The high cost of traditional fuel leads the scientists to look at new sources of energy. Solar energy is the best renewable source of energy as it is free of running cost and has no pollution of the environment. So, solar distillation is a cheap way to produce fresh water. In this work, the design, construction, and performance evaluation of flat plate solar collector (FPSC) using gravity assisted heat pipes (Thermosyphon) and using acetone as a working fluid is presented. Two systems are designed, the first system is a flow water heat exchanger connected with FPSC welded with 11 thermosyphon, Effect of tilt angle of FPSC was performed from 12, 17, 20 and 25 and 30 with filling ratio of thermosyphon was 80% of the evaporator volume. Measuring was conducted in August and September 2021 at Faculty of Engineering, Menoufia University, Shebin El-Kom, Egypt, latitude 30.5 N and Longitude 31 E. The results were as follows, average effectiveness all over the day of measurements was 73% at 12. The other average effectiveness was 69.35% for 17, 62.47% for 20, 67.14% for 25 and 66.68% for 30. So, the results showed that the best angle performance was 12 with absorber maximum temperature of 70.36 C at 12:30 PM, and adiabatic section temperature of 60.35 C, and condensing section temperature of 42.46 C.