Backtracking Parameter Management

When defining the backtracking strategy, PVsyst has to identify two reference trackers, to determine the relationship between them (tracker width and pitch). During the simulation, the backtracking angle calculation will be the same for all trackers, based on this reference.

"Native" PVsyst scenes with arrays of trackers

When defined within PVsyst, the 3D scenes are usually defined with arrays of trackers.

In this case the pitch is specified in the array's definition. When there are several arrays, most of the times the GCR is the same for all arrays. If this is not the case, PVsyst will choose as reference the array with the highest width/pitch ratio (GCR).

Even if there were some arrays with a lower GCR, the backtracking will not produce mutual shadings.

Imported 3D scenes with independent trackers

In the external CAD software, the trackers are defined independently, without gathering them as arrays. Within PVsyst, this is also the case when you fill a zone.

Therefore, it is necessary to identify a pair of two reference trackers to serve as a basis for the full backtracking calculation. This is the objective of the Backtracking Management tool, available in the Tools menu of the 3D editor.

When using this tool, all the pitch distances between neighboring trackers of the selected orientation group are identified and listed, sorted by decreasing pitch. You simply need to select a tracker with a higher Ground Coverage Ratio (GCR), and the tool will automatically propose and select the corresponding neighboring tracker (in orange).

There is a relationship between this tool and the 3D scene: the chosen reference tracker appears in green, and its neighbor in orange. This allows to visually check that the chosen tracker is really representative of the full set of trackers.

The visualization of this pair—highlighted in green and orange—is only displayed when the backtracking for the selected orientation group is not in automatic mode. Automatic mode is disabled when the user selects a specific tracker from the list, making that tracker appear in green and its neighboring reference tracker in orange.

The detailed parameters involved in the backtracking calculation are shown in the frame "Heliostats parameters" on the left.

By deselecting the reference pair of trackers, one may also enter custom values.

Extended analysis

Furthermore, this tool allows refined analysis of your system.

If you have an irregular system, with some different pitches, and you are not satisfied with the "maximum pitch" choice, you can choose another pair of tables. The tool will show all the tables with a higher pitch in red. For these tables the backtracking will not be perfectly operational: there will be some possible mutual shadings. If you accept this situation, you have to activate the Electrical shading effects in your simulations.