The conversion of solar energy into electrical energy by the design of energy-efficient way is the key objective of this paper, which can be used as a main source of power for the main building of Polytechnic Institute to meet its daily energy requirement by replacing the all exist-ing fluorescent lighting loads to LEDs. The main purpose to choose a standalone photovoltaic system is due to the huge power cut in this location. This institute is situated in a rural area of West Bengal, India. The use of photovoltaic power relies upon assortment factors, such as structuring, topographical area, climate condition, sun-based irradiance, and burden utilization. Point by point use examinations including the two sorts of lighting burden, establishment, and upkeep of sun-based PV framework amid its life expectancy has been completed. Moreover, the analysis has two dimensions, one is cost comparison and payback calculation with respect to energy by replacement of load and another is, though the initial investment is high in a off-grid photovoltaic system, during the life span of the scheme, it not only returns this capital in-vestment but also gains substantial dividend.