In the present study, effect of thermal stratification on energy and exergy storage amount in vertical mantled hot water storage tanks, which are used common in solar domestic hot water systems, has been investigated. Placing obstacle inside the tank has enhanced thermal stratification and so energy and exergy of the tank. A commercial vertical mantled hot water tank was selected for experimental study. Four different obstacles were placed in four different heights from the tank bottom. Effect of the obstacle types and positions on energy and exergy storage capacity of tank has been researched experimentally. As a result, placing obstacles inside tank has enhanced the energy and exergy of tank. The best increasing has been seen for Obstacle A in Y/H = 0.250 position. In this situation energy amount increased 1.86 times and exergy amount increased 2.02 times higher than ordinary tank.