham (2005), while m a is the sea level air mass, calculated according to Kasten and Young (1989). Both expressions are given below. ...
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Understanding and quantifying the influence of tree structure and ground vegetation on albedo in the boreal-alpine treeline is urgently needed to assess and predict the biophysical climatic feedback effect of forest- and treeline expansion. Fine-spatial resolution in-situ radiation measurements sensitive to small-scale variability enable precise albedo estimation for complex heterogeneous landscapes. In this study, horizontally measured single-tree albedo of mountain birch and their spatially consistent tree- and ground vegetation properties were collected in the boreal-alpine treeline over a period of 14 days in summertime. The aim was to identify properties of tree structure and ground vegetation driving single-tree mountain birch albedo. In addition, it was of interest to analyze the relationship between the vegetation properties and a slope-estimated albedo when a simplified correction of slope and aspect of the terrain was applied to the horizontally measured incoming shortwave radiation. Both properties of tree structure and ground vegetation were strongly related to albedo. The results imply that expansion of mountain birch forests at the expense of the prevalence of bright-colored lichens, bare rock, graminoids and mosses will reduce summertime boreal-alpine treeline albedo. Taller trees with wider tree crowns will absorb more solar radiation than smaller trees and hence also reduce albedo. Overall average difference of albedo of sample plots with and without presence of mountain birch was 0.06, corresponding to 27% of the albedo for plots without birch. Horizontally measured albedo was more strongly correlated with the vegetation properties than when corrected for terrain slope and aspect. The findings show that the appropriateness of horizontally measured albedo of single trees and tree clusters in open sloping terrain, depends on the spatial size of the footprint of the downward-looking radiation sensor relative to the size of the tree subject to observation.
... : Relative mass of ozone (dimensionless) [10]. : Relative aerosol mass (dimensionless) [11]. : Correction factor for the Sun-Earth distance (dimensionless) [12]. ...
Chapter
This research work has as main objective to apply Newton's method in Matlab. 19.0 to minimize a nonlinear spread function infrared direct solar radiation (2100 nm to 4000 nm). The methodology that was applied consisted of the analysis of the components of direct infrared radiation: Rayleigh scattering, aerosols, water vapor between the atmosphere and the Earth, to generate a theoretical model of infrared radiation that depends on of the parameters: turidity coefficient ???? and length of the ozone layer ????, precipitable water vapor W. In the which this model was compared with experimental data through of a nonlinear Dispersion Function, that was minimized through Newton's method, obtaining as a result the theoretical model of infrared radiation using the parameters: ????= 0.9499, ???? = 1.0889 cm and predominant in W= 3.8342 cm. for the Costa Rica station, corresponding to a cloudy white sky atmosphere without the presence of an ozone hole with a considerable presence of water vapor.
... If the direct beam travels a longer path length in the air, ISSN: 0067-2904 the air mass increases with a lot of absorption and scattering. This creates more scattering in the shorter wavelengths range (ultraviolet and visible) [9], [10]. This work aims to develop a low-cost UV and incoming solar irradiance measuring device incorporating a data logger that can be used to study these parameters at any location. ...
Article
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In-situ measurement of ultraviolet (UV) and solar irradiance is very sparse in Nigeria because of cost; it is estimated using meteorological parameters. In this work, a low-cost UV and pyranometer device using locally sourced materials was developed. The instrument consists of a UV sensor (ML8511), a photodiode (BPW34) housed in a carefully sealed vacuumed glass bulb, the UV and solar irradiance sensor amplifiers, a 16-bit analog-to-digital converter (ADS1115), Arduino mega 2560, liquid crystal display (LCD) and microSD card for data logging. The designed amplifier has an offset voltage of 0.8676 mV. The sensitivity of the irradiance device is 86.819 Wm-2 /mV with a correcting factor of 27.77 Wm-2 and a maximum range of 1200 Wm-2. The instrument validation error is 9.67%, and a correlation coefficient of 0.89 when compared with a standard SRS100 pyranometer. The UV sensor showed a close response with a correlation of 0.99 in comparison with a standard Skye instrument. From 08:00 to 16:00 local time (LT), there is a very close agreement between the standard device and the developed counterpart, with marginal differences of about 9.6% observed at the two extremes.
... where dz is the infinitesimal thickness of the horizontal layer, I the intensity [W m −2 ] of the light beam and m 0 is the optical mass of the incident beam which in the plane parallel approximation can be considered as 1/ cos θ, where θ is the zenith angle corresponding to the given path if θ < 75 • (exact formulation for θ > 75 • can be found in Kasten and Young (1989)). ...
Thesis
The understanding of the uncertainties in the retrieval of the aerosol and surface properties is very important for an adequate characterization of the processes that occur in the atmosphere. However, the reliable characterization of the error budget of the retrieval products is a very challenging aspect that currently remains not fully resolved in most remote sensing approaches. The level of uncertainties for the majority of the remote sensing products relies mostly on post-processing validations and inter comparisons with other data while the dynamic errors are rarely provided. This study describes, discusses and evaluates a concept realized in GRASP (Generalized Retrieval of Atmosphere and Surface Properties) algorithm for providing the dynamic estimates of uncertainties for retrieved parameters. The approach employs a rigorous concept of statistical optimization for estimating the effects of measurement uncertainties propagation to the retrieval results. The approach accounts for the effect of both random and systematic uncertainties in the initial data and provides error estimates both for directly retrieved parameters included in the retrieval state vector and for the characteristics derived from these parameters. The efficiency of the realized error estimation concept is extensively analyzed for GRASP applications for aerosol retrieval from ground-based observations by sun/sky photometer and lidar. The diverse aspects of the generations and evaluations of the error estimates are discussed and illustrated. The evaluation of the error estimates was realized using the series of comprehensive sensitivity tests when simulated sun/sky photometer measurements and lidar data are perturbed by random and systematic errors and inverted. The results of the retrievals and their error estimations obtained in the tests are analyzed and evaluated. The tests are conducted for the different observations of several types of aerosols including biomass burning, urban, dust and their mixtures. The study considers popular observations by AERONET sun/sky radiometer at 440, 675, 870 and 1020 nm and multi-wavelength elastic lidar at 355, 532 and 1064 nm. The sun/sky radiometer data are inverted aloneor together with lidar data. The analysis shows that the generated error estimates overall satisfactory of the uncertainties of different retrieved aerosol characteristics including aerosol size distribution, complex refractive index, single scattering albedo, lidar ratios, aerosol vertical profiles, etc. Also, the analysis shows that the main observed error dynamic agrees well with the errors tendencies commonly known fromthe retrieval experience. For example, the serious retrieval accuracy limitations for all aerosol types are associated with the situations with low optical depth. Also, for observations of multi-component aerosol mixtures, the reliable characterization of each component is possible only in limited situations, for example from radiometric data obtained for low solar zenith angle observations or from a combination of radiometricand lidar data. At the same time, total optical properties of aerosol mixtures tend to be always retrieved satisfactorily. In addition, the study includes the analysis of the detailed structure of correlation matrices for the retrieval errors of mono- and multi-component aerosols. The conducted analysis of error correlation appears to be a usefulapproach for optimizing observations schemes and retrieval setups. The illustration of the developed approach application to real data is provided for co-located observations of sun/sky photometer and lidar over Buenos Aires. Furthermore, the preliminary results for utilizing the error estimates for the retrieval of aerosol from satellite data are provided.
... In astronomy, this is captured by the number of 'airmasses' that the signal traverses [22], which as defined as equal to 1 for a zenith-pointing telescope at sea level. The number of airmasses traversed for a given zenith/elevation angle can be approximated with the Kasten and Young 1989 model (see Figure 5) [23]. The total attenuation is then S(λ) A(θ el ) , where S(λ) is the zenith-pointing attenuation spectrum, A(θ el ) is the airmass number corresponding to elevation angle θ el . ...
