Asian Journal of Applied Sciences (ISSN: 2321 – 0893) Volume 02 – Issue 02, April 2014 Asian Online Journals (www.ajouronline.com ) 126 Estimation of Global Solar Radiation over Makurdi, Nigeria M. O. Audu 1 , U. E. Utah 2 , J. U. Ugwanyi 3 1 Department of Physics, University of Agriculture Makurdi, Nigeria . Email: audumoses53 {at} yahoo.com 2 Department of Physics, University of Uyo, Nigeria 3 Department of Physics, University of Agriculture Makurdi, Nigeria _________________________________________________________________________________ ABSTRACT— Solar radiation studies have been carried out using meteorological parameters to assess the feasibility of solar energy utilization in Makurdi (7.74 o N, 8.51 o E and 104m above sea level). Measured solar radiation, relative sunshine hours, air temperature and relative humidity data for Makurdi covering a period of 10 years (2000 - 2010) were used to establish Angstrom type correlation equations to estimate global solar radiation. Among the models formulated, the model equation with R 2 of 84.3%, MBE of 1.079 x 10 -1 and RMSE of 2.466 x 10 -2 , which can best be used to estimate the global solar radiation, was obtained. From this formulated equation, the highest global solar radiation of 15.702 MJm -2 day -1 was estimated in the dry season against the measured value of 15.690 MJm -2 day -1 for the same period, while the lowest radiation of 11.805 MJm -2 day -1 was obtained for rainy season as against 11.354 MJm -2 day -1 of measured value. The observed performance of this formulated model implies that it can be used to predict global solar radiation for Makurdi and its environs. Keywords— solar radiation, relative sunshine hour, temperature, Makurdi. ________________________________________________________________________________ 1. INTRODUCTION With the rapid depletion of fossil fuel reserves, it is feared that the world especially Nigeria will soon run out of its energy resources. Under these circumstances, it is highly desirable that alternative energy resources should be utilized with maximum conversion efficiency to cope with the ever increasing energy demand. Among the renewable resources, only the solar energy has the greatest potentiality, availability and is free from environmental hazards. The comprehensive design and assessment of solar energy systems depend largely on adequate information of the solar radiation characteristics of the region where the systems are to be located. Obviously, the best radiation information is that obtained from experimental measurements of the global solar radiation at the location in question. Makurdi is the capital of Benue State located in the north-central region of Nigeria. Makurdi, having an area of about 33.16 km 2 , is located at latitude 7.74 o N and longitude 8.51 o E. It is noted for its hotness during the dry season with an average air temperature of about 33 o C. This high temperature is attributed to the presence of River Benue (the second largest river in Nigeria) which cuts across the middle of the city, and serves as heat reservoir. Benue State is regarded as the food basket of the nation since agriculture is the main occupation in the state and about 90% of its population is engaged in it. However, each year large quantities of agricultural produce especially vegetables and fruits are allowed to waste due to lack of adequate preservation and storage facilities. This research work hopes to give detail information about the availability of solar energy in the state which can be used by solar energy technology to design and fabricate solar dryers and appropriate solar refrigeration units. There are many empirical and theoretical relations developed for the estimation of global solar radiation using meteorological parameters such as relative sunshine hour, relative humidity, maximum and minimum air temperature and total solar radiation on the horizontal surface. Among the existing correlation for determining the global radiation, the simplest is [4] regression equation which relates the monthly average daily global irradiation, H to the number of hours of bright sunshine, n. The equation is of the form:           (1)