Solar Radiation Measurements Research Articles

Kinematics and dynamics of the stratocumulus average diurnal dissipation process at Atacama Desert

Stratocumulus-type clouds constitute a stable system over the Southeast Pacific Ocean. Their phenomenology is well known particularly over the ocean, but a quantitative analysis of their diurnal cycle over the Pacific continental coastal desert strip of South America remained unaddressed. In this work, the stratocumulus average morning dissipation process at two sites in the Atacama Desert is documented through simple empirical mathematical equations. Based on the change rate analysis of the visible cloud optical depth (COD) inferred from solar irradiance measurements, the kinematics and the dynamics of the stratocumulus dissipation process is established, showing that it develops at an average constant “acceleration of dissipation” (d2COD/dt2) of about −3.3 h−2, equivalent to a cloud geometrical vertical thickness change at an average constant “acceleration of thinning” of about −40 m/h2. Towards the end of the dissipation process when cloudiness vanishes, the average “velocity of dissipation” (dCOD/dt) and “velocity of thinning” round −16 h−1 and −175 m/h, respectively. A simple plane-parallel optical and geometrical model explains the average behavior of the phenomenon in the region on a wholly radiative base, with an absorbed fraction of solar irradiance acting as exclusive driver of the average dissipation process. About 13 kJ/m2 of net irradiation is needed to change the COD of the stratocumulus deck by one unit. The progressive morning cloud dissipation from the land on the east towards the sea on the west is evidenced. The analysis of the cloud effective transmittance and a full set of checks, including test of robustness, support these results and their interpretation.

The Comparison of Performance Polycrystalline and Amorphous Solar Panels under Malang City Weather Conditions

Amorphous Silicon type solar panels, which had a bad reputation in the past, are now considered very reliable, with several significant advantages over Mono Crystalline and Polycrystalline solar panels. Research on the effectiveness of the capture power of Amorphous Silicon compared to Silicon Crystalline solar panels types is still not much done.The purpose of this study was to explain the effect of solar radiation on the capture power of polycrystalline and amorphous solar panels.This research method includes solar panel installation, measurement of solar radiation, measurement of the resulting current and voltage, data analysis, discussion, and conclusions. The independent variables of the study were the resulting current and voltage, and the type of solar panels (Polycrystalline and Amorphous). The dependent variable of this research are actual power and efficiency.The results showed that the greater the solar radiation, the higher the actual power and efficiency produced by the solar panels. Polycrystalline type solar panels are capable of producing higher average actual power and average efficiency, namely 86.83 W and 11.92%, compared to amorphous solar panels, namely 43.88 W and 6.01%.
 Keywords: Monocrystalline, Polycrystalline, Normalized Power Output Efficiency, Performance Ratio

Caracterizacion de Energia Solar Fotovoltaica utilizando el Modelo Aniso Trópico de Muneer

En este artículo se evalúa el recurso solar con el fin de determinar su caracterización mediante el modelo anisotrópico de Muneer. En comparacion con el modelo de variables difusas de Liu Jordan. Se realiza un análisis conceptual de la irradiancia difusa del cielo al igual que un análisis del modelo ya que este distingue entre superficies sombreadas y no sombreadas y dentro de estas últimas entre cielos cubiertos o despejados. Se desarrolló un modelo matemático que en base al modelo ya mencionado, se realice la caracterización del recurso solar, la cual está enfocada a la producción de energía eléctrica. Ya definidos los parámetros a considerar en el modelo, se procederá a modelar el mismo mediante Matlab con mediciones de radiación solar tomados de la Universidad Politécnica Salesiana.

