Solar Water Pump Sizing
Pump power and PV array size for a solar water pump from daily water need, total head and sun hours.
Inputs
m³/day
m
%
h/day
%
Results
- PV array size
- 1.82 kWp
- Pump input power
- 1.45 kW
- Hydraulic energy
- 3.27 kWh/day
- Average flow during sun hours
- 6 m³/h
Formula
Hydraulic energy (kWh) = ρ·g·H·V ÷ 3.6×10⁶
Electrical energy = Hydraulic ÷ efficiency
Pump kW = Electrical ÷ peak sun hours
Array kWp = Pump kW ÷ derating
Assumptions & limits
- Total dynamic head = static lift + friction losses.
- Use the worst month's peak sun hours for year-round supply.
Worked example
9.81 × 40 × 30 ÷ 3600 = 3.27 kWh ÷ 0.45 = 7.27 kWh ÷ 5 h = 1.45 kW ÷ 0.8 = 1.82 kWp.