Scale the curve by the electrical shading

Method

On every timestep with electrical shading, the current of the array's whole current-voltage curve is multiplied by the share of the module-model power that the electrical shading leaves. The voltage is unchanged. The maximum-power current, the loss in the DC cables, the cable voltage drop and every operating point the inverter finds on the curve use the reduced current. On a bifacial array the rear-side mismatch reduces the current the same way, by the second factor of (1).

The math

1. Current factor
2. Array curve

$$f_I = \left(1 - \frac{\Delta P_{elec}}{N\,P_{mpp,mod}}\right)\left(1 - \frac{\Delta P_{rear}}{P_d}\right) \tag{1}$$ $$I_s(V) = f_I\,I(V) \tag{2}$$

where

Symbol	Meaning	Unit
$f_I$	the current factor of the timestep, between 0 and 1	—
$\Delta P_{elec}$	the electrical shading loss of the timestep	W
$N$	the number of modules	—
$P_{mpp,mod}$	the maximum power of one module from the module model at the timestep's irradiance and cell temperature	W
$\Delta P_{rear}$	the rear-side mismatch loss of the timestep; 0 on a monofacial array	W
$P_d$	the array power after the flat derates, before the rear-side mismatch	W
$I_s(V)$	the array current at voltage $V$ after the electrical shading	A
$I(V)$	the array current at voltage $V$ without the electrical shading	A

References

1. Analysis of PVsyst 8.1.5 outputs shows this convention in its results.

API

inverter.iv_shading_current_scale = electrical_fraction

Symbols follow the symbol registry.