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<< Click to Display Table of Contents >> Metal resistivity, wire resistance |
  
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<< Click to Display Table of Contents >> Metal resistivity, wire resistance |
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Metal resistivity
The resistivity of wiring metals is strongly dependent on the temperature, which can widely vary due to dissipating currents.
The basic value is specified for pure metal, at 20°C :
| Copper: | Rho = 1.68 E-8 * (1 + 0.0039 * (Temp - 20) [°C] ) [Ohm·m] |
| Default value: | Temp = 50°C => Rho[50°C] = 1.88 E-8 [Ohm·m] |
= 18.8 [mOhm·mm²/m]
| Aluminium: | Rho = 2.82 E-8 * (1 + 0.0039 * (Temp - 20) [°C] ) [Ohm·m] |
| Default value: | Temp = 50°C => Rho[50°C] = 3.15 E-8 [Ohm·m] |
= 31.5 [mOhm·mm²/m]
However the resistivity may increase when the metal is not quite pure, we don't know the real resistivity of industrial wires.
These values at 50°C are the default in PVsyst.
You can eventually modify these values (for use in the simulation) in the Hidden parameters. In the main menu, please use "Settings > Edit Hidden parameters". In the category "System design parameters losses, shadings", you will find the items "Copper Resistivity" and "Aluminium resistivity".
Wire resistance
The resistance of one wire is calculated as:
Resistance [mOhm] = Rho [mOhm·mm²/m] * Wire length [m] / Section [mm²]
:In the wiring definitions of PVsyst:
| - | The tool for the PV array resistance (DC side) supposes defining the wire lengths as the total wire as "seen" from the input of the inverter (back-and-forth) |
| - | On the AC side, there may be 2 or 3 wires, depending on mono or tri-phased circuits. Here the considered length is the distance between concerned devices, i.e. the length of one wire. |
In the AC side dialog, you can choose the metal (copper or aluminium) for each circuit.
In the DC side, this choice is available by the button "Wire", where you can also define a price for the wires.