Troubleshoot PVcase design in PVsyst

This article provides troubleshooting steps for PVcase designs imported into PVsyst. 

Here's an overview of the topics covered:

• Imported .PVC file and terrain data misalignment
• Rotate the whole scene for Southern Hemisphere
• The number of modules and orientation changed
• PVsyst 8.0 – An orientation needs a representative tracker to be defined for the diffuse shadings calculation
• PVsyst 8.0 – Orientation referenced but no 3D field attached
• Advanced parameters settings
• Bifacial 2D model error
• Area of 3D fields error
• Tracker axis tilt difference is too high
• PVsyst 8.0 – The difference between the tilts of the field and of the average orientation is too high
• Pvsyst 8.0 – The angle between the field and the average orientation (#°) is too high

Imported .PVC file and terrain data misalignment

When importing both the 3D shading scene and the terrain data, these 2 files can become misaligned due to the PVsyst origin auto selection, and the result can look like below:

To correct this, when prompted with the Import result window, you must uncheck the automatic translation and change it to x=0, y=0, and z=0.

The reason is that when importing the terrain data, PVsyst automatically sets the terrain object at the origin of PVsyst. However, when importing the 3D shading scene, PVsyst detects and sets the origin according to the AutoCAD design. This action will correct the misalignment by setting the 3D shading scene file (.PVC) origin to the same origin as your terrain file (.csv).

Rotate the whole scene for Southern Hemisphere

PVsyst defines its coordinate system as follows:

This issue occurs when the project location in PVsyst is set in the Southern Hemisphere. There are two ways to correct the orientation of the imported design depending on the PVsyst version that is available or the user.

PVsyst 7.3 or newer

PVsyst will automatically detect and suggest rotating the import result orientation:

PVsyst 7.2 or older

PVsyst did not support project location detection in 3D scenes, therefore the rotation suggestion is not available. You can adjust the orientation of the project manually by selecting Edit, rotating the whole scene, and inputting the desirable azimuth.

The number of modules and orientation changed

It is important for PVsyst and any yield calculation software to get the collective plane area. When there is no user input for the module type in the system setting that the simulation can use, PVsyst collects this data by assuming the sensitive area from the 3D model. That results in the module orientation discrepancy between the 3D model and the AutoCAD layout.

Occasionally, frames with multiple joint gaps or motor gaps also have an incorrect number of modules in length compared to the frame setting defined in PVcase. 

You should ensure that the PV module is selected for the system. At this point, PVsyst will automatically calculate the sensitive area by the reference PV module, and modify the module orientation within the 3D scene to the correct orientation.

You can modify both the number of modules and the module orientation manually by selecting the frames and using the Modify selected objects option under the Edit tab.

You should be able to modify the sizes detected by the module, the module orientation to be in portrait, and the number of modules in the X direction.

PVsyst 8.0 – An orientation needs a representative tracker to be defined for the diffuse shadings calculation

In PVsyst 8.0, when importing a 3D scene with trackers, PVsyst prompts you to define a representative tracker to calculate the diffuse loss of the layout.

In order to define it, go to Tools and select Trackers diffuse shading definition: 

In the following window, it is up to you to decide which option to select.

Usually, Central tracker works fine, but here is a brief description for each of the three options:

• All trackers: All trackers in the scene are considered for the diffuse shading calculation. This is the most precise calculation, but may become resource intensive for large or complex scenes.
• Central tracker: Among the most geometrically central trackers, the one with the highest number of surrounding trackers casting shade on it is selected. According to PVsyst, this approximation is quite acceptable in most cases (especially for big homogeneous systems) where the trackers are uniformly arranged.
• Custom tracker: You can choose the tracker.

After selecting one option in the left-side panel and defining the representative tracker in the right-side panel, the user can click OK. This will clear the error and the simulation can be ran. For more information, refer to this PVsyst article. 

PVsyst 8.0 – Orientation referenced but no 3D field attached

In PVsyst 8.0 it is possible to have multiple orientations within one project. If an orientation is pre-defined, and the imported 3D scene does not exactly match with it, a new orientation will be created instead of modifying the existing one. This is likely to happen if we import a terrain-based layout, as the “Avg base tilt angle” (for fixed tilt) or “Avg axis tilt” (for trackers) are almost impossible to know before importing the 3D scene.
The following two screenshots (first one for fixed tilt, second one for trackers), show Orientation #1 as the orientation created by the user in PVsyst without knowing how the terrain would affect the layout, and Orientation #2 as the one automatically created after importing the 3D scene from PVcase. As can be seen, the only difference is that Orientation #2 takes the terrain into account and has a different base tilt angle for fixed tilt and axis tilt angle for trackers. 

