Exporting low-polygon STL files for shading geometry

This guide covers how to export a low-polygon STL from SolidWorks or Onshape for use as shading geometry in SunSolve Yield. The goal is a mesh that captures the outer envelope of a part accurately enough to model shading impact, without unnecessary geometric detail. Meshes with more than 10,000 triangles can be simplified during import using the built-in simplification tool on the preview tab. For details on importing STL files into SunSolve Yield, see Custom objects.

Scene size limits

The total size of all custom objects in a scene must not exceed 10 MB, and no individual part may be larger than 5 MB. Keeping triangle counts low is essential to staying within these limits. Follow the guidance below to produce compact STL files that are well suited for shading analysis.

Why low polygon count matters

For shading geometry, you only need the gross shape of a component — the silhouette that blocks light. Fine surface detail (bolt heads, chamfers, fillets, cable glands) adds triangles without meaningfully changing the shading result. A motor housing rendered as a rough 10-sided polygon is indistinguishable from a smooth cylinder at the scale of a solar array.

Targeting a low polygon count also keeps your simulation scene light and fast to compute, and helps you stay within the scene size limits above.

Choosing your settings

Three parameters control triangle count in SolidWorks STL export:

ParameterWhat it does

Angular deviation, Maximum angle between adjacent facet normals. Higher = fewer triangles on curved surfaces.

Chordal tolerance, Maximum distance between the mesh and the true surface. Higher = fewer triangles overall.

Minimum facet width, Smallest triangle edge allowed. Higher = prevents slivers but also removes fine detail.

Recommended settings by part size

Part sizeChordal toleranceAngular deviationMin. facet widthSmall (< 0.2 m), 0.01 m, 25–30°, 0.005 mMedium (0.2 m – 1 m), 0.05–0.1 m, 25–30°, 0.02 mLarge (> 1 m), 0.1–0.2 m, 25–30°, 0.05 m

Rule of thumb: Set chordal tolerance to approximately 10% of the largest dimension of the part.

SolidWorks export workflow

Step 1 — Suppress unnecessary features

Before exporting, suppress any fine detail that won’t affect shading:

• Bolt holes and fasteners
• Chamfers and small fillets
• Connectors, cable glands, and labels

Right-click features in the Feature Tree and select Suppress.

Step 2 — Save as STL

1. Go to File > Save As
2. In the Save as type dropdown, select STL (*.stl)
3. Click Options before saving

Step 3 — Set export options

In the Options dialog:

• Set Resolution to Custom
• Set Deviation to your target chordal tolerance (e.g. 0.1 for a 1 m part — note SolidWorks uses mm by default, so enter 100 mm)
• Set Angle to 25 – 30 degrees
• Enable Save all components of an assembly in a single file if exporting an assembly

Click OK, then Save.

Step 4 — Verify the output

Open the STL in a free viewer such as MeshLab or Microsoft 3D Viewer to confirm the shape looks correct and the triangle count is reasonable (typically 500–3,000 triangles for a motor assembly).

Check the file size — if it exceeds 5 MB, further decimation is needed (see below).

Onshape

Onshape

is a browser-based CAD platform with a free plan that supports STL export with configurable resolution settings. It is a good alternative if you do not have access to SolidWorks.

Step 1 — Simplify the model

As with SolidWorks, suppress or remove fine detail that won’t affect shading before exporting. Use Feature suppression or create a simplified configuration of your part.

Step 2 — Export as STL

1. Right-click the part or assembly in the parts list
2. Select Export
3. Set Format to STL

Step 3 — Set export options

In the export dialog:

• Set Resolution to Custom
• Set Chord tolerance to your target (e.g. 0.1 for a 1 m part)
• Set Max facet width to limit triangle density on flat surfaces
• Set Min facet width to prevent tiny slivers
• Adjust Angular tolerance to 25 – 30 degrees

Click Export.

Step 4 — Verify the output

Download the file and check it in a free viewer such as MeshLab to confirm the shape and triangle count are appropriate. Check the file size stays under 5 MB.

After export — further simplification

If the resulting file still has more triangles than needed, you can simplify it during import. The import tool includes a built-in mesh simplification slider on the preview tab that lets you reduce the triangle count and see the result before importing. For best performance, aim for fewer than 10,000 triangles.

Quick reference

ToolChordal tolerance (1 m part)Angular deviationMin. facet widthSolidWorks, 100 mm, 25–30°, 50 mmOnshape, 0.1 m, 25–30°, 0.05 m

Note

SolidWorks uses millimetres in its STL export dialog. Onshape uses metres for its STL export tolerances. If the triangle count is still too high after export, use the built-in simplification tool during import.