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The sun and wind are the natural source of energy for an independent water supply. Solar pumps operate anywhere that the sun shines, and the longer it shines, the more water they pump. When it's cloudy, they pump less water, but often you need less water when it is cloudy. Photovoltaic modules, the power source for solar pumping, have no moving parts, require no maintenance and last for decades. A properly designed solar pumping system will be efficient, simple and reliable. Whereas wind power is good where there is prevailing winds and are also a good backup for solar powered pumping.
Solar water pumping systems operate on direct current. The output of the solar power system varies throughout the day and with changes in weather conditions. The nature of variable electricity in the form of direct current (DC) is quite different from conventional, steady alternating (AC) current from the utility grid or a generator. To use solar energy economically, the pumping system must utilize the long solar dary, drawing a minimum of power. This means pumping slower than conventional pumps. Pumping at rates of less than 6 GPM requires different mechanisms from the conventional (centrifugal) pumps.
Small solar pumps are unique, both electrically and
mechanically. The most efficient pumps are "positive displacement"
pumps; that pump a certain amount of water with each rotation. If it is
cloudy or early morning, the pump will receive less energy and run
slower. A "positive displacement" pump will pump approximately ½ as much
water with ½ as much energy.
Conventional AC pumps are usually centrifugal pumps that turn at high speed to pump as many gallons per minute as possible. They also consume a large amount of power. If you run a centrifugal pump at ½ speed, it pumps ¼ the water. Their efficiency is very low at low speeds and when pumping against high pressure.
If your water sources are remote from power lines, add up your long-term costs of fuel and repairs on generators, or the cost of utility line extensions. Now consider the savings with a solar pump that needs attention only once every 2 to 20 years depending on model.
Solar powered pumps can provide an equal volume of water per day without the high and inefficient energy demands of a large capacity AC pump. Instead of pumping a large volume of water in a short time and turning off, the solar pump works slowly and efficiently all day. Often a solar pump will work fine in a well with a recovery rate too slow for a conventional AC pump.
If you are pumping from a well, we have solar pumps that can deliver from 1 gallon per minute (GPM) to over 75 GPM.
The smallest pump, the low power diaphragm pump from Shurflo, operates from two 50 to 75 watt solar modules, depending on the head (vertical distance) they are pumping. It can pump 500 to 1000 gallons per day and lift water 200 feet. This pump requires service every 2 to 4 years.
If you have a higher lift, need more water or want a pump that does not require service for 15 to 20 years, the Grundfos SQFlex pump is a good choice. The SQFlex can lift water 525 feet and can pump over 20,000 gallons per day at lower lifts.
For greater water needs or deeper wells, the Grundfos SQ-series AC submersible pump can easily be powered by an inverter or generator.
Larger conventional single and three phase AC pumps, up to 10 HP, can be solar powered with the Aerovironment AC Pump Controller and a large PV array.
Surface pumps are less expensive than DC submersibles, where applicable. A surface pump is not submersible. It can draw water from a dug well, spring, pond, river or tank, and push it far uphill and through a long pipeline to fill a storage tank or to pressurize it for home use or for irrigation, livestock, etc. The pump may be placed at ground level, or suspended in a well in some cases.
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All pumps are better at pushing than pulling. Surface pumps
must be placed no higher than 10 or 20 feet above the surface of the
water source at sea level (subtract one foot per 1000 ft. Elevation).
Suction piping must be oversized a bit and not allow air entrapment
(much like a drain line) and should be as short as possible. Pumps can
push very long distances. The vertical lift and flow rates are the
primary factors that determine power requirements.
