Customers wanting to pump water with solar or wind energy.
For locations without power lines, we feature ultra high
quality Dankoff Solar Pumps which offer a clean and simple
alternative to fuel-burning generators and windmills. They
require no fuel deliveries, and very little maintenance. A
solar pump, produces the most water when it is needed the most
-- when the weather is sunny and dry! Dankoff specializes in
pumps with DC motors since they are more efficient than AC
pumps. Their pumps can operate directly off of solar electric
panels, batteries or any DC power source. They are most
commonly operated off solar electric panels which is why they
are known as solar pumps. Some of Dankoff's pump models can be
ordered to operate off AC power for situations where utility
or generator power is available but efficiency is paramount.
Solar water pumps are
specially designed to utilize DC electric power from
photovoltaic panels. They must work during low light
conditions at reduced power, without stalling or overheating.
Low volume pumps use positive displacement (volumetric)
mechanisms which seal water in cavities and force it upward.
Lift capacity is maintained even while pumping slowly. These
mechanisms include diaphragm, vane and piston pumps. These
differ from a conventional centrifugal pump that needs to spin
fast to work efficiently. Centrifugal pumps are used where
higher volumes are required.
A surface pump is one that is mounted at ground level. A
submersible pump is one that is lowered into the water. Most
deep wells use submersible pumps.
A pump controller (current booster) is an electronic device
used with most solar pumps. It acts like an automatic
transmission, helping the pump to start and not to stall in
weak sunlight.
A solar tracker may be used to tilt the PV array as the sun
moves across the sky. This increases daily energy gain by as
much as 55%. With more hours of peak sun, a smaller pump and
power system may be used, thus reducing overall cost. Tracking
works best in clear sunny weather. It is less effective in
cloudy climates and on short winter days.
Storage is important. Three to ten days' storage may be
required, depending on climate and water usage. Most systems
use water storage rather than batteries, for simplicity and
economy. A float switch can turn the pump off when the water
tank fills, to prevent overflow.
Compared with windmills, solar pumps are less expensive, and
much easier to install and maintain. They provide a more
consistent supply of water. They can be installed in valleys
and wooded areas where wind exposure is poor. A PV array may
be placed some distance away from the pump itself, even
several hundred feet (100 m) away.
What solar pumping is used for:
Livestock Watering: Cattle ranchers in the Americas,
Australia and Southern Africa are enthusiastic solar pump
users. Their water sources are scattered over vast rangeland
where power lines are few, and costs of transport and
maintenance are high. Some ranchers use solar pumps to
distribute water through several miles (over 5 km) of
pipelines. Others use portable systems, moving them from one
water source to another.
Irrigation: Solar pumps are used on small farms,
orchards, vineyards and gardens. It is most economical to pump
PV array-direct (without battery), store water in a tank, and
distribute it by gravity flow. Where pressurizing is required,
storage batteries stabilize the voltage for consistent flow
and distribution, and may eliminate the need for a storage
tank.
Domestic Water: Solar pumps are used for private homes,
villages, medical clinics, etc. A water pump can be powered by
its own PV array, or by a main system that powers lights and
appliances. An elevated storage tank may be used, or a second
pump called a booster pump can provide water pressure. Or, the
main battery system can provide storage instead of a tank.
Rain catchment can supplement solar pumping when sunshine is
scarce. To design a system, it helps to view the whole picture
and consider all the resources.
Thinking Small
There are no limits to how large solar pumps can be built.
But, they tend to be most competitive in small installations
where combustion engines are least economical. The smallest
solar pumps require less than 150 watts, and can lift water
from depths exceeding 200 Feet (65 m) at 1.5 gallons (5.7
liters) per minute. You may be surprised by the performance of
such a small system. In a 10-hour sunny day it can lift 900
gallons (3400 liters). That's enough to supply several
families, or 30 head of cattle, or 40 fruit trees!
Slow solar pumping lets us utilize low-yield water sources. It
also reduces the cost of long pipelines, since small-sized
pipe may be used. The length of piping has little bearing on
the energy required to pump, so water can be pushed over great
distances as low cost. Small solar pumps may be installed
without heavy equipment or special skills.
The most effective way to minimize the cost of solar pumping
is to minimize water demand through conservation. Drip
irrigation, for example, may reduce consumption to less than
half that of traditional methods. In homes, low water toilets
can reduce total domestic use by half. Water efficiency is a
primary consideration in solar pumping economics.
A Careful Design Approach
When a generator or utility mains are present, we use a
relatively large pump and turn it on only as needed. With
solar pumping, we don't have this luxury. Photovoltaic panels
are expensive, so we must size our systems carefully. It is
like fitting a suit of clothes; you need all the measurements.
Here is a guide to the data that you will need to determine
feasibility, to design a system, or to request a quote from us.
First, we will determine whether a submersible pump or a
surface pump is best. This is based on the nature of the water
source. Submersible pumps are suited both to deep well and to
surface water sources. Surface pumps can only draw water from
about 20 feet (6m) below ground level, but they can push it
far uphill. Where a surface pump is feasible, it is less
expensive than a submersible, and a greater variety is
available.
Next, we need to determine the flow rate required. Here is the
equation, in the simplest terms:
Gallons (Cubic Meters) per Hour = Gallons (Cubic Meters) Per
Day / Available Peak Sun Hours per Day
Peak Sun Hours refers to the average equivalent hours of
full-sun energy received per day. It varies with the location
and the season. For example, the arid central-western USA
averages 7 peak hours in summer, and dips to 4.5 peak hours in
mid-winter.
With this information we can now refer to Dankoff's pump
performance charts for the type of pump that is appropriate.
They will specify the size and configuration (voltage) of
solar array necessary to run the pump.
If you need assistance in
selecting a pump just give us a call and provide us with
information about your water source such as depth, gallons per
hour needed, whether it is a surface application or
submersible application and will do the rest. 1-888-647-6527
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