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This paper presents some initial results on the use of hyperspectral imaging technology and machine learning to characterise the surface composition of space objects and reconstruct their attitude motion. The paper provides a preliminary demonstration that hyperspectral and multispectral analysis of the light absorbed, emitted and reflected by space objects can be used to identify, with some degree of accuracy, the materials composing their surface. The paper introduces a high-fidelity simulation model, developed to test this concept, and a validation of the model against experimental tests in a laboratory environment. The paper shows how to unmix the spectra to provide an estimation of the materials composing the surface facing the sensor. A machine learning approach is then proposed to reconstruct the attitude motion from the time series of spectra.
... The AM and AM -K spectral correction functions have been derived from the same NREL data used to derive ( ). The derived functions are presented in Figs. 8 and 9. AM values are calculated using the method proposed in [58]. Atmospheric pressure was measured on site and the solar position parameters, namely the zenith and azimuth angles, were calculated using the solar position algorithm [59]. ...
Article
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Accurate photovoltaic (PV) performance modelling is crucial for increasing the penetration of PV energy into the grid, analysing returns on investment, and optimising system design prior to investment and construction. Performance models usually correct an output value known at reference conditions for the effects of environmental and system variables at arbitrary conditions. Traditional approaches to correct for the effect of the solar spectrum on performance are based on proxy variables that represent spectral influences, such as absolute air mass (AMa) and clearness index (Kt). A new methodology to account for the spectral influence on PV performance is proposed in this study. The proposed methodology is used to derive a novel spectral correction function based on the average energy of photons contained within the measured solar spectral distribution. The Average Photon Energy (APE) parameter contains information on the combined effects of multiple proxy variables and is not limited by climatic conditions such as cloud cover, as is the case with most traditional models. The APE parameter is shown to be capable of explaining almost 90% of the variability in PV spectral efficiency, compared to around 65% for AMa. The derived APE function is validated and shown to offer an increase of 30% in predictive accuracy for the spectral efficiency compared with the traditional AMa function, and a 17% improvement relative to the AMa-Kt function.
... These values were provided as a weather file to PVlib's ModelChain object with the following default settings. clearsky_model: ineichen [29], [30] transposition_model: haydavies [31] solar_position_method: nrel_numpy [32] airmass_model: kastenyoung1989 [33] dc_model: pvwatts_dc [34] ac_model: pvwatts_inverter [34] aoi_model: physical_aoi_loss [35] spectral_model: no_spectral_loss temperature_model: sapm_temp [36] losses_model: no_extra_losses (selected in order to introduce custom dynamic soiling model later) ...
Article
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In this article, a vertical bifacial + reflector configuration is presented as a candidate for solar canals and other applications that allow dual use of the land. Modeling with weather data from Merced, CA shows output to be competitive with fixed 20° tilt systems, with south-facing vertical orientation showing 117% and 87% of annual output of south-facing 20° systems with and without a reflector, respectively. Repetition with weather data from Houston, Denver, and Miami produces similar results, with values ranging from 112%–121% and 82%–94%, which serve as conservative estimates due to lack of modeled soiling on tilted systems in the latter comparison. South-facing vertical orientations have better performance in nonsummer months relative to other systems, resulting in a flatter seasonal curve, with useful implications for load balancing and energy storage. East- and west-facing vertical orientations outperform their fixed tilt defaults, even without a reflector, and tolerate higher dc/ac inverter ratios than similar south-facing vertical orientations before appreciable clipping effects are seen.
... In a single layer, plane-parallel atmosphere, the geometry of the direct solar irradiance measurement is illustrated in Fig. 1, where it can be seen that there is a geometrical relation between the optical depth in the measurement (slant) path and the optical depth in the vertical, which is denoted by air mass, m and depends on the solar zenith angle as m ¼ sec(y) in our plane-parallel approximation. More elaborated formulas exist for the air mass (Kasten and Young, 1989;Komhyr et al., 1989) that take into account the vertical distribution of the scatterer/absorber, the Earth curvature, or the refraction in the atmosphere. The solar zenith angle can be calculated following the formulation by Michalsky (1988). ...
Chapter
Sun photometry is an extended technique for monitoring the atmospheric composition and support satellite product validation. By measuring the direct solar irradiance, the amount and characteristics of the atmospheric aerosol particles, precipitable water vapor column, and ozone columns can be derived. Global operational networks such as the Aerosol Robotic Network (AERONET), Global Atmosphere Watch-Precision Filter Radiometer Network (GAW-PFR), Maritime Aerosol Network (MAN), or the Brewer spectrophotometer networks constitute sustained efforts for long-term monitoring of the atmosphere, with invaluable data production using cost-effective and relatively simple instrumentation. The data quality relies on the standardization of these networks, with special emphasis on the calibration as the key element in Sun photometry.
... crescent vision. We assume that the right ascension of the Moon remains unchanged during the short time that it is in the window of visibility, so we find 2 1 w H T H H H T UT t             T is sidereal time and UT is universal time. ...
Preprint
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We define the width of the window of visibility of the first lunar crescent as the interval of altitudes of the Moon between which we can see the crescent. We define the duration of the visibility window or time during which we see the crescent; and we also define the altitude of optimal vision of the crescent. We check the parameters on which the visibility window depends. We determine the variation of the visibility window with the phase angle, the atmospheric attenuation constant, the latitude of the observation site, and the declinations of the Sun and the Moon.
... where SZA is the Sun zenith angle and a 1 = 0.50572, a 2 = 96.079951, and a 3 = 1.63643, as proposed in [13]. ...
Conference Paper
This paper exhibits a hybrid model for the intrahour forecasting of DNI. It combines a knowledge-based model, that is used for clear-sky DNI forecasting from DNI measurements, with a machine-learning-based model, that evaluates the impact of atmospheric disturbances on the solar resource, through the processing of high dynamic range sky images provided by a ground-based camera. The performance of the hybrid model is compared with that of two machine learning models based on past DNI observations only. The results highlight the pertinence of combining knowledge-based models with data-driven models, and of integrating sky-imaging data in the DNI forecasting process.
... This serves as a reference while modifying the Formula (4) for assessment of the integral transparency of real atmosphere with non-homogeneous distribution of pressure, temperature, humidity, extension of the trajectory of beams due to refraction, etc. The present work applies a modified formula of Kasten-Jong [29][30][31], recommended by the European Solar Radiation Atlas (ESRA) [32,33] ...
Article
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With regard to the problem of current solar irradiation of the tracking surface by the tracker, this can be rationally assessed using a modeled flux with parameters close to the natural direct in accordance with the maximum transparent atmosphere. As part of the experimental research, the values of the air optical mass index in the zenith angle ranging from 0° to 90° were presented for the surface at sea level. The conducted analysis made it possible to confront the experimental research with the models of the optical air transparency mass index. In order to maximize the energy of the controlled beam of the sun’s rays, the angle of their incidence on the tracking surface by the tracker should be minimized. The modeling results show the actual hourly dependencies, which are average values of the intensity of the multi-year measurement. It was found that seasonal dependencies can be considered as theoretically possible and then used to assess the energy efficiency of the tracking surface. Theoretically, they also correspond to the maximum possible energy efficiency of continuous tracking of the Sun with a two-axis rotary tracker. A polar-rotary tracker is a device where the axis of rotation is parallel to the axis of the earth and orients the tracking surface using the simplest synchronous algorithm with a constant angular speed ω = 15 grad/h. The novelty of the article is a method presenting the combination of a normal trajectory with direction towards the sun. Due to the deviation towards the polar axis, the normal touches the horizon, not at six hours after full sun, but earlier and simultaneously. In this way, an uniaxial pole-rotating tracker provides the same irradiation regime as a biaxial one in terms of the deviation of the tracking surface from the axis of rotation, which is equal to the tilt of the sun.
