Water Pumps for Off-Grid
Why use DC powered pumps
instead of 120V or 240V AC household current? ...and why the Grudfos pumps
are an exception.
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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