# pvlib.pvsystem.dc_ohms_from_percent#

pvlib.pvsystem.dc_ohms_from_percent(vmp_ref, imp_ref, dc_ohmic_percent, modules_per_string=1, strings=1)[source]#

Calculates the equivalent resistance of the wires from a percent ohmic loss at STC.

Equivalent resistance is calculated with the function:

$Rw = (L_{stc} / 100) * (Varray / Iarray)$

$$Rw$$ is the equivalent resistance in ohms $$Varray$$ is the Vmp of the modules times modules per string $$Iarray$$ is the Imp of the modules times strings per array $$L_{stc}$$ is the input dc loss percent

Parameters
• vmp_ref (numeric) – Voltage at maximum power in reference conditions [V]

• imp_ref (numeric) – Current at maximum power in reference conditions [V]

• dc_ohmic_percent (numeric, default 0) – input dc loss as a percent, e.g. 1.5% loss is input as 1.5

• modules_per_string (int, default 1) – Number of modules per string in the array.

• strings (int, default 1) – Number of parallel strings in the array.

Returns

Rw (numeric) – Equivalent resistance [ohm]

References

1

PVsyst 7 Help. “Array ohmic wiring loss”. https://www.pvsyst.com/help/ohmic_loss.htm