“…Located in a tropical climate, alternative energy in Indonesia still has the potential to be developed, such as water energy [2], wind energy [3][4][5], biogas energy [6,7], biomass energy [8], photovoltaic [9]. Water energy or hydropower in the smallest scale category producing no more than 5 kW is called picohydro [10,11]. In its application, hydropower on a picohydro scale can be generated in a water piping system or water tubular on a horizontal flow [1].…”