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Selecting the correct size and type of wire will enhance the
performance and reliability of your PV system. The size of the
wire must be large enough to carry the maximum current expected
without undue voltage losses. All wire has a certain amount of
resistance to the flow of current. This resistance causes a drop
in the voltage from the source to the load. Voltage drops cause
inefficiencies, especially in low voltage systems ( 12V or less
). There are several different types of wire available depending
on how and where it will be used. For example, there are wire
types designed for resistance to sunlight exposure, high temperatures
and direct burial. Specify wiring that will withstand the worst
conditions.
The wire sizing charts below provide the minimum wire size
needed to limit voltage drops to 2% and 5% at a given distance
in a 12V or 24V system. For a 48V system multiply the distance
taken from the 24V chart by 2. The dashes represent currents
which cannot be handled by the wire size. Do not exceed the 2%
drop for wire between PV modules and batteries. A 4 to 5% loss
is acceptable between batteries and lighting circuits in most
cases.
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Solar Electric
Wiring Reference Guide