... In a single layer, plane-parallel atmosphere, the geometry of the direct solar irradiance measurement is illustrated in Fig. 1, where it can be seen that there is a geometrical relation between the optical depth in the measurement (slant) path and the optical depth in the vertical, which is denoted by air mass, m and depends on the solar zenith angle as m ¼ sec(y) in our plane-parallel approximation. More elaborated formulas exist for the air mass (Kasten and Young, 1989;Komhyr et al., 1989) that take into account the vertical distribution of the scatterer/absorber, the Earth curvature, or the refraction in the atmosphere. The solar zenith angle can be calculated following the formulation by Michalsky (1988). ...
Preprint
This work aims to assess differences in the aerosol optical depth (AOD) trend estimations when using high quality AOD measurements from two different instruments with different technical characteristics, operational (e.g. measurement frequency), calibration and processing protocols. The different types of Sun photometers are the CIMEL that is part of AERONET (AErosol RObotic NETwork) and a precision Filter Radiometer (PFR), part of the Global Atmosphere Watch Precision Filter Radiometer network. The analysis operated for two wavelengths (500/501 nm and 870/862 nm for CIMEL/PFR) in Davos, Switzerland, for the period 2007–2019. For the synchronous AOD measurements, more than 95 % of the CIMEL-PFR AOD differences are within the WMO accepted limits, showing very good measurement agreement and homogeneity in calibration and post correction procedures. AOD trends per decade in AOD for Davos for the 13-year period of analysis were approximately -0.017 and -0.007 per decade for 501 nm and 862 nm (PFR), while the CIMEL-PFR trend differences have been found 0.0005 and 0.0003 respectively. The linear trend difference for 870/862 nm is larger than the linear fit standard error. When calculating monthly AODs using all PFR data (higher instrument frequency) and comparing them with the PFR measurements that are synchronous with CIMEL, the trend differences are smaller than the standard error. The trend differences are also larger than the trend uncertainty attributed to the instrument measurement uncertainty, with the exception of the comparison between the 2 PFR datasets (high and low frequency) at 862 nm. Finally, when calculating time-varying trends, they differ within their uncertainties.
... And the optical air mass was calculated by the following formula 41 : ...
Article
In this paper, a detailed performance analysis of a capillary heat pipe coupled with a parabolic trough collector is performed. The influence of different parameters on the overall system's performance was studied namely; beam radiation and the inclination of the PTC. Results showed that using a heat pipe as an absorber improves the performance of the PTC. At ∆Tmax, the coupling of the heat pipe with PTC leads to a 33 % increase in the system's global efficiency and a significant reduction in the heat losses by 46.55%. The inclined arrangement configuration improved the global efficiency of the system by 13 %. The obtained results were compared with the experimental data provided by the literature and reasonable agreement was observed, thus confirming the model's validity. This article is protected by copyright. All rights reserved.
... In recent years, a massive surge in the use of PV cells has been seen in satellites regardless of their size, with a total ~85% of all SmallSat spacecraft using solemnly solar panels as the primary power-generating source [86]. The solar cells used in space applications, compared to the terrestrial ones, harvest energy from a broader spectrum of solar irradiation [87]. More specifically, space-qualified solar cells are designed for the spectrum AM0 (ASTM E-490), with an integrated power density of 1366.1 W/m 2 [88], while terrestrial cells correspond to the direct and global spectrums AM1.5D and AM1.5G (ASTM G-173) respectively, with the corresponding integrated power densities of 900 W/m 2 and 1000 W/m 2 . ...
Article
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The Small Satellite (SmallSat) industry has recorded incredible growth recently. Within this class, among Mini-, Micro-, and Nanosatellites, the Cube Satellite (CubeSat) is primed for an explosion of growth. These satellites are fascinating for remote sensing, earth observation, and scientific applications. Remarkable attention from the space operators makes it valuable because of its low cost, cubic shape, less manufacturing time, lightweight, and modular structure. Among the various subsystems comprising the SmallSat, the Electrical Power System (EPS) is the most crucial one because unreliable power supply to the rest is most of the time detrimental to the mission. The EPS is formed by electrical sources, storage units, and loads, all interconnected via different power converters, the operation of which must be closely orchestrated to accomplish efficient use of photovoltaic power, optimal battery management, and resilient power delivery. At the same time, the EPS design must address a series of challenges such as size restrictions, high power density, harsh space environments (e.g., atomic oxygen, radiation, and extreme temperatures) which significantly impact the EPS electrical and electronic equipment. In terms of power systems, a SmallSat EPS can be considered a space microgrid owing coordination and control of distributed generation (DG), storage and loads in a small-scale electrical network. From this point of view, this paper reviews and explores SmallSat microgrid’s research developments, energy transfer and architectures, converter topologies, latest technologies, main challenges, and some potential solutions which will enable building a more robust, resilient, and efficient EPS. The research gaps and future developments are underlined before the paper is concluded.
... where, Eλ is the output voltage signal detected by the instrument and E0,λ is the calibration coefficient. mr(θ) [37], mO3(θ) [38], ma(θ) [39] ...
Article
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Aerosol optical depth measurements of 2017-2020 in urban Hohhot of Mongolian plateau, a transition zone between the depopulated zone and East Asian urban agglomeration, were analyzed for the first time. Results show that annual AOD500 and α440-675 were 0.36 ± 0.09 and 1.11 ± 0.16 (2017), 0.41 ± 0.12 and 0.90 ± 0.28 (2018), 0.38 ± 0.09 and 1.13 ± 0.24 (2019), 0.38 ± 0.12 and 1.17 ± 0.22 (2020), respectively, representing a slightly polluted level with a mixed type of coarse-mode dust aerosol and fine-mode urban/industrial aerosol. Throughout the year, Hohhot was dominated with depopulated-zone continental air flows (i.e., NW-quadrant wind), accounting for 82.12% (spring), 74.54% (summer), 63.61% (autumn), and 100% (winter), respectively. The clean and strong NW-quadrant air flows induced by the south movement of Siberian anticyclone resulted in a low 500-nm AOD of 0.30 ± 0.29, 0.20 ± 0.15, 0.24 ± 0.29, and 0.13 ± 0.08 from spring to winter; While the local emissions from Hohhot city, as well as anthropogenic urban/industrial aerosols transported by south and west air masses originating from south urban agglomeration and west industrial cities (Baotou, Wuhai, etc.), contributing to the highest aerosol loading with significant transformation rates of secondary aerosols Sulfate-Nitrate-Ammonium (SNA) of 47.45%, 57.39%, 49.88%, and 45.16- 47.36% in PM2.5 in each season. Extinction fraction of fine aerosols under these anthropogenic trajectories can be as high as 80%, and the largest fine mode aerosol size was around 0.2-0.25 μm. Dust aerosols were suspending in urban Hohhot all the year, although in different levels in different seasons, and the extinction fraction of dust aerosol during sandstorms was generally higher than 70%.
... where G b;0 ¼ 1000 W=m, h cell;0 ¼ 25 C and AM 0 = 1.5. The air mass AM is calculated according to Kasten and Young (1989): ...
Article
A simulation tool for the operation of a hybrid PV/Wind plant coupled with a hydro-pumping storage (HPS) was built; it was used for simulating the behavior of such a system among an energy mix constituted by fuel oil generators and electrical cables in an insular electrical network. Each subsystem is modeled with a variable efficiency depending on the operating regime and on solar and wind sources variability. An optimization of the hydro-pumping system operation was developed using four reversible pumps in parallel. The objective is to shave the electrical peak demand in replacement of costly and polluting combustible turbines. An energy situation like the one in Corsica Island is considered and all the electrical productions are taken into account, not only renewables but also fuel and imported electrical energy. The covered part of the peak demand can reach 80% in an annual basis and the influence of the hybrid system characteristics on the performances were studied. Some hybrid systems configurations were highlighted.
... Where G β is the solar irradiance on the PV module tilted from β 0 have high effects on the PV efficiency, G β,0 =1000W/m 2 , θ cell,0 =25 0 C and AM is the relative mass of air (5) , in the normal conditions is AM 0 =1.5. ...
