Glossary > GCR - Ground coverage Ratio

The GCR (Ground Coverage Ratio) is an indicator of the geometry of your PV array, basically defined as:

GCR = Sensitive area / Ground occupation area

However we cannot give a strict and universal definition of the GCR:

-	The sensitive area may be the PV modules area, or the area occupied by the PV modules (including spaces, inactive bands, etc).

-	The ground area is difficult to specify in a general way: what area around a single table ? Around the full system ? Include the circulation ways? Etc...

Therefore the GCR may take different values, according to situations and the use we want to do.

BIPV systems

In BIPV systems (Buiding integration) the ground occupation doesn't make much sense: for example a façade will have a null Ground area.

Arrays of Sheds or Trackers

This is the main use of the GCR. The GCR expresses the "density" of the PV sensitive areas. The higher GCR, the higher mutual shading losses.

When defining "Unlimited sheds" or "Unlimited trackers" in the Orientation part, we have a 2D representation ignoring the extremities.

In this case we define the ground area as the area between the basis of a shed, and the basis of the next shed. I.e. proportional to the Pitch.

But for the sensitive area, we may want to specify the effective sensitive area (i.e. proportional to the width of the collectors or PV modules), or the width of the full mechanical shed or tracker if we are interested in the mutual shadings or backtracking.

-	For sheds we will define "Collector width + top inactive band", the bottom inactive band doesn't contribute to the shading factor.

-	For trackers we will define "Collector width + Left inactive band + Right inactive band" (useful for backtracking).

For rather regular arrays defined in the 3D scene, PVsyst evaluates (and averages) the GCR of each array. This doesn't represent the additional spaces between arrays for circulation or other not-equipped areas in the plant's area.

Arrays of Tables or Independent trackers

When importing 3D scenes (especially on a terrain) the tables have not necessarily a regular arrangement.

PVsyst tries to evaluate the average distance of each table with respect to the next one in the 3D geometry. And rejects the case of double pitches or more for evaluating an average. This is a fuzzy evaluation: the result may look a little bit strange in some special situations.

The terrain width for each table is the width of the table. Therefore the eventual spaces between adjacent tables is not taken into account.

This evaluation also doesn't include the circulating areas, and should be representative of the density of tables.

Results on the report

Therefore the GCR mentioned on the report may be different according to the situations (system, bi-facial, etc).

But don't worry: this is just an indicator, the GCR value is not used as such in the simulation.