• ST-5 Sun Tracker
  • ST-5 Sun Tracker with SolarSIM-G

direct irradiance measurement platform

ST-5 sun tracker

By employing the latest advances in tracker technology, the ST-5 makes direct and POA irradiance measurements refreshingly simple and affordable for research and industry alike.

Compatible sensors: SolarSIM-D2, SolarSIM-G, third-party pyrheliometers.
Technology: Dual/single-axis, SPA-based, automated sun tracker.
Highlights: State-of-the-art technology ensures the optimal combination of performance and price for all applications.

A dedicated direct irradiance measurement platform.

By employing the latest advances in tracker technology, the ST-5 achieves a breakthrough in the cost of accurate, reliable solar tracking.

The ST-5’s compact size and weight make transport, installation and maintenance refreshingly simple and affordable. With a payload limit of 5 kg, the ST-5 can be configured to hold up to 4 direct or global SolarSIMs, or an equivalent mass of non-Spectrafy instruments.

The ST-5’s automated control box employs a highly accurate and efficient solar positioning algorithm to determine the sun’s location, while the precision engineered hardware ensures pointing accuracy of ±0.1º. For custom uses, optional PC-based software allows manual control.

The on-board GPS automatically configures time and location upon start-up and eliminates internal clock drift, while the ST-5’s integrated leveling feet, azimuth adjustment and tie-down bolts enable swift and easy installation via the integrated bubble level.

Total control - if you want it.

Standard operation

Under standard operation, the ST-5 Sun Tracker requires no external comms connection to operate.

PC Connectivity (optional)

The ST-5 Sun Tracker can be connected to a PC to enable custom control of pointing algorithms and position.


Pointing accuracy ± 0.1 º
Payload 5 kg
Elevation range 0º to 125º
Azimuth range 0º to 360º
Over-rotation protection Physical limit stops
Tracking mode SPA based (open loop)
Heating Optional
Control Automated control box or RS-485 ASCII direct to PC


Weight 6 kg
Dimensions (W x D x H) 233 x 140 x 235 mm
Power supply and use 12 VDC, 34W in motion, 4W when idle, ~70 Whr/day
Operating temperature range -25°C to +55 °C (-40°C to +65 °C optional)
Humidity range 0 to 100% RH
Environmental protection IP66
Standard cable length 10 m

The go-to solution for a wide range of applications.

Solar R&D The most affordable and flexible direct irradiance measurement platform for R&D. The ST-5's software allows for unmatched flexibility in tracker control.
Meteorological networks Upgrade your network with the ST-5 to realise lower longterm maintenance costs.
Solar resource assessment - DNI The ST-5 makes on-site DNI measurements a feasible and affordable component of resource measurement campaigns - significantly reducing the expanded uncertainty of PV performance models.
Solar resource assessment - POAI The ST-5 can be deployed in elevation-only mode, mounted with the SolarSIM-GPV, in order to measure spectrally corrected, plane-of-array irradiance. Thereby providing the most accurate assessment of the solar resource for modern PV plants.
Solar power plant O&M Better monitor, understand and optimize your PV asset in real-time with on-site DNI measurements.
CSP & CPV The ST-5 represents a big step towards routine, affordable DNI measurements for CSP and CPV plants.
Custom applications The ST-5 Sun tracker can be controlled/programmed by the user to follow custom positioning algorithms.

Why would I choose the ST-5 over other solar trackers?

The ST-5's embrace of modern PTU technology makes it the most cost-effective, direct irradiance measurement platform on the market.

What sensors can I mount on the ST-5?

The ST-5 is sensor agnostic. It can be used to mount our SolarSIM sensors, or any third-party pyrheliometer or pyranometer. A range of mounting fixtures are available to support all major sensor manufacturers.

What measurements can I perform with the ST-5?

The ST-5 currently supports direct irradiance measurements - either direct normal or direct global. Contact us if you would like to use the ST-5 to measure diffuse irradiance or global horizontal irradiance.

Does Spectrafy sell complete measurement systems?

Yes, we can provide you with a complete turn-key system so you can hit the ground running.


MP-D2 Mounting Plate

We offer a range of standard, anodized aluminum mounting plates suitable for mounting the SolarSIM-D2 to various solar trackers, including Spectrafy's ST-5 solar tracker. Custom options are also available.


The original SolarSIM, for measuring spectral and broadband DNI and atmospheric parameters.