EXCEL 25 SOLAR is a glass-fibre reinforced bitumen waterproofing membrane with ALPA® binder. The finish on the surface and undersurface is a thermofusible film. Second layer in Excel Solar PVFLEX waterproofing system. Axter SOLAR PVFLEX CIGS* flexible photovoltaic modules are adhered in situ to the membrane surface, into the ALPA binder, when the thermofusible film is heated. EXCEL 25 SOLAR is designed for multi or single layer applications. *CIGS=Copper Indium Gallium Selenide.