PVSyst 7.2 Problem with Single Axis Tracker and automatic altitude

[J. Behrschmidt]

We have a surface that slopes 1.6° to the north. Single-axis trackers with a north-south axis should be installed on this surface. The arrangement of the trackers has a misalign. To map the field we use several tracker arrays. To align the trackers in the correct height we have defined a ground object that gets a tilt of -1.6°. We align the height of the trackers with Set auto. altitude. We now have some trackers in the field that are optically lower than the others, although mathematically the height in the coordinates was calculated correctly by PVSyst. Can someone help here?

 

[Michele Oliosi]

Hi !
Could you send us (support@pvsyst.com) your scene ? This would make it much easier to understand the geometry of your problem.!

[Michele Oliosi]

Hi, after reviewing the scene, I have a better view of the situation.

Basically, the auto-altitude tool is not working as you think it does. At the moment it is not possible to have an array of trackers that has trackers with different altitudes.
What I mean is that because of the misalign, your array has trackers that are more or less distributed along the NS axis. In your case, you want the northernmost trackers to be lower in altitude than the southernmost, in order to follow the slope. However this is not what is happening in PVsyst, which has all trackers stay at the same altitude. For example for the array in red:

now the horizontal view:

For this specific case, I would suggest to try to work with zones, which produces single trackers instead of arrays of trackers. There are a few ways to do this, see for example :

[J. Behrschmidt]

Thank you for the explanation.

The problem with the zone is, that then I am not able to work with bifacial modules, which should be used.

[dtarin]

I did not encounter issues with tracker zones and bifacial modules. The module declaration is done under system and not in the shading menu. 

[dtarin]

One thing to note is that when using tracker zones or placing trackers with the auto-altitude tool, it will not adjust the NS slope, only the elevations of the trackers.

For @Michele Oliosi, any possibility to have this be implemented in PVsyst such that NS slope is modified? That is, placing the trackers orthogonal to the surface using whatever reference point is selected. 

[Michele Oliosi]

@dtarin I raised a ticket we will see what we can do. I believe it won't be that easy (trackers at different altitudes complicates some calcualtions) but it would be a good feature.

[MicheleANE]

Hello,

@dtarin We usually don't use the internal tool to fit arrays on terrain but this could be an idea for a workaround:

Instead of using trackers from the beginning, fill the areas with fixed tilt arrays of the same size of the trackers and use an azimuth that gives you the same shape of the trackers (SN axis -> 90 degrees azimuth for fixed tilt) and tilt equal to the max tilt of the trackers.

After positioning them convert them to trackers with the internal tool and they will keep the SN slope too.

Best regards

[J. Behrschmidt]

Thank you all for your support.

[dtarin]

On 5/30/2022 at 5:28 PM, MicheleANE said:

Hello,

@dtarin We usually don't use the internal tool to fit arrays on terrain but this could be an idea for a workaround:

Instead of using trackers from the beginning, fill the areas with fixed tilt arrays of the same size of the trackers and use an azimuth that gives you the same shape of the trackers (SN axis -> 90 degrees azimuth for fixed tilt) and tilt equal to the max tilt of the trackers.

After positioning them convert them to trackers with the internal tool and they will keep the SN slope too.

Best regards

Great point and a good reminder. I have done the same method in years prior before utilizing PVcase for this.