Quoted from:Ulgen K ,  Hepbasli A . Estimation of solar radiation parameters for Izmir, Turkey[J]. International Journal of Energy Research, 2002, 26(9):807-823.https://www.sci-hub.ren/10.1002/er.821

In this study, the solar radiation parameters (global and diffuse solar radiation) are correlated with respect to ambient temperatures in the fifth-order polynomial form for Izmir in Turkey. Experimental data were measured in the Solar-Meteorological Station of Solar Energy Institute in Ege University over a 5-yr period, 1994–1998. The ratios of the total daily diffuse to global radiation intensities for each month range from 0.38 to 0.45 averaged for the same period, with an average value of 0.41. It can be concluded that the present models predict the solar radiation parameters reasonably well with the correlation coefficients over 0.95 for the projections. Copyright 2002 John Wiley & Sons, Ltd.

INTRODUCTION

The need for meteorological parameters is essential in the design and study of solar energy conversion devices (Al-Riahi and Al-Kayssi, 1998). In other words, a reasonably accurate knowledge of the availability of the solar resource at any place is required by solar engineers, architects, agriculturists and hydrologists in many applications of solar energy such as solar furnaces, concentrating collectors, and interior illumination of buildings (Tasdemiroglu and Sever, 1991a; Tiris and Tiris, 1997; Togrul and Onat, 1999; Kaygusuz, 1999). On the other hand, the determination of solar energy capacity effectively through the empirical models plays a key role in developing solar energy technologies and the sustainability of natural resources (Ertekin and Yaldiz, 2000). In this regard, recently, several empirical formulas using various parameters have been given to estimate the solar radiation around the world (e.g. Munroe, 1980; Barra, 1983; Hutchinson et al., 1984; Ma and Iqbal, 1984; Badescu, 1987; Bahel et al., 1987; Soler, 1988; Samuel, 1991; Kudish and Lanetz, 1992; El Aroudam et al., 1992; Nfaoui and Buret, 1993; Srivasta et al., 1993; Rehman and Halawani, 1997; Aksakal and Shafiq-ur-rehman, 1999; Mosalam Shaltout et al., 2001; Hassan, 2001). These parameters include extraterrestrial radiation, sunshine hours, relative humidity, ambient temperature, soil temperature, number of rainy days, altitude, latitude and cloudiness. Numerous researchers have conducted experiments to develop correlations for various locations in Turkey, e.g. Gebze (Dincer et al., 1995; Tiris and Tiris, 1997; Sen and Tan, 2001), Elazig (Togrul and Onat, 1999), Trabzon (Kaygusuz, 1999), Antalya (Ertekin and Yaldiz, 1999; Ertekin and Yaldiz, 2000), Izmir (Ulgen and Hepbasli, 2002) and also for Turkey’s general values (Tasdemiroglu and Sever, 1991a; Tasdemiroglu and Sever, 1991b).

The main objectives of this study are to develop some simple empirical relations for Izmir, Turkey in order to estimate the monthly average hourly global and diffuse solar radiation intensities with respect to ambient temperatures based on a period of 5 yr and to evaluate the results of this study with the actual measured data in the same period by using statistical test methods.

Ulgen and Hepbasli proposed the third-order relation for Izmir in Turkey, as follows:

\( H/H_0 = 0.2408 + 0.3625S/S_0 + 0.4597(S/S_0)^2 − 0.3708(S/S_0)^3. \)