Inverter output

Method

Every load-dependent AC loss is computed on the inverter output of the timestep. The stages are the AC cables, the copper of the MV transformer, the MV line, the copper of the HV transformer and the HV line. Each stage has its own fraction and reference. The AC cables and the MV transformer act on one inverter's output with that inverter's reference; the later stages act on the sum of the outputs with the system's reference.

The math

$$L_{n,i} = k_n\,P_{n,i}^2,\qquad k_n = \frac{f_n}{P_{ref,n}\,\text{PF}^2} \tag{1}$$

where

Symbol	Meaning	Unit
$L_{n,i}$	the loss of stage $n$ at timestep $i$	W
$k_n$	the loss coefficient of stage $n$	1/W
$P_{n,i}$	the power stage $n$ carries at timestep $i$: one inverter's output for the AC cables and the MV transformer, the sum of the outputs for the later stages	W
$f_n$	the loss of stage $n$ at its reference power and unit power factor, as a fraction of that reference power	—
$P_{ref,n}$	the AC power reference of stage $n$: one inverter's for the AC cables and the MV transformer, the system's for the later stages	W
$\text{PF}$	the power factor	—

References

1. PVsyst 8 help, AC losses
2. Analysis of PVsyst 8.1.5 outputs shows this convention in its results.

API

ac_losses.resistive_reference = inverter_output

Symbols follow the symbol registry.