The Combined Effect of Ozone and Aerosols on Erythemal Irradiance in an Extremely Low Ozone Event during May 2020

In this study we focus on measurements and modeled UV index in the region of Athens, Greece, during a low ozone event. During the period of 12–19 May 2020, total ozone column (TOC) showed extremely low values, 35–55 Dobson Units (up to 15%) decrease from the climatic mean (being lower than the −2σ). This condition favors the increase of UV erythemal irradiance, since stratospheric ozone is the most important attenuator at the UVB spectral region. Simultaneously, an intrusion of Saharan dust aerosols in the region has masked a large part of the low ozone effect on UV irradiance. In order to investigate the event, we have used spectral solar irradiance measurements from the Precision Solar Radiometer (PSR), TOC from the Brewer spectrophotometer, and Radiative Transfer Model (RTM) calculations. Model calculations of the UV Index (UVI) showed an increase of ~30% compared to the long-term normal UVI due to the low TOC while at the same time and for particular days, aerosols masked this effect by ~20%. The RTM has been used to investigate the response in the UV spectral region of these variations at different solar zenith angles (SZAs). Spectra simulated with the RTM have been compared to measured ones and an average difference of ~2% was found. The study points out the importance of accurate measurements or forecasts of both ozone and aerosols when deriving UVI under unusual low ozone–high aerosol conditions.

Simulated reflectance above snow constrained by airborne measurements of solar radiation: implications for the snow grain morphology in the Arctic

Abstract. Accurate knowledge of the reflectance from snow/ice-covered surfaces is of fundamental importance for the retrieval of snow parameters and atmospheric constituents from space-based and airborne observations. In this paper, we simulate the reflectance in a snow–atmosphere system, using the phenomenological radiative transfer model SCIATRAN, and compare the results with that of airborne measurements. To minimize the differences between measurements and simulation, we determine and employ the key atmospheric and surface parameters, such as snow grain morphologies (or habits). First, we report on a sensitivity study. This addresses the requirement for adequate a priori knowledge about snow models and ancillary information about the atmosphere. For this aim, we use the well-validated phenomenological radiative transfer model, SCIATRAN. Second, we present and apply a two-stage snow grain morphology (i.e., size and shape of ice crystals in the snow) retrieval algorithm. We then describe the use of this new retrieval for estimating the most representative snow model, using different types of snow morphologies, for the airborne observation conditions performed by NASA's Cloud Absorption Radiometer (CAR). Third, we present a comprehensive comparison of the simulated reflectance (using retrieved snow grain size and shape and independent atmospheric data) with that from airborne CAR measurements in the visible (0.670 µm) and near infrared (NIR; 0.870 and 1.6 µm) wavelength range. The results of this comparison are used to assess the quality and accuracy of the radiative transfer model in the simulation of the reflectance in a coupled snow–atmosphere system. Assuming that the snow layer consists of ice crystals with aggregates of eight column ice habit and having an effective radius of ∼99 µm, we find that, for a surface covered by old snow, the Pearson correlation coefficient, R, between measurements and simulations is 0.98 (R2∼0.96). For freshly fallen snow, assuming that the snow layer consists of the aggregate of five plates ice habit with an effective radius of ∼83 µm and having surface inhomogeneity, the correlation is ∼0.97 (R2∼0.94) in the infrared and 0.88 (R2∼0.77) in the visible wavelengths. The largest differences between simulated and measured values are observed in the glint area (i.e., in the angular regions of specular and near-specular reflection), with relative azimuth angles <±40∘ in the forward-scattering direction. The absolute difference between the modeled results and measurements in off-glint regions, with a viewing zenith angle of less than 50∘, is generally small ∼±0.025 and does not exceed ±0.05. These results will help to improve the calculation of snow surface reflectance and relevant assumptions in the snow–atmosphere system algorithms (e.g., aerosol optical thickness retrieval algorithms in the polar regions).

High-resolution estimates of diffuse fraction based on dynamic definitions of sky conditions

Accurate monitoring and operation of solar power systems require high-resolution solar radiation measurements and precise separation models. This study aims to improve the accuracy of classic diffuse fraction-clearness index piecewise separation models by applying data-driven classifications of sky conditions. This is achieved through a novel outlier-insensitive clustering algorithm and shape prescriptive modeling, applied to 1-, 10-, 30-, and 60-min ground measurements from 4 different locations in the MENA region. This study shows that classifications of sky conditions are not uniform among the selected locations even though all stations fall in the arid desert climate category. This highlights the importance of extracting the sky conditions from measurements rather than using available classifications in the literature. The selection of the number of clusters has to undergo optimization. The number of clusters is also a function of the time resolution. One of the selected locations shows four optimal clusters for 1-min data and six clusters for 60-min data. All developed piecewise separation models show high accuracy and stability with the mean bias errors approaching zero values and the mean absolute errors ranging between 8.7 and 11.8%. The models also outperform existing ones and have good generalization capabilities under the same climate classification.

