Reduction of reflection losses by structured surfaces of solar cells

Structuring the transparent cover of solar cell modules reduces reflection losses particularly at large angles of incidence. Relevant aspects are good transmission efficiency independent of wavelength and a low sensitivity to pollution. The macroscopic, linearly grooved structure proposed in this paper shows good performance only in combination with a textured cell, because large angles are likely to occur inside the structured cover. A classification is made with the concept of annual averaged transmission efficiency for the climatic zone of Freiburg. Calculations and measurements for different combinations of smooth and structured covers and solar cells are presented. From the calculated 97.8% entering the structured glass cover, a measured 93.2% can be coupled into a pyramidal textured monocrystalline solar cell. This is an absolute improvement of 17% compared to a smooth, uncoated solar cell with a smooth glass cover.