Custom

Method

The width is the value entered from the tracker controller settings, limited to the pitch (1). It takes the place of the collector width in the backtracking equation (2), and the rotation is then held within the rotation stops of the Racking tab.

The math

1. Width over the pitch
2. Rotation

$$\text{GCR}_{bt} = \min\!\left(1,\ \frac{W_{bt}}{P}\right) \tag{1}$$ $$\psi_c = \arccos\!\left(\min\!\left(1,\ \frac{\cos\rho_0}{\text{GCR}_{bt}}\right)\right),\qquad \rho = \operatorname{sign}(\rho_0)\,\max(0,\ |\rho_0| - \psi_c) \tag{2}$$

where

Symbol	Meaning	Unit
$\text{GCR}_{bt}$	the ratio of the backtracking width to the pitch	—
$W_{bt}$	the backtracking width entered (array.backtracking_width_m)	m
$P$	the row pitch, the distance between the rows	m
$\psi_c$	the correction angle at which the shadow just clears the next row	degrees
$\rho_0$	the rotation that would point the plane at the sun	degrees
$\rho$	the rotation the tracker takes, before the rotation stops	degrees

References

1. Lorenzo, Narvarte & Muñoz 2011, Tracking and back-tracking, Progress in Photovoltaics 19(6) 747–753

API

array.backtracking_width_method = custom, array.backtracking_width_m = <m>

Symbols follow the symbol registry.