Parabolic trough collector (PTC) is a two dimensional solar focusing collector which collects beam radiation on tracking. In this research, closed parabolic trough solar collector of aperture area 0.6979 m2, copper tube receiver with black powder coating of diameter 22.6 mm, surface area of 0.05996 m2 is used. The concentration ratio (CR=Aa/Ar) of the PTC is 11.3. PTC is provided with top glass cover to induce greenhouse effect and to protect the reflector surface from dirt, weather, oxidation. The significance of insulation & thermal stratification and its effect on the performance of parabolic trough collector is studied. Non insulated storage tank led to high collection efficiency till 14:00 pm whereas it lead significant drop in system efficiency after that. Because of stirring the effect of thermal stratification was collapsed which reduces the thermo symphonic effect. This led to reduction in the system efficiency (difference of 16 %) of parabolic trough collector and also reduced the final temperature attained by water (difference of 4oC) in the storage tank. Hence insulation of storage tank without stirring is preferred for higher efficiency (maximum storage efficiency of around 73.91 %) and higher final temperature of water (59.7o C).