scholarly journals Estimation of the ratio of diffuse solar radiation to global radiation in the northern basin of Lake Biwa.

1985 ◽  
Vol 46 (2) ◽  
pp. 143-144 ◽  
Author(s):  
Ichiro AOKI
Keyword(s):  
Solar Radiation ◽  
Lake Biwa ◽  
Global Radiation ◽  
Diffuse Solar Radiation ◽  
Northern Basin

Improved Accuracy Models For Hourly Diffuse Solar Radiation

2005 ◽  
Vol 128 (1) ◽  
pp. 104-117 ◽  
Author(s):  
T. Muneer ◽  
S. Munawwar
Keyword(s):  
Solar Radiation ◽  
Regression Models ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Evaluation Procedure ◽  
Accuracy Score ◽  
Error Statistics ◽  
Diffuse Solar Radiation ◽  
Energy Applications ◽  
Extensive Evaluation

Solar energy applications require readily available, site-oriented, and long-term solar data. However, the frequent unavailability of diffuse irradiation, in contrast to its need, has led to the evolution of various regression models to predict it from the more commonly available data. Estimating the diffuse component from global radiation is one such technique. The present work focuses on improvement in the accuracy of the models for predicting horizontal diffuse irradiation using hourly solar radiation database from nine sites across the globe. The influence of sunshine fraction, cloud cover, and air mass on estimation of diffuse radiation is investigated. Inclusion of these along with hourly clearness index, leads to the development of a series of models for each site. Estimated values of hourly diffuse radiation are compared with measured values in terms of error statistics and indicators like, R2, mean bias deviation, root mean square deviation, skewness, and kurtosis. A new method called “the accuracy score system” is devised to assess the effect on accuracy with subsequent addition of each parameter and increase in complexity of equation. After an extensive evaluation procedure, extricate but adequate models are recommended as optimum for each of the nine sites. These models were found to be site dependent but the model types were fairly consistent for neighboring stations or locations with similar climates. Also, this study reveals a significant improvement from the conventional k-kt regression models to the presently proposed models.

scholarly journals Monthly average daily diffuse solar radiation in Poland within the period 2005–2015

2018 ◽  
Vol 23 ◽  
pp. 00020
Author(s):  
Małgorzata Kleniewska ◽  
Dorota Mitrowska ◽  
Bogdan H. Chojnicki
Keyword(s):  
Solar Radiation ◽  
Linear Relationship ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Diffuse Fraction ◽  
Diffuse Solar Radiation ◽  
Monthly Average

In this paper an 11-year series of daily values of diffuse solar radiation registered at 8 actinometric stations in Poland was used to describe the characteristics of diffuse radiation and diffuse fraction of global radiation for the area of Poland. Based on the monthly average daily diffuse, global and extraterrestrial solar radiation a linear relationship between these elements was determined. The obtained equation enables the calculation of the monthly average daily diffuse solar radiation for Poland and the application of its values to further climatology studies.

scholarly journals Annual and Seasonal Trends of Solar Radiation in Athens, Greece

2018 ◽  
Vol 5 ◽  
Author(s):  
Harry D. Kambezidis
Keyword(s):  
Solar Radiation ◽  
Global Radiation ◽  
Winter Season ◽  
Negative Trend ◽  
Positive Trend ◽  
National Observatory ◽  
Seasonal Trends ◽  
Diffuse Solar Radiation ◽  
Sky Conditions ◽  
Radiation Time

This study deals with the solar radiation levels recorded at the Actinometric Station of the National Observatory of Athens, focusing on the trends of the global and diffuse horizontal irradiances in the period of 1992-2017 (26 years). The analysis shows that the annual global radiation time series over Athens in the above period presents a positive trend (+0.40%/decade and +2.38%/decade for all and clear skies, respectively), while its diffuse counterpart shows negative trend (-5.19%/decade and -6.77%/decade for the same sky conditions, respectively) during the same period. Also, the seasonal trends of both solar radiation components are examined. The global horizontal radiation shows positive trends in summer (+1.85%/decade and +2.10%/decade under all and clear skies, respectively), while a negative trend is calculated in the winter season (-2.46%/decade and -1.99%/decade for the same sky conditions, respectively). In the case of the diffuse solar radiation there are found negative trends in both seasons and both sky conditions. These findings confirm a recovery in the solar radiation levels over Athens in the recent 26 years.

