N. N. Gana and D. O. Akpootu
An accurate knowledge of the solar radiation distribution at a particular geographical location is of vital importance for the development of many solar energy devices and for estimates of their performance. In this paper, the measured data of global solar radiation on a horizontal surface and number of bright sunshine hours for Kebbi (Latitude 12.47ºN, Longitude 4.3ºE, Altitude 205m above the sea level) were analyzed. Regression constants for the first order Angstrom-type correlations for Kebbi was calculated and developed using the method of regression analysis. The monthly calculated clearness index and monthly sunshine duration were correlated and modeled using four sunshine-based models i.e. linear, quadratic, exponential and power equations. Comparing these models, it was observed that the quadratic equation model performed better in terms of coefficient of determination(R²) and correlation coefficient (r) than the other three models, given R² = 100% and r = 1.00
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