Conference Paper
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The paper is focused on analyzing the first grid-connected PV system recently installed in the building of the Institute of Geosciences, Energy, Water and Environment, composed of two sets of 12 panels of crystalline silicon modules connected in parallel with an open-circuit voltage of 44.8 V DC and nominal power is 195 Wp. The study's objective is to find a suitable empirical method to calculate the electrical energy output of the system. Meteorological data (temperature, solar radiation, etc.) used to calculate electrical energy output for both ways are taken from the meteorological DAVIS station of the Experimental Laboratory of the Faculty of Electrical Engineering, Polytechnic University of Tirana. A MATLAB code was developed to compare the results of each empirical method regarding the efficiency and productivity of electrical energy output. A comparison of experimental data of electrical energy output from a grid-connected PV system and calculated values using two different empirical methods, the Evans method and the Durisch method, showed a consistence difference. Both practical ways give more significant discounts on output electrical energy than experimental ones. Good linear correlation between three sets of data demonstrates that the more substantial part of the differences originates from losses in the electrical system of the PV system. Modifying the Evans and Durisch methods with respective linear approximation equations defined experimentally offers a good empirical equation. The approximation equation is used in the analytical analysis and modeling of the PV systHowever, not Not very good correlation coefficients show that further experimental data are needed.
... Kambezidis et al. (2017); (CM2)Rigollier et al. (2000); (CM3)Hammer et al. (2003); (CM4)Ineichen (2008a); (CM5)Atwater and Ball (1978); (CM6)Gueymard (2003); (CM7)Maxwell (1998). (AM1)Kasten and Young (1989); (AM2)Hammer et al. (2003); (AM3)Kasten (1965). (TR1)Psiloglou et al. (1995); (TR2)Kasten (1996); (TR3) Hammer et al. (2003); (TR4) Bird and Hulstrom (1981). ...
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The clear-sky radiative effect of aerosol-radiation interactions is of relevance for our understanding of the climate system. The influence of aerosol on the surface energy budget is of high interest for the renewable energy sector. In this study, the radiative effect is investigated in particular with respect to seasonal and regional variations for the region of Germany and the year 2015 at the surface and top of atmosphere using two complementary approaches. First, an ensemble of clear-sky models which explicitly consider aerosols is utilized to retrieve the aerosol optical depth and the surface direct radiative effect of aerosols by means of a clear-sky fitting technique. For this, short-wave broadband irradiance measurements in the absence of clouds are used as a basis. A clear-sky detection algorithm is used to identify cloud-free observations. Considered are measurements of the short-wave broadband global and diffuse horizontal irradiance with shaded and unshaded pyranometers at 25 stations across Germany within the observational network of the German Weather Service (DWD). The clear-sky models used are the Modified MAC model (MMAC), the Meteorological Radiation Model (MRM) v6.1, the Meteorological-Statistical solar radiation model (METSTAT), the European Solar Radiation Atlas (ESRA), Heliosat-1, the Center for Environment and Man solar radiation model (CEM), and the simplified Solis model. The definition of aerosol and atmospheric characteristics of the models are examined in detail for their suitability for this approach. Second, the radiative effect is estimated using explicit radiative transfer simulations with inputs on the meteorological state of the atmosphere, trace gases and aerosol from the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis. The aerosol optical properties (aerosol optical depth, Ångström exponent, single scattering albedo and asymmetry parameter) are first evaluated with AERONET direct sun and inversion products. The largest inconsistency is found for the aerosol absorption, which is overestimated by about 0.03 or about 30% by the CAMS reanalysis. Compared to the DWD observational network, the simulated global, direct and diffuse irradiances show reasonable agreement within the measurement uncertainty. The radiative kernel method is used to estimate the resulting uncertainty and bias of the simulated direct radiative effect. The uncertainty is estimated to -1.5±7.7 and 0.6±3.5Wm-2 at the surface and top of atmosphere, respectively, while the annual-mean biases at the surface, top of atmosphere and total atmosphere are -10.6, -6.5 and 4.1Wm-2, respectively. The retrieval of the aerosol radiative effect with the clearsky models shows a high level of agreement with the radiative transfer simulations, with an RMSE of 5.8Wm-2 and a correlation of 0.75. The annual mean of the REari at the surface for the 25 DWD stations shows a value of -12.8±5Wm-2 as the average over the clear-sky models, compared to -11Wm-2 from the radiative transfer simulations. Since all models assume a fixed aerosol characterization, the annual cycle of the aerosol radiation effect cannot be reproduced. Out of this set of clear-sky models, the largest level of agreement is shown by the ESRA and MRM v6.1 models.
... m is the relative optical air mass giving the slant path of the Sun's rays relative to the zenith, which is given by m = 1/ cos(SZA) for a plane-parallel atmosphere. For a spherical atmosphere, more accurate expressions for m are necessary when the SZA is greater than 70 • ; in order to account for the curvature of the atmosphere and the refraction effects, various expressions were developed for each atmospheric component (Kasten and Young, 1989;Gueymard, 1995Gueymard, , 2005Tomasi et al., 1998;Chiron de la Casinière and Cachorro Revilla, 2008;Rapp-Arrarás and Domingo-Santos, 2008). ...
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The aim of this work is to describe the features of and to validate a simple, fast, accurate, and physically based spectral radiative transfer model in the solar wavelength range under clear skies. The model, named SSolar-GOA (the first “S” stands for “spectral”), was developed to evaluate the instantaneous values of spectral solar irradiances at ground level or at a given altitude of the atmosphere. The model requirements are designed based on the simplicity of the analytical expressions for the transmittance functions in order to be easily replicated and applied by a wide community of users for many different applications (atmospheric and environmental research studies, satellite remote sensing, solar energy, agronomy and forestry, ecology, and others). Although spectral, the model runs quickly and has sufficient accuracy for the evaluation of solar irradiances with a spectral resolution of 1–10 nm. The model assumes a single mixed molecule–aerosol scattering layer where the original Ambartsumian method of “adding layers” in a one-dimensional medium is applied, obtaining a parameterized expression for the total transmittance of scattering. Absorption by the different atmospheric gases follows “band model” parameterized expressions. The input parameters must be realistic and easily available since the spectral aerosol optical depth (AOD) is the main driver of the model. The validation of the SSolar-GOA model has been carried out through comparison with simulated irradiance data from the libRadtran package and with direct and global spectra measured by spectroradiometers. Thousands of spectra under clear skies have been compared for different atmospheric conditions and solar zenith angles (SZA). The SSolar-GOA is validated by a quantitative comparison with libRadtran, showing that it underestimates direct normal, global, and diffuse spectral components with relative differences of +1 % (RMSE % = 4.6–8), +3 % (RMSE % = 5.3–8), and 8 % (RMSE % = 9.3–9.6), respectively, when the SZA varies from 6 to 60∘. Compared with the measured irradiance data of the LI-1800 and ASD spectroradiometers, the relative differences of direct normal and global components are within the overall experimental error, about ±2 %–12 % (RMSE % = 5–8.3), with underestimated or overestimated values. The diffuse component presents the highest degree of relative difference that can reach ±20 %–30 % and RMSE of 25 %–50 %. The relative differences depend strongly on the spectral solar region analysed and the SZA, but the high values of RMSE are due to the artifice generated by the different spectral resolution of the absorption coefficients of both models. Model approach errors combined with calibration instrument errors may explain the observed differences. The SSolar-GOA v1.0 is implemented in Python and open-source licensing.
... For zenith angle greater than 80°, equation 9 fails to give accurate values of AM. Kasten and Young [15], in 1989, suggested the following formula that best fits the measured data for all expected values of zenith angles, ...
