Journal Article

Analysis of Optimum Tilt Angles and Their Effects on Receptors of Solar Radiation in Some Locations in Nigeria

Abstract

Tilt angle is considered as one of the critical parameters in optimizing the amount of captured solar radiation by solar collectors. In this work, optimum tilt angles for three selected locations in Nigeria: Maiduguri (11.9oN, 13.2oE), Abuja (9.2oN, 7.2oE) and Port Harcourt (4.9oN, 7.0oE) were evaluated. Global Solar Radiation Data at Horizontal Surface for the three locations were obtained from the data provided by National Aeronautics Space Administration (NASA). Klein and Theilacker (KT) method was adopted for determination of optimum orientation of the collectors and the computation was carried out using „Solver-add-in‟ obtained from Microsoft excel options. The analysis showed that if the collectors are to be fixed permanently, the best orientation is southward tilted slightly above the latitudes of the locations. However, for optimal performance of periodically adjustable collector, the colletors should be oriented southward during the months of September to February and oriented northward during the months of April to August. The gains of energy as a result of changing the orientation were also investigated which showed that the effect of tilt is more significant at locations farther away from the equator as compared to locations nearer to the equator. In addition, monthly adjustment of collector orientation resulted in energy gain of approximately 1.79MJ/m2 day while for a permanently fixed system (annual optimization) the maximum energy gain is about 0.45MJ/m2 day as compared to that available at horizontal surface. The result will be useful for Solar Installers (both thermal and photovoltaic) in making decisions on the orientation of the collectors thereby maximizing the solar radiation available to solar collectors and, hence, minimizing the overall cost of the system.

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