Flat fraction

Method

The rear mismatch loss of the bifacial section, a fixed fraction, is taken from the part of the array's power that the rear irradiance adds, at every timestep.

The math

$$P_{rm} = f_{rm}\,\frac{b_f\,G_{rear}}{G_{front} + b_f\,G_{rear}}\,P_{arr} \tag{1}$$

where

Symbol	Meaning	Unit
$P_{rm}$	the rear mismatch loss of the timestep	W
$f_{rm}$	the rear mismatch loss of the bifacial section, a fraction	—
$b_f$	the bifaciality factor	—
$G_{rear}$	the rear irradiance	W/m²
$G_{front}$	the effective front irradiance	W/m²
$P_{arr}$	the array power before the rear mismatch	W

References

1. PVsyst 8 help, Bifacial systems, 2D unlimited sheds model

API

bifacial.rear_mismatch_model = flat, bifacial.rear_mismatch_loss

Symbols follow the symbol registry.