Terrain mesh

Introduction

In PVcase Ground Mount,  the Terrain mesh is a digital ground topography model generated before PV frame design. The Terrain mesh is an extremely useful tool, as it allows you to assess site topography, identify surveyor data errors, and locate problematic PV area regions.

This article is a step-by-step guide on how to use the Terrain mesh effectively to accurately represent and analyze the topography of your project. 
 

Select topography

Before you can work with the Terrain mesh, you need to select the topography. Begin by opening the Layout generation settings.

1. Activate the Topographic layout setting.
2. Click on Select.
3. Select all of the topographical data in the drawing.
4. Press Space or Enter on the keyboard to confirm the selection.

To modify the slope units: 

1. Go to the Layout generation settings window 
2. Select either percent or degrees from the drop-down menu

Generate the Terrain mesh 

Typically, you should generate the terrain mesh before any PV frame design. This is because the Terrain mesh:

• Allows for an early assessment of the PV plant site's topography.
• Helps identify any errors in the surveyor data.
• Makes it easier to pinpoint problematic regions within the PV area.
   

To begin, click the Terrain mesh icon, which launches the tool.

Then continue with the steps described below. 

Slope parameters 

You can define the slope table parameters in the Terrain mesh menu :

1. Go to the Slope table setup

• Set the start value (for example, to 0%)
• Set the end value (for example, to 14%)

2. Specify the number of rows:

• Set the number of rows to 10 (or 7 or more for easier terrain evaluation). This controls the step size of the mesh.

3. Click Fill table to populate the table with indication ranges and their corresponding colors.

You are free to customize both the color of the range and the range values. You can double-click and modify the values as you see fit.

To customize the colors of the ranges:

1. Click on the color you want to change
2. Select the desired color using the color-picking tool
3. Click Confirm

Mesh settings

With the slope table and coloring now defined, you can proceed to configure the Mesh settings.

Mesh density

The mesh density controls the distance between the centers of the triangular mesh components:

• A higher density creates a more detailed mesh; however, this comes at the expense of longer computation time and reduced performance.
• A lower density results in a less detailed outcome, but it significantly reduces the generation time and generally lessens the computational load on AutoCAD.

You can adjust the mesh density by moving the slider or by entering the desired value manually. Generally, we advise using a lower-density mesh initially - for example, 5 meters or more. In most cases, a terrain mesh with a density of 5 meters offers sufficient details for initial assessment, without severely impacting performance. This reduces the computation time and if there is a need for a finer mesh, it can be revisited and re-generated with a denser value.

Slope direction

You can set the slope direction to: 

• Any direction

• East-West (mostly used with fixed-tilt systems) 

• North-facing / South-facing (generally used for Single-axis trackers and East-West systems)

• North-South

East-West & North-South systems evaluate the inclination in two orientations simultaneously. The individual North & South slope directions will only indicate the slope in that respective direction.

For example, if you were to perform a North-facing mesh generation, the software will only indicate slopes that are in the north direction. This may be useful to consider when working with Single-Axis Tracker systems, as the Northern slope may influence the energy production capabilities.

In this example, we will use the North-South slope direction, as it is appropriate for a Single-axis Tracker system.

Once you have set your parameters, it’s time to generate the mesh.

1. Click Generate mesh 
2. Select the PV area boundary line.
3. Press Space or Enter on the keyboard.
4. Wait for the mesh to be generated.

The mesh is colored in a way that corresponds to the values in the slope table. To see this more clearly, either switch to a South-West Isometric view or adjust the viewing angle manually by holding down the Shift key and the middle mouse button while moving the cursor.

Restriction zones

The terrain mesh allows you to identify and locate regions with severe slopes in one or more directions. Depending on the severity of the slope and the needs of your system, you may choose to designate some areas as unsuitable terrain.

For this example, the project specifications dictate that you cannot place frames in areas where the North-South slope exceeds 12.25%.
After generating the terrain mesh, you can then restrict specific areas based on the outcomes of this generation process.

1. Hover the mouse over the row range that has the Minimum angle value at 12.25% 
2. Click on the pencil icon of Draw restriction zone

PVcase will draw polylines around areas that have a slope of more than 12.25% in North-South direction. 

If you click on the newly-drawn restriction line, you can see it is in the PVcase offsets layer. 

This means that when you generate our PV area, the software will not place any frames where these polylines were generated.

Export to CAD

You may also export the slope table and the information within it anywhere in your design area. 

To do so:

1. Click the Export to CAD button 
2. Place the table on your workspace by left-clicking on the target location

Export to PVsyst

You can export the Terrain mesh to PVSyst by selecting the option Export to PVsyst in the ribbon. 

1. In the dropdown menu, click Export to PVsyst.
2. An action window will pop up; select Terrain and frames from the dropdown.
3. PVcase will prompt you to select the Terrain mesh. Select it.
4. Choose the desired save format: .DAE or .PVC.
5. Click Export.

Two files will be generated:

• One with the extension .PVC or .DAE

• A CSV file

Using terrain data in CSV format, instead of a 3D object file, improves the computation speed when running yield reports within PVSyst.