Abstract :
The aim of the present research is the comparative development of a variety of models for the estimation of solar
radiation on a horizontal surface. By using two different methodologies,models of various complexities have been
developed and tested. The first methodology refers to the traditional and long-utilized A ˚ ngstro¨m s linear approach
which is based on measurements of sunshine duration. The second methodology refers to the relatively new approach
based on artificial neural networks (ANN) and it can be based on sunshine duration measurements but also on other
climatological parameters. Three A ˚ ngstro¨m-type models and seven ANN-type models are presented. All of these models
are verified against independent data and compared. Lack of sunshine duration measurements renders A ˚ ngstro¨m s
approach inapplicable; hence the feasibility of applying the ANN models for the calculation of solar radiation in places
where there is a lack of sunshine duration measurements is investigated.
2004 Elsevier Ltd. All rights reserved
