Quoted from:Tarhan S ,  Sari A . Model selection for global and diffuse radiation over the Central Black Sea (CBS) region of Turkey[J]. Energy Conversion and Management, 2005, 46(4):605-613.

https://www.sci-hub.ren/10.1016/j.enconman.2004.04.004

Solar radiation over the Central Black Sea Region of Turkey, covering the five provinces (Amasya, orum, Ordu, Samsun and Tokat), was analyzed to guide future projects. The maximum monthly average global solar radiation ranged from 20.05 (for Ordu) to 23.71 MJm (for Tokat). The maximum monthly average daily measured sunshine duration ranged from 6.89 (for Ordu) to 11 h (for orum). A quadratic polynomial equation was empirically developed to predict the monthly average daily global radiation. A hybrid model was also developed based on the predictions of six existing models to predict the monthly average daily diffuse and beam radiation. Various statistical tests (analysis of variance for model adequacy and test for significance of model parameter etc.) have shown that the models developed in this study are adequate for solar radiation prediction.

Introduction

The growing aspects of today’s modern life are sustainable development and environmental protection. Both of them require renewable and clean energy sources such as solar energy. Its potential varies in time and in any geographical location. Thus, long term monthly average values of daily global, diffffuse and beam radiation are needed for engineering design and planning projects. The Turkish State Meteorological Service has been measuring global solar radiation on ahorizontal surface daily with actinographs at 163 stations and bright sunshine duration with sunshine recorders at 192 stations all over the country since 1964. It was reported that the measurements of the sunshine recorders were accurate, while the measurements of the actinographs had some errors because of the thermal sensitivity of their mechanical components. On the other hand, Gunes .plotted the actinograph measurements versus pyranometer measurements from 1993 to 1996 for fifive cities in Turkey. In that study, the plots indicated that there are no consistent deviations between the actinographs and pyranometer measurements. Thus, the actinograph measurements are still reliable enough to use in engineering and scientifific studies on solar radiation.

The public interest in various solar energy applications such as solar water heating and solar drying has been growing recently in the Central Black Sea Region (CBS region) of Turkey. The solar radiation over the CBS region has not been analyzed previously in detail to guide future engineering and scientifific projects. The objective of this paper is to develop two separate mathematical equations to predict the monthly average daily global and diffffuse radiations over this region.

Tarhan and Sarhave proposed second and third-order polynomial models to predict solar radiation over the Central Black Sea Region of Turkey, as follows:

\( H/H_0 = 0.1874 + 0.8592 S/S_0 − 0.4764(S/S_0)^2, \)

\( H/H_0 = 0.1520 + 1.1334S/S_0− 1.1126(S/S_0)^2 + 0.4516(S/S_0)^3. \)

A statistically-significant quadratic polynomial model was developed to predict the monthly average daily global radiation over the Central Black Sea Region of Turkey based on the dataobtained from the Turkish State Meteorological Service. A hybrid model was also developed based on the predictions of six existing models for the monthly average daily diffuse radiation since diffuse radiation measurements were unavailable. Both models are adequate to predict monthly average daily global and diffuse radiations over the selected region of Turkey.