Solar water pumps and other DC powered pumps are used throughout world to circulate water, irrigate crops, water livestock, and provide potable drinking water. In remote areas where the cost of running traditional water piping is cost prohibitive, a solar water pump may be the solution. Solar water pumps can also be used in solar hot water systems. Some solar pumping applications use gravity “pressure” tanks, where the pump runs to fill a tank elevated above the point of use. The water is then released on an as needed basis for use in gardens, vineyards, orchards, to supply water to livestock, or to any number of other applications. And with a solar water pump, you can even pump water when the electricity goes out!
Typical solar water pump applications:
Types of Solar Water Pumps
Solar pumps fall into two main categories: Surface pumps – which include pressure, delivery, and booster pumps; and Submersible pumps – primarily submersible well pumps. The type of solar water pump you need will depend on your application and the configuration of the water source.
Used primarily in solar water heating applications. These pumps run directly from a small solar panel. No battery is required.
Surface pumps like the Flowlight Booster or Solar Force pumps, as well as Shurflo’s AC and DC powered diaphragm pumps, are used for shallow wells, ponds, surface springs, creeks and storage tanks where the water surface is within 10 feet of ground level. Surface pumps are placed near the water source and cannot be submerged. Water is drawn up into the pump through tubing and can then be pushed up to 100 feet higher than the source, and/or across considerable horizontal distances. Surface pumps can be used to provide household water pressure. Each pound of pressure rating of a pump gives 2.3 feet vertical lift.
Important notes about surface pumps:
Suction lift should be kept to a minimum. The shorter the suction lift, the more reliable and quiet your pump will be. The maximum possible suction limit for a surface pump is 31 vertical feet at sea level (subtract 1 ft. for every 1000 ft. of elevation). However 6 to 25 foot suction is the limit for most. Some pumps, such as the Shurflo pump will pull from about 5 to 8 feet at sea level.
Delivery pumps are used to move water from one place to another. Some are capable of high pressure while others are intended mainly for moving large volumes at low pressure (such as moving water from a cistern to a stock watering tank). Flows can be small (1/2 gallon per minute or so) up to 30-40 gpm. Some (such as the popular 12 volt Shurflo pumps) are often used for pressurizing small water systems in homes, RV’s, and boats.
Submersible Pumps (Solar Well Pumps)
Submersible solar pumps are generally used for low to medium lift wells (up to 650 feet) where high flow capacity is required. Submersible pumps are designed to fit inside the well casing in a drilled hole; the most common casing sizes are between 4″ to 6″. Some older wells may be smaller than 4″, and solar submersible pumps will not fit. Submersible pumps can operate directly off solar panels, batteries or in some cases an AC power source. Solar powered well pumps are seldom suitable for pumping large amounts of water, for uses such as irrigating large fields.
DC powered submersible well pumps use only about 20% as much energy per gallon of water pumped as an AC centrifugal pump. Most pump very slowly, so they are less likely to drain a low producing well. They can be operated solar PV direct, without batteries, or they can be powered by house batteries, like any DC appliance. Some submersible DC pumps allow for AC operation, a nice feature if you ever need to pump more water than your DC system will allow. Submersible pumps will not freeze or lose their prime.
AC powered centrifugal pumps push water faster than DC powered pumps, and last many years with no maintenance or repairs. The drawback of AC pumps, particularly in remote locations or when used in backup water systems, is that they use 4 to 8 times the power per gallon pumped than slower DC pumps. AC pumps use much of the full capacity of the inverter, and come on at unpredictable times. Pumping and running a washer at the same time may require a relay to pause the washer, giving the pump priority when it runs. A submersible deep well pump of 1/3 or 1/2 horsepower with 120 volt motor can pump a 300 foot well and be powered by a 2500 watt or larger inverter. If you use an AC pump, get 110 volt, 1/2 horse maximum, with external starting box. The start box must be relay start control, not solid state control, if used with a modified sine wave inverter. Solid state start will only work with a true sine wave inverter. No surge, or soft-start pumps are best if depth of water in the well is within their range.
Powering Your DC Water Pump
Solar panels, batteries and other things required to power your DC water pump are sold separately from the pumps themselves. Exactly which items you will need depends on a variety of factors, so please call or email us so we can help you find the right solution.
Need help selecting a pump or designing a system to power it? Give us a call and we can help you find the solution that will best fit your application AND your budget.
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