Solar-powered Livestock Watering Systems

Solar-powered Livestock Watering Systems
NCAT
Energy Brief
Solar-powered Livestock Watering Systems
R
emote or off-grid pumping (including solar, windmill,
and generator-power) provides cost-effective
livestock watering sources far from the utility grid. These
systems give livestock greater access to forage. They also
reduce livestock pressure on stream banks, preventing
nutrient loading, damage to streamside vegetation,
erosion and pollution.
Why should you consider installing a solar-powered
livestock watering system on your farm or ranch? These
factors may affect your decision:
✹ Utility line extension costs versus solar power
✹ Maintenance costs of a solar system versus a
windmill or gasoline, propane, or diesel generator
✹ The uncertainty of future electricity prices
✹ Rising costs of propane, gasoline, and diesel fuel
✹ Season of use — summer versus winter
Cost
Many people considering installing a solar water pumping
system are put off by the expense. Viewing the expense
over a period of 10 years, however, gives a better idea of
the actual cost. By comparing installation costs (including
labor), fuel costs, and maintenance costs over 10 years,
you may find that solar is an economical choice. A solarpowered pumping system is generally in the same price
A typical solar-powered stock watering system includes a solar array,
pump, storage tank and controller.
range as a new windmill but tends to be more reliable and
require less maintenance. A solar-powered pumping
system generally costs more initially than a gas, diesel, or
propane-powered generator but again requires far less
maintenance and labor. NCAT estimated likely costs for
six demonstration projects over a 10-year period. The
cost of solar-pumped water per cow ranged from $0.03
to $0.15 per day. The cost per gallon of water pumped
ranged from $0.002 to $0.007 per gallon.
Solar Pumping Technology
— What You Need to Know
Before talking to a dealer, it’s helpful to become
acquainted with the terms and equipment:
Solar Modules - Solar electric systems are sometimes
called photovoltaic systems. The word “photovoltaic” is
often abbreviated “PV.” Most solar panels, or modules,
generate direct current (DC) electricity. A group of
modules is called an array.
Twenty-four solar panels on the Sauerbier Ranch power a system that
pushes water uphill to a storage tank over two miles away.
Mounting Structures - There are two ways to mount
solar modules: either on a fixed structure or on a tracking
structure. Fixed mounts are less expensive and tolerate
higher wind loading but have to be carefully oriented so
they face true south (not magnetic south). An array can
easily be mounted on a trailer to make it portable. A
tracking array follows the sun across the sky. A tracker
will add at least $400 to $800 to the cost of a system, but
can increase water volume by 25 percent or more in the
summertime, compared to a fixed array.
Pumps - DC water pumps in general use one-third to
one-half the energy of conventional AC (alternating
current) pumps. DC pumps are classed as either
displacement or centrifugal, and can be either submersible or
surface types.
Displacement pumps use diaphragms, vanes or pistons to
seal water in a chamber and force it through a discharge
outlet. Centrifugal pumps use a spinning impeller that
adds energy to the water and pushes into the system,
similar to a water wheel. Submersible pumps, placed
down a well or sump, are highly reliable because they are
not exposed to freezing temperatures, do not need special
protection from the elements, and do not require priming.
Surface pumps, located at or near the water surface, are
used primarily for moving water through a pipeline. Some
surface pumps can develop high heads and are suitable
for moving water long distances or to high elevations.
Storage - Batteries are usually not recommended for
solar-powered livestock watering systems because they
reduce the overall efficiency of the system and add to the
maintenance and cost. Instead of storing electricity in
batteries, it’s generally simpler and more economical to
install three to 10 days’ worth of water storage.
Controller or Inverter
The pump controller
protects the pump
from high- or lowvoltage conditions and
maximizes the amount
of water pumped in
less than ideal light
conditions. An AC
pump requires an
inverter—an electronic
component that
converts DC electricity
from the solar panels
into AC electricity to
operate the pump.
Solar pumping replaced a gas-powered
generator on the Tomlinson Ranch near
Gold Creek.
Other equipment - A float switch turns a pump on and
off when filling the stock tank. It’s similar to the float in a
toilet tank but is wired to the pump controller. Low water
cut-off electrodes protect the pump from low water
conditions in the well.
Designing and Installing Systems
Every pumping and stock-watering situation is unique.
The average consumer is likely to be intimidated by the
prospect of sizing and designing a solar pumping system,
and most people need the assistance of a qualified solar
dealer. In general dealers are eager to help. Many will
provide a no-cost proposal based on a few simple
questions that can be asked over the phone. If the price
seems too high, you can easily get bids from other
dealers.
In order to size and design a system correctly, the dealer
will want to know:
✹ how much water you need
✹ when you need the water
✹ whether your water source is a stream, pond,
spring, or well
✹ water available in gallons per minute (gpm)
✹ well depth
✹ how far the water needs to be pumped, and with
what elevation gain
✹ water quality problems (e.g., silt or high mineral
content) that may damage the pump
A tracking PV array replaced an old and unreliable windmill on the
Ballard Ranch near Lavina.
