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A single-axis tracker can increase energy yield compared with fixed tilt, but the gain depends on the weather file, terrain, row spacing and control strategy. Compare modelled annual production, capital cost and maintenance for the actual site rather than assuming a universal percentage.
This page is for developers and EPCs deciding between fixed tilt and tracking on a ground-mount project. It covers the site conditions that decide it, what backtracking actually does, and the failure modes that are specific to trackers.
What the tracker is actually buying you
Tracking gain varies with solar resource, weather, row layout, ground coverage and control strategy. Model the site weather file and terrain; latitude alone does not establish the gain or make low-latitude tracking unsuitable.
Use the site production model and financial assumptions to compare tracking with fixed tilt. The break-even gain depends on equipment cost, maintenance, energy value and layout, so it is not a universal percentage.
Ground slope is the first screen
Check longitudinal and cross-row slopes against the selected tracker geometry, articulation and foundation tolerances. Permitted terrain variation is model-dependent, and any grading or stepped foundations must be included in the structural and cost review.
If the site needs significant grading to be tracker-ready, that earthworks cost has to be in the comparison — and it is often the item that tips a marginal site back to fixed tilt. Our ground-mount racking tolerates more site variation per pound spent.
Row spacing and backtracking
Tracking rows are spaced wider than fixed rows, because a row at a steep morning angle casts a longer shadow. Backtracking is the control strategy that handles this: instead of pointing every row directly at the sun, the controller rotates rows away from the ideal angle in the early morning and late evening so they do not shade each other.
The trade-off is real — backtracking gives up a little energy to avoid a larger shading loss — and the ground coverage ratio it produces is a design input, not a default. On land-constrained sites the spacing decision drives the whole layout.
Wind stow is a design item
A tracker is designed to move to a stow position when wind exceeds a set speed, and that setpoint and the stow angle are part of the structural design rather than an afterthought. Two things matter: the anemometer placement, which has to see representative wind rather than a sheltered corner, and the failure behaviour if power or communications are lost.
A tracker that cannot reach stow when it needs to is a structural problem, not a production problem. Confirming the fail-safe behaviour and the backup power arrangement before commissioning is worth the half hour.
What fails, and what to hold as spares
Trackers have a small number of failure modes that account for most of the downtime:
- Drive and motor failure — the most common single item. Hold at least one spare drive.
- Controller and communications — a network fault can take a whole motor group off tracking, which shows up as lost production rather than as an alarm.
- Bearings and fasteners — inspection items on a schedule, not when something sounds wrong.
- Anemometer and sensors — cheap, and a failed one either stows the field unnecessarily or fails to stow it when needed.
Availability is a contractual number
Tracker availability targets above 98 percent are normal, but they depend on spares holding and service access, both of which are decisions made at design stage rather than later. Two questions to settle early: how quickly can a failed drive be replaced, and can a service vehicle reach the row in wet weather.
When fixed tilt is the better call
Be honest about these four, because they are the cases where a tracker costs more than it returns:
- Sites where the production and financial model does not justify tracking, regardless of latitude
- Sites needing heavy grading to take rows
- Small arrays, where the controller cost does not spread far enough
- Sites with difficult access or no maintenance capacity
Specifications at a glance
Configuration reference
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| Parameter | Typical value | What it depends on |
|---|---|---|
| Type | Horizontal single-axis tracker, one module in portrait or two in landscape | Module format and row length |
| Rotation range | Typically plus or minus 60 degrees | Latitude and the production model |
| Modules per row | 30 to 60 depending on format and row length | String layout and drive torque |
| Drive | Slewing drive per row, or a shared drive per motor group | Row count and redundancy philosophy |
| Control | Astronomical tracking with backtracking, wind stow on anemometer | Row spacing and site wind climate |
| Foundation | Driven pile or ground screw, one per pier | Soil conditions and pull-out capacity |
| Ground slope tolerance | Commonly up to 10 percent north-south, more with stepped piers | Site grading and earthworks budget |
| Wind load | Calculated to ASCE 7 or EN 1991-1-4, with a defined stow wind speed | Region, terrain and the stow strategy |
| Materials | Hot-dip galvanised steel, stainless fixings | Design life and corrosion class |
| Availability target | Define any availability target and measurement method in the contract | Selected system, maintenance, spares and exclusions |
| Documentation | Layout, foundation drawing, wind stow procedure, maintenance schedule | Issued with every project |
| Warranty | Confirm structural, coating and component warranty terms for the selected system | Selected model and written order terms |
Figures are selection references. Confirm the final ratings, dimensions, available certifications and warranty against the current datasheet and written proposal for the selected model or system.
Questions buyers ask about trackers
How much more energy does it really produce?
It depends on latitude and on the local weather file, and it should be modelled rather than taken from a range. Send the site location and we will put the modelled difference next to the capital and O&M difference.
What if the power fails while the wind is up?
That is why the fail-safe behaviour matters. The design should define what position the rows take on loss of power or communications, and it should be a stow position. Confirm it before commissioning rather than assuming.
Do we need more land?
Land use depends on the selected row geometry, ground coverage ratio and backtracking strategy. Compare the tracker and fixed-tilt layouts using the site production model rather than assuming one always needs more land.
How much maintenance does it need?
More than fixed tilt: periodic inspection of drives, bearings and fasteners, plus controller and communications checks. The schedule comes with the project, and availability depends on holding the right spares.
Can we mix trackers and fixed tilt on one site?
Yes, it is common on sites with mixed ground — trackers on the good flat areas, fixed tilt on the parts that would need grading. It does mean two sets of spares and two maintenance routines.
What to send us
Send the site location, the land area and its slope, the soil conditions if you have them, and the array size. We come back with a layout, the modelled production difference against fixed tilt, the wind stow procedure, and a written delivery date.
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Send the terrain, the row length and the wind speed
With the terrain, row length, wind speed and snow load, and module dimensions, we confirm tracker suitability for the site and the controller and power supply requirements.
Send your requirementsOr reach us directly: +86 136 7367 3267 · sales@gtpsolar.com