Path-Q Solar

Would a ground-mounted system work if the soil is rocky or difficult to excavate?

Answer

Possibly. Rocky or difficult soil can make conventional driven posts or excavated foundations impractical, but alternatives may include drilled foundations, rock anchors, concrete foundations, ground screws where suitable, or a redesigned array. The best option depends on the soil, rock, slope, access, and structural requirements.

Key points

  • Rock can increase drilling, equipment, labor, and foundation costs.
  • A geotechnical or foundation assessment may be needed if subsurface conditions are uncertain.
  • Steep or uneven ground can create additional grading, drainage, and erosion concerns.
  • The array may remain feasible even if the original mounting method is not.

What it depends on

  • Depth, hardness, and distribution of rock
  • Soil bearing capacity, frost or ground movement conditions, and slope
  • Array size, height, wind exposure, and foundation design
  • Equipment access and the amount of grading allowed

Risks and trade-offs

  • Alternative foundations may cost substantially more than standard driven posts.
  • Heavy drilling or grading can disturb drainage, vegetation, or nearby structures.
  • An attractive quote based on assumed soil conditions may increase after refusal or rock is encountered.

Information you may need

  • A site survey and proposed array location
  • Any prior excavation, well, septic, geotechnical, or foundation information
  • Installer assumptions about foundation type and refusal or rock-removal charges
  • Access constraints for drilling and material delivery

Your next step

What to do next

Have the installer inspect or test the proposed area and obtain comparable quotes that state the assumed soil conditions and how unexpected rock will be handled.

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