Estimation of solar radiation from cloud cover data of Bangladesh

Abstract

In this study, an analysis of the monthly mean values of the fraction of the sky covered by clouds (C) of all types and the duration of bright sunshine hours (S) and global solar radiation on the horizontal surface (H) was carried out to establish relationship for solar radiation estimation for Bangladesh. The relationship between C and (1 − S/S 0 ), where S 0 is the maximum possible hours of sunshine, was found to be nonlinear. The relationship between C and (1 − H/H 0 ), where H 0 is the extraterrestrial solar radiation, was also found to be nonlinear. Few quadratic regression equations were derived for different regions of Bangladesh. The data were separated in Zone 1 (below the tropic of cancer, i.e., ≤23.5°N) and Zone 2 (above the tropic of cancer, i.e., ≥23.5°N). All the developed models were checked statistically. It was found that it is always better to estimate solar radiation from sunshine duration as it gives the best estimation and accuracy, but if there is no sunshine duration data available for a site, then solar radiation can be estimated directly from cloud cover data. Estimating sunshine duration first from cloud data to estimate solar radiation introduces more error as it has to go through the modeling stage twice. In case of the need of sunshine duration data only, the estimation from cloud cover is quite helpful. It was also found from the study that for small country like Bangladesh separating data according to latitude has insignificant effect.

Models and hierarchical methodologies for evaluating solar energy availability under different sky conditions toward enhancing concentrating solar collectors use: Texas as a case study

“…However, the uncertainty influence of scattered clouds and their movement in the sky is still representing a great obstacle in estimating a nature and quantity of received radiations on the earth surface [56]. The estimation of sunshine duration data from cloud cover by developing an empirical correlation is quite useful to calculate global solar radiation on a horizontal surface [57]. In the same context, a simple theoretical model has been presented that represents the interrelation of sunshine duration and cloud cover fraction to predict cloud cover fraction that can be further used to calculate global solar radiation on a horizontal surface (GHI) under different sky conditions [56].…”

“…Over the last decades, there were considerable endeavors for evaluating and interpreting the Angstrom-Prescott equation [60]. New formulations (either linear or non-linear) of the Angstrom-Prescott equation were proposed by many researchers using clearness index against sunshine fraction [8,36,47,57,[61][62][63][64][65][66][67][68][69], ambient temperature [8,47,62,67,69,70], relative humidity [8,47,69], precipitation [47,62,71,72], cloud cover [47,57,61,73], and multi-parameters [47,60,67,69,74].…”

The Effect of Irradiance Related Temperature on Microalgae Growth in a Tubular Photo Bioreactor for Cleaner Energy

“…The term c indicates the clearness index and the average value is taken for Chittagong from the data set in the paper of Sarkar [19]. The transmittance property of the photo bioreactor keeps a vital effect on the growth of microalgae cells as how much radiation is transmitted through the tube and reaches the microalgae cells to heat them up to maintain the broth temperature within the optimum range.…”

“…As CUET is located in Chittagong, Bangladesh thus the values are taken for Chittagong, collected from the data from Sarkar [19]. Global solar radiation (H 0 ) can be expressed as follows [17] ( ) …”

Determination of a Suitable Solar Radiation Model for the Sites of Chad

“…The monthly mean of the daily extraterrestrial solar radiation on a horizontal surface is determined according the following relation [21] …”