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Enabling better global research outcomes in soil, plant & environmental monitoring.

Apogee Thermopile Pyranometers

The SP-510 (upward-looking) and SP-610 (downward-looking) thermopile pyranometers are designed for accurate and stable global shortwave radiation measurement and reflectance.

Accurate, Stable Measurements
Calibration in controlled laboratory conditions is traceable to the World Radiometric Reference in Davos, Switzerland. The upward-looking model is cosine-corrected, with directional errors less than 20 W m2 at 80° solar zenith angle. Long-term non-stability, determined from multiple replicate pyranometers in accelerated aging tests and field conditions, is less than 2% per year.

Rugged, Self-cleaning Housing
Patented domed shaped sensor head (diffuser and body) for the upward-looking model facilitates runoff of dew and rain to keep sensor clean and minimise errors caused by dust blocking the radiation path. Sensors are housed in a rugged anodised aluminium body, and electronics are fully potted.

Output Options
Multiple analogue output options are available including: 0 to 114mV, 0 to 2.5V, and 0 to 5.0V ranges. The thermopile pyranometer is also available attached to a hand-held meter with digital readout.

A thermally-insulated base is included to be mounted between the sensor and levelling plate. The AM-110 mounting bracket facilitates mounting the AL-100 levelling plate to a mast or pipe. The bubble-level in the plate makes levelling simple and accurate.

Unique Design
Designed to optimise performance and price. The upward-looking model combines a blackbody thermopile detector and acrylic diffuser, and is a significant improvement when compared to the spectral response of silicon-cell pyranometers, but keeps the price close to that of silicon-cell pyranometers. The downward-looking model combines a blackbody thermopile detector and flat glass window. It performs similarly to domed downward-looking thermopile pyranometers, but without the cost of the dome.

On-board Heater
A 0.2 W heater keeps water (liquid and frozen) off the sensor and minimises errors caused by dew, frost, rain, and snow blocking the radiation path.


The SP-510 (upward-looking) is available in a preconfigured IoT (Internet of Things) setup for continuous real-time global shortwave radiation monitoring.

Typical Applications

Applications include shortwave radiation measurement in agricultural, ecological, and hydrological weather networks and solar panel arrays.





Sensitivity (variable from sensor to sensor, typical values listed) 0.057 mV per W m-2 0.15 mV per W m-2
Calibration Factor (reciprocal of sensitivity)
(variable from sensor to sensor, typical values listed)
17.5 W m-2 per mV 6.7 W m-2 per mV
Calibration Uncertainty ±5%
Output Range 0 to 114 mV 0 to 300 mV
Measurement Range 0 to 2000 W m-2 (net shortwave irradiance)
Measurement Repeatability Less than 1%
Long-Term Drift Less than 2% per year
Non-Linearity Less than 1%
Detector Response Time 0.5s
Field of View 180° 150°
Spectral Range
(50% points)
385nm to 2105nm 295 to 2658nm
Directional (Cosine) Response Less than 20 W m-2 at 80° solar zenith
Temperature Response Less than 0.1% °C-1
Zero Offset A Less than 5 W m-2; Less than 10 W m-2 (heated)
Zero Offset B Less than 5 W m-2
Uncertainty in Daily Total Less than 5%
Dimensions 28.7mm height,
23.5mm diameter
28.7mm height,
23.5mm diameter
Mass 90g 100g
Warranty 4 years against defects in materials and workmanship
  • AA-100: Protective Carrying Case
    Protective carrying case designed to transport and store Apogee meters, sensors, and accessories.
  • AL-100 Solar Sensor Leveling Plate
    AL-100 Solar Sensor Leveling Plate
  • AL-130 Albedometer Mounting Bracket
    The AL-130 Albedometer Bracket is designed to accommodate the SP-510 upward-looking thermopile pyranometer and SP-610 downward-looking thermopile pyranometer to create an albedometer. The AL-130 bracket is designed to be mounted to a mast or pipe with a 1.3" - 2.1" outer diameter and has an integrated bubble level to make leveling simple and accurate for proper sensor installation.