Instantaneous Solar Radiation Research Articles

Electrochemical treatment of plastic industry wastewaters powered by photovoltaic solar energy

Electrochemical processes combined with renewable energy sources are considered sustainable and efficient for wastewater treatment. The combined photovoltaic – electrochemical (PV-EC) method can produce electrolytic hydrogen and purify industrial wastewaters by combining solar energy with electrocoagulation and electrooxidation processes. The PV-EC system's adaptability resides in its capacity to modify wastewater flow rate in response to the PV array's current intensity and instantaneous solar radiation. Operating parameters that affect process efficiency include wastewater flowrate, applied current intensity, electroprocessing time and solar irradiance were examined and optimal conditions were identified. The experimental results revealed that the initial chemical oxygen demand (COD) of 19 460 mg L-1 of the plastic industry wastewater, were decreased to 8000 mg L-1, after 2 h electroprocessing time using iron or aluminium electrodes at 600 mA current intensity. Further increase of COD removal efficiency was not possible either with increasing processing time, current intensity or using electrooxidation process. The results of our study indicate that the electrochemical treatment can reduce COD from wastewater generated during the production of plastic products. Moreover, the proposed method is applicable in decentralized areas without access to the electricity grid.

Comparison Of The Electricity Generation Potentials Of Solar ORC Designed With Different Fluids Depending On Instantaneous Solar Radiation In Four Districts Of Türkiye

In this study, the solar Organic Rankine Cycle (ORC) system was analyzed to meet some of the electrical energy needed in large and medium-sized buildings and large enterprises such as hotels from solar energy. A simulation study was conducted for different districts in Türkiye that are rich in solar energy potential. These counties and the provinces they are affiliated with; Silifke-İçel, Alanya-Antalya, Bodrum-Muğla, Çeşme-İzmir. The power value transferred to the ORC was determined by considering the instantaneous radiation values and sunshine durations for the districts. The performance of solar ORC was determined by comparing fluids from three different organic fluid types. Organic fluids and types used in design; benzene-aromatic hydrocarbon, cyclohexane-alkane, octamethylcyclotetrasiloxane (D4)-siloxane. Considering the maximum electrical energy values obtained from Solar ORC in the summer months, it was seen that 205 MWh electricity generated was obtained for Silifke with benzene at a heat source temperature of 223 oC in July. Maximum solar parabolic trough collector (PTC) specific electric power value was determined as 59.52 W/m2 in Alanya district with benzene in June. When the four districts are evaluated together, it has been determined that benzene performs better than cyclohexane by 3.8% on average and 23% better than D4. When the annual electrical energy values are examined, the highest production was determined as 1625 MWh with benzene fluid in Alanya district.

Comparative energy and exergy analysis of a CPV/T system based on linear Fresnel reflectors

Abstract An energy generation system that is highly appealing is the integration of a photovoltaic system with linear Fresnel reflectors, especially when combined with a cooling thermal system. This research study involves a comparative analysis of energy and exergy of a CPV/T system that uses traditional linear Fresnel reflectors. The calculations indicate that, given the prevailing weather conditions and an average instantaneous solar radiation of 559 W/m2 at the location, the system can generate an average of 271.23 kWh of electricity and 613.63 kWh of thermal energy per month by utilizing highly efficient, long-lasting, and cost-effective monocrystalline solar cells in the considered the CPV/T system. The overall efficiency of the system is determined to be 54.1 %. According to exergy analysis, the setup experiences some loss of exergy in both its thermal and electrical components. The overall exergy efficiency is calculated as 54.96 %. Thus, on average, the system experiences an exergy loss of 1.01 kWh per day due to thermal factors and 1.70 kWh due to electrical factors. Although the system appears to be more efficient in exergy than energy, the exergy values highlight the need to reduce energy and exergy losses in order to improve the overall system performance.

