Solar Water Pumps
| Grundfos SQF Pumps | Price (US $) |
|---|---|
| Check Grundfos SQF Water Production Pump Sizing Chart | |
| Grundfos 3 SQF-2 | 1786.24 |
| Grundfos 3 SQF-3 | 1786.24 |
| Grundfos 6 SQF-2 | 1786.24 |
| Grundfos 6 SQF-3 | 1786.24 |
| Grundfos11 SQF-2 | 1786.24 |
| Grundfos 16 SQF-10 | 1958.61 |
| Grundfos 40 SQF-5 | 1786.24 |
| Grundfos SQF IO 50 Disconnect Box | 62.91 |
| Grundfos SQF IO 101-115V Switch Box | 394.14 |
| Grundfos SQF CU200 Smart Box | 306.03 |
| Grundfos SQF Float Switch (CU200) | 20.49 |
| SHURflo 9300 Subersible Pump | |
| SHURflo 9300 Subersible Pump 24V | 645.00 |
| SHURflo 9300 Pumps Control 902-100 24V | 118.33 |
| SHURflo 9300 Pumps Control 902-200 12 - 24V | 251.45 |
| El-Sid Pump | |
| EL-Sid 10PV Pump | 273.28 |
| El-Sid 10B-12 (Bat.) | 273.78 |
| El-Sid 10B-24 (Bat.) | 345.50 |
| El-Sid 20B12 | 381.49 |
Solar Water Pumping
The sun is the natural source of energy for an independent water supply. solar pumps operate anywhere the sun shines and the longer it shines, the more they pump. When it's cloudy, they pump less water, but often you need less water when it's 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.
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.
To use solar energy economically, the pumping system must utilize the entire solar day, while drawing a minimum of power. This means pumping more slowly than conventional pumps. Many solar pumps are designed to produce less than 6 gpm. To obtain the most output from the least amount of solar electricity, these small pumps generally use motors and pumping mechanisms that are more efficient than conventional AC powered centrifugal pumps.
The most efficient pumps are "positive displacement" pumps which pump a certain amount of water with each rotation. If it is cloudy or early morning, the pumps will receive less energy and run more slowly. A positive displacement pump will pump approximately half as much water with half as much energy.
Conventional AC pumps are usually centrifugal pumps that spin at a 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 half speed, it pumps one quarter the pressure. 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. Compare that with the cost of a solar pumping system that needs attention only once every 2 to 20 years depending on the 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.
Submersible Pumps
If you are pumping from a well, we have solar pumps that can delivery from 1 gallon per minute to over 75 gpm. The smallest pumps, the low-power diaphragm pumps from SHURflo can be powered by two 50- to 100-watt solar modules, depending on the head (vertical distance) they are pumping. They can pump 500 to 1000 gallons per day and lift water 200 feet. These pumps require service every 2 to 4 years.
If you have a higher lift, need more water or want a pumps that does not require service for 10 to 20 years, the Grundfos SQF pump is a good choice. The SQFlex can lift water over 800 feet and can pump over 20,000 gallons per day at lower lifts. The SQFlex pump can be powered by solar modules, a wind generator, a fuel powered generator, an inverter, the utility grid, or a conventional of several of these.
For information on which Grundfos SQFlex pump would best suit your needs, see our chart.
Surface Pumps
Surface pumps are less expensive than DC submersibles, where applicable. A surface pump is not submersible. It can draw water from a spring, 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.
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 feet 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 factor that determine power requirements.
Pressurization
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 what is required for the household use.
An AC pressure pump 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 because the sun may not be shining when you need pressure and thus the pump may not keep up with the 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 lease 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. 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 "draw down volume" of the tank.
Calculation of Solar Power Needs
If you are using a pump driven directly by solar panels, the 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 its maximum output for more hours of the day, delivering more gallons per day.
