Mean slope
Mean slope is the average terrain gradient (%) across all valid analysis points in your boundary. It is the primary metric for overall constructability and a strong first filter for fixed-tilt ground mount.
Maximum slope
Max slope is the steepest single grid cell. A site with low mean slope but high max slope often has localized steep strips — ridges, cuts, or drainage features — that need layout or grading attention even when averages look excellent.
Cross-row slope (trackers)
For single-axis trackers, grade measured perpendicular to row direction (cross-row) drives structural clearance, drainage, and grading cost. A rolling site can show modest mean slope while cross-row statistics flag areas where torque tube clearance or pile reveal becomes challenging.
TerrainIQ reports cross-row mean and high-percentile statistics for tracker screening. PVMath may label tracker verdicts with Review Zones when cross-row metrics suggest clearance review — even if mean slope looks favorable.