With an integrated GPS receiver, 4-quadrant precision sun sensor, and Harmonic Drive® technology, the STR-21G Sun Tracker is built to deliver unparalleled precision, optimal positioning, and reliability, whatever the weather.

Easy to set up, the STR-21G automatically adjusts to the sun’s position, even if the tracker is not perfectly oriented or levelled, and can support a range of Global, Diffuse and Direct Radiation measurement sensors for custom configurations.

The single configurable arm of the STR-21G can mount the MS-57 Class A Pyrheliometer for DNI readings and the optional MD-81-10 shading disk assembly, shielding any top-mounted pyranometer for diffuse solar radiation measurements.

For over 20 years, clients who have deployed STR sun-trackers have enjoyed easy set-up, smooth operation, and reliable tracking.