Achieving sustainable architecture may be feasible by using renewable energies. Solar power can be exploited in building via photovoltaic and collectors to produce electricity and heat and it will lead to GHG reduction. Building integrated photovoltaic (BiPV) systems can form a cohesive design, construction, and energy solution for the built environment. PVs produce electricity and have special aspects that can be utilized. The expressive and impressive aspect of a photovoltaic system designed and applied on the envelope of the buildings can not be ignored and the architect should appreciate PV's abilities to perform as an exterior material as well. Designing a BiPV needs a team in which everyone plays his/her own role to reach the maximum output through the system. This paper will analyze the best architectural form and specification of a BiPV in Tehran. In this research diagrams of annual and seasonal total of global radiation in Tehran will be produced. With regard to diagrams the best tilt angle will be discussed. Finally, some basic forms such as cube, prism and box will be analyzed to receive the maximum solar radiation and an isosceles triangle for the best choice.