Electrical performance analysis of PV modules with bifacial silicon solar cells and white diffuse reflector

Abstract

Most of PV modules designed to use bifacial cells are based on curved specular reflectors or on albedo reflectors to enhance the module output power. This paper describes PV modules assembled with bifacial cells and with a white aluminum reflector in order to enhance the solar radiation reaching the rear face of the solar cells. Two modules were fabricated by using p+nn+ bifacial cells and they were electrically characterized. The aluminum reflector with reflectance near to 90% for the wavelength range 350–1100nm associated to the non-covered area between cell strings can enhance the output power of the modules in 29%. Modules with bifacial cells were installed in a stand-alone system in Porto Alegre, Brazil. After operation during 18months, we observed that dust induced power degradation in the range of 1–4%, similar to that observed in standard modules. After cleaning, no power degradation was observed in the n-type bifacial cell modules. Temperature of bifacial cells estimated by infrared images was between 5°C and 9°C higher than that of standard modules. Bifacial cell modules presented the same behavior than standard modules when applied to stand-alone PV systems and achieved an average performance ratio of 0.79.