Solar Water Pumping Kits

Water Pump Selection

The depth of the well or water source will ultimately determine the type of pump that you should use.

SHALLOW WELL

A shallow well, spring, creek, or storage tank where water surface is within 10' of ground level, can use the Flowlight DC or Aquatec AC or DC powered booster pumps located at the surface to suck the water up to the pump, and then push it as much as 100' higher than the source and great horizontal distances. These pumps can pressurize a tank in your house for better delivery of water to fixtures. Each rated pound of pressurizing ability equals 2.3 feet vertical lift and should be calculated accordingly for power usage. Surface pumps must be protected from freezing and can often be a hassle to keep primed.

DEEP WELL SYSTEMS

Deep wells that are 15 feet or more down to the water level cannot have the water sucked from the top of the well. Suction can lift water only about 15-20 feet. For deeper distance to water, a submersible pump must PUSH the water up.

DC POWERED submersible deep well pumps may be the best choice because they do not require large bursts of power or use the inverter at all. DC submersible pumps use only 20% as much energy per gallon pumped as an AC centrifugal pump. Most pump very slowly so do not deplete the water level in a slow recovery well. They can be powered direct by solar modules, without batteries. Or they can be powered by house batteries like any DC appliance, if the well is within about 200 feet distance from the house. The submersible pump will not freeze or lose its prime.

AC POWERED centrifugal pumps are faster and last many years with no repairs. But they use 4 to 8 times more power per gallon pumped than slow 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 and give the pump priority when it runs. A submersible deep well pump with a 1/2 horsepower, 120-volt AC motor can pump a 300 foot well and be powered by a 2500 watt or larger inverter. If you use an AC pump with external start box, get 120-volt AC, 1/2 horsepower maximum. The start box must be relay start control, not solid-state control, if used with a modified wave inverter. Solid state start will work with true sine wave inverters. No-surge pumps are best, if the depth to water in the well is within their range.

VERY DEEP WELL SYSTEMS

These are wells that have a water level deeper than 230’ need a higher power pump. Grundfos SQFlex submersible pumps lift up to 820’. Or a 240-volt AC pump might be used to fill a large tank once a week operating on generator power, or a large inverter and transformer, or two large inverters. 

STARTING QUESTIONS FOR A SOLAR WATER PUMPING SYSTEM

Backwoods Solar designs and sells hundreds of deep well submersible pumping systems each year and with every system, we ask the same questions. In order to properly satisfy your water pumping needs, we need the following information from you:

  1. How deep is the well or alternative water source?
  2. What is the static water level in the well (the static level is the height in the well to which the water rises under its own pressure)?
  3. How many gallons per minute does the well produce?
  4. How many gallons per day are needed?
  5. Will water be pumped to a non-pressurized holding tank or to a pressure tank?
  6. In either situation, how many feet above the well head is the tank located?
    1. Or what is the total lift from the depth that the pump will be located in the well, to the outtake?
    2. If a pressure tank is used, how many pounds of pressure is desired?
    3. Will the pump be powered directly from a PV array implying water is only needed when the sun is shining, or,
    4. Will the pump be powered by a battery bank either DC-direct or AC from an inverter?
    5.  If PV direct, how many feet from the array to the well head?
    6. If battery based, how many feet from the battery system to the well head?

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