Method: Daily hydraulic energy = water volume × total dynamic head ÷ 367. Electrical energy required = hydraulic energy ÷ pump efficiency. Pump power = electrical energy required ÷ peak sun hours. Solar array capacity = electrical energy required ÷ peak sun hours ÷ solar system efficiency. Required flow rate = daily water requirement ÷ peak sun hours. This provides preliminary sizing. Final pump selection should use the manufacturer’s pump curve at the required flow and total dynamic head. Water-source yield, seasonal solar conditions, storage requirements and actual pipe losses should also be checked.