Hyper-spherical search algorithm (HSSA) is proposed for optimal allocation and sizing of Photovoltaic Distributed Generation System (PVDGS) in the distribution network. Firstly, Power Loss Index (PLI) technique is presented to get the highest candidate buses for installing PVDGS. Secondly, the proposed HSSA is developed to decide the most optimal locations of PVDGS and their economic sizing at the elected buses by PLI. Herein, the cost objective function is designed to diminish the total cost of the system losses, and subsequently increase the annual net saving. Hourly variation of solar radiation, and temperature is taken into account in cost calculation of the PV system. In addition, the present worth value for the costs of the maintenance and the PV system components is estimated as function of interest and inflation rates. The proposed algorithm is tested on 69- IEEE and 118 IEEE radial distribution systems to ensure the effectiveness of the proposed algorithm in increasing the net saving via precise cost calculation