Understanding your single-axis tracker output
Why axis orientation drives most of the gain
A north-south axis tracker, which rotates panels from east to west across the day, captures far more of the sun's daily path than an east-west axis tracker. Standard single-axis trackers with a north-south axis produce roughly 20% more output than a fixed mount, while an east-west axis setup captures closer to 12%. Nearly every commercial tracker installation uses the north-south configuration for this reason. A DOE study of federal PV systems found performance ratios reaching as high as 101% at some sites, though tracking hardware introduces its own maintenance considerations.
Backtracking and why row spacing matters
Backtracking is when a tracker tilts back from its ideal sun-facing angle early and late in the day to avoid casting a shadow on the next row of panels. Tighter row spacing forces more backtracking and gives up more potential output than wider spacing. This tradeoff between land use and output is a core design decision for any tracker field. NLR's own modeling documentation covers this same row-to-row shading and backtracking behavior as one of the standard factors accounted for in professional tracker system design.
Why tracking range has diminishing returns
Yes, especially with ranges under 90 degrees total rotation. A tracker with a full plus or minus 60 degree range captures nearly the full benefit, while a more limited range misses meaningful output during early morning and late afternoon hours. Some tracker designs intentionally limit range to reduce wind loading and mechanical stress, trading a small amount of output for durability. Compare the overall gain against a simpler tracking vs fixed mount comparison if you're still deciding between mount types.
Land requirements for tracker installations
Single-axis tracker fields typically need more ground space per panel than a fixed array, since rows must be spaced further apart to limit self-shading during backtracking. This makes trackers more common on ground-mount installations with available land than on tight residential lots. Compare against the ground mount vs roof mount comparison if space constraints are part of your decision.
What to do with this number next
Compare your tracker output gain against the dual-axis tracker calculator to see whether the added complexity of a second axis is worth it for your site. Since tracker hardware adds meaningful upfront cost alongside its output gain, the total cost of ownership calculator can help weigh whether that added output actually pays for the extra equipment over the system's lifetime.