On the choice of the angle of tilt for south facing solar collectors in the Athens basin area

This paper seeks to furnish a fundamental piece of information to the solar engineer or scientist regarding the proper choice of the solar collector's tilt angle. Global radiation monthly average daily values are analyzed by a simple correlation into diffuse and beam components. The diffuse and beam components are then used to calculate monthly average hourly and daily values on an inclined surface. The results of these calculations are tabulated and plotted against the angle of tilt for summer, winter and all-year-round intended use. Global radiation measurements used in this work come from (a) the Climatological Bulletin of the National Observatory of Athens, years 1957–1981, (b) the unpublished records of the National Weather Service of Greece (referred to as EMY), years 1977–1982, and (c) the Scientific Publications of the Public Power Co. (referred to as PPC) on measurements of solar potential of Greece, years 1982–1983; the latter was the source of solar diffuse data as well.