Spectral characterization, radiative forcing and pigment content of coastal Antarctic snow algae: approaches to spectrally discriminate red and green communities and their impact on snowmelt

Abstract. Here, we present radiative forcing (RF) estimates by snow algae in the Antarctic Peninsula (AP) region from multi-year measurements of solar radiation and ground-based hyperspectral characterization of red and green snow algae collected during a brief field expedition in austral summer 2018. Our analysis includes pigment content from samples at three bloom sites. Algal biomass in the snow and albedo reduction are well-correlated across the visible spectrum. Relative to clean snow, visibly green patches reduce snow albedo by ∼40 % and red patches by ∼20 %. However, red communities absorb considerably more light per milligram of pigment compared to green communities, particularly in green wavelengths. Based on our study results, it should be possible to differentiate red and green algae using Sentinel-2 bands in blue, green and red wavelengths. Instantaneous RF averages were double for green (180 W m−2) vs. red communities (88 W m−2), with a maximum of 228 W m−2. Based on multi-year solar radiation measurements at Palmer Station, this translated to a mean daily RF of ∼26 W m−2 (green) and ∼13 W m−2 (red) during peak growing season – on par with midlatitude dust attributions capable of advancing snowmelt. This results in ∼2522 m3 of snow melted by green-colored algae and ∼1218 m3 of snow melted by red-colored algae annually over the summer, suggesting snow algae play a significant role in snowmelt in the AP regions where they occur. We suggest impacts of RF by snow algae on snowmelt be accounted for in future estimates of Antarctic ice-free expansion in the AP region.

Testing the adequacy of luminous change descriptors to represent dynamic attributes in outdoor views

Outdoor views are critical for sustaining well-being in urbanized environments, as they increase opportunities for contact with natural and dynamic features. Yet, current view assessment procedures do not investigate the role of dynamic attributes in views. In this study, we evaluated a systematic procedure to test the adequacy of representing dynamic outdoor attributes as a function of lightness changes over time. Using image processing and monitoring techniques, we examined the presence of lightness changes in views in two seasons and as a function of three spatial parameters. In Part 1, we evaluated light variations in 16 distinct view scenes collected in summer (n = 320 intervals). In Part 2, we examined daylight changes in four pairs of identical view scenes collected in summer and fall (n = 80 intervals each). Continuous solar radiation measurements anchored lightness changes values as a function of sky conditions. The results showed the recurrence of lightness changes in views for Part 1 (77%) and Part 2 (75%), suggesting the prevalence of light changes in views across the year. In Part 1, lightness changes in views presented statistical significance in naturalistic conditions and three sky types, yet more data is needed for comparative analysis. In Part 1, the prevalence of Global variation in views was demonstrated. Likewise, two view types (i.e., Roof and Wall) showed a clear frequency of lightness changes under naturalistic conditions (76% and 74%). These outcomes help to sustain the adequacy of lightness change for describing dynamic attributes in views.

Solar Radiation Climatology in Camagüey, Cuba (1981–2016)

