Optimized White Laminate and Redirecting Film as Back Reflectors for High-Efficiency Monofacial and Bifacial Photovoltaic Modules

Abstract

In this work, we have presented the analysis and optimization of white EVA, white backsheet and redirecting film as back reflector (BR) options applied to the commercial half cell (HC) photovoltaic (PV) modules. White EVA and white backsheet are diffusively reflecting to enhance efficiency on monofacial modules and redirecting film is a structured film applied in the areas between the cells/strings reflecting incoming light at specific angles to the cell surface, which is beneficial for bifacial modules. The influence of BR designs on the optoelectronic performance of PV modules is studied theoretically and experimentally. The combination of white EVA and white backsheet is found to be optically more efficient because of improved light reflecting and scattering, and by applying an optimized transparent/white EVA with an thickness of 0.23/0.22 mm, the maximal electric power of 574.3 W (efficiency of 22.23%) could be obtained. The bifacial module with redirecting film generates about 1.7%∼2.1% more current/power from front side with varying cell/string spaces, but the reduced bifaciality factors of approximate 77.6%∼77.5% are observed.