Abstract
Solar thermosyphon(TS) can transport solar heat by spontaneous circulation of working fluid without pump. The working fluid of the TS is water. We attempted hydroelectricity generation by the TS for the first time. At present, the observed power output was 10^<-6>W in the order of magnitude under the solar irradiation of 1000 to 1200W. Considering Carnot's coefficient, there is a large margin for the improvement. To increase the present low efficiency, it is needed to understand the flow characteristics and to establish proper design of hydroelectric generation unit.
