Incidental solar radiation according to the solar collector slope - Horizontal measurements conversion on an inclined panel laws

Abstract

In this article we are interested in the optimal choice of the tilt angle of solar water heaters, in the case of Tunis (lat 36°.85, long 10°.2). We studied several variations of usage months: spread all year round or solely reduced for some months: nine, seven or five months centered on winter - the most difficult period to satisfy in term of solar energy. Results show that a more elevated tilt of the collector for some degrees in relation to the latitude of the place [1] is essential especially if we want to make favorable the conditions of collecting in winter where resources in solar energy are at their minimum, whereas, the needs in hot water are at their maximum. In a second part of this article, means of conversion are given, for a collector plane tilt of an angle "i", of the solar data of the received global and diffuse solar radiation by the horizontal plane. The results are resemble those of to Duffie [2] but the correlation is shorter. Thus, we can help laboratories which are not equipped with measure devices of solar energy; an apparent data to determine performances of all solar energy conversion system or using it as primary energy source. We can rely on solar data which will be converted according to both the tilt angle and the orientation of the solar panels. © 2009 Nova Science Publishers, Inc.