Many conventional AC powered water systems pump from a well or other water source, into a pressure tank that stores water and stabilizes the pressure for household use. When you turn on water in the house, an air-filled bladder in the tank forces the water into the pipes. When the pressure drops, a pressure switch turns on the pump, refilling and repressurizing the tank. This works fine because of the ability of the AC pump to deliver a volume of water larger than the household uses. This can work in systems with an inverter large enough to run a standard AC pump. However, this will not work with pumps operating directly from PV modules. First, the sun may not be shining when you need pressure. Second, many solar pumps deliver water too slowly to keep up with household use. There are two ways to solve this problem. A non-pressurized water tank can be located high enough above the house for gravity to supply the water pressure. This can be on a hill or a tower. Water pressure in PSI = Head in feet times 0.433. For reasonable pressure the tank needs to be at least 40 feet above the house. If this is not possible, a battery operated pressure booster pump can fill a pressure tank as needed from a storage tank that is filled by a solar pump during the day. The Flowlight Booster pump, as well as the Shurflo 2088 pumps can be used for this purpose. You must use a pump that can deliver the maximum GPM required by the house, or have a pressure tank that is large enough to make up the difference between what the pressure pump can deliver and what is required, for the amount of time it is required. This is called the "drawdown volume" of the tank. Air filled pressure tanks can be obtained locally from a pump dealer. Calculation of Solar Power Needs With all solar powered pumps, the necessary solar array can be determined by looking at the watts required for the head and flow in your situation. Solar array watts should be at least 20% higher than the power required by the pump in your situation. If you use a larger array or a tracking array, the pump will operate at it's maximum output for more hours of the day, delivering more gallons per day. If the pump runs on 24 volts, you can use pairs of 12V solar modules wired in series or 24V modules. Two solar modules with total wattage equivalent to or exceeding the wattage required by the pump must be used. If the pump uses 48 volts, you can use groups of four 12V solar modules wired in series or group of two 24V modules whose total wattage exceeds the pump’s power requirement. |
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Linear current boosters from Solar Converters are used in solar direct pumping applications. They can achieve a 30-90 percent increase in water pumped over connecting the pump directly to the solar panels. We can special order 90V units that can operate 12-, 24-, 36-, and 48-volt pumps from several modules in series. This will be useful where the panels must be a long distance from the motor, allowing wiring with a smaller wire size as the current is reduced. The wire savings alone can easily pay for the controller. Call for details.
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Solar
Converters model |
Array
volts nominal |
Current
max amps |
PART NUMBER | OUR PRICE | Purchase |
| PPT 12/24-7 | 12 or 24 | 7 | 075-00124 | $112 |
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| PPT 12/24-15 | 12 or 24 | 15 | 075-00126 | $247 |
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| PPT 12/24-30 | 12 or 24 | 30 | 075-00128 | $449 |
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| PPT 48-10 | 48 | 10 | 075-00136 | $263 |
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The SPDT float switch can be used to control a pump in tank filling or tank-emptying operation.
Contacts located in the float will switch at 12 degrees above and below horizontal. Use a pipe clamp or cable tie to secure the cable to a pipe or weight in tank.
The length of cable from clamp to float determines the difference between turn-on level and turn-off level. For larger pumps, use float switch to turn a relay on and off and let relay contacts control pump. Safe for domestic water systems.
2-year warranty.
ON WHEN FULL is used to turn on a pump when a tank is full and pump it down.
OFF WHEN FULL turns the pump off when a tank is filled. These are SPST switches.
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Description of operation |
Maximum
amps |
PART NUMBER | OUR PRICE | Purchase |
| SPDT three-wire | 5 | 075-05270 | $52 |
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| On when full | 13 | 075-04420 | $46 |
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| Off when full | 13 | 075-04422 | $46 |
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| On when full | 25 | 075-04407 | $105 |
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| Off when full | 25 | 075-04410 | $105 |
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The Solar Stream LJ-01 solar fountain pump provides a unique feature for any pond, garden pool, or business display. Powered by a 3 Watt photovoltaic module, the fountain sends a stream of water 6 feet into the air two times a second in full sun. The pump is a stainless steel cylinder 6 inches high and 3 inches in diameter. It fits into a 5 inch foam collar that allows the pump to float at the waters surface. An 8 foot cord allows connection to the commercial grade 3 Watt photovoltaic module which is supplied with the kit.
These pumps have only one moving part – a free piston. Electricity from sunlight (from the PV module) charges a capacitor. When the capacitor voltage reaches a fixed level (about 16 Volts), an electronic switch feeds the capacitor energy into the pump coil which drives the piston, creating a pulse of water. The more sunlight, the more pulses of water are delivered. 1-year warranty.
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Model Number |
Description |
PART NUMBER |
OUR PRICE |
Purchase |
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LJ-01 |
Solar Fountain Pump Kit |
075-08157 |
$150 |
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WE ACCEPT... |
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This page last up-dated on August 04, 2010