Linear Actuator and Slewing Drive for Solar Trackers

A solar tracking structure must move a large panel array slowly, accurately, and reliably. Depending on the tracker design, that movement may require one linear axis, one rotary axis, or a combination of both. An Elerover SLA-15KB linear actuator can provide the push-pull motion used to change panel tilt, while an Elerover slewing drive can provide controlled rotary motion around the tracker structure.

Used together in a dual-axis architecture, these two drive types separate the motion into two clear functions: the linear actuator adjusts elevation, and the slewing drive adjusts azimuth. This makes the system easier to control and allows each component to be selected for the load it handles.

What Does Each Drive Do in a Solar Tracker?

Although both products move the panel structure, they do not perform the same mechanical task.

SLA-15KB Linear Actuator: Panel Tilt or Elevation

The SLA-15KB converts the rotation of its electric motor into linear extension and retraction. When its mounting points are connected between the fixed support and the moving frame, a change in actuator length changes the panel tilt angle.

The actuator is suitable for applications that need:

• Controlled push-pull movement
• High axial force at low speed
• A defined stroke and repeatable end positions
• Position feedback for closed-loop tracking
• Self-locking behavior to help hold the mechanism when the motor stops

The actuator stroke cannot be selected from panel angle alone. The pivot locations, lever arm, closed length, open length, and required angular range must all be considered.

Slewing Drive: Tracker Rotation or Azimuth

A slewing drive produces high-ratio rotary movement. In a dual-axis solar tracker, it can rotate the tracker structure around a vertical or inclined axis to follow the sun from east to west. A worm gear design also provides compact speed reduction and high holding capacity.

The slewing drive is normally selected according to:

• Required output torque
• Static holding torque
• Tilting moment load
• Gear ratio and output speed
• Backlash or positioning requirement
• Mounting interface and available space
• Motor voltage and control method

The exact model should be calculated from the tracker structure and site loads rather than selected from panel area alone.

Single-Axis and Dual-Axis Configurations

The correct drive arrangement depends on the tracker geometry.

Tracker configuration	Typical drive function	Suitable Elerover solution
Single-axis tilt tracker	Changes the angle around one pivot axis	SLA-15KB linear actuator
Single-axis rotary tracker	Rotates the array around one main axis	Slewing drive
Dual-axis tracker	Controls both elevation and azimuth	SLA-15KB plus slewing drive

In a dual-axis system, the controller sends separate commands to the two drives. The linear actuator changes the elevation angle, while the slewing drive rotates the supporting structure. Hall sensor feedback from the actuator can help the controller monitor linear position. Rotary feedback can be added according to the slewing drive and control-system design.

SLA-15KB Specifications for Solar Tracking

The SLA-15KB is designed for high-load, low-speed linear motion. Available options allow the actuator to be matched to different tracker sizes and linkage geometries.

Parameter	SLA-15KB options
Maximum load	10,000 N, 12,000 N, or 15,000 N
Rated speed options	1.4 mm/s, 2.0 mm/s, or 3.0 mm/s
Stroke range	50-1,200 mm
Input voltage	12 V DC or 24 V DC
Position feedback	Hall sensor
Limit control	Built-in or external magnetic limit switch
Dynamic protection rating	IP66
Main materials	Aluminum housing and stainless-steel extension rod
Holding function	Integrated brake and strong self-locking design

These values describe the available product range, not a universal solar tracker configuration. Actual thrust, speed, stroke, mounting dimensions, and duty cycle should be confirmed for each project.

Why Combine a Linear Actuator with a Slewing Drive?

Using a separate drive for each motion axis gives the designer several practical advantages.

1. Each mechanism handles the motion it is designed for

The SLA-15KB creates linear force efficiently, while the slewing drive handles rotary torque and overturning loads. This avoids forcing one mechanism to perform both tasks through a complicated linkage.

2. Low-speed movement is easier to control

Solar tracking does not require fast motion. It requires stable, incremental positioning. The slow actuator speeds and high reduction of a slewing drive are well suited to this operating pattern.

3. The two axes can be controlled independently

Elevation and azimuth can follow separate control commands. This supports scheduled tracking, light-sensor tracking, or a controller that combines both methods.

4. The system can hold position between adjustments

The SLA-15KB uses a brake and self-locking mechanism. A worm gear slewing drive also provides high holding capacity. The complete structure still requires an engineering check for wind, imbalance, shock loads, and emergency conditions.

