H1 = Depth below ground of water levelH2 = Height of tank stand base above borehole outletH3 = Height of tank standH4 = Height of water inlet above base of tankHs = Depth to water pump outletHy = Total static head = H1 + H2 + H3 + HaLe = Total pipe length from pump outlet to outlet in tankDi = Pipe inside diameter

When sizing a solar pump system, the major parameters which should be specified are: HT, Di and Sp together with the following:
QT = required daily delivery (L/day)SH = average daily sun-hours (typically between 4 and 5 hours for sub-Saharan Africa)N = number of pipe fittings such as elbows, etc.Ƞh = pump hydraulic efficiency (typically between 40% & 60%)