The transition to renewable energies is an unavoidable step to guarantee a peaceful and sustainable future for humankind. Although solar radiation is one of the main sources of renewable energy, there are broad regions of the planet where it has not been characterized appropriately to provide the necessary information for regional and local planning and design of the different solar powered systems. The Caribbean, and Cuba in particular, lacked until very recently at least one long-term series of surface solar radiation measurements. Here we present the first long-term records of solar radiation for this region. Solar radiation measurements manually conducted and recorded on paper were rescued, reprocessed and quality controlled to develop the solar radiation climatology at the Actinometrical Station of Camagüey, in Cuba (21.422°N; 77.850°W; 122 m a.s.l.) for the period 1981–2016. The diurnal cycle based on the average hourly values of the global, direct and diffuse horizontal variables for the entire period have been determined and analyzed showing the dependence on solar zenith angle (SZA) and clouds. The annual cycle of global solar component given by the mean monthly daily values presents two maxima, one in April and another one in July with values of 5.06 and 4.91 kWh m−2, respectively (18.23 and 17.67 MJ m−2 per day for insolation), and the minimum in December (3.15 kWh m−2 or 11.33 MJ m−2). The maxima are governed by the direct solar components and are modulated by cloudiness. Both, diurnal and annual cycles of the diffuse solar component show a smoothed bell shaped behavior. In general solar radiation at this station presents a strong influence of clouds, with little seasonal variation but with higher values during the rainy season. Daily global radiation annual averages showed its maximum value in the year 1983, with 17.45 MJ m−2 explained by very low cloudiness this year, and the minimum value was reported in 2009 with a value of 12.43 MJ m−2 that could not explained by the cloud coverage or the aerosols optical depths registered that year. The effects of the 1982 El Chichón and 1991 Mount Pinatubo volcanic eruptions on the solar radiation variables at Camagüey are also shown and discussed. The results achieved in this study shown the characteristics of solar radiation in this area and their potential for solar power applications.

Performance of the FAO Penman-Monteith equation under limiting conditions and fourteen reference evapotranspiration models in southern Manitoba

Evapotranspiration is a key component of water and energy balance. An accurate estimate of reference evapotranspiration (ETo) is important for determining the water demand of field crops, water management, and hydrological modelling. The FAO-PM ETo equation is the standard equation for estimating ETo. Its use is limited by the requirement for too many observed inputs that are not always available in most weather stations. Empirical models requiring readily available inputs have been developed as an alternative. However, their performance is location-specific. Therefore, this study assesses the performance of the FAO-PM ETo computed with limited data and fourteen empirical ETo models. Meteorological data (2012–2019) was analyzed under the semi-arid climate conditions in southern Manitoba. Model performance was assessed using statistical indices, including R2, RMSE, NSE, MPE, and MAE. Results showed that ETo estimates under missing wind speed, relative humidity, or solar radiation were acceptable, although model performance decreased with increased missing data yielding average to poor performance. Based on R2, RMSE, and NSE values, among the 14 models compared, the best performing models are Valiantzas-1, Valiantzas-3, Irmak, Valiantzas-2, and Priestly-Taylor models. New empirical coefficients were developed, requiring one or two climatic inputs to improve empirical models. Results showed that the calibrated models performed better than the original equation. The sensitivity analysis showed that ETo is most sensitive to maximum temperature (Tmax) and solar radiation (Rs), followed by vapour pressure deficit (VPD), wind speed (U2), and minimum temperature (Tmin). Therefore, it is recommended to ensure accurate measurements of temperature and solar radiation for accurate ETo estimates. This study provides alternative ETo models with reasonable and accurate ETo estimates for southern Manitoba and other areas with similar climate characteristics.

Predicting Global Solar Radiation on A Horizontal Surface A Case Study For Zambia

Insolation models have been recognized for many years in solar energy systems as important tools to determine radiations for locations lacking insolation data base. Unfortunately, for most geographical areas in Zambia, the insolation data is not available. Correlations between the daily measurements of global solar radiation and the meteorological parameters were presented in tabular form for the selected locations. A common relationship to estimate global solar radiation for the all Zambia is also established. The values of correlation coefficients established varied from 53% to 97% and the errors of estimation were between 0.24 and 0.0.84.

Autonomous complex for electro-thermal heating of oil wells fed by a photovoltaic installation

Paraffin deposits are a serious problem causing complications in oil production. This article describes the creation of a complex operatingonphotovoltaic installations to combat paraffin deposits. The authors offer an innovative method for accurate calculation of the parameters of photovoltaic installations, taking into account changes in total solar radiation, geographical and climatic conditions, the angle of inclination of solar panels, characteristics of the power source, and oil parameters. Measurements of solar radiation are carried out on the basis of mathematical and simulation modeling in Matlab Simulink. The results of the studies confirm the adequacy of the proposed method of oil well heating. This method of electric heating has a simple design and does not require underground works and well shutdown. Thus, it will improve the efficiency of oil production, prevent the formation of paraffin deposits, and ensure energy savings by reducing power losses and electricity consumption.