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Directing solar panels in a way that collects the largest possible amount of solar energy is still attracting a lot of attention due to the continuous need to get clean, inexpensive renewable energy. Iraq is one of the countries characterized by the abundance of solar energy but the investment in this field has been far below ambition. In this study, an application developed with the visual basic programing language was used to compute precisely various solar angles and parameters , as a powerful tool for engineers and researchers. The outputs of the model were tested and discussed in detail. The air mass values were also computed for three cities: Mosul, Baghdad, and Basra. The results showed that the best time to acquire the solar radiation would be from 10 am to 2 pm (local time), the period that has the lowest values of air mass. Additional useful calculations that can be estimated by the application were the terrestrial irradiances from four empirical models for the clear sky: Roledo-Soler, Adnot, Kasten-Czeplak, and Berger-Duffie. The calculated values of terrestrial irradiance were compared with observed data measured by automatic weather station. The application simulated the actual values with some deviations due to the existence of clouds and aerosols. Kasten-Czeplak model was recommended to be used in Iraq since it was the best model to simulate the measured values. The comparison between the model's output and the measured values on a daily basis on the 21 st of June showed good agreement. The study suggested that the solar panels should face the south direction with a change of the tilt angle of the panels from 25 o in June to a value of 60 o each month towards the coldest months by an increment of 5 degrees.
... AM est définie comme la longueur du chemin optique que doivent traverser les rayons solaires pour atteindre la surface de la terre et est relative à la position du soleil pour laquelle = 0° (AM=1) pour laquelle ce chemin est le plus court. La La masse d'air relative (au niveau de la mer) peut être exprimée en fonction de à l'aide de la formule de Kasten et Young [6] selon l'Equation (1). Celle-ci est corrigée pour tenir compte de l'altitude en la multipliant par le rapport de la pression atmosphérique locale Patm en mbar et celle au niveau de la mer (1013,25 mbar), elle est appelée la masse d'air absolue. ...
Thesis
La production d’électricité par conversion photovoltaïque est aujourd’hui bien connue ; l’utilisation de cellules multi-jonction à haute performance est encore peu répandue et relève encore d’un marché de niche. Ces cellules, composées pour la plupart de trois jonctions photovoltaïques à base de matériaux appartenant aux troisième et cinquième colonnes du tableau de Mendeleïev, permettent d’atteindre des rendements supérieurs à 45%. Du fait de leur coût élevé, ces cellules sont fabriquées en très petite taille (allant de quelques cm² à quelques centaines de μm²) et alignées à des éléments optiques pour concentrer plusieurs centaines de fois le rayonnement solaire direct incident. Les modules fabriqués à base de ces cellules sont montés sur un tracker solaire très précis. La modélisation du fonctionnement de ces systèmes est très complexe ; de nombreux paramètres météorologiques tels que l’éclairement solaire direct, la température ambiante, la masse optique atmosphérique et les caractéristiques spectrales du rayonnement entrent en jeu dans le processus de conversion ; ces paramètres sont difficiles à mesurer, nécessitent une couteuse instrumentation et une maintenance contraignante. L’objectif de ces travaux est de développer un modèle opérationnel de puissance électrique utilisant des grandeurs d’entrée souvent mesurées et disponibles aisément pour l’exploitant de la centrale CPV. Il pourra être utilisé comme un outil d’aide à la décision pour l’investisseur en lui fournissant une estimation précise de l’énergie productible sur le site d’installation envisagé. Trois sites d’expérimentation ont été retenus : Le Bourget du Lac, Ajaccio et Aigaliers, sur chacun est installé un système CPV de technologie légèrement différente. Les mesures réalisées sur ces systèmes ont été filtrées et validées, de nombreuses défaillances techniques ayant été constatées notamment liées au fonctionnement du tracker. De nombreux modèles inspirés de la littérature, différents par leur forme, par le nombre et le type de variables d’entrée, ont été testés et ont montré des performances proches en termes d’erreur quadratique. Un modèle a été retenu du fait de ses performances, de sa simplicité et du faible nombre d’entrées (3 : rayonnement solaire direct, température ambiante et masse d’air atmosphérique). Ce modèle établi à partir de données mesurées sur le système CPV d’Ajaccio permet d’estimer la puissance produite avec une erreur quadratique de l’ordre de 5% sur les 2 sites d’Ajaccio et du Bourget du Lac, valeur satisfaisante pour ce type de systèmes. Ce modèle présente l’avantage d’être aisément utilisable et transposable à d’autres systèmes de technologie semblable et de ne pas nécessiter la mesure de variables liées au fonctionnement du système. Il pourrait être introduit au sein de logiciels de dimensionnement et d’estimation de la production photovoltaïque.
... m appearing in Eq. 5 constitutes the mass air optical coefficient (Kasten & Young, 2000a). This factor defines the direct optical path length through the earth's atmosphere, expressed as a ratio relative to the path length vertically upwards, i.e., at the zenith. ...
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The present paper consists of designing, modeling, and simulating a Dish-Stirling photothermal concentrator. The developed system intends to satisfy the electrical needs of a small residential building in a coastal Algerian city located at the edge of the sun-belt region, with the perspective of moving toward small-scale sustainable agglomerations. The adopted approach consisted of two steps. At the first step, the energy balances were established at the collector, receiver, absorber, and Stirling engine, considering hydrogen as a work fluid. The energy flows were reported to the surface unit of the reflector optical plane with three variants of concentration ratios, namely 500, 1000, and 1500. The second step consisted of parametric analysis of the effects of optical, thermal, and Stirling engine properties. This approach allowed us to design a Dish Stirling system of 10.52 m in diameter, with a concentration factor of 1000, and using hydrogen as a working fluid. The parametric study revealed that the highest effect is due to the regeneration efficiency; its increase of an order of 10% induces an enhancement of the delivered power exceeding 40%. The designed system showed a good performance during April, June, July, August, and September, as compared to the site demand. It proved to reach 23 kW in July around solar noon, which is equivalent to satisfying the needs of the households by around 153%.
... There are several formulas for air-mass X that conform to realistic atmospheric models; among them is the formula of Kasten and Young (1989)   1.6364 1 cos 0.50572 6.07995º 90º X z z      z is the apparent zenith distance in degrees (that is, topocentric and with refraction). * Phase angle. ...
Preprint
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Bruin (1977) devised a procedure to find out the visibility of the first crescent Moon. He applied various simplifications to his theory, not all of them acceptable. We rethink Bruin's method by making some corrections: we take into account the variation of the luminance of the Moon with the phase, we use the experimental results of Knoll et al. (1946) on threshold contrast, we apply Riccò's law, and we consider the atmospheric extinction coefficient to be variable. We use the theory to derive the Danjon limit.
... = (90° − ) Air Mass (AM) depends on Zenith Angle ( ) and Elevation Angle (⍺). Both of the angles aretaken into consideration to specify Air Mass (AM), while the used formula[17] [18] is - ...
Thesis
The objective of this work is to carry out a performance analysis of building integrated photovoltaic systems. The proposed system will occupy the majority of the unused space of vertical walls and harness more solar energy that can be used as the back up electrical energy resources for daily usage in urban areas. Here mono-facial solar panel is considered that harnesses energy from the front side of the panel. A special parameter i.e. cloud shadow effect is taken into consideration throughout the study. Results show that, proposed system mounted in the rooftop gives 30% less electrical energy in the cloudy days where as the vertically mounted system can generate 26% less electrical energy. The system is more recommendable for the vertical space than rooftop installation.
... 33,34 The spectral losses were calculated from the air mass using referenced methodologies. 35,36 All the parameters needed for the corrections were set as those of a polycrystalline 72-cell glasscell-polymer module on the Sandia module database. ...
