Last updated: 2026-11-04
Colorado State University Extension's example sizes a solar well pump array at about 1.25 times the pump's electrical demand, which follows from daily water, total dynamic head and pump efficiency. This guide's worked example, 4,000 litres a day from a 45 m head on 5 peak sun hours, lands near 350 W of panels.
Your borehole sits a few hundred metres from the nearest power pole, the water has to come up every day, and extending the grid line is not practical. A solar well pump answers that by running the pump from panels during daylight, but it only works when the pump, the array and the water storage are sized together. This guide walks through the head calculation, the panel sizing and the details a supplier needs before quoting a solar water well pump.
How a solar well pump system works
A solar well pump system lifts water with a pump powered by a PV array through a controller, and it stores the pumped water in a tank instead of storing electricity in batteries.
The chain has four parts. Panels produce DC power while the sun is up, a controller matches that power to the pump motor, the pump lifts water up the well, and a tank holds the day's output. Household or livestock demand then draws from the tank at any hour, including at night.
Water storage often replaces batteries because a tank stores energy as water at height. The energy involved is easy to calculate: lifting 1 m3 of water by 1 m takes 9.81 kJ, which is about 0.0027 kWh. A battery bank would add a charge regulator and one more component to maintain, while a tank is a plain vessel with a float or level switch.
Batteries still make sense when the pump must run at fixed times regardless of sun, or when the same array also feeds lighting or a gate. For a pure water supply, a solar powered well pump system with a correctly sized tank is the simpler build.
The numbers to work out first
Five numbers decide a solar well pump design: the daily water need, the static water level, the drawdown, the rise from the well top to the tank, and the total dynamic head they produce.
Total dynamic head is the total vertical lift, plus an allowance for friction, that the pump must work against. Colorado State University Extension gives the formula as TDH = (depth from the static water table to the top of the well + drawdown at the pumping rate + rise from the well top to the top of the storage tank) x 1.1.
Static level is the depth to water when the pump is off. Drawdown is how far the water level falls once the pump runs at the chosen rate, and a well test or driller's record gives it. A long horizontal pipe run adds friction that a simple 1.1 multiplier may not cover, so a run of several hundred metres needs its own friction calculation.
The same Colorado State guide works an example for a stock-water system: 1,000 gallons per day for 50 cow-calf pairs at about 20 gallons per pair per day. For this guide, take an assumed borehole with a daily need of 4,000 litres, 30 m to static water, 5 m of drawdown and a tank 6 m above the well top.
| Input or step | Value | Basis |
|---|---|---|
| Daily water need | 4,000 L | Assumed |
| Depth to static water | 30 m | Assumed |
| Drawdown while pumping | 5 m | Assumed |
| Rise to the tank | 6 m | Assumed |
| Sum of the three heads | 41 m | 30 + 5 + 6 |
| Total dynamic head | 45.1 m | 41 x 1.1 |
How to size the panel array for the pump
The panel array size equals the pump's hydraulic power divided by the pump efficiency, then multiplied by an allowance for losses in the modules and electronics.
Hydraulic power in watts is the flow in litres per second times the head in metres times 9.81. The flow comes from the daily need and the sun available. Virginia Cooperative Extension describes peak sun hours as an estimate of the hours in a day when solar radiation equals 1 kW per square meter, and the same publication defines the design flow rate as daily water need divided by the peak sun hours.
Take 5 peak sun hours as an assumption. The design flow is 4,000 L / 5 h = 800 L/h, which is 0.222 L/s. Hydraulic power is 0.222 x 45.1 x 9.81, or about 98 W.
Pump efficiency is the next assumption. The Colorado State example needs 160 W at the pump for 90 ft of head at 3.5 gpm; the same arithmetic puts that pump's overall efficiency near 37%.
This guide assumes 35%, so the pump draws 98 / 0.35, or about 281 W. The Colorado State example then sizes the array at roughly 1.25 times the pump requirement, and applying that ratio gives 281 x 1.25, or about 351 W of panels.
For panel choices on smaller pumps, the guide on matching a solar panel for a water pump covers the voltage and wattage side.
Sizing for the worst month, not the average
A solar well pump array must be sized for the lowest peak sun hours in the months when water is needed, because the same daily volume then has to be pumped in fewer hours.
