About three meters. Hydroelectric generators use water with potential energy from high places such as rivers and lakes to flow to low places, convert the potential energy it contains into the kinetic energy of a hydraulic turbine , then use the hydraulic turbine as the driving force to drive the generator. to produce electrical energy. According to the formula, it is expressed as follows: N=7QH. In the formula: N is the installed capacity (瓩), Q is the flow rate (cubic meters/second), and H is the height difference (meters). Therefore, the water height difference for 8 kilowatt hydroelectric power generation is approximately three meters.
It also depends on the fall (height) of the water. Suppose the head is H (m), the flow rate is Q (m3/h), the power is P (kW) and the density of water is d (1000kg/ m3), the acceleration of gravity g = 10m/s2, taking into account theconversion efficiency μ, the relevant formula is: P = μdgHQ/3.6, if: μ=0.6, P=5kW, d= 1000kg/m3, H = 2m, Then Q = 3.6P/(μdgH) = 3.6x5/(0.6x1x10x2)= 1.5m3/h.
That is, when the generator has a height difference of 2 meters and a conversion efficiency of 0.6, the required water flow is about 1.5 meters cube per hour.