Voltage Loss Tables for AWG Wire

Wire Loss Tables for Solar Electric Systems

Includes 12, 24, and 120 volt charts and a metric to AWG size conversion table.

Example: For a pump drawing 9 amperes at 24 volts, located 88 feet from the battery bank: look at the center table for 24 volts. In the far left column find the next number higher than 9 (which is 10) and follow that line across the table until you find a distance figure greater than 88. At the top of the column find the gauge of wire (#6) that should be used. This method insures that wire losses are kept to an acceptable level without spending too much money on extra-heavy cable. Using a heavier wire than indicated, however, will result in even higher efficiencies and we do sometimes invest in the next larger gauge. Wire can get expensive, and it may not be worth the money to get that last 1% if you have to go to a much larger wire size.

Some of the newer grid tie systems inverters, such as the Sunny Boy, use up to 600 volts DC. Generally in these systems loss in wire is nothing to worry about. HOWEVER - you will have to be more careful about selecting and installing the wiring - high voltage DC is not something you want to do a 2nd rate wiring job on. Make sure the insulation is rated for 600 volts, and that there is no damage to the wire or insulation.

All distances are in FEET

Do not use any wire sizes that might fall into the red zone - this would exceed the amperage rating of the wire and it may overheat and burn.

120 Volts AC or DC Chart

24 Volts DC Chart

12 Volts DC Chart

These are one-way distances, measured from point A to point B. The out and back nature of electrical circuits has already been included. For PV arrays, figure the entire run, from the panels to the charge controller to the batteries

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