Models for obtaining daily global solar radiation with measured air temperature data in Madrid (Spain)

Solar radiation is a primary driver for many physical, chemical and biological processes on the earth's surface. Complete and accurate solar radiation data at a specific region are quite indispensable to the solar energy related research. For locations where measured values are not available, a number of formulas and models have been developed to estimate solar radiation. This study aimed to calibrate seven existing models and develop one new model for estimating global solar radiation data using temperature measured data for seven stations located in Madrid, Spain. This work concludes that empirical models based on temperature give good results in any location if the parameters are correctly adjusted. A newly developed model that include the difference between maximum and minimum daily air temperature, and the saturation vapour pressures at temperature maximum and minimum, provided estimates with less error than other models. According to the results, the new model showed the best estimation for all stations and therefore is recommended. It is believed that the model developed in this work is applicable for estimating the daily global solar radiation on a horizontal surface at any site in Community of Madrid, Spain. The daily global solar radiation values produced by this approach can be used in the design and estimation of the performance of solar applications. (C) 2010 Elsevier Ltd. All rights reserved.