Daily INSOLation (DINSOL-v1.0): an intuitive tool for classrooms and specifying solar radiation boundary conditions

Abstract. Climate modelling requires spending an extensive amount of time programming, which means reading, learning, testing, and evaluating source code. Fortunately, many climate models have been developed within the past decades, making it easier for climate studies to be conducted on a global scale. However, some climate models have millions of code lines, making the introduction of new parameterizations a laborious task that demands teamwork. While it is true that the high-complexity models perform realistic climate simulations, some researchers perform their studies using simplified climate models in the preliminary test phases. This realization motivated the development of Daily INSOLation (DINSOL-v1.0), a robust computer program to support the simplified climate models, performing solar radiation calculations while considering Milankovitch cycles and offering various simulation options for its users. DINSOL was intended to function as a program that supplies data (e.g. daily insolation, instantaneous solar radiation, orbital parameters of the Earth, and calendar dates), such as the Paleoclimate Modelling Intercomparison Project (PMIP). While preparing the boundary conditions of solar radiation for climate models, it was realized that the DINSOL model could also be a helpful tool for use in classrooms. Thus, it was decided that an intuitive graphical user interface would be required to cater to this educational purpose. The model was written in the Fortran 90 language, while its graphical user interface would be built using PyGTK, a Python application programming interface (API) based on GIMP ToolKit (GTK). Furthermore, the R language would also be used to generate a panel containing contour fields and sketches of the orbital parameters to support the graphical execution. The model evaluation made use of data from PMIP and other tools, and the data analysis was performed through statistical methods. Once all tests were concluded, an insignificant difference between the DINSOL-obtained results and the results obtained from other models validated the viability of DINSOL as a dependable tool.

The Use of Evolutionary Algorithms in the Modelling of Diffuse Radiation in Terms of Simulating the Energy Efficiency of Photovoltaic Systems

In light of the rapidly growing number of photovoltaic micro-grids, the modelling of their short-term power yields based on meteorological measurements is increasing in significance. This requires the knowledge of total and diffuse instantaneous solar radiation; however, most meteorological stations conduct actinometric measurements only with regard to total solar radiation, especially on a minute scale. This paper contains an analysis of the currently used PV cell mathematical model and suggests its modification aimed at calculating PV cell power with satisfactory accuracy, without the knowledge of diffuse solar radiation. Three function families were proposed to approximate the relationship between diffuse irradiance and the total and theoretical total irradiance variance for a cloudless sky. A program has been implemented to identify functions from the aforementioned function families. It leverages an evolution strategy algorithm and a fitness function based on the least-squares point method. It was employed to calculate the desired functions based on actual measurement data. The outcome was the sought-after dependence that enables predicting diffuse irradiance based on more frequently available measurement data.

Simulation of the Impact of Instantaneous Solar UV Radiation Enhancements on the Middle Atmosphere via UV Radiation Reconstruction

This study reconstructed the 0.01–399.5 nm ultraviolet (UV) radiation band with a time resolution of 5 min under solar minimum conditions (18 October 2006) to investigate the effects of the solar flare event on the middle atmosphere. Five-minute resolution 0.01–399.5 nm UV radiation was used instead of daytime scale data to observe the response of the middle atmosphere to the instantaneous solar UV radiation enhancement. The results indicate that small temperature increases of 0.05 K in low latitudes were observed in the lower thermosphere and the stratosphere. The UV radiation enhancement led to an ozone increase of 0.6% in the stratosphere, which caused small temperature increases; and there is an ozone increase of up to 4% at 80 km, while a change of −2% occurred at 60–70 km and a change of −6% occurred in the low thermosphere. There was a 0.05% increase in atmospheric density above 60 km, and there was an increase of up to 0.15% at 80–90 km. The responses of the atmospheric temperature and density in the middle atmosphere to instantaneous UV radiation enhancements can therefore be captured via the UV radiation reconstruction. The simulation results were weaker than the previous study.

MATLAB/Simulink Based Instantaneous Solar Radiation Modeling, Validation and Performance Analysis of Fixed and Tracking Surfaces for the Climatic Conditions of Lahore City, Pakistan

Mathematical modeling, simulation and experimental validation of instantaneous solar radiation is conducted in this article. The input parameters of the developed model are solar constant, latitude & longitude of the selected site, collector surface azimuth and elevation angle. The whole model is developed in MATLAB/Simulink and plots global radiation for any selected day of the year. To validate the model, actual data from RETScreen (energy management software) is taken and compared with the predicted data from developed model. During the whole year the predicted specific insolation is 226.65 MJ/m2/day and actual is 202.14 MJ/m2/day. The percentage error of the predicted data is 10.8% higher than the actual data. The validated model is used to calculate the monthly received solar radiation energy for the fixed surface and tracking surface. The yearly harvested solar energy by horizontal, yearly and monthly optimal tilt surfaces are 6828 MJ/m2, 7405 MJ/m2 and 7761 MJ/m2 respectively. Yearly insolation gain of the yearly optimal tilt and monthly optimal tilt collector surface is 8% and 14% as compared to the energy harvested by horizontal surface. For the single and dual axis tracking surfaces, yearly harvested energy is 8843 MJ/m2 and 9374 MJ/m2 respectively and this figure is 30% and 37% more as compared to the horizontal surface. If the insolation received by yearly optimal tilt is considered as reference value, then energy gain for monthly tilt, single and dual axis tracking is recorded as 5%, 19% and 27% respectively

The effect of annular phase-change material layer on the thermal behavior of solar collector tube

The temperature of the Heat Transfer Fluid (HTF) in the solar collector tube is greatly affected by the instantaneous solar radiation and which usually causes the HTF temperature large fluctuations. To improve this performance, a novel solar collector tube integrated by annular phase-change material (PCM) layer and solar collector tube was proposed in this study, and the thermal behavior of the tube with 630 mm in length and 20/70 mm in diameter inside and outside has been studied. Solar Salt (60 wt% NaNO3 and 40 wt% KNO3) was applied as the PCM. Air was selected as HTF. The thermal characteristics of the novel and traditional solar collector tubes were experimentally and numerically investigated under different solar radiations and air flow rates. The results show that the temperature in the solar collector tube with PCM were 65.45–128.75 °C higher than that without PCM after cooling for 4 h in different solar radiations. The temperature in the solar collector tube decreased as the air flow rate increased. The average temperature falling rate with PCM were 35.6–76.4 °C/m·s−1 slower than that without PCM during the heat storage process, the solar collector tube with PCM shows more advantages at high flow rates. Within the measuring time of 300 min, the total thermal efficiency of the collector tube with PCM layer is higher than that of without PCM layer. The solar collector tube with PCM is better suited to create a stable mid-temperature and high-temperature environment in continuous solar radiation and heat extraction.

ESTIMATION OF DAILY GLOBAL SOLAR IRRADIANCE FROM HIMAWARI-8 PRODUCTS OVER CHINA

Abstract. Daily global surface solar irradiance (SSI) is of great importance parameter in the surface energy balance, climate modelling, and solar energy utilization. However, it is still challenging to extend the estimated instantaneous solar radiation to the daily global SSI from either geostationary satellites or polar-orbiting satellites. In this study, a method for estimating the daily global SSI is proposed based on the Himawari-8 hourly SSI products using pixel-by-pixel Gaussian fitting to simulate the diurnal SSI variation. Compared with ground-based observations, the daily global SSI estimated by Gaussian fitting have higher accuracy under various weather conditions than by the simple accumulation or quadratic polynomials, and the coefficient of determination (R2) between the estimated and observed values exceeds 0.86. The verification results also show different estimation accuracies under different weather conditions. The root-mean-square errors (RMSEs) under clear-sky and all-sky conditions are 2.36 MJ/m2 and 3.06 MJ/m2, respectively. In addition, experimental results show that the daily global SSI in China has high spatial heterogeneity. For higherelevation areas with low cloud cover, such as the Qinghai-Tibet Plateau, Inner Mongolia, and Northwest China, the daily global SSI is higher than other areas. In contrast, the values of daily global SSI is relatively low in the eastern regions of Southwest and Northeast China.

Reconstruction of All-Weather Daytime and Nighttime MODIS Aqua-Terra Land Surface Temperature Products Using an XGBoost Approach

Generating spatiotemporally continuous land surface temperature (LST) data is in great demand for hydrology, meteorology, ecology, environmental studies, etc. However, the thermal infrared (TIR)-based LST measurements are prone to cloud contamination with missing pixels. To repair the missing pixels, a new XGBoost-based linking approach for reconstructing daytime and nighttime Moderate Resolution Imaging Spectroradiometer (MODIS) LST measurements was introduced. The instantaneous solar radiation and two soil-related predictors from China Data Assimilation System (CLDAS) 0.0625°/1-h data were selected as the linking variables to depict the relationship with instantaneous MODIS LST data. Other land surface properties, including two vegetation indices, the water index, the surface albedo, and topographic parameters, were also used as the predictor variables. The XGBoost method was used to fit an LST linking model by the training datasets from clear-sky pixels and was then applied to the MODIS Aqua-Terra LSTs during summer time (June to August) in 2017 and 2018 across China. The recovered LST data was further rectified with the Savitzky–Golay (SG) filtering method. The results showed the distribution of the reconstructed LSTs present a reasonable pattern for different land-cover types and topography. The evaluation results using in situ longwave radiation measurements showed the RMSE varies from 3.91 K to 5.53 K for the cloud-free pixels and from 4.42 K to 4.97 K for the cloud-covered pixels. In addition, the reconstructed LST products correlated well with CLDAS LST data with similar LST spatial patterns. The variable importance analysis revealed that the two soil-related predictors and the elevation variable are key parameters due to their great contribution to the XGBoost model performance.