Design of Cascaded PI-Fractional Order PID Controller for Improving the Frequency Response of Hybrid Microgrid System Using Gorilla Troops Optimizer

This paper proposes a cascaded Proportional Integral-Fractional Order Proportional-Integral-Derivative (PI-FOPID) controller to improve the frequency response of a hybrid microgrid system. The optimum gains of the proposed controller are fine-tuned using Gorilla Troops Optimizer (GTO) which is a recent metaheuristic optimization algorithm. The case study is a two-area microgrid system that contains diesel generators, various renewable energy sources such as photovoltaic and wind generation systems, as well as different energy storage devices. Moreover, real wind speed and solar irradiance measurements have been collected for proper system modeling. The performance of the proposed cascaded PI-FOPID controller is compared to the single structure fractional order PID (FOPID) controller based on GTO and numerous other optimization techniques presented in the previous literature such as Genetic Algorithm and Particle Swarm Optimization. The robustness of the proposed cascaded PI-FOPID controller is investigated under different scenarios such as different step load perturbations, random load disturbances, and renewable energy sources variation. The simulation results are carried out using MATLAB/Simulink. The results show that the proposed controller provides an improvement in the maximum overshoot/undershoot and settling time of 99.8% and 75.9%, respectively, compared to other competing techniques.

Estimating Building Airtightness from Data – A Case Study

The focus on energy conservation in buildings is increasing. Despite that, the yearly building renovation rate is only at around 1 %. To increase the renovation rate, new and time-efficient methods used for screening of large building portfolios’ energy saving potential are needed. In this paper, a re-engineered take on the classical energy signature method is applied to two renovated apartments in Denmark. The energy signature model relies on time-series measurements of space heat consumption, outdoor temperature, solar irradiation, and wind speed. The estimates obtained from it consist of—among other things—heat loss coefficient and wind-induced heat loss. This paper focuses on the latter. To validate the model estimate, the airtightness has been quantified by blower door-tests in both apartments: the results showed that one apartment is reasonable airtight, while the other suffers from significant air leakages. The energy signature and two other infiltration models, based on blower door test results, were compared. Good agreement between the results obtained from the data-driven energy signature and the blower door test were found. With use of a simple linear relation between the average infiltration and the blower door test result (q50), from the Danish national building code, the energy signature was found to overestimate the blower door test result (q50) by 33 % for the leaky apartment and underestimate the same air flow by 18 % for the other apartment. Both estimates are within the standard error of the infiltration model in the Danish national building code.

Evaluation of heat transfer during the process of heating water in containers using a solar cooker box-type

This work presents the experimental results and the evaluation of the heat transfer mechanisms by conduction, convection, and radiation that occur during the water heating process inside four containers with volumes of 250, 500, 750, and 1000 ml. using as for this process a box-type solar cooker. For the experimental measurements, a type k thermocouple arrangement was used, located in the water, the exterior surfaces of the containers, and the glass that forms part of the solar cooker cover. For the acquisition of the data perceived by the thermocouples, a Compact Field Point from National Instruments was implemented and for the measurement of global solar radiation, an Eppley 8-48 radiometer was used. The results obtained from the evaluation show that the most important heat transfer mechanism is by conduction located in the exterior glass of the solar cooker cover and the convection heat transfer in this same glass is the one with the lowest values. The evaluation of the results achieved contributes to the knowledge of the operation of solar cookers, which can contribute to the design and improvements of these solar energy devices.

Assessment of UVB solar radiation in four different selected climate locations in Saudi Arabia

ABSTRACT In this paper, we used the data measurements of average hourly and monthly of UV solar radiation from 2003 to 2017 at four different selected locations in Saudi Arabia for optimisation and evaluation of UVB, UVBest., UVI and KtUVB solar radiation and total ozone column TOC (DU). The scattering phenomena on by stratospheric ozone is high extremely attenuation of UVB solar radiation. The predicted values of UVB solar radiation are a good agreement with the measurement of the UVB solar radiation. The accuracy between measured and predicted values of UVB solar radiation in selected locations in the present research varies from 1.27 to 3.87%. The maximum values of the total ozone column TOC are occur between March and April months at all selected locations with exception Taif site which occur between April and may months, and in whole the highest values of TOC occur about Spring time in all study locations.The relation between UVI and (SZA) at all selected locations in the present research is discussed. The monthly average has a correlation coefficient equal to 72%, 82%, 85% and 83% at Al-Baha, Abha, Jeddah and Taif sites, respectively, so the SZA is responsible for variations of UVI by 72%, 82%, 85% and 83% at Al-Baha, Abha, Jeddah and Taif locations for the monthly values respectively.

