How to use the Free Solar Cable Size Calculator
This solar wire size calculator calculates the wire size of copper wire taking into account electrical parameters of the solar array or other device /power, voltage and current/ and cable’s temperature working conditions as well.
To calculate wire size just enter:
-solar system working voltage in V or working voltage over cable wire /for example if this cable connects battery bank to load add the voltage of battery bank/
– expected working peak power: for example solar array peak power in W or kW
-cable’s working temperature in Celsius or Fahrenheit
-desired voltage drop in % or in other words this is the cable resistive loss. Every cable has its own resistance which is directly proportional to the cable length and inversely proportional to the cable diameter. This resistance is temperature dependant as well. Our calculator takes into account all above mentioned factors to calculate cable resistance so as to be received a voltage drop equaled to the desired one.
– supposed cable length in meters or feet. Actually you will use two wires-one positive and one negative, so do double the cable length by summing up the lengths of positive and negative wire.
Then you will get calculated:
- Cable wire size needed in mm2 for Europe
- Wire diameter in inches for AWG/American Wire Gages/
Always choose cable type that satisfied both conditions: calculated wire diameter in inches (or cable wire size in mm2) and rated maximum ampers for power transmission if cables are wired in a bundle or maximum amps for chassis wiring if each wire is routed separately and exposed directly to air as per table given below calculator area or manufacturers data.
If calculated wire diameter has lower ampers current rating choose cable with higher wire diameter which covers corresponding amp rating.
Failure to do so may lead to fire hazard and cable’s evaporating under system’s current!
Have in mind when cable interconnects solar modules on an open rack it may experience temperatures of 61-70 C /141-158 F/.
Higher working temperatures cause increase in cable’s resistance which in turn leads to voltage drop increase and decrease in maximum current which this cable is capable of sustaining.
Let’s consider the following example:
- Solar system voltage 12V
- Solar Array Peak Power 281W
- Cable working temperature 20 C
- Desired Voltage Drop 5%
Estimated cable length 12.4m needed for connecting the solar array to the next solar power system unit for example charge controller.
We get calculated that we need copper wire with 0.128 diameter in inches and recommended maximum current of 29A defined by choosen solar system voltage .
This corresponds to AWG gauge 8.
However we also get calculated that the cable should be capable of withstanding 29A maximum current in case of a bundle wiring. Since we are running 2 wires , positive and negative one, we may consider that we are working under scenario of a bundle wiring. This means that we must choose cable with larger diameter for example at least AWG gauge 7.
By using this solar wire sizing calculator you will notice that the higher solar system voltage translates into:
- cable with smaller diameter for the same cable length, i.e more cheaper cable
- longer cable for the same voltage drop if you keep the same gauge used for lower solar system voltage.
Please use the update button if the calculated data are not refreshed automatically by solar cable size calculator.
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