The process of acquiring photovoltaic power involves designing, selecting and determining specifications depending on a variety of factors, such as geographical location, weather condition, solar irradiance, and load consumption. In this paper a detailed design of a standalone rooftop solar PV system to provide uninterrupted power supply for a hostel building is presented. It outlines the detailed procedure for specifying each component of the stand-alone rooftop solar PV system and its performance analysis using simulation software. Detailed cost analysis including installation and maintenance of a rooftop solar PV system during its life span has also been carried out. The cost of PV generation and environmental benefit are also highlighted.