Experimental Assessment of Nanoimprinted Textured Frontsheets for PV Modules

Textured frontsheets can significantly reduce the optical losses of PV modules at high angles of incidence. These frontsheets can potentially be used in building-integrated PV applications like façades or roofs with suboptimal orientation in order to improve electrical energy yields and cost-effectiveness. In this work an experimental assessment of nanoimprinted micro-textures on PV single-cell laminates is done to quantify reduced angular-dependent optical losses in detail. PV single-cell laminates under test with size of 180 mm x 180 mm and nanoimprinted textures on 3 mm thick soda-lime-silicate float glass and 0.125 mm thick polyethylene terephthalate substrates. The textures are composed of periodically arranged pyramids with heights of 30 µm and a base area of 50 x 50 µm. The gain in relative transmission of the textured samples compared to the non-textured samples on PET film substrate is 12.1 % at 70°, 22.0 % at 75°, 42.2 % at 80° and 91.6 % at 85°. In comparison, the gain of textured flat glass samples shows 7.9 %, 19.2 %, 13.7 % and 69.7 % at 70°, 75°, 80° and 85°, respectively. The results give clear indications that the textured frontsheets have a significant effect on the angle-dependent losses of PV modules.