Article
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The present paper evaluates the soiling losses of a 3.25‐MW photovoltaic (PV) system installed in central Chile, 200 km north of Santiago, and analyzes the nonuniform soiling deposition between the various strings for a period of 3 years. A robust methodology is developed to extract, in the most systematic way, 142 reliable soiling profiles from the 256 PV power time series recorded on site. It is found that, if unmitigated, soiling would reduce the annual DC energy generation by 8%, with a factor of 2× between the losses of the most and least affected strings. Most of the losses are registered on the edges of the plant, closer to traffic and unpaved roads. The most soiling intense months are in summer, result of the infrequent rainfalls and of the high concentrations of suspended particles that characterize this season. The revenues and the costs of different manual cleaning frequencies are evaluated and compared to identify the optimal soiling mitigation strategy for this site. Three cleanings per year are found to return the highest profits for the economic conditions considered in this study. However, a sensitivity analysis shows how different cleaning costs and electricity prices would affect the soiling mitigation strategy. In addition, in light of the nonuniform soiling deposition distribution, the possibility of cleaning only selected strings rather than the full PV plant is discussed. The magnitude and the spatial distribution of soiling at a 3.25‐MW PV system in Chile are investigated, along with potential profits of an optimized mitigation strategy. A yearly average 8% loss is found, with a factor of 2× between the losses of the most and least affected strings, respectively, located at the sides and at the center of the plant. Most of the losses occur in summer because of the infrequent rainfalls and the high suspended particle concentrations. For a cleaning cost of $1.9/kW and an electricity price of $0.16/kWh, three cleanings per year are recommended.
... There are several formulas for air-mass X that conform to realistic atmospheric models; among them is the formula of Kasten and Young (1989)   1.6364 1 cos 0.50572 6.07995º 90º X z z      z is the apparent zenith distance in degrees (that is, topocentric and with refraction). * Phase angle. ...
Preprint
Full-text available
Schaefer (1991) determined the Danjon limit or minimum angle between the Sun and the Moon from which the Moon can be seen shortly after the conjunction. Schaefer's method uses Hapke's (1984) lunar photometric theory and considers a fixed value for the threshold illuminance. We show Schaefer's method and its shortcomings, and we expose a modified theory, where the threshold illuminance to see the lunar crescent depends on several factors, mainly atmospheric absorption. We consider that vision is a probabilistic phenomenon; that is, when we use the experimental data of Blackwell (1946), we cannot be sure whether or not the Moon will be seen. Finally, we conclude that «perhaps» Hapke's theory overestimates the shielding of the sun's rays by the irregularities of the lunar surface at large phase angles.
... where the numerical coefficients are either a ¼ 0.50572, b ¼ 0, c ¼ 96.07995, and d ¼ 1.6364 according to (Kasten and Young, 1989), or a ¼ 0.48353, b ¼ 0.09585, c ¼ 96.741, and d ¼ 1.754 according to (Gueymard, 2003). At sunrise or sunset (Z ¼ 90 ), AM reaches its maximum, namely 37.9 and 38.2 for the two sets of coefficients, respectively. ...
Chapter
Various technical aspects of the measurement and modeling of the solar energy potential are addressed in this chapter to provide a solid understanding of the different steps involved in the practice of solar resource assessments. The information presented here represents the state of the art with regard to the availability of solar resource databases developed from satellite imagery or meteorological reanalysis, and their derivatives, such as solar resource maps or typical meteorological years. The fundamentals that are reviewed include measuring, modeling, and applying solar radiation resource data to meet various needs, such as site selection, solar system design and simulation, or financial projections.
... The air mass is calculated using the formula of Kasten and Young [23]. ...
Article
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Solar resource assessment by clear sky models is of great importance in the solar energy field: verifying the performance of photovoltaic systems during stable conditions, clouds effects evaluation, the determination of geographical areas where irradiation is more uncertain and the preparation of forecasts with sky cameras. But before using these models they must be validated against high performances soil measurements. Since there is no radiometric sensor that measures clear-sky radiation, then historical clear-sky time periods must be identified only from long-term all-sky irradiation records. The contribution of this study is to exploit the ground measurements, analyze them and retrieve the information they contain concerning the clear sky instants. The study will be performed by comparing the clear sky instants identified by an algorithm proposed by Reno and Hansen with a physical clear sky model. This comparison is made using high frequency global horizontal irradiation (GHI) data from high performances meteorological station installed at Benguerir in Morocco.
... O que define o espectro incidente de um local é a atmosfera que atua como um filtro, modificando a quantidade e a distribuição espectral . Essa atenuação depende da quantidade de substâncias percorridas pelos raios solares em seu curso através da atmosfera e das propriedades ópticas dos diferentes constituintes atmosféricos (KASTEN, 1989 Do espectro irradiado pelo sol, a região UV corresponde a faixa de comprimento de onda que vai de 100 a 400 nm e é dividida em três bandas: UVA (315-400 nm), UVB (280-315 nm), UVC (100-280 nm). Os pequenos comprimentos de onda da Radiação Ultravioleta fazem com que essa faixa do espectro seja mais sensível a massa de ar, aerossol e água precipitável (ELTBAAKH, 2012). ...
Conference Paper
Das diferentes fontes de energia utilizadas pelo homem, àquelas advindas de recursos não renováveis são extensivamente exploradas em todo o planeta, exigindo ações que combatam a potencial escassez futura destes recursos, que se não geridos adequadamente, deverão se tornar insuficientes para atender a demanda mundial, podendo acarretar em conflitos e privações principalmente às pessoas de classes sociais mais baixas. Sendo assim, tecnologias e fontes de energias renováveis aparecem como alternativas dentro do setor energético, com destaque para a fonte solar. Diante disso, este projeto consiste no dimensionamento e estudo avaliativo acerca da viabilidade técnica e econômica da implementação de um sistema fotovoltaico capaz de suprir a demanda energética de um determinado prédio do campus da UFSCar-Sorocaba. Para dimensionar o sistema foram adotados dois métodos: utilização de planilhas e simulação feita no software PVsyst. A análise econômica se deu pelo cálculo de índices como VPL, TIR e Payback Descontado. Os resultados obtidos propõem um sistema composto por cerca de 128 painéis com aproximadamente 42 kW de potência instalada, ocupando cerca de 248 m² de área. Isto demanda um investimento inicial de aproximadamente 115 mil reais. Uma vez que o sistema projetado atende à demanda energética do prédio, ocupando uma área menor do que a disponibilizada para a instalação das placas, com um VPL positivo, TIR acima da TMA e um payback estimado de 2,9 anos, prazo considerado aceitável para a recuperação do investimento, a instalação do sistema se mostra técnica e economicamente viável
... where h is the elevation. The optical air mass (AM) is calculated by Kasten and Young's formula [43]: ...
Article
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The proliferation of photovoltaic (PV) power generation in power distribution grids induces increasing safety and service quality concerns for grid operators. The inherent variability, essentially due to meteorological conditions, of PV power generation affects the power grid reliability. In order to develop efficient monitoring and control schemes for distribution grids, reliable forecasting of the solar resource at several time horizons that are related to regulation, scheduling, dispatching, and unit commitment, is necessary. PV power generation forecasting can result from forecasting global horizontal irradiance (GHI), which is the total amount of shortwave radiation received from above by a surface horizontal to the ground. A comparative study of machine learning methods is given in this paper, with a focus on the most widely used: Gaussian process regression (GPR), support vector regression (SVR), and artificial neural networks (ANN). Two years of GHI data with a time step of 10 min are used to train the models and forecast GHI at varying time horizons, ranging from 10 min to 4 h. Persistence on the clear-sky index, also known as scaled persistence model, is included in this paper as a reference model. Three criteria are used for in-depth performance estimation: normalized root mean square error (nRMSE), dynamic mean absolute error (DMAE) and coverage width-based criterion (CWC). Results confirm that machine learning-based methods outperform the scaled persistence model. The best-performing machine learning-based methods included in this comparative study are the long short-term memory (LSTM) neural network and the GPR model using a rational quadratic kernel with automatic relevance determination.
... In the context, scholars in Sandia National Laboratory reported that the influence of solar spectrum on crystalline silicon solar cells can be adequately addressed by only considering the absolute air mass [34]. Based on this finding, King and Eckert [35] developed a new method which included the spectrum modification for characterizing the electrical performance of PV arrays. ...