Fixed Tilt

Trackers

After importing the 3D scene, the frames are assigned to the Orientation #2. However, the subarray probably remains linked to Orientation #1 and thus an error message will be shown.
In order to clear this error, go to the “System” menu in PVsyst and change the orientation assigned to our subarray. 

Now the subarray, the orientation and the 3D scene are matching, but the original empty orientation remains, so PVsyst will show another warning. In order to clear this new warning and be able to run the simulation, the empty orientation needs to be deleted, as shown in the following screenshot.

Advanced parameters settings

We recommend that you consider using other methods, unless it is an utmost necessity to use the described methods below. Modifying the advanced parameters should only be done by expert users. The default values are set to ensure the accuracy of the simulation. Modifying these values might result in some inaccuracies, due to working with an idealized model.

Bifacial 2D model error

After a seemingly smooth export, you might want to simulate a fixed tilt design on a complex terrain with a bifacial module to capture the additional production. However, after selecting the bifacial system in the PVsyst system, you get an error warning as the simulation cannot be executed.

The PVsyst internal algorithm checks to ensure the 3D model accuracy for most projects. However, on a more complex terrain, these limitations can prevent you from performing the simulation. In order to correct this error, you must update the advanced parameters to increase the tolerance check these parameters using the steps below:

1. Save and exit the current project

2. On the main page, select Setting > Edit advanced parameters

3. Search for Pitch RMS limit for bifacial 2D models and increase this tolerance. By default, this value is 0.1m, and the threshold is four times this value at 0.4 for the calculation. By increasing the value of this parameter, you allow PVsyst to simulate the module with a threshold of four times the value of the advanced parameter

4. For N-S horizontal axis trackers designs, PVsyst also checks for the homogeneity of the axis tilt. The threshold for this value is 2 degrees, and it can be modified by editing the Max tilt axis for the bifacial 2D model

As PVsyst suggested, these parameters should only be modified by advanced users. To learn more about the impact of these modifications, you can consult the PVsyst help article here.

However, it is important to be able to capture bifacial yield on complex terrain without risking the accuracy of the production model. You can request a trial to PVcase Yield, which can simulate the site’s performance without layout geometry limitations.

Learn more about PVcase Yield.

Area of 3D fields error

After importing and/or manually modifying the imported near-shading scene (.PVC file), you may receive an error message that the PV area in the 3D field is higher/lower than the area defined in the system.

When encountering this error message, it is recommended that you follow the steps in this article to conduct the initial check between PVcase design and PVsyst System.

If this error persists even after the initial check, you can consider a more drastic approach in the advanced parameters setting by following the steps below:

1. Save and exit the current project

2. On the main page, select Setting > Edit advanced parameters

3. Search for Shading: absolute min shading/field area ratio and decrease this tolerance. By default, this value is 0.92 (7% difference). By decreasing this value, you increase the percentage difference in the active area between the 3D scene and the System, which allows you to continue the simulation.

Tracker axis tilt difference is too high

When exporting the PVC file for tracker systems into PVsyst, you might be prompted with the following warning: Several tracking fields defined in the scene. Field "Tracker #X" incompatible with field "Tracker #Y": the axis tilts difference (Zº) is too high.

If that is the case, you can follow the procedure shown below in order to modify the PVsyst settings, so that the tilt axis tilt range is increased above the warning value (19.9 is that value in this example, so increasing to 20 would be enough).

Once done, the error will not show and the file will be ready for simulation.

PVsyst 8.0 – The difference between the tilts of the field and of the average orientation is too high

If a warning stating that "the difference between the tilts of the field and of the average orientation is too high" shows in PVsyst 8.0, you can increase the tolerance by closing the project and in under the Settings header selecting the Edit advanced parameters option: 

For trackers, the Tracking maximum axis tilt spread tolerance needs to be increased:

For fixed tilt, the Max. spread of tilts between planes tolerance needs to be increased:

Once done, the error will not show and the file will be ready for simulation.

PVsyst 8.0 – The angle between the field and the average orientation (#°) is too high

When importing a PVcase GM layout into PVsyst 8.0, a warning might show stating that "the angle between the field and the average orientation (#°) is too high": 

In order to resolve this and continue working on the PVsyst simulation, you can try to increase the "Maximum orientation difference for defining average (spread) orientation" angle in the Project Settings: 

To a value above the problematic #°:

Following this process should clear the error, and the user will be prompted to save the project in order to continue: