Detection of clear sky instants from high frequencies pyranometric measurements of global horizontal irradiance

Alani, Omaima El; Ghennioui, Hicham; Ghennioui, Abdellatif; Dahr, Fatima-ezzahra

doi:10.1051/e3sconf/202122901008

Cited by 4 publications

(6 citation statements)

References 22 publications

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“…El Alani et al [11] validated the McClear model [20] by comparing it to 1-min average GHI clear sky irradiance data in Benguerir (Green Energy Park, Morocco). The validation results are summarised in Table 1.…”

Section: Literature Reviewmentioning

confidence: 99%

“…It is important to know how much solar energy is available at any given location, and clear sky irradiance, specifically GHI, provides that information. This information is essential for predicting or estimating the performance of solar energy technologies [11]. As a result, determining the clear sky GHI at a given location is important for projecting the optimum performance of solar technologies before they are implemented.…”

Section: Introductionmentioning

confidence: 99%

“…The McClear clear sky model was used as a reference because there were no observed GHI data to be used to validate the clear sky models in the study area. Among alternative data sets, the McClear clear sky model was chosen because it performed very well when compared to GHI observation data, for example [11,38,44,45], and it was already preconfigured. ERA5 hourly fractional cloud cover data [43] were used to identify clear-sky days in the study area because a recent study by Mabasa et al [45] in South Africa confirmed that it can identify cloudy and clear-sky days.…”

Section: Introductionmentioning

confidence: 99%

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Calibration and Validation of Global Horizontal Irradiance Clear Sky Models against McClear Clear Sky Model in Morocco

et al. 2022

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This study calibrated and compared the capabilities of hourly global horizontal irradiance (GHI) clear sky models for six Moroccan locations, using the McClear clear sky model as a reference. Complex clear sky models, namely Bird, Simplified Solis, Ineichen and Perez, and simple clear sky models, namely Adnot–Bourges–Campana–Gicquel (ABCG), Berger–Duffie, and Haurwitz were tested. The SOLCAST satellite-based dataset estimates were validated against the McClear clear sky model. pvlib python was used to configure the models, and ERA5 hourly fractional cloud cover was used to identify clear-sky days. The study period was from 2014 to 2021, and the study sites were in different climatic regions in Morocco. Bar graphs, tables, and quantitative statistical metrics, namely relative mean bias error (rMBE), relative root mean square error (rRMSE), relative mean absolute error (rMAE), and the coefficient of determination (R2), were used to quantify the skill of the clear sky model at different sites. The overall rMBE was negative in 5/6 sites, indicating consistent overestimation of GHI, and positive in Tantan (14.4%), indicating frequent underestimation of GHI. The overall rRMSE varied from 6 to 22%, suggesting strong agreement between clear sky models and the McClear clear sky model. The overall correlation was greater than 0.96, indicating a very strong relationship. Overall, the Bird clear sky model proved to be the most feasible. Complex clear sky models outperformed simple clear sky models. The SOLCAST satellite-based dataset and ERA5 cloud fraction information could well be used with quantifiable certainty as an accurate clear sky model in the study region and in other areas where complex clear sky models’ inputs are not available.

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Section: Literature Reviewmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calibration and Validation of Global Horizontal Irradiance Clear Sky Models against McClear Clear Sky Model in Morocco

et al. 2022

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“…In some areas, even when measurements are available, gaps may exist in the measurement records that may need to be filled up to efficiently characterize the resource [4,5]. Clear sky irradiance, in particular, the global horizontal irradiance (GHI), provides information about the maximum possible solar energy resource available at the location under consideration, which is crucial in estimating or forecasting the performance of solar energy technologies [6]. It is therefore important to estimate, locally, the clear sky GHI in order to forecast the optimal performance of the solar technologies before deployment.…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis of Clear Sky Global Horizontal Irradiance Models: Simple Models Adapted for Local Conditions

Kwarikunda

Chiguvare

2021

Journal of Renewable Energy

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Evaluation of the maximum solar energy potential of a given area for possible deployment of solar energy technologies requires assessment of clear sky solar irradiance for the region under consideration. Such localized assessment is critical for optimal sizing of the technology to be deployed in order to realize the anticipated output. As the measurements are not always available where they are needed, models may be used to estimate them. In this study, three different models were adapted for the geographical location of the area under study and used to estimate clear sky global horizontal irradiance (GHI) at three locations in the subtropical desert climate of Namibia. The three models, selected on the basis of input requirements, were used to compute clear sky GHI at Kokerboom, Arandis, and Auas. The models were validated and evaluated for performance using irradiance data measured at each of the sites for a period of three years by computing statistical parameters such as mean bias error (MBE), root mean square error (RMSE), and the coefficient of determination (R2), normalized MBE, and normalized RMSE. Comparative results between modelled and measured data showed that the models fit well the measured data, with normalized root mean square error values in the range 4–8%, while the R2 value was above 98% for the three models. The adapted models can thus be used to compute clear sky GHI at these study areas as well as in other regions with similar climatic conditions.

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“…The drawbacks of purely optical imaging can be addressed through a hybrid system which allows for radiometric sensing as well as optical imaging, used in deep space exploration (17) . Pyranometric measurement techniques have also been explored as a viable solution in (18) . However recent models employing brightness temperature measurements for meteorological estimation have been found to yield accurate results for the 0.5-2 GHz band (19) .…”

Section: Introductionmentioning

confidence: 99%

Determination of sky status by ground based radiometric data analysis

Maiti¹,

Bhattacharyya²,

Biswas³

et al. 2021

IJST

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Objectives: To predict meteorological phenomena such as rain events from sky status during rainy and non-rainy periods. Methods: The method used here is based on brightness temperature ratio measurement at two different frequencies, namely 23.8 GHz and 30 GHz respectively, using ground based dual frequency radiometric data. The ratios of brightness temperature readings obtained by the dual-frequency radiometer at the two above mentioned frequencies are calculated for each simultaneously-taken pair of measurements. Data obtained by the authors for the year 2009 at Cachoeira Paulista in Brazil has been used for analysis. Findings: The major results obtained from the analysis of data collected over a continuous period of seven months are used to construct corresponding histograms and cumulative count graphs of brightness temperature ratios. The histograms and graphs clearly show three peak values that could be interpreted as thresholds between clear sky, cloudy sky and rainy sky conditions respectively. Novelty: The study implements detection of rain events from sky status during rainy and non-rainy periods using peak brightness temperature values obtained from graphs generated using the observation data. The outlined technique can therefore be used to clearly determine sky conditions and accurately predict rain phenomena. The ratio of brightness temperatures at the two frequencies is a unique parameter which is critical to the successful estimation of rain from sky status. The results agree well with multi-channel radiometric data obtained by other researchers at lower frequencies.

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Detection of clear sky instants from high frequencies pyranometric measurements of global horizontal irradiance

Cited by 4 publications

References 22 publications

Calibration and Validation of Global Horizontal Irradiance Clear Sky Models against McClear Clear Sky Model in Morocco

Calibration and Validation of Global Horizontal Irradiance Clear Sky Models against McClear Clear Sky Model in Morocco

Performance Analysis of Clear Sky Global Horizontal Irradiance Models: Simple Models Adapted for Local Conditions

Determination of sky status by ground based radiometric data analysis

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