Article
Solar spectrum plays an important role on electrical performance of PV modules via affecting their short circuit current. In this study, a new model combining the impacts of both air mass and diffuse solar radiation ratio is developed to evaluate the solar spectrum impacts on the short circuit current of photovoltaic (PV) modules. A new method, named air mass cumulative distribution function method (AMCDF), is introduced to represent the relationship between air mass and solar spectrum effect. The experimental data shows that when air mass is less than 4.5, the relationship between the normalized short-circuit current and the air mass cumulative distribution function can be well represented by a five-order polynomial. However, when air mass is larger than 4.5, the relationship becomes irregular. Further study on the irregular data indicates that the chaotic relationship is caused by the impact of diffuse solar radiation ratio (R d). Based on these findings, the new model which combines the air mass cumulative distribution function and the diffuse solar radiation ratio is developed to evaluate the spectrum effect. Compared to conventional models, the proposed model has higher prediction accuracy and it also can predict short circuit current even when the air mass is high.
... where AM is the atmospheric mass, calculated based on Kasten and Young's equation [99], which is able to provide accurate results even for zenith angles reaching 90°: ...
Chapter
Among the different materials for solar cells, Si crystalline based are the ones that dominate the current market (>90% [1, 2]).
... where AM is the atmospheric mass, calculated based on Kasten and Young's equation [99], which is able to provide accurate results even for zenith angles reaching 90°: ...
Chapter
Solar cells correspond to the basic unit where the photovoltaic effect takes place.
... where AM is the atmospheric mass, calculated based on Kasten and Young's equation [99], which is able to provide accurate results even for zenith angles reaching 90°: ...
Chapter
Dispatch strategy (also known as scheduling) refers to the operation and power control of the different energy sources in a system. In this study, the sources correspond to the PV system, battery system and diesel generators.
Article
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Reliable estimates and forecasts of Photovoltaic (PV) power output form a fundamental basis to support its large-scale integration. This is recognized in literature, where a growing amount of studies deal with the development of PV power estimation and forecasting models. In particular, machine learning techniques received significant attention in the past decade. Yet, the importance of predictor variables are consistently ignored in such developments and as a result those models fail to acknowledge the value of including physics-based models. In this study we quantify the value of predictor variables for PV power estimation and forecasting, assess deficiencies in estimation and forecasting models, and introduce a number of pre-processing steps to improve the overall estimation or forecasting performance. To this end, we use common physical models to create so-called expert variables and test their impact on the performance of single-point and probabilistic models. In addition, we investigate the optimal selection of predictor variables for PV power estimation and forecasting. By means of a sensitivity analysis, the paper shows how the value of expert variables is affected by the tilt angle of the PV system. To allow for a deeper insight into the importance of predictor variables, two case studies in different climate regions are considered in the numerical evaluation.
Article
In this work, a method to calculate the aerosol content in the atmosphere and the prevailing spectral irradiance of the sunlight is introduced. This method does not aim for low measurement uncertainty but for cost effectiveness and does not require sophisticated equipment. The bases of the method are the clear sky direct normal irradiance (DNI) and a look‐up table calculated with the software tool SMARTS2. The ratio of clear sky DNI to the prevailing DNI in combination with the look‐up table allows the determination of aerosol optical depth (AOD), spectral matching ratios (SMR), and spectral irradiances. Besides the prevailing DNI, the following ambient condition parameters are required: Air pressure, relative humidity, and ambient temperature. This means a weather station and a pyrheliometer are sufficient for the determination of the prevailing spectral irradiance. Obviously, this method cannot guarantee the same accuracy as conventional spectral irradiance measurement methods (e.g., using a spectroradiometer). However, in this work, we demonstrate the potential of this new method as a fall‐back strategy for missing spectral irradiance data. This method is worth using when (C)PV module power output data needs to be evaluated in dependence of the composition of the spectral irradiance, but no regular spectral irradiance data are available. In this paper, the AOD and SMR values determined with the introduced method are compared to measurement data with common measurement devices demonstrating a satisfying agreement. The spectral irradiances calculated with this method are successfully tested for using as the basis for energy yield calculations and for the determination of the CPV module power output at Concentrator Standard Conditions according to IEC 62670‐1. A simple method to calculate the aerosol content in the atmosphere and the prevailing spectral irradiance of the sunlight is introduced. A weather station and a pyrheliometer are sufficient for the determination of the prevailing spectral irradiance using this method. In this paper, the AOD and SMR values determined with the introduced method are compared to measurement data with common measurement devices demonstrating a satisfying agreement.
Chapter
This chapter presents solar resource‐related notions essential for its measurement, assessment or forecasting. Solar radiation reaching the ground depends on the position of the Sun, extra‐terrestrial radiation and the atmospheric specificities of the site being studied. The chapter presents a general presentation of these concepts. A fraction of the extra‐terrestrial irradiance was absorbed while traveling through the atmosphere. Another fraction of this radiation is scattered, leading to an indirect radiation for the observer. The chapter offers a detailed presentation of the direct and indirect components of the irradiance, as well as the associated measurement instruments. It then presents the forecasting of the solar resource used by concentrated solar power plants, namely the direct normal irradiance. After a review of the essential notions to be known, the various existing approaches for making a direct normal solar irradiance forecasting are presented, differentiating them according to the expected spatial–temporal horizon.
Article
In this study we introduce an open-source dataset holding power measurements of 175 residential photovoltaic (PV) systems that are distributed throughout the province of Utrecht, the Netherlands. The dataset features power measurements with a high temporal resolution, i.e. 1-min, for the period January 2014 until December 2017 (over 260 million data points). Spatial information of the PV systems is mapped through latitude and longitude grids, with a resolution up to 150 by 150 meters. In addition, we develop and publish a quality control routine that can be applied to validate and filter PV power measurements. Finally, we propose a method to estimate the rated DC capacity of a PV system based on the power measurements. We have deposited five files into the Zenodo repository (https://doi.org/10.5281/zenodo.6906504), which are publicly available. Four numerical datasets are enclosed, holding unfiltered power measurements, filtered power measurements at two different stages and metadata. The latter includes information on the tilt angle, azimuth angle, the estimated DC and AC capacity, and location. Finally, a Python package featuring the quality control routine developed to validate and filter PV power measurements is published.
Article
The study examines aerosol optical depth (AOD) measurements at 320 nm wavelength by a Brewer MKIII spectrophotometer located in Hobart, Australia. A climatology was developed from records encompassing the period 4 April 2002 to 27 February 2019. A methodology is described to extract cloudless episodes and cloudless half‐days. Extraterrestrial irradiances are obtained using a travelling calibration standard and are supplemented by Langley analyses on cloudless and stable half‐days. Aerosol optical depths are obtained by applying Beer’s law to every reading and subtracting known values of ozone optical depth and Rayleigh scatter. Statistics are provided on the daily, monthly and interannual variability. Concurrent measurements from a Multifilter Rotating Shadowband Radiometer (MFRSR) operating in the visible band enabled the spectral variability of AOD to be determined. They showed the dominance of oceanic aerosols but with some input from land‐based aerosols originating mostly from biomass burning.
Thesis
By moving away from finite fossil fuels to regenerative and sustainable energy production, Europe can ensure a reliable, economical, and environmentally compatible energy supply. The substitution of fossil energy sources by regenerative energies and the resulting decoupling of energy production and resource consumption limit the irreversible climatic changes facing the global population and protect people and the environment by decarbonizing the energy sector achieving independence from gas and coal exporters. That can be done by using solar energy supply directly through photovoltaic systems or in an indirect way as wind energy through wind turbines. With the supporting pillars of photovoltaics and wind power, the change from a centralized, unidirectional energy system to a decentralized, bidirectional system can be accomplished. Due to the characteristics of fluctuating power generation plants, the need for storage increases but can be reduced to a minimum through energy demand reduction measures, such as general technical efficiency improvements and changes in consumer behavior, as well as through load shifting and the expansion of domestic and cross-border transmission grid capacities. In this context sector coupling combines the electricity, heat, and transport sectors into a holistic system. Energy system modeling makes a valuable contribution to understanding and building the future energy supply system. This work aims to investigate an energy system 100 percent based on renewable energy by the year 2050. For this purpose, a complete sector-coupled energy model (UCB-SEnMod) of all energy sectors was modeled at the Institute for Business and Technology Management IBT, located at the Environmental Campus Birkenfeld of the Trier University of Applied Sciences, in which the interaction of energy supply and energy consumption can be investigated with hourly resolution. The result of the present work is that a 100 percent renewable energy system in Europe is technically possible. The overall system will be characterized by a high degree of photovoltaic and wind power, whose volatile power generation requires storage technologies. By displacing combustion-based technologies as far as possible and using more efficient electrical consumers, primary and final energy consumption can be significantly reduced. The further expansion of the European interconnected system can increase the security of supply and ensure energy supply at all times in Europe.