Electrical and Thermal Performance Analysis of a Linear Fresnel Reflector- Photovoltaic/Thermal System

A photovoltaic system integrated with linear Fresnel reflectors constitutes a very attractive energy generation system when combined with a cooling thermal system. In this study, a photovoltaic system using high efficiency and extremely durable monocrystalline solar cells is theoretically discussed. Although cheap but relatively less effective solar cells have been proposed, it has been shown that a very good cost-effective photovoltaic system can be produced by concentrating sunlight with a linear Fresnel reflector system and obtaining additional heat energy by cooling the photovoltaic panel. The electrical and thermal performance of the proposed system is theoretically analyzed under relatively low solar radiation conditions. Under the given climatic conditions and the average instantaneous solar radiation of 559 W/m2 at the location, it is concluded that when a cooling mechanism is implemented, an average of 228.8 kWh of electricity and 1229.8 kWh of thermal energy can be obtained per month from the system.

Applicability and comparison of solar-air source heat pump systems between cold and warm regions of plateau by transient simulation and experiment

Solar-air source heat pump (solar-ASHP) system has a potential application in the field of hot water and space heating in residential buildings. Such system features the complementary advantages to solve the discontinuous operation of the single solar system and the frosting issue of the single ASHP system. This paper built the solar-ASHP systems in Kunming and Shangri-La, and tested the system performance under different weather conditions in these two regions of plateau. Meanwhile, the transient heat balance models of the system were established under the sunlight time and non-sunlight time and were verified by the experimental results. Moreover, the verified model was applied to reveal the energy balance performance between the energy supply and building heat demand. The law of the system performance affected by the ambient temperature, effective heat collecting area, and cumulative heating capacity of collector was explored by the validated model. The results indicate that when the ambient temperature decreases by 1 °C during non-sunlight time, the energy efficiency ratio decreases by about 0.07. A square meter decline in the effective heat collecting area pushes an increase in the heating capacity of 5.75 MJ. Meanwhile, the cumulative heating capacity of collector increases by 5 MJ, and the ASHP energy consumption decreases by 0.54 kWh. The dynamic changes of the ambient temperature and instantaneous solar radiation are the main reasons of the heat balance errors. Therefore, both the developed system and model are feasible and reliable in different climate regions.

CALCULATION OF THE INSTANT MODEL OF SOLAR RADIATION DISTRIBUTION ON CURVED SURFACES IN HIGH-RISE BUILDINGS

The aim of research is to simulate the zones of solar radiation on the curved surfaces of the shells of high-rise buildings for the effective use of renewable solar energy. An urgent task is the development of tools that can substantiate the decision-making by designers about the location of solar thermal devices in the energy-efficient design of curvilinear high-rise buildings. The main attention is paid to high-rise buildings, is actively growing in modern megalopolises and requires a significant energy resource. To optimize the integration of solar thermal devices in high-rise buildings, it is important to take into account a set of design parameters, including parameters of surface shape and location in space. A feature of curved surfaces, considered in the study, is their aerodynamic properties, which provide them with the advantage of choosing among modern high-rise buildings. At the same time, the complexity of setting the parameters of a curved surface to determine the zones of solar radiation for the effective use of regenerative solar energy lies in providing reliable and convenient tools for optimizing decision-making.
 The study proposes an application of the method based on a discrete geometric model of solar radiation input on the surface of the shells of high-rise buildings, described by compartments of curved geometric surfaces. As a result of modeling, let’s obtain a family of lines of the same level of solar radiation on a certain curved surface for the given parameters of time and geographic location. As an example of simulation modeling, the performed calculations of the instantaneous model of the distribution of solar radiation on the compartments of the curved surfaces of an ellipsoid of revolution, hemisphere, hyperbolic paraboloid. On the basis of the proposed model for the distribution of solar radiation over curvilinear surfaces of buildings, the influence of factors arising in the design process is investigated: changes in the geometric parameters of the surface shape, orientation to the cardinal points, the formation of zones of its own shadow on surfaces. Calculations were performed and instantaneous solar radiation zones were constructed on the surfaces of a hemisphere, a hyperbolic paraboloid with various geometric parameters, taking into account different orientations relative to the cardinal points, and determining the zones of its own shadow.
 At this stage of the study, the result is an algorithm for constructing zones of different levels of solar radiation on curved surfaces of high-rise buildings. The advantage of the algorithm is the ability to analyze the results of changes in the design parameters of the surface of a high-rise building when placing solar systems on them. The proposed approach will provide a basis for automating the modeling process, will help expand the scope of solar systems in high-rise construction and increase the efficiency of their work

