In the present research, we report fabrication, experimental characterization and theoretical analysis of semi and full flexible dye sensitized solar cells (DSSCs) manufactured on the basis of bare and roughened stainless steel type 304 (SS304) substrates. The morphological, optical and electrical characterizations confirm the advantage of roughened SS304 over bare and even common transparent conducting oxides (TCOs). A significant enhancement of about 51% in power conversion efficiency is obtained for flexible device (5.51%) based on roughened SS304 substrate compared to the bare SS304. The effect of roughening the SS304 substrates on electrical transport characteristics is also investigated by means of numerical modeling with regard to metal-semiconductor and interfacial resistance arising from the metallic substrate and nanocrystalline semiconductor contact. The numerical modeling results provide a reliable theoretical backbone to be combined with experimental implications. It highlights the stronger effect of series resistance compared to schottky barrier in lowering the fill factor of the SS304-based DSSCs. The findings of the present study nominate roughened SS304 as a promising replacement for conventional DSSCs substrates as well as introducing a highly accurate modeling framework to design and diagnose treated metallic or non-metallic based DSSCs.