Design flow is daily need divided by peak sun hours, so fewer hours push the flow up, and hydraulic power rises in step with flow. Suppose the same borehole has only 3 peak sun hours in its dullest working month. That figure is an assumption for illustration; a real design reads the location's own data.
| Quantity | 5 peak sun hours | 3 peak sun hours |
|---|---|---|
| Design flow | 800 L/h | 1,333 L/h |
| Hydraulic power at 45.1 m | 98 W | 164 W |
| Pump input at 35% | 281 W | 468 W |
| Array at 1.25 x | 351 W | 585 W |
The table holds head at 45.1 m to isolate the effect of sun hours. A 1,333 L/h rate draws the well down further than 800 L/h, so re-check the drawdown and confirm the well can sustain that rate.
The array for the dull month is about two thirds larger than the array for the bright month. Two other levers reduce that gap. A tank sized for the daily need times the days of autonomy wanted (8,000 L for two days in this example) carries demand through cloudy spells; refilling it afterwards needs array and pump capacity above the daily need, and a lower daily target in the dullest month removes the peak entirely.
Submersible or surface pump, DC or AC
A submersible pump suits wells where the water sits deeper than a surface pump can pull, while a surface pump suits shallow water, ponds and tank transfer.
A surface pump pulls water up by suction, and atmospheric pressure caps that lift at about 10.3 m in theory. The usable lift is lower once friction and pump losses count, so read the suction lift from the pump datasheet.
A submersible pump sits below the drawdown level and pushes water up, so it handles the 35 m of static level plus drawdown in the worked example. Its body must fit the well casing, which is why casing diameter belongs in any enquiry.
The USDA Agricultural Research Service reports that with a 160 W PV array, most diaphragm pumps can draw enough water from wells 100 ft (about 30 m) deep or less to supply 75 head of cattle. A 2010 USDA ARS article on remote water pumps reports that solar is usually the best power choice for pumps with motors rated under 1,500 W, drawing on 31 years of testing near Bushland, Texas.
On the electrical side, a DC pump runs from the array through a controller, and its speed follows the sunlight. An AC pump needs an inverter sized to the motor, which adds a component but opens a wider choice of motors. For loads like the 281 W example, a DC submersible pump is the direct fit.
Ask for dry-run or low-water protection, because a pump can be damaged if the water level falls below its intake.
The water pumps LinkSolar lists today are small fountain and aeration pumps, such as the 5W solar fountain pump with a color LED ring, rated at a maximum flow of 120 L/h and a maximum lift of up to 50 cm. The 5W solar air pump kit and the 2W solar air pump with a 2000mAh battery are aeration products. None of these is a well pump, and none can draw well water.
What to send for a quote
A quote request for a solar deep well pump or shallow well system needs seven inputs: well depth, static level, casing diameter, daily water, location, power preference and quantity.
- Well depth: the total drilled depth and the depth at which the pump would sit.
- Static water level and, if a test exists, the drawdown at the pumping rate.
- Casing diameter: inner diameter in millimetres or inches, since it limits the pump body.
- Daily water need in litres or gallons, plus the months when it peaks.
- Location: country and region, so peak sun hours can be checked for the dullest working month.
- Power preference: DC direct from panels, AC with an inverter, or a battery-backed arrangement.
- Quantity of complete systems, and whether the tank and pipework are in scope.
With those seven answers the head and array calculation above can be repeated on your real numbers. Well pump systems are quoted to the specification you send, and whether a given system can be supplied is confirmed at quotation. LinkSolar is a China-based B2B supplier of custom & OEM solar panels, solar cells and mounting hardware.
FAQ
Can solar power run a well pump?
Solar power can run a well pump when the array is sized for the pump's electrical demand and the water is stored in a tank. A 2010 USDA ARS article on remote water pumps reports that solar is usually the best power choice for pump motors rated under 1,500 W.
What size solar panel does a well pump need?
Colorado State University Extension's example sizes the array at about 1.25 times the pump's electrical demand, and this guide uses the same ratio. In the worked example above, 4,000 L a day from a 45.1 m head on 5 peak sun hours needs roughly 351 W. Your own well depth, water need and local sun hours will change that figure.
Does a solar well pump kit need batteries?
A solar well pump kit usually does not need batteries when it fills a storage tank. The pump runs while the sun shines and the tank supplies water at night and on cloudy days. Batteries are an option when the pump must start at fixed times.
Can the small solar fountain pumps on your site lift well water?
The small solar fountain pumps on the LinkSolar site cannot lift well water. They are rated for a maximum lift of up to 50 cm, while the worked example in this guide needs about 45 m. Browse the Solar Pumps Fountains Aerators collection for fountain and aeration use only.
Next step
For a well, use the Quote Now button on this page and include those seven inputs. The linked collection is for ponds, fountains and aeration.
For a pond or fountain, have the water volume and lift ready, then Browse the matching products