The Effect of Melt Pond Geometry on the Distribution of Solar Energy Under First‐Year Sea Ice

AbstractSea ice plays a critical role in the climate system through its albedo, which constrains light transmission into the upper ocean. In spring and summer, light transmission through sea ice is influenced by its iconic blue melt ponds, which significantly reduce surface albedo. We show that the geometry of surface melt ponds plays an important role in the partitioning of instantaneous solar radiation under sea ice by modeling the three‐dimensional light field under ponded sea ice. We find that aggregate properties of the instantaneous sub‐ice light field, such as the enhancement of available solar energy under bare ice regions, can be described using a new parameter closely related to pond fractal geometry. We then explore the influence of pond geometry on the ecological and thermodynamic sea ice processes that depend on solar radiation.

Risk-Constrained Stochastic Optimization of a Concentrating Solar Power Plant

A central concentrating solar power (CSP) plant is increasing in the power systems as novel technology in the solar energy sources. Also, solar thermal storage unit is combined with the CSP plant to increase flexibility and decrease the dependence on the instantaneous solar radiation. Furthermore, the CSP plant can be obtained the optimal offering strategies to submit to the electricity market in order to sell the produced power and increase the expected profit. In this paper, the uncertainty modeling of solar irradiation and electricity market price is a big challenge for a CSP plant. Therefore, the scenario-based stochastic framework is proposed for optimal scheduling of a CSP plant in the presence of uncertainties to obtain optimal offering curves in order to sell to power market. Also, the risk related to uncertainties is considered via the downside risk constraints (DRC), which leads to obtain risk-constrained stochastic optimization of a CSP plant. The proposed model is formulated as mixed-integer linear programming, which is solved via CPLEX solver under GAMS optimization software. Risk-averse strategy is introduced in comparison with risk-neutral strategy to investigate the impacts of DRC implementation, which leads to decrease the expected profit while the expected risk-in-profit reduced.

Assimilating remote sensing data into GIS-based all sky solar radiation modeling for mountain terrain

Solar radiation is the ultimate energy resource of earth surface energy balance and the main driving force of atmospheric, ecological and hydrological processes. Solar radiation over complex terrain has large spatial and temporal variation because of terrain shading and high cloud heterogeneity. While most existing GIS-based solar radiation models only work under clear sky condition, this research presents a solar radiation model which considers both terrain shading and anisotropic cloud attenuation and diffuse radiation using MODIS atmospheric products. Specifically, we use skyshed map, sky cloud maps, and sky weight map to represent angular distribution of sky obstruction, anisotropic cloud properties, and diffuse radiance over hemispherical sky, respectively. Combining skyshed map, sky weight map and sky cloud maps, we develop a solar radiation model where 3D geometrical relationships among sun, cloud, and terrain are considered and anisotropic diffuse radiance and cloud attenuation are modeled. Model results are evaluated using field observations in the Kunlun Mountains of western China. At Terra and Aqua overpass time, our model performs well with a mean relative bias (MRB) of −0.2%. It underestimates in clear and partly cloudy sky with a MRB of −5.86% and −4.79% and has a mean absolute relative bias (MARB) of 8.11% and 21.59% respectively. It overestimates under overcast sky with a MRB of 1.68% and has a MARB of 31.71%. Our model performs better when compared with existing instantaneous solar radiation products. For daily solar radiation, our model shows good performance with a MRB of 1.43% and MARB of 17.02%. Our model shows significant spatial variation of solar radiation within the study area with the influences from terrain and cloud. Our research provides a novel and improved approach to assimilating remote sensing data into GIS-based solar radiation modeling in mountainous terrain where observations are sparse and difficult to obtain.