Chapter
The photoelectrochemical (PEC) water splitting (WS) process has attracted a lot of attention during the past decades since it represents one of the possible ways to reduce the production costs of hydrogen and other solar fuels. This complicated task can, in principle, be achieved, by PEC WS, in a single step using the largest source of renewable energy: the sun. This chapter is intended to guide the reader to the comprehension of the basics of the WS process and the necessity to go beyond the use of simple electrolyzers that rely on expensive electrocatalysts. An ideal, yet ambitious, solution to this problem is the PEC approach. The basic concepts of PEC cells are described together with the common materials used for the construction of photoanodes and photocathodes. Different strategies to improve the PEC performances of these materials like doping, nanostructuration, and the formation of heterojunctions are also described with some examples. The protection of photoanodes and photocathodes based on typical semiconductors materials like Si, GaAs, InP, etc., in aggressive electrolytes, like KOH, is also discussed. Emphasis is dedicated to the evaluation of the photoelectrodes' performances in terms of charge injection efficiency and recombination processes. Finally, the “Conclusions and Perspectives” section is dedicated to the possibility of assembling stand‐alone PEC cells that do not require the use of external bias, thus minimizing the cost of solar fuels production.
Article
In order to evaluate energy saving performance of multi-coated glazings and photovoltaic systems in buildings, spectral solar irradiance data are required. Although broadband solar irradiance data are included in existing weather data for building energy simulation, spectral solar irradiance data are not included. In this paper, a simplified regression formula that estimates spectral global solar irradiance between 0.3 and 2.5 μm under all weather conditions from broadband global solar irradiance, air temperature, and humidity, is presented. Furthermore, three kinds of correction equations to correct the regression formula are created using clearness index, air-mass, and precipitable water.
Article
I evaluated conversion efficiency of hot-carrier solar cells (HC-SCs) of the original type and two improved types: an HC-SC with intraband transition (HC-SC+intra) and an intermediate-band-assisted HC-SC (IB-HC-SC) that utilize sub-bandgap photons. For this purpose, three realistic points of great importance were involved in the newly constructed detailed-balance model: Shockley–Read–Hall (SRH) recombination of photogenerated carriers, characteristics of the energy-selective contacts (ESCs), and solar spectrum variation. I have revealed that the HC-SC+intra and IB-HC-SC can potentially yield annual electricity production comparable to those of triple-junction and quad-junction solar cells (3J- and 4J-SCs) when sub-bandgap photons are almost perfectly absorbed. The ESCs consisting of wide-bandgap layers extract the photogenerated carriers more rapidly owing to their larger conductance and consequently yield higher conversion efficiency than the ESCs using resonant tunneling diodes composed of quantum dots and quantum wells. This, in turn, enables the use of an absorber with a short SRH recombination time of the carriers. In other words, the efficiency is less sensitive to SRH recombination than those of the 3J- and 4J-SCs. In particular, for the IB-HC-SC, the requisite of the SRH recombination time is 1 ns, and that of the thermalization time is 0.1 ns; the latter is an order of magnitude shorter than the previous requisite. These HC-SCs are more robust against the solar spectrum variation because they are free from the current-matching problem unlike the 3J- and 4J-SCs, which also contributes to the large annual electricity production.
Technical Report
Full-text available
Este documento é uma tradução adaptada do manual de referência técnica para a ferramenta de progressão de arquivos climáticos Climate Change World Weather File Generator (CCWorldWeatherGen). A tradução do manual foi elaborada a partir da pesquisa de mestrado de Gustavo Henrique Nunes, sob orientação da Profa. Dra. Thalita Gorban Ferreira Giglio. A iniciativa não tem fins lucrativos e a versão original do manual (em inglês), está livremente disponível para download. O Laboratório de Eficiência Energética e Sustentabilidade em Edificações (E3SLab), bem como os autores deste documento, não atestam informações ou assumem responsabilidade pela exatidão de parâmetros técnicos adotados na criação do CCWorldWeatherGen – de méritos exclusivos dos desenvolvedores. Apesar dos profundos esforços dos autores para traduzir e adaptar a obra original, e escrever e revisar o texto deste documento, é possível que eventuais inexatidões surjam durante a leitura do trabalho. Sendo assim, críticas e sugestões para melhorias, e/ou correções do conteúdo, são bem-vindas.
Article
Photosynthetically active radiation (PAR; wavelength 400 ~ 700 nm) is the spectral range of solar radiation used by plants for photosynthesis. PAR data are used in various fields of research, such as that focusing on surface vegetation growth, the light energy-chemical energy conversion process, and the terrestrial carbon cycle. In this study, we analyze the variability between Global Horizontal Irradiance (GHI) and PAR according to the solar zenith angle, the clearness index, using GHI and PAR observations from 2016 to 2020 at Anmyeondo Flux Tower of Korea Forest Research Institute (KFRI). We confirm that the PAR decreases and the variability of the ratio of PAR to GHI increases as the atmospheric optical path increases. We also confirmed that the PAR increased and the ratio of PAR and GHI decreased as the clearness index increased. Using the results of these relationships and prior studies, we develop and evaluate empirical models that estimate PAR from GHI. The R 2 representing the estimation accuracy of the model was 0.988 to 0.996, indicating very high accuracy. With these results, the observation data from the KFRI's Wando, Pyeongchang, and Samcheok Flux Towers during the same period showed that R 2 was very high at 0.977 ~ 0.988, confirming its transferability in other regions. Despite the high R 2 , the Mean Bias Error (MBE) for each site was shown to be different. To solve this problem, a model with relative humidity and temperature was developed to apply regional conditions for each site, and showed similar R 2 to prior models with less MBE. It is expected that the results of this study will be used as policy references such as attracting solar power complexes by drawing up a seasonal map of the Korean peninsula of PAR with solar radiation data observed at the Korea Meteorological Administration's Automated Synoptic Observing System (ASOS).
Conference Paper
The aim of this study is to evaluate the potential of using standard photovoltaic (PV) modules on board of cruise ships to increase the share of renewable energies in the total energy demand. Due to the limited space available, also partial shaded areas must be considered for installation. As a large part of the ship hull is covered by cabin balconies, this area is of particular interest. An analysis for a clear sky scenario will be carried out based on a simulation, which reflects the solar irradiation on these areas during a representative cruise.
Article
Solar irradiance during daylight hours was calculated using the Iqbal formula, taking into account total and aerosol optical thicknesses extracted from AERONET to determine the attenuation by the atmosphere and by aerosols. Comparison of the results for sites in the equatorial zone (Singapore, San Cristobal and Mbita) and temperate zone (New Delhi, Carthage and Laguna) shows that a cloudless atmosphere weakly reduces solar irradiance in the equatorial zone, which is characterized by more regular meteorology, in comparison to the temperate zone, which is characterized by more human activity. The attenuation in the clear sky (without aerosols) seems to be independent of the region and approximately 8 ± 1% on average, except for New Delhi, for which maximum attenuation by aerosols (46%) was observed due to the high diversity of seasonal and anthropogenic sources. Attenuation by the atmosphere does not exceed 24% at sites far from industrial pollution sources (Laguna and San Cristobal). For Singapore and Carthage, where anthropogenic aerosol emissions are weak, the attenuation by the atmosphere is around 30%.
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