In this research, having the limited rooftop area of the condominium, the Solar PV system is optimally designed on the roof of multi-story condominium apartment having 2 basements for car parking, Ground floor with 11 shops, first and second floors having 11 shops + 1 café and 11 shops respectively constituting commercial floors and starting the third to the above all floors as residential floors in which there are 2 One bed room type, 6 two bed room types and 2 three bed room types in each floors. The total load demand is estimated to be 195.764MWh/Year for a single block by considering demand factor as 0.9 for lighting, 0.6 for common appliances for residential floors and 0.7 for appliances for commercial floors. A single block of Condominium has a total roof top area of 408.6 x 2 = 817.2 sq. m. In this total rooftop area, the PV system is designed optimally by considering a minimum shade loss, energy generation, the number of modules and the space required for maintenance. Summarizing the result, considering a tilt angle of 100, row spacing of 1m, Azimuth angle of 1800, 142Modules (SPR-X22-360-COM) with 0.5 % Shade loss on half of the roof top area of 408.6 sq. the designed system can generate of 88.7MWh of Energy (that means 88.7x2= 177.4MWh for full roof area of 817.2 sq. m for a single Block), peak power production of 51.1KWp per day on half rooftop area (that means 51.1 x 2=102.2KWp power production for a single condominium block). From the load demand analysis result of condominium block, a total annual Lighting demand is 75.816MWh of Energy and a total annual Load demand is 195.764.04MWh of Energy. From the rooftop PV system designed on a single block of a condominium, it is shown that the designed PV system can supply 100 % for lighting load demand only or can supply 90.6 % of all the electrical load demands of a single condominium block.