%K Thermal resistance, CPV, cell temperature, wind, operation conditions %L upm38829 %X Thermal characterization of Concentrating Photovoltaics (CPV) modules and Arrays is needed to determine their performance and modelling of energy forecast. Module-ambient thermal resistance is easily obtained from its definition but the cell-module thermal resistant needs to be estimated from indirect procedures, two of them are presented in this paper. In addition, an equivalent parameter is defined, the Concentrator Nominal Operating Module/Cell Temperature (CNOMT/CNOCT), the temperature at Concentrator Standard Operating Conditions (CSOC). Definitions and expression to relate (CNOMT/CNOCT) to thermal resistances are presented, plus several examples of estimations from real operating arrays. %B 10th International Conference on Concentrator Photovoltaic Systems (CPV-10) %J AIP Conference Proceedings %I American Institute of Physics %D 2014 %P 144-148 %A Rubén Nuñez Júdez %A Ignacio Anton Hernandez %A Stephen Askins %A Gabriel Sala Pano %A Kenji Araki %R 10.1063/1.4897048 %C Albuquerque, New Mexico, USA %N null %T Characterization of CPV arrays based on differences on their thermal resistances