This paper describes field investigations performed and the evaluated temperature behaviour of 13 different types of PV modules, which have been exposed to real conditions both in Stuttgart, Germany and Nicosia, Cyprus. The temperature coefficients have been evaluated in two ways. The first using direct outdoor measurements and the second through the application of data manipulation techniques on the measured meteorological and operational data collected by the installed sensors present at the test sites. The results from the two methods are finally compared and validated demonstrating the reasonable agreement with the manufacturers' data. (C) 2008 Elsevier B.V. All rights reserved.