Módulos fotovoltaicos com células solares bifaciais : fabricação, caracterização e aplicação em sistema fotovoltaico isolado

Abstract

The main objective of this work was to fabricate and to characterize static concentrator photovoltaic modules (MEC-P) with bifacial solar cells and diffuse reflector. PV concentrator modules and PV standard modules with the same solar cell area were installed in a stand-alone PV system at 1.5 years and these were electrically characterized after the solar radiation exposure. The PV systems were monitored, measuring the irradiance (total and ultraviolet) at the same plane of PV modules, the voltage of battery, the electric current to the load and the electrical voltage and current of PV modules. Two PV concentrators were manufactured with dimensions of 775 mm x 690 mm x 70 mm (length x width x thickness) and with 36 bifacial solar cells with 80 mm x 80 mm, soldered in series. With cells whose average efficiency was (13.8 ± 0.2) % and (13.2 ± 0.2) % for front and rear mode illumination, respectively, one module with efficiency of 7.8 % was fabricated. By using solar cells of (13.7 ± 0.2) % / (13.1 ± 0.3) % for front / rear illumination mode, the efficiency achieved by the PV module was 7.6 %. It was estimated that the temperature of the solar cells in PV module concentrators was about 5 °C to 9 °C higher than that of PV standard modules with the same type of glass and similar lamination materials. The PV concentrators were subjected to total radiation of around 1.9 MWh/m² (6.84 x 109 J/m²) for 1.5 years and presented no degradation of their visual appearance as well as its electrical characteristics. The PV stand-alone system installed with MEC-P modules showed a monthly average efficiency of (6.5 ± 1.0) % in the period in which the load was held constant. The efficiency was 1.0 % lower than that obtained with the modules MEC-P was due to the higher operating temperature, the higher reflectance of solar radiation when the PV modules are installed on the tilted plane and has variation of the angle of incidence during the day, the resistive losses in the system and because in the calculation of system efficiency it was considered the electrical energy produced and stored.