In this study, the using heat pipes for passive cooling on the PV was experimentally investigated. Gravity assisted two-phase closed thermosiphon type heat pipes using two different working fluids as water and ethanol were manufactured. Prepared heat pipes were placed on the back surfaces of two of the three PVs with the same characteristics for passive cooling. Passive cooled PVs with water-heat pipe and ethanol-heat pipe were compared experimentally with reference PV at the same time and under the same conditions. As a result of the experiments, the highest power values of 10.49W, 10.56W and 10.56W were achieved, respectively, for reference, water-heat pipe and ethanol-heat pipe PVs.