Resistive loss

Method

On every timestep the line loss is the entered fraction of the reference power, times the square of the ratio of the power the line carries to the reference power, divided by the square of the power factor. The reference power is that of the whole system. The power carried is the sum of the inverter outputs, or under the cascade reference of the AC resistive reference step, the power that leaves the HV transformer.

The math

1. Loss coefficient
2. Loss

$$k_{HVL} = \frac{f_{HVL}}{P_{ref,sys}\,\text{PF}^2} \tag{1}$$ $$L_{HVL} = k_{HVL}\,P_c^2 \tag{2}$$

where

Symbol	Meaning	Unit
$k_{HVL}$	the loss coefficient of the HV line	1/W
$f_{HVL}$	the HV line loss at the reference power and unit power factor, as a fraction of the reference power	—
$P_{ref,sys}$	the AC power reference of the system: the sum of the inverters' AC nameplates, or the STC reference power (AC power reference step)	W
$\text{PF}$	the power factor	—
$L_{HVL}$	the HV line loss	W
$P_c$	the power the loss is computed on: the sum of the inverter outputs, or the power leaving the HV transformer under the cascade reference	W

References

1. PVsyst 8 help, AC losses

API

ac_losses.use_hv_line = true

Symbols follow the symbol registry.