Hi Claudio,
We did not have time to document the terrain inputs before we release SAM 2021.12.02. We are working on Help revisions for the first update that we plan to release in late January or early February 2022.
Here is the description:
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Terrain Angles
The terrain slope and azimuth angles describe the inclination of the ground with respect to horizontal, assuming the subarray is installed on uniformly sloped, flat land. Terrain inputs are only enabled for systems with one-axis tracking. Their effect depends on the self shading options on the Shading and Layout page:
- Backtracking enabled: Backtracking algorithm takes the terrain angles into consideration to calculate the tracker rotation angle.
- Linear self shading enabled: Self-shading algorithm accounts for terrain angles to calculate the shaded fraction of the array.
- Non-linear self shading enabled with no backtracking: Terrain angles do not affect the self-shading calculations.
Note. The terrain angles are not available for fixed (no tracking) subarrays.
The terrain slope model is described in Anderson, K.; Mikofski, M. (2020) Slope-aware Backtracking for Single-axis Trackers. National Renewable Energy Laboratory. 24 pp. NREL/TP-5K00-76626. (
PDF 783 KB
), also listed at
sam.nrel.gov/photovoltaic/pv-publications.html.
Terrain slope, degrees (0 to 90 degrees)
The grade slope angle, defined as the angle between the slope plane and the horizontal plane. Zero is for horizontal ground with no slope.
Terrain azimuth, degrees (0 to 360 degrees)
Grade azimuth angle, defined as the angle clockwise from north of the horizontal projection of falling slope. Zero is for a north-facing slope, or ground that slopes down toward the north.
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I did some testing and am having trouble getting the slope to affect results. I will follow up with you after I investigate more.
Best regards,
Paul.
