This dissertation was written as a part of the MSc in Energy Systems from the School of Science and Technology at the International Hellenic University, Thessaloniki, Greece. Renewable energy and especially solar energy has become an integral part of today’s society. Usually data of solar radiation are measured for horizontal surfaces or in sunshine hours, but in this form they are not so useful in engineering applications. This dissertation deals with the issue of converting those data to solar irradiance incident on inclined surfaces and more specifically on vertical surfaces. Solar models are divided into two distinct categories, isotropic and anisotropic models, according to the way they estimate diffused irradiance. Different models have been described from both categories and six of them were analyzed and compared to the actual inclined irradiance and between them. The models included in estimations were those of: Liu-Jordan, Koronakis, Temps-Coulson, Hay-Davies, Perez and Reindl. Also, sunshine solar models were described and a second analysis between one of those, Black model and total horizontal irradiance was held. All meteorological data and information about weather conditions were taken from the meteorological station placed on the roof of a building inside the campus of International Hellenic University. The selected measurements concern an entire year, from 1st September of 2013 until 31st of August 2014 and one month from each season, October, January, April and July, were used in calculations. Furthermore, I would like to thank my supervisor, Dr. G. Martinopoulos, Academic Assistant in International Hellenic University, for the assignment of this dissertation and his valuable assistance throughout the preparation of it.