✹ how much volume is available in storage tanks
and how the tanks are arranged
Ballard Ranch, Lavina
Jim and Adele Ballard installed a solar pumping system to
replace an old windmill that pumped water from a 65
foot deep well to a pair of stock tanks holding about
4000 gallons. The new system employs four 80-Watt PV
modules on a tracking rack and a submersible piston
pump with a maximum flow rate of 5.5 gpm to water
100 cow/calf pairs. The system produces average flows
of 2000 to 3000 gpd during the summer months. Solar
component costs: $5,500.
This solar pumping system on the Hirsch Ranch near Deer Lodge is
protecting stream banks along Racetrack Creek, an important trout
spawning stream.
Based on these factors, the dealer will recommend a
system, putting together a list of suitable components.
This is one area where the dealer’s experience and
familiarity with systems is essential. A dealer can also
save you time and aggravation by providing the correct
hardware: clips, screws, nuts, bolts, washers, cable (cut to
correct lengths), and assorted wiring and connectors. The
customer usually provides peripheral material, such as
water piping and fittings, tanks, mounting structure
support post, concrete, and grounding materials.
Installing a solar pumping system is generally something
the landowner can do. A few words of caution are
necessary, however. Installing a solar pump is a complex
task, combining elements of electrical work, plumbing,
and heavy construction (often including earthmoving,
pouring concrete, and welding). Written instructions are
not always as complete as they should be. A backhoe or
tractor with a front-end loader is almost a necessity for
some larger projects.
Project Descriptions
Tomlinson Ranch, Gold Creek
Jim Tomlinson installed a solar-powered pumping system
on his 160-foot deep well to provide water for 25 cow/
calf pairs. The system uses two 120-Watt PV modules, a
passive tracking rack, and a submersible diaphragm pump
with a maximum flow rate of just under one gpm. Water
is pumped to a 1350-gallon underground cistern and
flows by gravity into two 700-gallon stock tanks, with a
float valve ensuring that the flow stops once the tanks are
full. The system produces between 750 and 950 gallons
per day (gpd) during the summer months. Solar
component costs: $3,200.
Ueland Ranch, Anaconda
Don and Dan Ueland drilled a 50-foot deep well near the
stack yard of their ranch to water cows that are moved
into the feeding area after spring calving. Twelve 64-Watt
PV modules on a tracking rack and a submersible
centrifugal pump produce a maximum flow rate of 17
gpm. The pump is set at 43 feet in the well and
connected to low water cutoff electrodes that will shut
the pump down if the pumping rate exceeds the well
capacity. The water is pumped into a concrete tank with
an overflow drain that leads to a drainfield. The system is
designed to produce flows from 7800 gpd in March to
10,500 gpd in May. Solar component costs: $7,700.
Hirsch Ranch, Racetrack
Rick and Pam Hirsch installed a solar pumping system on
a 10-foot-deep backhoe-dug well on their property to
water 36 cow/calf pairs. The pumping system uses two
64-Watt PV modules, a passive tracking rack, and a
submersible diaphragm pump equipped with a sand
shroud and low water cut-off electrodes to protect the
pump. The system is designed to produce flows of 2600
to 2800 gpd during the summer months. Solar
component costs: $2,400.
Painted Robe Watershed Group, Lavina
The Painted Robe Watershed Group has been working to
develop off-stream sources of drinking water for cattle
along Painted Robe Creek, a tributary to the Musselshell
A trailer-mounted PV system is improving range management and water
quality along Painted Robe Creek near Lavina.
Solar pumping systems aren’t just for summer use, as this project
on Ueland Ranch near Anaconda demonstrates.
River with water quality problems. The group received a
trailer-mounted solar pumping system from the Montana
Department of Environmental Quality. It was first
installed on the Leo Schraudner Ranch to water 150 cattle
at the site of a 60-foot-deep well. Seven 60-Watt panels
on a fixed trailer-mounted rack use an inverter to convert
solar-produced DC to the AC electricity needed by the
submersible centrifugal pump. Water is pumped into two
1100-gallon tanks. The system is designed to produce
average flows of 2880 to 4000 gpd during the summer
months. Solar component costs: $10,650.
3040 Continental Drive
P.O. Box 3838
Butte, MT 59702-3838
1-800-275-6228
www.ncat.org
National Center
for Appropriate
Technology
Sauerbier Ranch, Sweetwater Basin
(between Sheridan and Dillon)
Dan Doornbos installed an ambitious solar pumping
system to water about 300 cow/calf pairs on a remote
pasture in the Sweetwater Basin. The Natural Resources
Conservation Service engineered 12,000 feet of pipeline
to pump water from Sweetwater Creek up to an 8000gallon water storage tank at a high point in the northeast
corner of the pasture. A valve on the tank allows
firefighters to fill tanker trucks. Other smaller watering
tanks are located at lower elevations in the pasture.
Twenty-four PV modules on two passive tracking racks
provide power to a three-horsepower surface piston
pump. The pump is set in a sump near the stream and is
equipped with low-water cut-off electrodes. Total
dynamic head is 421 feet, and the design flow is 11 gpm
during the summer months. The system produces flows
averaging 6600 to 7500 gpd during the summer. Solar
component costs: $24,500.
More information
To learn more about solar water pumping, or to find a
directory of solar equipment dealers and installers, visit
www.montanagreenpower.com or call NCAT at
800-275-6228 (800-ASK-NCAT).
This solar project was made possible by Universal System Benefits
Charge funding from Montana Power Company.
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