Solar tracker systems are one of the fastest-growing applications for slew drives globally. A well-chosen slew drive can increase the energy yield of a solar installation by 20–40% compared to fixed-tilt panels. But choosing the wrong slew drive — the wrong type, undersized torque, or poor IP rating — leads to premature failure, costly downtime, and lost energy generation.
This buying guide from Kavitsu Robotronix, a manufacturer and global exporter of slew drives for over 30 years, covers everything you need to know to select the right slew drive for your solar tracker project — whether you are building a small rooftop tracker or a large utility-scale solar farm.
Why Solar Trackers Use Slew Drives
A solar tracker must do three things: rotate solar panels to follow the sun, hold the panels in position against wind loads, and operate reliably outdoors for 25+ years with minimal maintenance. A slew drive is the ideal mechanism for all three requirements because:
- Self-locking worm gear — holds the panel position against wind without any brake power consumption. When the motor stops, the load cannot back-drive the gear. Critical for safety and energy savings.
- High torque in a compact unit — delivers the torque needed to rotate large panel arrays while fitting within the slim structural profile of a tracker frame
- All-in-one sealed unit — the bearing, gear, and motor interface are integrated in a single IP65 housing that survives rain, dust, humidity, and temperature extremes for 25 years
- Precise positioning — accurate sun-following with minimal backlash, directly increasing energy capture efficiency
SE Type vs WE Type Slew Drive — Which One for Solar?
Slew drives for solar trackers come in two primary configurations. Understanding the difference is the first selection decision:
SE Type Slew Drive (Horizontal / Azimuth)
Single Axis – Horizontal Most Common for SolarThe SE (Standard Enclosed) type slew drive has a horizontal worm shaft. The motor mounts on the side and drives a horizontally-oriented worm gear. This configuration is ideal for single-axis solar trackers that rotate panels along an East–West horizontal axis to track the sun's daily arc from sunrise to sunset.
- Motor mounts horizontally on either side of the housing
- Rotation axis is vertical — the output flange rotates about a vertical axis
- Available in sizes from SE3 through SE25+ depending on torque requirement
- Most widely used configuration in ground-mounted solar tracker installations worldwide
WE Type Slew Drive (Vertical / Elevation)
Dual Axis – ElevationThe WE (Worm Enclosed, Vertical) type has a vertical worm shaft with the motor mounted above or below the housing. This configuration provides the elevation-axis rotation in a dual-axis solar tracker — tilting panels to follow the sun's changing altitude angle (higher in summer, lower in winter).
- Motor mounts vertically above or below the housing
- Output flange rotation is horizontal — tilts the panel frame up and down
- Used as the elevation-axis drive in dual-axis tracker systems
- Typically paired with an SE type drive on the same tracker for full two-axis tracking
7 Key Parameters for Selecting a Solar Tracker Slew Drive
1. Output Torque (kNm)
The most critical parameter. The slew drive must deliver enough torque to rotate the solar panel array under maximum wind load. Calculate the design torque as: wind moment load on the panel array + structural friction + safety factor (typically 1.5×). For utility-scale single-axis trackers, torque requirements typically range from 5 kNm to 50 kNm depending on panel array size and wind design speed.
2. Holding Torque (Self-Locking)
The holding torque is the torque the slew drive can resist without moving — this must be at least equal to the maximum wind moment load on the panel array at the design wind speed (often 60+ m/s survival wind speed for utility solar farms). Kavitsu slew drives use worm gear self-locking, which provides a holding torque typically 1.5–2× the output driving torque.
3. Gear Ratio
The gear ratio determines the motor speed needed to achieve the required panel rotation speed. Solar trackers typically need to rotate approximately 180° per day (East to West), so rotation speed is very slow — typical rotation rates are 0.1–1 RPM at the output. A higher gear ratio means a faster (and smaller, cheaper) motor can be used. Typical solar tracker slew drive gear ratios are 50:1 to 150:1.
4. IP Protection Rating
All outdoor solar applications require at minimum IP65 protection — completely dust-tight and protected against water jets from any direction. For coastal solar farms exposed to salt spray, IP66 or IP67 is preferable. Kavitsu solar tracker slew drives are rated IP65 as standard, with enhanced sealing options available for marine and coastal environments.
5. Backlash
Backlash is the small amount of free movement in the gear before the output begins to respond to the motor input. For solar trackers, low backlash is important for accurate sun-tracking — high backlash means the panel "hunts" around the target position and loses tracking accuracy. Kavitsu slew drives use precision-ground worm gears to minimise backlash, typically less than 0.1°.
6. Motor Interface
Specify whether you will use an electric motor (DC or AC) or hydraulic motor. The slew drive motor flange must match your motor's mounting dimensions (IEC frame or custom flange), shaft diameter, and keyway dimensions. Kavitsu can supply slew drives with standard IEC motor flanges or custom motor interfaces to match your specified motor.
7. Mounting Configuration and Size
Specify the output flange bolt circle diameter (BCD) and the number and size of mounting bolts. The slew drive must physically fit within your tracker's structural framework. Share your tracker drawing or envelope dimensions and our engineers will confirm the correct slew drive size.
Slew Drive Size Selection Reference Table
| Drive Size | Torque Range | Typical Application | Motor Type |
|---|---|---|---|
| SE3 / SE5 | Up to 5 kNm | Small single-axis tracker (residential/C&I) | Small DC/AC motor |
| SE7 / SE9 | 5–15 kNm | Medium single-axis tracker (commercial) | AC induction motor |
| SE12 / SE14 | 15–35 kNm | Large single-axis tracker (utility scale) | AC motor or hydraulic |
| SE17 / SE21 | 35–80 kNm | Very large utility trackers, large dual-axis | Hydraulic motor |
| WE5 / WE7 | 5–20 kNm | Elevation axis – dual-axis tracker | DC or AC motor |
| WE9 / WE12 | 20–50 kNm | Large elevation axis – utility dual-axis | AC or hydraulic motor |
Why Buy Solar Tracker Slew Drives from Kavitsu (India)?
Solar EPC developers and tracker OEMs in the USA, Germany, Spain, Australia, UAE, and other markets source slew drives from Kavitsu for four key reasons:
- Cost: Indian-manufactured slew drives offer 25–40% cost savings versus equivalent European products at the same quality specification
- Quality: 30+ years of manufacturing experience, precision-machined worm gears, induction-hardened raceways, IP65 sealed housings
- Customisation: Any size, any torque, any motor interface — fully custom-engineered to your tracker drawing
- Export expertise: Full export documentation, material certificates, FOB/CIF pricing to all major ports, English-language support throughout
How to Order Solar Tracker Slew Drives from Kavitsu
- Send your enquiry with: tracker type (single/dual axis), required torque (kNm), gear ratio, motor type and frame size, IP rating requirement, quantity, and target delivery date
- Our engineers will review, ask any clarifying questions, and provide a technical confirmation within 24 hours
- Receive a detailed quotation with unit price, FOB/CIF pricing, packing details, and lead time
- On order confirmation and advance payment, manufacturing begins
- Completed drives are inspected and supplied with dimension inspection report and material test certificates
- Sea freight dispatch from JNPT (Mumbai) to your port of destination
Get a Competitive Quote for Solar Tracker Slew Drives
Tell us your tracker type, required torque, and quantity. Kavitsu Robotronix will provide engineering confirmation and a competitive export price within 24 hours — with full support for USA, Germany, UAE, Australia, Spain, and 30+ other countries.
Request Solar Tracker Slew Drive Quote