How to Select the Correct SLA-15KB Stroke

Stroke is determined by the tracker linkage, not simply by the desired panel angle. Before selecting an actuator, define:

1. The coordinates of both actuator mounting points
2. The minimum and maximum panel angles
3. The actuator length at each end position
4. The shortest required retracted length
5. The highest force throughout the full movement
6. Clearance around the actuator, cable, and joints

The required stroke is the difference between the calculated extended and retracted installation lengths, with appropriate design allowance. Moving a mounting point closer to the pivot may reduce required stroke but can significantly increase actuator force. Moving it farther from the pivot may reduce force but require more travel and installation space.

How to Select the Slewing Drive

For the rotary axis, calculate operating torque and holding requirements under the most demanding design condition. The selection should include the array center of gravity, wind load, axis offset, support stiffness, dynamic factor, and required safety margin.

Key project values include:

Selection input	Why it matters
Operating torque	Determines the torque required during tracking movement
Holding torque	Checks whether the drive can maintain position when stopped
Tilting moment	Accounts for overturning load on the rotary assembly
Required rotation range	Defines travel limits and cable-management needs
Output speed	Must match the tracker control strategy
Backlash	Influences positioning accuracy and movement under load reversal
Mounting dimensions	Ensures compatibility with the column and tracker frame

Elerover supplies multiple slewing drive models for solar tracking and other rotary applications. Model selection should be based on the calculated loads and interface requirements.

Electrical and Control Integration

A typical system includes a 12 V DC or 24 V DC power supply, tracker controller, actuator feedback input, motor reversing outputs, and travel-limit protection. For a two-axis tracker, each motor needs an independently controlled channel.

The controller should prevent movement beyond the mechanical range and provide a safe response to sensor faults, power interruption, or abnormal current. The structural design should also use mechanical stops where required. The actuator’s Hall signal can provide relative position information, but the final control architecture depends on the required positioning accuracy and homing method.

Information Needed for an Application Review

To recommend a suitable actuator configuration and slewing drive, please provide:

• Panel dimensions, quantity, and total moving mass
• Tracker drawing with pivot and mounting-point locations
• Required elevation and azimuth ranges
• Design wind speed and calculated wind loads
• Required linear force, rotary torque, holding torque, and tilting moment, if available
• Target tracking speed and daily operating cycles
• Power supply voltage and controller signal type
• Ambient temperature and installation conditions
• Prototype quantity and expected annual volume

One important distinction is that 15,000 N is linear actuator force, not the allowable weight of the complete solar array. The actual actuator load changes with linkage geometry and panel angle. Likewise, slewing drive capacity must be checked using torque and moment loads, not only the structure’s mass.

A Practical Drive Package for Solar Tracker OEMs

For a dual-axis tracker, a practical starting architecture is:

• One SLA-15KB linear actuator for elevation adjustment
• One correctly sized Elerover slewing drive for azimuth rotation
• Independent motor-control outputs for both axes
• Position feedback and calibrated travel limits
• Mechanical interfaces designed around the calculated load cases

This arrangement combines high-force linear positioning with compact rotary movement in one coordinated system. Elerover can support actuator stroke selection, feedback options, cable requirements, and slewing drive matching for prototype and production projects.

Frequently Asked Questions

Can the linear actuator replace the slewing drive?

Not directly. A linear actuator creates push-pull motion, while a slewing drive creates rotary motion. A linkage can convert linear travel into rotation around one pivot, but continuous or wide-range azimuth rotation normally requires a rotary solution.

Can the SLA-15KB be used in a single-axis tracker?

Yes. If the tracker geometry uses a linear linkage to rotate one axis, the SLA-15KB can provide the required extension and retraction after force and stroke calculations are completed.

Why is Hall sensor feedback useful?

Hall pulses allow the controller to monitor actuator movement and estimate position. They can support repeatable tracking, synchronization logic, and fault detection when correctly integrated and calibrated.

Which slewing drive model should I choose?

The image alone is not enough to identify the correct size. Output torque, holding torque, tilting moment, gear ratio, backlash, mounting dimensions, and site loads must be reviewed before a model is selected.

Discuss Your Solar Tracker Drive Requirements

Need a coordinated linear and rotary drive solution? Review the SLA-15KB linear actuator and our slewing drive range, then contact Elerover with your tracker drawing and load data. We can help define the actuator stroke, force option, feedback configuration, and slewing drive selection for your project.