Comparison between Regenerator Model and the Instantaneous Direct Solar Radiation for Port Harcourt

This paper compares the result generated by the Regenerator technique and the Ideriah’s method for instantaneous solar radiation. It considered the generation of the actual power input from the regenerator. The actual power input to the photovoltaic panel was calculated from a power model derived from the regenerator’s standard power that is nominally provided, regenerator material and reflectivity of the material. The amount of visible radiation absorbable by photovoltaic plates was further derived in the model and a value of 0.386Pi was obtained. The Ideriah’s model was used to calculate global solar radiation from extraterrestrial solar radiation. It utilized the concept of transmittance to arrive at the amount of insolation received locally (i.e. at the point of interest). It also calculated the amount of insolation at optical thicknesses (Air mass values) representing top of the hour from 5.0am to 7.0pm. Comparison & result showed that the regenerator model gave 84% to 97% correctness or an approximated average correctness of 94% when compared to the Ideriah’s model. Chi-square was used to test the relationship between the results. Chi-square results showed a high level of significance in the similarity of the results obtained. Python software was used to simulate the results and graph presentation.

Comparison between Regenerator Model and the Instantaneous Direct Solar Radiation for Port Harcourt

This paper compares the result generated by the Regenerator technique and the Ideriah’s method for instantaneous solar radiation. It considered the generation of the actual power input from the regenerator. The actual power input to the photovoltaic panel was calculated from a power model derived from the regenerator’s standard power that is nominally provided, regenerator material and reflectivity of the material. The amount of visible radiation absorbable by photovoltaic plates was further derived in the model and a value of 0.386Pi was obtained. The Ideriah’s model was used to calculate global solar radiation from extraterrestrial solar radiation. It utilized the concept of transmittance to arrive at the amount of insolation received locally (i.e. at the point of interest). It also calculated the amount of insolation at optical thicknesses (Air mass values) representing top of the hour from 5.0am to 7.0pm. Comparison & result showed that the regenerator model gave 84% to 97% correctness or an approximated average correctness of 94% when compared to the Ideriah’s model. Chi-square was used to test the relationship between the results. Chi-square results showed a high level of significance in the similarity of the results obtained. Python software was used to simulate the results and graph presentation.

Risk assessment in a central concentrating solar power plant

In this paper, optimal scheduling of a central concentrating solar power (CSP) plant which is one of the most promising technologies in the solar energy is investigated in the presence of different uncertainties. Thermal energy storage is integrated with the CSP plant in order to allow the plant to be independent from the instantaneous solar radiation. In order to model different uncertainty such as power market price and solar irradiation, a new hybrid information gap decision theory (IGDT)-stochastic method is introduced which is a mixed-integer linear programming method and presents more reliable results in a suitable computation time. In the proposed method the uncertainty of the solar irradiation is modeled by IGDT method while power market price uncertainty is considered by a set of fifty scenarios. Three different strategies as risk-averse, risk-neutral and risk-taker are introduced to analyze the operation of the CSP plant. In the risk-neutral strategy, obtained profit is equal to $3895 which is reduced in the risk-averse strategy by increasing robustness value indicating increased uncertainty of the solar irradiation. In the risk-taker strategy, the CSP operating profit will be equal to $4245 by 15% of increase in solar radiation, comparing with the risk-neutral case shows almost 8.2% increase in profit.

Effects of solar radiation and correction of surface temperature by net radiation estimates in northern Pantanal

Net radiation (Rn) is a critical variable in estimating energy balance and evapotranspiration by remote sensing techniques on a regional scale. The objective of this paper is to evaluate the effect of estimated and measured instantaneous solar radiation (Rg) and the atmospheric correction of surface temperature by Landsat 8 images on the estimated surface Rn in northern Pantanal. Rn and meteorological factors were measured on a floodplain and on two nonflooded areas in northern Pantanal. Rg was estimated by models proposed by Zillman et al. (RgZillman) and Allen et al. (RgAllen). Surface temperature was corrected by atmospheric and emissivity effects. Annual and seasonal averages of solar radiation were not different among the experimental sites. The floodplain area featured higher net radiation than both nonflooded areas. Instantaneous Rninst estimated by measured Rg and with RgAllen were not different from measured Rninst. Rninst estimated by surface temperature was, on average, 5.7% higher, with a 22% error lower than Rninst estimated with brightness temperature. The current study highlights the possibility of estimating Rninst by RgAllen and the need for correcting the effect of the atmosphere and surface emissivity to estimate surface temperature and Rninst.