Angular efficiency of solar panels: how nanotextured anti-reflection surfaces improve annual energy output

The annual power generation of solar panels is often maximized by installing the panels at an optimum angle towards the equator. In incident angles higher than 55 degrees from normal, the reflection from the glass surface, as well as thin-film anti-reflection coatings, dramatically increases and results in loss of energy. However only up to 30% of the time, the sun is at the angle of incidence lower than 55 degrees. The use of anti-reflection technologies that reduces reflection at such wide angles can significantly increase the annual electricity output of solar panels. In this paper, we present the impact of glass anti-reflection technologies on the annual power generation for solar panels installed in diverse geographical and climate conditions. For panels installed at the optimal angle, annual enhancements reach up to 7%. Not surprisingly, the benefit for building-integrated and rooftop installations are even greater. For south-facing vertically installed panels, annual enhancements reach up to 10.3%.