OPTIMUM SLOPE OF A NORTH-SOUTH ALIGNED ABSORBER PLATE FROM THE NORTH TO THE SOUTH POLES

The analytical method developed by Nijegorodov et al. [Renewable Energ y, 4, 529-543 (1994)] in order to find the optimum slope of an absorbe r plate, variously oriented at any latitude, is applied to study the v ariation of daily optimum slope with latitude from the north to the so uth poles. For a clear, cloudless condition the daily optimum slopes a re found to have symmetry features which reflect the symmetry of the m otion of the sun and the north-south symmetry about the equator. Such symmetry features of the optimum slope are discussed. However, the act ual optimum slope also depends on the local meteorological and sunshin e conditions, due to which the symmetry features of optimum slope are not always exploitable. The effects of meteorological parameters such as temperature, pressure, relative humidity, visibility and cloud cove r on the optimum slope are assessed. The method is applied to obtain t he mean monthly optimum slopes for the locations of 12 synoptic statio ns in Botswana from which the climatic and sunshine data are available , and preliminary maps of mean monthly optimum slopes for Botswana for the months of June and December are presented. (C) 1997 Elsevier Scie nce Ltd.