Solar water pumps offer a practical way to move water in locations where running a power line from the electric grid is too difficult or expensive. Unlike solar thermal systems that capture the sun’s heat, these setups use photovoltaic (PV) panels to generate electricity that runs a pump directly. The Mississippi State University Extension describes this as an option for remote areas that do not have easy access to the public power grid, noting that running electrical lines over one-third of a mile can become cost-prohibitive just to operate a single water pump.
This approach is distinct from the solar thermal systems covered in our guide to how solar water heating works, which use the sun’s heat directly. A solar water pump is a focused subcategory that shares some components with other off-grid solutions but follows its own design rules. For a broader look at where these systems fit, see our overview of solar pool heating and solar water pumps.
How a PV water pumping system is put together
The Mississippi State University Extension outlines the key pieces that make up a solar-powered pumping system. Each component plays a specific role in getting water from the ground to where it is needed.
PV array
According to the U.S. Energy Information Administration, a photovoltaic cell is a nonmechanical device that converts sunlight directly into electricity. When photons strike the semiconductor material in a cell, they can dislodge electrons, creating a flow of electricity. Individual cells are packaged into weather-tight panels, and multiple panels can be connected to form a PV array. The Mississippi State University Extension explains that the array is what most people refer to as solar panels, and once all the necessary equipment is connected and electricity is being generated, it becomes a fully functioning PV system.
Pump controller and float switch
The Mississippi State University Extension calls the pump controller the “brain” of the system. The pump, PV array, and a float switch in the storage tank all connect to this controller. It recognizes signals from the float switch or a low-water sensor in the pump and turns the pump on and off accordingly.
DC pump
The pump itself is the most expensive single part of the system, according to the Mississippi State University Extension. Because PV modules output direct current (DC) electricity, it is more economical to use a pump that operates on DC and forego the cost of an inverter. The pump must have enough lift to get water out of the well and be able to pump enough volume to meet daily water needs.
Storage tank
The Mississippi State University Extension recommends that a storage tank be large enough to hold several days’ supply of water. This stored water carries the system through periods when the solar panels are not generating power, such as at night or during cloudy weather. Water can be pumped directly into a large, open stock tank, or it can be pumped into a closed storage tank that gravity-feeds into a stock tank.
| Component | Role | What to check |
|---|---|---|
| PV array | Converts sunlight to DC electricity | Clean panels; check for shading, damage, and secure mounting |
| Pump controller | Manages on/off signals from float switch and sensors | Confirm indicator lights and connections are intact |
| DC pump | Lifts water from the well to the surface | Listen for unusual noise; verify flow rate at the tank |
| Storage tank | Holds water for use during no-sun periods | Inspect for leaks, cracks, and float switch operation |
| Float switch | Signals the controller when the tank is full or low | Ensure it moves freely and wiring is not damaged |
Sizing a system to water demand and well conditions
The Mississippi State University Extension stresses that a system must be matched to both the daily water requirement and the physical characteristics of the well. The publication walks through an example scenario to show how these factors come together.
Daily water demand
Start by estimating how many gallons per day (gpd) the system must deliver. The Mississippi State University Extension uses an example of 50 cattle at 20 gpd each, totaling 1,000 gpd. The storage tank should be sized to hold about three days’ worth of this average demand.
Well depth and total dynamic head
The deeper the water table at the well location, the more expensive it will be to drill the well and the larger the pump and power requirements become. The Mississippi State University Extension calculates total dynamic head as the height water needs to be pumped, which includes the pumping level (static water level plus well drawdown), the vertical rise from the ground to the tank inlet, and an adjustment for friction loss in the pipes.
Matching the pump and array
Once the required flow rate and total dynamic head are known, a pump curve can be used to find a pump that meets those conditions. The Mississippi State University Extension demonstrates this with a specific pump model, showing how the curve reveals both the flow rate and the power in watts needed to operate the pump. The solar array is then sized by multiplying that power requirement by a factor of roughly 1.25 to account for energy losses in the modules, controller, and wiring. It is also important to make sure the output voltage of the solar panels matches the voltage requirements of the pump.
Why storage replaces batteries
The Mississippi State University Extension points out that little to no power is generated from solar panels at night and during cloudy or overcast days. Instead of relying on a bank of batteries to run the pump around the clock, the system configuration uses a large storage tank. Water is pumped during sunny hours and held in the tank, so it is available whenever needed. The publication notes that a battery-operated system is an alternative that allows pumping outside daylight hours, while the configuration it describes stores water rather than electricity.
Site and orientation considerations
The Mississippi State University Extension explains that peak sunlight hours (PSH) are crucial for estimating how long the pump will run each day and how many gallons it can move. A peak sunlight hour is defined as 1,000 watts of solar energy striking a one-square-meter area for one hour, which is not the same as total hours of daylight. The publication states that Mississippi receives 4.5 to 5.2 PSH per day, while a state like New Mexico receives 6.0 to 8.5 PSH per day. An identical system in New Mexico can pump more gallons per day simply because the panels receive more intense sunlight for a longer portion of the day.
The U.S. Energy Information Administration notes that PV panels produce the most electricity when they are directly facing the sun. Most systems use a fixed position, usually facing directly south in the northern hemisphere, at an angle that optimizes performance. Tracking systems that keep panels aimed at the sun are available but add expense.
Maintenance and routine checks
The Mississippi State University Extension says solar-powered pumping systems have been installed successfully in livestock watering applications and have proven reliable. Keeping a system that way involves periodic attention to its parts. Inspect the PV array for dirt, debris, or shading that could reduce output. Check that the float switch in the storage tank moves freely and that its wiring is intact. Look over the tank itself for leaks or cracks. Confirm that the pump controller’s indicator lights show normal operation. Listen for changes in the sound of the pump, which can signal a problem. Any electrical work or well-related repairs should be handled by a qualified professional.
Professional design for wells and electrical work
The Mississippi State University Extension advises contacting a local, licensed water-well contractor for the well portion of the project. The publication also notes that if you are not comfortable with basic electrical concepts, it would be wise to contact an expert to help make sure the system will function properly and reliably. Any installation that connects to a home’s pressurized drinking-water supply must follow local plumbing and building codes and usually requires a permit and a qualified, licensed installer. In regions where freezing is possible, the system design must account for freeze damage to exposed pipes and components. The roof or mounting structure must be able to carry the load of the PV array.
Frequently asked questions
Is a solar water pump the same as a solar water heater?
No. A solar water pump uses photovoltaic panels to make electricity that runs a pump, moving water from a source to a storage tank. A solar water heater, covered in our solar water heating basics guide, uses solar thermal collectors to capture the sun’s heat and warm water for domestic use. The two technologies serve different purposes and have different components.
Do I need batteries for a solar water pump?
Not necessarily. The Mississippi State University Extension describes a configuration where water is pumped into a storage tank during sunny hours. The tank holds enough water to cover demand during nights and cloudy periods, so batteries are not required. A battery-operated system is an alternative if you need to pump outside daylight hours.
How do I know what size pump and panels I need?
The Mississippi State University Extension explains that sizing starts with your daily water demand in gallons per day and the total dynamic head of your well, which accounts for the pumping level, vertical rise, and friction loss. A pump curve is then used to find a pump that meets those conditions and to determine the power in watts it requires. The solar array is sized by adding a margin to that power figure to cover system losses. A professional designer can perform these calculations for your specific site.
For more on related off-grid water solutions, visit our other solar water solutions section or the main solar water pumps category page.
