P_nom inverter

Method

The AC loss fractions are stated at the inverter's AC nameplate (1). Losses on the sum of the inverters are stated at the sum of the inverters' AC nameplates. A three-phase cable of known resistance gives its loss fraction at unit power factor by (2).

The math

1. Reference power
2. Fraction of a three-phase cable

$$P_{ref} = P_{nom,inv} \tag{1}$$ $$f_X = \frac{R_c\,P_{nom,inv}}{U_{LL}^2} \tag{2}$$

where

Symbol	Meaning	Unit
$P_{ref}$	the AC power reference of one inverter	W
$P_{nom,inv}$	the inverter's AC nameplate	W
$f_X$	the cable loss at the reference power and unit power factor, as a fraction of the reference power	—
$R_c$	the resistance of one conductor of the cable	Ω
$U_{LL}$	the line-to-line voltage of the cable	V

References

1. PVsyst 8 help, AC ohmic losses: reference power

API

ac_losses.power_reference = pnom_inverter

Symbols follow the symbol registry.