Quoted from:Panday C K ,  Katiyar A K . Temperature base correlation for the estimation of global solar radiation on horizontal surface[J]. International Journal of Energy & Environment, 2010, 1(4):737-744.

http://ijee.ieefoundation.org/vol1/issue4/IJEE_16_v1n4.pdf

INTRODUCTION

In the present study, a correlation have been developed for the extraction of monthly mean daily global distribution of solar radiation from the ratio of monthly mean daily maximum to minimum ambient air temperature. The reason for this approach comes from the fact that, although the air temperature is a worldwide measured meteorological parameter, it rarely used in solar radiation techniques. Numerical calculations have been made using the new model corresponding to five Indian locations (viz. Jodhpur, Ahmedabad, Calcutta, Bombay and Pune) and the results are compared against the models available in literature and with the measured values. Statistical tests of root mean square error (RMSE), mean bias error (MBE) and t-test are also performed to compute the accuracy of present correlation. Based on overall results it was concluded that air temperature successfully substitutes the sunshine duration data in the estimation of the solar energy.

Angstrom proposed first theoretical model for estimating global solar radiation based on sunshine duration. Page and Prescot reconsidered this model in order to make it possible to calculate monthly average of the daily global radiation on a horizontal surface from monthly average daily total insolation on an extraterrestrial horizontal surface. Recently, Bakirchi developed a correlation based on bright sunshine hours for Turkey. A new type of approach has been proposed by Bristow and Campbell , Allen, Chandel et. al. and Paulescu to find a correlation based on ambient day temperature to estimates global radiation.

Since, air temperature is measured at large number of locations therefore, the prime objective of the present study is to analyze the global solar radiation and temperature data of five Indian cities viz. Jodhpur (Latitude 26.30°N, Longitude 73.03°E), Ahmedabad (Latitude 23.07°N, Longitude 72.06°E), Calcutta (Latitude 22.65°N, Longitude 88.35°E), Bombay (Latitude 19.12°N, Longitude 72.85°E) and Pune (Latitude 18.53°N, Longitude 73.91°E) considering first to third order Angstr m type correlations for India continent to correlate daily global solar radiation with ambient air temperature. Performance of the new constants is checked by comparing present estimated global solar radiation with other available theoretical values along with the measured data for each mentioned station.

Pandey and Katiyar proposed the following First- to third-order equations for the pairs of (H/H0) and (θ/θo) at Jodhpur, Ahmedabad, Calcutta, Bombay, and Pune stations, India:

\( 𝐻/𝐻_0= 0.2889 + 0.1562*( 𝜃/𝜃_0) \)

\( H/H_0 = −1.148 + 1.901 ∗(𝜃/𝜃_0)− 0.5109 ∗ ( 𝜃/𝜃_0)^2, \)

\( 𝐻/𝐻_0= − 5.159 + 9.126 ∗ (𝜃/𝜃_0) − 4.766 ∗ (𝜃/𝜃_0) ^2 + 0.8201∗ (𝜃/𝜃_0) ^3, \)

On the basis of the obtained results for five locations in India, it is concluded that third order correlations provides much accuracy over first and second order for the estimation of monthly average daily global radiation as a function of ambient air temperature incident on a horizontal surface. The results also indicate that the proposed model has good potential for use in estimating values of monthly average global solar radiation on horizontal surface for the locations where measurements of the sunshine duration are not available. Present correlation can also be tested for other in house or out locations on the availability of measured data.