abstractThis paper deals with the determination of optimum tilt angle and orientation for solar photovoltaicarrays in order to maximize incident solar irradiance exposed on the array, for a specific period of time.The method is extended, by introducing a second objective, i.e. minimization of variance of the producedpower, in terms of hourly power generation throughout the given period of time. The proposed methoduses both well-established models and data collected from the particular area where the photovoltaicpanels will be installed and is built upon four steps. In the first step, the recorded data are used in orderto select the most accurate, among several isotropic and anisotropic models that can be found in theliterature, for predicting diffuse solar irradiance on inclined surfaces. In the second step, the recordeddata and the selected model are used to construct a database that contains the averages and the variances of the hourly global solar irradiance on tilted surfaces over specific periods of time, for various tiltangles and orientations. In the third step, the database of the previous step is utilized to produce metamodels that correlate tilt angle and orientation with mean global irradiance and its variance on tiltedsurfaces. Finally, an optimization problem is formulated, aiming to determining the optimum values oftilt angle and orientation, taking into account the constraints and limitations of the system.