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STR-21G Sun Trackers

Make:  Eko       Model:  STR-21G
✅ All-Weather Tracking with Integrated GPS Receiver & 4-Quadrant Sun Sensor
✅ Measurand: Global, Diffuse and Direct Radiation.
✅ Sensor Type: Harmonic Drive® mechanical gear system, for maximum positioning accuracy
✅ Signal Output: RS-232 serial Interface
✅ Supplied With: 10 m Power supply cable (AC or DC type), 3m Communication cable

The compact single arm sun tracker is perfectly suited to support all kinds of Global, Diffuse and Direct Radiation measurement sensors. STR-21G is the base of the Solar Monitoring Systems (STR-21G-S), a turnkey measurement solution from EKO. The STR-21G provides a fully automated set up procedure through a GPS receiver providing increased reliability and enhanced functionality.

From sunrise to sunset the compact sun-tracker guarantees accurate sun tracking and pointing of the attached solar sensors. The 2-axis tracker automatically adjusts to the sun’s position by the sun sensor closed-loop control system, even if the tracker is not oriented or leveled properly.

The sun-tracker comes standard with a small table tripod (larger tripod available). The 24 VDC low power consumption tracker can be powered by a solar-powered battery system or DC power supply. A wide range AC power adapter can be supplied to connect to the grid.

For over 20 years our clients who have deployed the STR sun-tracker, experience ease of set-up, operating and reliable tracking.







Pointing accuracy Solar elevation: 0 to 87°

< 0.01 °

Angle resolution

0.009 °

Rotation angle Zenith

-15 to 95 °

Rotation angle Azimuth

0 to 360 °


12 Nm

Payload side arms

7 kg

Sun sensor FOV

30 °

Ingress protection IP


Operating temperature range

-40 to 50 °C


RS-422 / 232C

Power consumption

< 10 W

Power Supply

Power supply: 21 to 32 VDC / 20W
Power supply(Power Adapter): 100 to 240 VAC / 20W

Dimensions mm

430 (W) x 380 (L) x 440 (H)


14.5 kg (With tripod)


Stepper motor

Driving Technology

Harmonic drive®

Tracking mode

Solar postion / Free positioning


Table tripod

Pyrheliometer mount

Adjustable / One position

Cable length

10 m