What is a single-axis tracker?
A single-axis tracker is a mounting structure that rotates rows of solar modules through the day to follow the sun's east-to-west motion. The axis of rotation is typically a horizontal torque tube oriented north-south. Modules mounted on the tube tilt east in the morning, lie flat at noon (or close to it), and tilt west in the afternoon. Motorised actuators driven by control software perform the rotation.
The benefit is straightforward: modules better aligned to the sun capture more direct sunlight. Field-measured single-axis tracker installations in Indian utility-scale solar typically generate 15 to 25 percent more annual energy than equivalent fixed-tilt installations on the same site. Combined with bifacial modules, the combined gain can exceed 30 percent.
Trackers add cost, complexity, and maintenance compared to fixed-tilt mounting. The capital cost premium is typically 8 to 15 percent of total project cost. For utility-scale and large ground-mounted commercial, the energy gain justifies the premium. For rooftop, the lack of space and structural constraints make trackers impractical; fixed-tilt is universal.
Why single-axis trackers matter
For utility-scale developers, trackers are now the default in most Indian projects since around 2020. The economics of trackers improve as inverter costs, land costs, and tariff competition tighten the project IRR margin. Adding 20 percent annual yield while adding 10 percent capital cost is a clear improvement.
For SECI auction bidders, tracker deployment is implicit in the discovered tariff trajectory. Modern Indian utility-scale tariffs (around ₹2.20 to ₹3.00 per kWh) are largely calculated with single-axis tracker + bifacial assumptions.
For ground-mounted large commercial and industrial projects with land available, trackers offer an alternative to building more land-intensive fixed-tilt arrays.
For policy, tracker manufacturing is part of the broader Atmanirbhar Bharat push, with some Indian companies building domestic tracker capacity to reduce import dependence.
How a single-axis tracker works
- Row layout. Modules mounted on a horizontal torque tube, multiple panels long.
- Torque tube orientation. North-south, so the modules rotate east-west through the day.
- Drive system. Motorised actuator (typically one motor per row) rotates the torque tube.
- Control software. Uses solar-position algorithms to compute the optimal angle each minute.
- Backtracking. In early morning and late afternoon, the tracker reverses to prevent row-on-row shading.
- Stow mode. During high winds or storms, modules flatten to reduce wind loading.
- Monitoring. Tracker status (position, motor health, sensor data) is reported to a SCADA system.
- Maintenance. Periodic inspection of motors, bearings, and structural connections.
Real example: 100 MWp single-axis tracker plant in Rajasthan
Project. 100 MWp ground-mounted utility-scale plant near Phalodi, Rajasthan. Single-axis tracker, bifacial PERC modules.
Annual generation. 188 GWh (1,880 kWh per kWp). CUF: 21.5 percent.
Comparison with fixed-tilt baseline. Same project as fixed-tilt mono-facial: estimated 165 GWh (1,650 kWh per kWp), CUF 18.8 percent. Tracker + bifacial added 14 percent over baseline.
Cost premium. Tracker capital cost: about ₹40 crore added to a ₹450 crore project. About 9 percent premium.
Revenue impact. 23 GWh additional annual generation at ₹2.55 PPA tariff = ₹5.9 crore annual additional revenue.
Payback on tracker premium. About 7 years.
Benefits of single-axis trackers
- 15 to 25 percent more annual energy. Compared to fixed-tilt at the same site.
- Better afternoon generation. Higher output during peak-tariff hours in time-of-day regimes.
- Synergistic with bifacial. Combined gain can exceed 30 percent.
- Higher CUF. Pushes Indian utility-scale CUF from 18-19 percent to 21-24 percent.
- Better land utilisation. More energy per acre of project footprint.
- Mature supply chain. Indian and international tracker manufacturers serve the market.
- Standardised installation. Well-documented procedures across major brands.
Limitations of trackers
Capital cost premium. 8 to 15 percent above fixed-tilt.
Higher maintenance. Motors, bearings, sensors require periodic service.
Wind exposure. Stow modes must operate correctly during high winds.
Not for rooftop. Roof space and structural support do not accommodate trackers.
Land slope sensitivity. Trackers prefer flat ground; sloped sites need terraced installation.
Failure modes more complex. Tracker failures can affect entire rows.
Snow loading constraint. Not relevant for most India but matters for high-altitude or international projects.
Trackers in Indian solar
| Aspect | Status |
|---|---|
| Utility-scale standard since | ~2020 onward, default in most new projects |
| Typical annual gain | 15 to 25 percent over fixed-tilt |
| Combined with bifacial | Combined gain over 30 percent in good sites |
| Indian utility-scale CUF range | 21 to 25 percent with tracker + bifacial |
| Major suppliers | Nextracker, Array Technologies, PV Hardware, Soltec, Trinatracker, Antaisolar, Indian Tier-2 suppliers |
| Cost premium | 8 to 15 percent of total project cost |
| Rooftop use | Negligible |
Quick facts
| Term | Single-Axis Tracker (Horizontal Single-Axis Tracker) |
|---|---|
| Axis | North-south oriented horizontal torque tube |
| Rotation | East-west, following the sun's daily motion |
| Typical annual gain | 15 to 25 percent over fixed-tilt |
| Backtracking | Standard feature, prevents row-on-row shading |
| Stow mode | Standard, protects against high winds |
| Application | Utility-scale ground-mounted, large commercial ground installations |
| Cost premium | 8 to 15 percent of project cost |
Common mistakes about single-axis trackers
- Considering trackers for rooftop. Not viable for residential or commercial rooftop.
