I am trying to determine if a given property may be amenable for a ground based commercial solar project.

Among basic requirements there is flatness (5% slope or less), so I am trying to determine the slope suitability.

What is the best method to determine it?

If it helps I have a DEM LiDAR image of the area pulled in and have created 1' contours off of it already.

closed as primarily opinion-based by xunilk, aldo_tapia, whyzar, Kersten, tinlyx Jan 16 '18 at 0:01

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Voting to reopen; clear question (after the edits it improved); suitable answers with clear positive feedback from OP. – Andre Silva Jan 17 '18 at 12:32
  • 1
    Don't forget to take the Tour and to accept (green checkmark) the answer that helped you the most. – PolyGeo Jan 17 '18 at 12:32

You mention 3D Analyst so I am assuming you have ArcGIS.

  • Use the tool ArcToolbox-3D Analyst Tools-Raster Surface-Slope to create a slope surface from your LiDAR data.
  • Use the tool ArcToolbox-3D Analyst Tools-Raster Reclass-Reclassify and give all the values > 5% slope NoData, and all the areas <=5% slope a value of 1. All the pixels with a value of 1 are all the places that have adequate slope.

You could do a similar reclassification with all your raster layers, then add the resulting layers up. The resulting summation will likely have values between 1-3. The 3 value pixels will be the areas that satisfy your three conditions. Build there.


You can take the DEM and run the "Slope" tool in 3D Analyst. It is under the "Surface" Toolset. Choose "percentage" as the output type.

Once you have the "Slope" raster you can run the Reclass tool to find the ideal slope you are needing (5%). You can reclassify 5% as 1 and everything else as 0. You could add additional classes to identify those areas moderate to less ideal. You can convert the reclassed raster to polygon for use in your model.

  • Ok I just performed that function. I chose the percent rise as my output measurement. Once I pull Up my symbology and go to reclassification, I'm seeing break values in 9 classes with the lowest being 0.6174475373 and the highest being 13.12076092. Are these the percentage values? If so, How can I simply this by only showing 5% or less? – Natedawg5509 Jan 15 '18 at 20:02
  • Yes. Those are percentages. Click the classify button and using the options choose the ranges you want for your classification. – Keagan Allan Jan 15 '18 at 20:06

Not the answer you're looking for? Browse other questions tagged or ask your own question.