Diffuse Sky Measurements and Determination of Corrected Shadow Band Multiplication Factors

1983 ◽  
Vol 105 (3) ◽  
pp. 305-310 ◽  
Author(s):  
W. D. Turner ◽  
A. M. Mujahid
Keyword(s):  
Solar Radiation ◽  
Correction Factor ◽  
Global Radiation ◽  
Diffuse Radiation ◽  
Monitoring Station ◽  
Radiation Measurement ◽  
Correction Factors ◽  
Diffuse Solar Radiation ◽  
Variable Factor

A meteorological monitoring station was operated at Blytheville, Arkansas, from April 1978 to April 1980. Direct normal, global, and diffuse sky radiation were monitored. From these data, models have been developed for the prediction of solar radiation, and discussions of several diffuse solar radiation models are included herein. Comparisons are made with these current diffuse models, and the correlation is quite good. In addition, instantaneous shadow band correction factors are presented which will allow a more accurate correction to be applied to the measured diffuse sky reading. The instantaneous correction factors are keyed to the global radiation measurement. Instead of applying a fixed correction factor to the diffuse measurement, regardless of sky condition, a variable factor can be applied. This will solve some of the current errors observed in diffuse measurements, because the current factors overpredict the diffuse radiation on cloudy days and underpredict the diffuse on clear days.

scholarly journals Diffuse solar radiation and associated meteorological parameters in India

1996 ◽  
Vol 14 (10) ◽  
pp. 1051-1059 ◽  
Author(s):  
A. B. Bhattacharya ◽  
S. K. Kar ◽  
R. Bhattacharya
Keyword(s):  
Solar Radiation ◽  
Meteorological Parameters ◽  
Global Radiation ◽  
Low Frequency ◽  
Diffuse Radiation ◽  
Global Solar Radiation ◽  
Surface Radiation ◽  
Diffuse Solar Radiation ◽  
Sunshine Hours ◽  
The Tropics

Abstract. Solar diffuse radiation data including global radiation, shortwave and longwave balances, net radiation and sunshine hours have been extensively analyzed to study the variation of diffuse radiation with turbidity and cloud discharges appearing in the form of atmospherics over the tropics. Results of surface radiation measurements at Calcutta, Poona, Delhi and Madras are presented together with some meteorological parameters. The monthly values of diffuse radiation and the monthly ratios of diffuse to global solar radiation have been examined, with a special emphasis in relation to the noise level of atmospherics at Calcutta in the very low frequency band. The results exhibit some definite seasonal changes which appear to be in close agreement with one another.

scholarly journals Proposal to Refine Solar Radiation of Typical Meteorological Year Database and Evaluation on the Influence of Air-Conditioning Load

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 524
Author(s):  
Jihui Yuan ◽  
Kazuo Emura ◽  
Craig Farnham
Keyword(s):  
Solar Radiation ◽  
Air Conditioning ◽  
Energy Savings ◽  
Energy Resource ◽  
Global Solar Radiation ◽  
Resource Assessment ◽  
Weather Data ◽  
Diffuse Solar Radiation ◽  
Chinese Standard ◽  
The Impact

The Typical meteorological year (TMY) database is often used to calculate air-conditioning loads, and it directly affects the building energy savings design. Among four kinds of TMY databases in China—including Chinese Typical Year Weather (CTYW), International Weather for Energy Calculations (IWEC), Solar Wind Energy Resource Assessment (SWERA) and Chinese Standard Weather Data (CSWD)—only CSWD is measures solar radiation, and it is most used in China. However, the solar radiation of CSWD is a measured daily value, and its hourly value is separated by models. It is found that the cloud ratio (diffuse solar radiation divided by global solar radiation) of CSWD is not realistic in months of May, June and July while compared to the other sets of TMY databases. In order to obtain a more accurate cloud ratio of CSWD for air-conditioning load calculation, this study aims to propose a method of refining the cloud ratio of CSWD in Shanghai, China, using observed solar radiation and the Perez model which is a separation model of high accuracy. In addition, the impact of cloud ratio on air-conditioning load has also been discussed in this paper. It is shown that the cloud ratio can yield a significant impact on the air conditioning load.

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