ON THE GENERATION OF HOURLY SHORTWAVE RADIATION DATA ON TILTED SURFACES

In this paper we describe a method for computing hourly values of glob al radiation on inclined planes at any desired location. Fundamental t o the computations are a 10 year series of global radiation and temper ature measurements from 64 weather stations in Switzerland. As a first step, the monthly mean values are interpolated to any desired locatio n. Hourly values are then generated stochastically on the basis of the interpolated monthly values. Using additional models, the hourly valu es of horizontal global radiation are transposed to inclined surfaces. This strategy involves a number of newly developed models, of which t hose for interpolation, and inclusion of skyline profile in calculatin g radiation on inclined surfaces, are the most important. The individu al models are combined in a single comprehensive procedure. This was b riefly validated, showing that coupling the independent models leads t o satisfactory results, and confirming the validity of the chosen appr oach. Although the methods and models were checked for Switzerland, th ey are based on components that have been tested over a wide range of geography. (C) 1998 Elsevier Science Ltd. All rights reserved.