Solar pump sizing calculator for borewells and irrigation
A solar water pump has to do two things: lift enough water each day, and get enough energy from the panels to do it. This solar pump sizing calculator starts from the water you need per day — or the flow in litres per minute and the hours you want to pump — and the heights involved, and gives you the pump size in HP and kW, the solar array in kWp and the number of panels.
It works for submersible borewell pumps and surface pumps alike. Enter the water level in the borewell, the drawdown when the pump runs, the delivery height to your tank or field, and a friction allowance; the calculator adds them into the total dynamic head. Peak sun hours come from the same regional presets as the solar panel calculator, or type your own. Every efficiency is an input, so you can match a pump’s data sheet.
How to use the Solar Water Pump Calculator
- Choose Water per day (m³ or litres) or Flow × hours, and metres or feet for heights.
- Enter the water level below ground, the drawdown while pumping, the delivery height and a friction allowance (5–10% of the lift for well-sized pipe).
- Pick your region to load peak sun hours, or type a value from a solar map.
- Adjust pump efficiency, motor and controller efficiency, array derating and panel wattage if you know them.
- Read the standard pump size and the array size, then copy the summary to compare quotes.
Solar Water Pump Calculator features
Total dynamic head
Water level + drawdown + delivery height + friction, in metres or feet.
Pump HP and kW
Motor output from hydraulic power and pump efficiency, rounded up to the next standard size (1, 2, 3, 5, 7.5, 10 HP …).
Solar array kWp and panels
Electrical input divided by the derating, then whole panels of your wattage.
Two ways to state demand
Cubic metres or litres per day, or litres per minute for a number of hours.
Shared sun-hour presets
The same 30 regional averages (ten for India) as the solar panel calculator, all editable.
How the solar pump is sized
- Total dynamic head: 30 m water level + 5 m drawdown + 5 m delivery = 40 m, plus 10% friction = 44 m.
- Hydraulic energy: E = ρ g V H. For 60 m³ a day: 9.80665 × 60 × 44 ÷ 3,600 = 7.19 kWh a day.
- Hydraulic power: a solar pump runs at full power for about as many hours as there are peak sun hours, so 7.19 ÷ 5 h = 1.44 kW (an average of 12 m³/h).
- Pump size: 1.44 kW ÷ 50% pump efficiency = 2.88 kW of motor output = 3.86 HP → a 5 HP pump.
- Solar array: 2.88 kW ÷ 85% motor and controller = 3.38 kW of electrical input; ÷ 75% derating = 4.51 kWp → nine 540 W panels, 4.86 kWp.
PM-KUSUM and buying a solar pump
- Under PM-KUSUM Component B, the central government pays 30% of the benchmark or tender cost of a stand-alone solar pump (50% in the North-East, Sikkim, J&K, Ladakh, Himachal Pradesh, Uttarakhand, Lakshadweep and the A&N Islands). With a state share the farmer pays less; without one, the farmer pays 70%. This is from the PIB/MNRE incentives annexure of August 2024; benchmark costs and shares change, so ask your state nodal agency.
- Pumps under the scheme are chosen from the water table, land area and water need — the same inputs as this calculator. New stand-alone pumps are not allowed in “dark zone” areas with over-exploited groundwater.
- Ask for the pump’s head–flow curve. A pump sized for 44 m delivers less water at 60 m and more at 30 m; the curve, not the HP figure, tells you the litres per day.
- For a mains-powered pump instead, use the water pump HP calculator, which also works out pipe friction from length and diameter.
Solar Water Pump Calculator FAQ
How do I calculate solar pump size?
Find the total dynamic head (water level + drawdown + delivery + friction), multiply by the water per day to get hydraulic energy (9.80665 × m³ × m ÷ 3,600 kWh), divide by peak sun hours for power, and by the pump efficiency for the motor size.
How many solar panels do I need for a 5 HP pump?
Usually about 4.5–5 kWp — nine or ten 540 W panels — with typical efficiencies and five sun hours. The exact figure depends on the head and water you need, which is what this calculator works out.
What is total dynamic head?
The height the pump must lift water, including how far the level drops while pumping, plus an allowance for friction in the pipes. It is the head printed on a pump curve.
How much water does a solar pump give per day?
About 3,600 × kWh of hydraulic energy ÷ (9.80665 × head). A pump that delivers 7.19 kWh a day of water power lifts 60 m³ through 44 m, or about 132 m³ through 20 m.
Does the calculator include the PM-KUSUM subsidy amount?
No amounts are built in because benchmark costs and state shares change. The note gives the central share (30% or 50%) from MNRE’s published criteria.
Can I use it for a borehole outside India?
Yes. Pick your region’s sun hours or type a value; the hydraulics are the same everywhere.