One of an energy storage was Thermal Energy Storage (TES). Method that used to exceed the lack of Solar Water Heater (SWH). TES required an energy storage media which called Phasa Change Material (PCM). Phase Change Material (PCM) had high energy density to save many energy latent. In this research, PCM that used was parrafin wax. But, the trial of TES used an experiment possessed weakness that was trickle and freezing of parrafin wax could not be predicted, therefore it needed Computational Fluid Dynamics (CFD) simulation study. The aim of this reserch was to know the time of trickle and freezing of parrafin wax. In this case the geometry consists of a tank in which there are 32 copper pipes containing PCM. This simulation study uses ANSYS Fluent 18.0 software, to simulate the charging and discharging continue. The charging process uses 0,6 LPM and 0.9 LPM debit 227 Volt heat flux variations. While the discharging process gradually uses a variation of 1.5 LPM and 2.5 LPM discharge. Simulation objects include temperature evolution and PCM melting and solidifitation. The result of simulation shown that the higher flux heat value, the faster trickle time and the bigger discharge of flow so that the faster of time freezing. This was proofed with a perfect time of trickle in variation charging process 600 W that was 1,25 hours and 900 W that was 2.9 hours. Besides, the time to achieve a perfect trickle in continous discharging process variation at 1,5 LPM that was 0.65 hours and 2,5 LPM that was 0,59 hours. The highest value of heat absorption had happened in variation 0.9 LPM in the amount of 638,74 J/s in water at sensible PCM and 216,43 J/s at latent PCM. In variation 0,6 LPM in the amount of 557,04 J/s in water, 55,95 J/s at sensible PCM and 228,71 in latent PCM. The highest value of heat discharge had happened in variation 2.5 LPM in the amount of : 810,75 J/s in water, 36, 95 J/s in sensible PCM and 7085.00 J/s in latent PCM. Meanwhile, the value of heat discharge in variation 1.5 LPM in the amount of : 526, 47 J/s in water, 28,55 J/s in sensible PCM and 3298 J/s in latent PCM. The highest value of temperature increasement had happened in variation 0.9 LPM in the amount of : 12,76 ℃/hour in water and 12,50 ℃/hour in PCM. Meanwhile, the increasement of temperature in variation 0.6 LPM in the amount of : 11,12 ℃/hour in water and 10,88 ℃/hour in PCM. The highest temperature of descent value had happened in variation 2,5 LPM in the amount of : 16,19 ℃/hour in water and 15,592 ℃/hour in PCM. In 1,5 LPM variation in the amount : 10,51 ℃/hour in water and 10,28 ℃/hour in PCM. The deviation value of trial charging variation 0.6 LPM that was 32,09% and in variation 0.9 LPM that was 17,80%. Meanwhile, discharging trial continously in 1.5 LPM variation that was 61,35% and in variation 2.5 LPM that was 48,79%.