Caracterización de instalaciones fotovoltaicas mediante técnicas de termografía infrarroja

Abstract

This Doctoral Thesis deals with the subject of thermal and electrical characterization of photovoltaic (PV) installations through the application of Infrared Thermography (IR). The infrared (IR) thermography is a non-destructive technique (NDT) which is used to carry out maintenance quickly and easily in photovoltaic (PV) systems. IR imaging with thermographic cameras under steady state conditions is a usual method for quality control of PV modules and PV plants in operation. For the proper IR inspection which determines the severity or the importance of the detected findings, it is necessary to consider different aspects of the configuration and the location of the thermographic equipment which allow reducing measuring errors. This Doctoral Thesis considers some elements which contribute to the accurate configuration of the thermographic equipment. The influence of the reflected apparent temperature in outdoor IR inspections is analysed and it is proposed a simple method for obtaining it. Besides, the importance of the emissivity in IR thermography is analysed. For that, the value of the emissivity in PV modules of various types both front and rear shape is determined experimentally. It is also studied the proper location of the thermographic equipment in order to minimize reflections of the sun and the sky. For this objective, it is studied the ideal and minimum height of inspection according to the layout of the PV system. The influence of the inspection distance is studied to obtain an adequate geometric resolution. In a particular case, it is also analysed the influence of the horizontal angle of thermographic inspection and the reflected radiation. The main contribution developed in this Doctoral Thesis is a proposal for an IR Thermography inspection procedure for outdoor PV installations. The purpose of this procedure is to measure the temperature as accurately as possible, for which it considers all possible sources of error in order to compensate and minimize them. This procedure proposal aims to be of general application, in a systematized way, for any type of outdoor PV installation. The proposed procedure complements the recent technical specification IEC TS 62446-3 (2017) considering relevant aspects for the measurement of temperature in outdoor PV systems. An original relevant contribution of this Doctoral Thesis is the extrapolation of results due to wind speed. To do this, the TamizhMani method has been considered according to a 3-parameter model to represent the thermal behavior of PV systems of any technology. This method allows obtaining a correction factor to apply to the temperature measured by IR thermography considering 3 parameters: the atmospheric temperature, the wind speed and the irradiance.