Metodologia para avaliação do desempenho de painéis fotovoltaicos utilizando um modelo elétrico-térmico e termografia quantitativa

Abstract

Photovoltaic technology stands out as a significant portion of the new installations within the context of distributed generation in Brazil. This market expansion demands a more efficient assets management, mainly in medium and large photovoltaic systems. The relationship between temperature rising and performance drop justifies the thermal monitoring of PVs, where thermography is a useful tool for a prompt identification of units operating below expected in the solar plant. However, it is a recurring practice the use of thermography only to search hot spots in the photovoltaic installation. This work proposes an alternative to determine the real performance of PVs by means of mathematical modeling and quantitative thermography. The methodology of this present work included mathematical modeling of PVs operation from electrical and thermal aspects, followed by a performance characterization by means of individual thermal inspections by thermography. The temperature values are combined with the instantaneous climate data in order to estimate the actual efficiency of the unit inspected, subsequently confronted with theoretical maximum limits. The results presented a complete optical properties characterization of PVs glass surface, in which = 0,78 and = 0,22 were obtained for inspections with 65° viewing angle. These considerations, coupled with measurement uncertainties, allowed reliable results of the operating temperature during frontal inspections in PV modules of TESLA Plant. It was defined in the scope of this work the PVs performance coefficient, evaluating variations in this parameter during clear and cloudy skies conditions. It was presented a temperature correction model from thermal imagers that, compared to measured data from a contact sensor during outdoor experiments, presented better results than FLIR model. Finally, the PV plant diagnostic proposal is tested in order to show, satisfactorily, the potential of thermography as monitoring technique and for PVs operational efficiency determination.