Solar-Powered Water Pumping

Intermediate

Inside this Article

Solar powered pumping for stock tanks.
Pump parts labeled in photo
This submersible pump is suspended from a raft near the center of this pond. Note the PV array that sits close to the pond’s edge.
A surface pump can move large amounts of water, but because it has a limited draw depth, it is not usually used in drilled wells.
An in-well pressure-tank assembly for freeze protection.
This SunPumps controller can run PV-direct or from batteries, and includes remote switching and a low-water cutoff.
This Grundfos controller operates on AC or DC, and in a variety of voltages.
Battery-based pumping systems provide water when the sun isn’t shining, but add cost and complexity.
A float switch hangs on a weight inside a storage tank.
A typical pressure switch can control a PV-powered pump.
Aboveground poly tanks are inexpensive and durable. White ones stay cooler, but allow light to penetrate, which can cause more algae growth.
Even a few feet of height can give a tank enough head for low-pressure gravity distribution.
SunPumps’ SCB 10-185 DC surface pump.
This Lorentz pump controller converts DC to three-phase, variable-frequency AC. Pictured next to the controller is a three-phase AC submersible pump.

Solar water pumps are a cost-effective and dependable method for providing water in situations where water resources are spread over long distances; power lines are few or non-existent; or fuel and maintenance costs are considerable.

Solar pumps are specifically designed to accept DC power directly from the solar modules and are optimized for operating under less-than-ideal sun conditions. Where conventional AC-powered pumps require a stable voltage and frequency to operate, solar pumps can operate over a wide range of voltage and available current.

Conventional AC-powered pumps require large amounts of power to move large volumes of water in a short period of time. Solar pumps typically move a smaller volume of water over an extended period of time. This method requires far less power, which minimizes the size and cost of the PV array.

There are several methods for pumping water in remote areas, such as windmills, gas/diesel pumps, and ram pumps. But most of these options are either too expensive to install, or for fuel and maintenance, or require specific site conditions to operate.

Solar pumps can work for most locations and are at full capacity when needed most: during warm, sunny days. In temperate regions, they can be used year-round—which can be particularly helpful for potable water, animal grazing, and other farming operations. For many sites, a solar pump is often the best option for reducing cost and labor.

In areas with a remote well and limited access to the power grid, solar pumps are the best option—particularly where utility interconnection costs more than $5,000, usually about one-quarter to one-third mile from the grid. (In my area—western New York—the cost for utility power is about $10 per foot, so even PV-based water-pumping systems that are one-eighth mile from the nearest power line can be cost-competitive.) Specific applications include:

Domestic water supplies for off-grid homes and cabins. Although solar water pumps are used in this application, usually the home has an existing power system. In that case, it’s far more cost-effective to run an efficient DC or AC pump off that system.

Livestock watering for pond and stream protection, rotational or prescribed grazing, and remote pasturing. This is the most popular use for solar pumping systems. They have proven to be cost-effective even without the use of federal or state incentives.

Aquaculture for aeration, circulation, and de-icing. Aquaculture is another application where the need for power coincides with peak solar availability. De-icing applications require oversized arrays due to less-than-optimum sun conditions in winter.

Irrigation for small-scale applications. With the recent reduction in the cost of PV modules, solar irrigation is fast becoming cost-effective. Solar pumps are available that can move the larger volumes of water needed for irrigation.

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Comments (8)

ellediarra's picture

I am very new to this and I am having trouble determining wattage for solar panels and thus selecting a pump. The system is fairly small, producing 0.25gpm at 80psi. I believe I have a total lift of 184ft. (0 vertical lift + pressure converted to feet of water). What would you recommend?

Poolman Dan's picture

I am looking for a solar powered water pump with extremely low head to push water up about 500' in elevation. This is not a well, it is from an external water tank. Any recommendations?

bullardrr's picture

500 feet of elevation is definitely not low head. You are looking at a turbine or piston type pump, most likely. You may want to start with Grundfos. If nothing else, you could drop one of their DC high head submersibles into your tank. It would not know the difference compared to being in a well as long as the operating range was a meter or so above the intake.

Almaqtary's picture

what are the hazard and accidents caused by control unit in the solar pumping water system

bullardrr's picture

If the water lift in the well is significant (say over 30 meters) requiring a multiple stage submersible in the well casing, an interesting energy storage option if there is sizable ground storage volume is to install a second well and insert a turbo generator with the lowest stage at 5 to 7 meters above the average aquifer saturation elevation. I am sure the HomePower gadgeteers are capable of devising a small down-hole turbo-generator that would extract at least 75 per cent of the kinetic (falling water to electricity) in the flow recharging the aquifer from surface storage. A lot cheaper than batteries in the long run.

Jim Palmer_3's picture

I want to use a floating PV/battery pump system to aerate a large pond for raising small fish for salmon enhancement. Is it better to pump water such that it will entrain air or to simply pump air into the water. If pumping air is better, what sort of pump would be suitable and efficient and how would I calculate size and energy requirements?

Thanks,

Jim

bullardrr's picture

In general, pumping water for aeration is more efficient, based on Ideal Gas Law (the PVT relationship), although at low pressures, the difference is rather small.

William Heidecker's picture

Good article.
There is very little sense to consider utility based power for livestock applications. The initial cost of accessing utility power has become extremely high in our area (Alberta). As well, the actual cost of power (especially the T&D) has become one of the highest in N.America. I intend to convert a utility based pump system with a PV system next season and it should have a 3 year payback (without subsidies or incentives).

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