Evaluation of the best solution for the functionalization of photocatalytic, superhydrophobic, and self-cleaning properties on asphalt mixtures

This research aims to develop asphalt mixtures with new capabilities, namely photocatalytic, superhydrophobic, and self-cleaning capabilities. Different solutions were prepared combining nano-TiO2 and micro-PTFE on water, ethyl alcohol, and dimethyl ketone with different concentrations. The solutions were sprayed over the asphalt mixtures, and the photocatalytic and superhydrophobic capabilities were evaluated via decolourization of Rhodamine B dye aqueous solution under simulated solar irradiation and Water Contact Angle (WCA) measurements, respectively. Among the combinations analysed, the best solution was TiO2-PTFE with ethyl alcohol (8 g/L), which provided a decolourization of about 60% after having spent 8 h in light exposure conditions and a superhydrophobic surface with WCA equal to 153º. Thus, this research work aims to contribute to advances in the field of clean technologies, assisting in the transition to the “Green Recovery”, which is environmentally friendly, inclusive, and sustainable.

Solar Extreme Ultraviolet Irradiance Uncertainties for Planetary Studies

AbstractAccurate estimates of extreme ultraviolet (EUV) irradiance are needed in order to understand the dynamical, chemical, and plasma processes occurring in planetary upper and tenuous atmospheres. Most studies rely on irradiance measurements made at Earth, which are extrapolated to the location of interest. The Mars Atmosphere and Volatile Evolution (MAVEN) orbiter includes the Extreme Ultraviolet Monitor (EUVM) instrument to measure the solar EUV irradiance in situ at Mars, which is used in this study to quantify the error introduced when phase‐shifting EUV measurements from Earth to other locations in the solar system. The MAVEN/EUVM solar soft X‐Ray (SXR) and Lyman‐α measurements are compared with analogous measurements made from Earth to characterize the typical error introduced when phase‐shifting solar EUV irradiance measurements made from Earth to other points in the solar system according to the 27.27 day synodic solar rotation period. The phase‐shifting error, εps, measured at SXR and Lyman‐α wavelengths are extrapolated to the full EUV spectrum by assuming it is proportional to the variability that occurs over the 27‐day timescale of solar rotation. Values for εps as a function of wavelength are reported and used to find the typical error for estimates of photoionization frequencies of some major species found in planetary upper atmospheres. Measuring EUV irradiance in situ reduces the random uncertainty by approximately half of that expected from phase shifting irradiances to the point of interest from Earth. These findings indicate that estimates of EUV induced variability in planetary atmospheres are highly uncertain at timescales of ∼10 days for large phase angles.

Development of a low-cost remote sensor for ground-based solar radiation and related data measurement

Development of a low-cost remote sensor for ground-based solar radiation and related data measurement

Estimation of Global Solar Radiation in Mubi, Nigeria

Application of solar energy system requires having knowledge about solar irradiation potential in different locations. This study therefore used artificial neural networks for predicting solar global radiation by using metrological data. There is no report about prediction of solar radiation potential for Mubi by using Artificial Neural Network (ANN) method. It is very encouraging to observe a very fine agreement between the measured and estimated values shown in study. The ANN Model is considered the best relation for estimating the global solar radiation intensity for Mubi region with an acceptable error. The MSE, RMSE, MBE, MABE and MAPE values are 0.930, 0.964, 0.3358 MJm−2day−1, 0.8175 MJm−2day−1 and 19.30%, respectively. The ANN models appear auspicious for estimating the Global Solar Radiation in the locations where there are no solar radiation measurement stations.