Why use DC powered pumps instead of 120V or 240V AC household current?
At lower volumes DC pumps are more efficient (gallon for gallon) than the cost and infrastructure required for AC pumps. Many off-grid applications use their first solar array setup for their DC powered water supply when upgrading to a larger system for the house.
DC pumps are available for almost all applications where AC pumps are used. From recirculating pumps for heating systems to pressure pumps and deep well pumps.
Disadvantages of DC pumps are related to electrical resistance and length of wire to be used. Long runs require heavy gauge wire to avoid power loss. A run of 50' may require 4 gauge wire, that's the same gauge of wire your car has leading from the battery!
To determine the correct model of pump required we match the flow rate (volume) needed and the height (head) it must be lifted. Pump options are varied, the power systems to run them are a function of how much water is needed, and how much energy (watts) it takes to get it to where you use it.
Assuming a pump efficiency of 25% Watts = liters per minute x feet of head x 0.1987
In general, if your application is for higher volumes of water or requires a long run to of wire to the pump, it may be best to consider a 120V or 240V pump.
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