pvperfsolar performance modeling

Reference / Backtracking width

Model option

GCR

The collector width as given by the ground cover ratio

Inputs used: Collector band width, GCR (ground cover ratio), Top inactive band, Bottom inactive band, Custom backtracking width

Method

The width the controller works with is the collector width, so that the width over the pitch equals the ground cover ratio. The rotation follows the backtracking equation (1), and it is then held within the rotation stops of the Racking tab.

The math

ψc=arccos⁡ ⁣(min⁡ ⁣(1, cos⁡ρ0GCR)),ρ=sign⁡(ρ0) max⁡(0, ∣ρ0∣−ψc)(1)\psi_c = \arccos\!\left(\min\!\left(1,\ \frac{\cos\rho_0}{\text{GCR}}\right)\right),\qquad \rho = \operatorname{sign}(\rho_0)\,\max(0,\ |\rho_0| - \psi_c) \tag{1}

where

Symbol Meaning Unit
ψc\psi_c the correction angle at which the shadow just clears the next row degrees
ρ0\rho_0 the rotation that would point the plane at the sun degrees
GCR\text{GCR} the ground cover ratio, the collector width over the pitch —
ρ\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 = gcr

Symbols follow the symbol registry.