I was responsible for creating the solar panel material in the High Tech material set we used for the moon outposts of the Stanton System.
It_s a fairly straight forward material, using a blend map to blend between dirty and clean (which provides a lot of flexibility for embedding these into different types of biomes), as well as a detail map to bring in the crystalline like pattern into each of the solar cells. This material is quite reliant on Parallax Occlusion to create the multi-angled look we wanted.