- Skipping backtracking configuration. Without it, row-on-row shading destroys morning and evening yield.
- Underestimating maintenance. Trackers need periodic service; budget for it.
- Ignoring soil and slope conditions. Tracker installation favours level, stable ground.
- Choosing the lowest-cost tracker. Reliability, monitoring, and service support matter for long-term performance.
- Quoting tracker gain without bifacial context. Combined design is what most modern projects use.
- Skipping wind-stow verification. Critical for storm safety.
Key takeaways
- Single-axis trackers rotate modules east-west through the day, adding 15 to 25 percent annual generation.
- Standard in Indian utility-scale solar since around 2020.
- Capital cost premium 8 to 15 percent, typically justified by yield gain.
- Combined with bifacial modules, total gain can exceed 30 percent.
- Backtracking and stow modes are essential features.
- Not viable for rooftop installations.
- Indian utility-scale CUF reaches 21 to 25 percent with tracker + bifacial.
Frequently Asked Questions
What is a single-axis tracker?
A single-axis tracker is a motorised mounting structure that rotates solar modules through the day along one axis (usually north-south oriented so the modules tilt east-to-west). The rotation keeps the modules better aligned to the sun, capturing more energy than fixed-tilt mounting.
How much extra generation does a tracker add?
Single-axis trackers typically add 15 to 25 percent annual generation over equivalent fixed-tilt installations. Combined with bifacial modules, the gain can exceed 30 percent in good Indian sites.
Are trackers used in Indian utility-scale solar?
Yes, increasingly. Most large utility-scale solar plants built in India after 2020 use single-axis trackers. The technology is mature, well-supported by Indian and international suppliers, and economically justified at utility scale.
Are trackers used in rooftop solar?
Rarely. Rooftops do not have the space, structural support, or economics for trackers. Fixed-tilt mounting is standard for residential and commercial rooftop. Trackers are for ground-mounted utility-scale and large commercial ground installations.
How does a single-axis tracker work?
A row of modules is mounted on a horizontal torque tube that runs north-south. Motorised actuators rotate the tube through the day so the modules face the sun. Control software typically optimises for maximum energy capture, including 'backtracking' to avoid module-on-module shading in early morning and late afternoon.
What is the difference between single-axis and dual-axis trackers?
Single-axis trackers rotate along one axis (typically east-west). Dual-axis trackers rotate along two axes, tracking both the daily east-west motion and the seasonal north-south altitude. Dual-axis adds another 5 to 10 percent over single-axis but costs significantly more and is rarely justified economically.
Are trackers reliable?
Yes, modern trackers are reliable when well-designed and maintained. Failure modes include motor failure, sensor drift, structural fatigue, and stow-mode failures during high winds. Good trackers operate for 25-plus years with periodic maintenance.
What is backtracking?
Backtracking is the tracker control mode used in early morning and late afternoon when low sun angles would cause one row of modules to shade the next row. The tracker temporarily reverses to keep modules from shading each other, sacrificing some sun alignment for avoided shading. Backtracking is a standard feature on quality trackers.
How do trackers handle wind?
Trackers have a stow mode where modules are flattened to minimise wind loading during high winds. Anemometers and weather forecasts trigger the stow. Structural designs account for the stowed configuration's wind load.
What is the cost premium for trackers?
Single-axis trackers typically add 8 to 15 percent to project capital cost. The 15 to 25 percent annual energy gain usually exceeds this premium, making trackers economic for utility-scale and large commercial ground-mounted projects.
Are trackers used with bifacial modules?
Yes, and the combination is particularly synergistic. Tracker-mounted bifacial modules see better rear-side light access throughout the day. Many utility-scale Indian projects combine single-axis tracker + bifacial for maximum yield.
What manufacturers supply trackers in India?
Several Indian and international tracker manufacturers serve the Indian market. Names include Nextracker, Array Technologies, PV Hardware, Soltec, Trina (now Trinatracker), Antaisolar, and Indian companies like Premier Energies, Mahindra, and a number of mid-tier suppliers.
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- NREL. Single-axis tracker performance modelling. nrel.gov
- Fraunhofer ISE. Tracker design and field-performance research.
- Tracker manufacturer technical documentation. Nextracker, Array Technologies, PV Hardware, Soltec, others.
- SECI tender documents. Tracker requirements in utility-scale auctions.
- Bridge to India and Mercom India. Tracker adoption trends in Indian utility-scale.
- IEC 62817. Standard for solar tracker design qualification.
- Indian utility-scale plant operational reports. Measured tracker gain over fixed-tilt.
Written by QuickEstimate Editorial, QuickEstimate Editorial (Surat).
Last updated: 4 June 2026.