Limited Availability ›
This product has limited availability. It will be replaced by: SR30-D1. Some accessories, replacement parts, or services may still be available when it is no longer available.
SR20-D2-L Digital Class A Pyranometer


The SR20-D2, manufactured by Hukseflux Thermal Sensors, is an ISO 9060:2018 spectrally flat Class A (secondary standard) digital pyranometer that measures solar short-wave radiation in a full hemisphere of the sky. It connects directly to a Campbell Scientific data logger and is designed for Modbus RTU applications that require high measurement accuracy in demanding applications such as scientific meteorological observation networks and utility scale solar-energy-power production sites.

Benefits and Features

  • Low temperature dependence
  • Onboard digital temperature sensor
  • Ultra robust connector, desiccant holder, and sun screen
  • Temperature dependence characterized and supplied for each instrument
  • Directional response tested on each instrument
  • Digital output (Modbus RTU)


Pyranometer with detached cable


Sensor HIgh-quality blackened thermopile protected by two glass domes
Measurement Description Monitors solar radiation for the full solar spectrum range
ISO Classification Spectrally flat Class A (secondary standard) pyranometer (ISO 9060:2018 )
WMO Performance Level High-quality pyranometer
Response Time 4.5 s
Zero Offset A 5 W/m2 (unventilated), 2.5 W/m2 (ventilated)
(response to 200 W/m2 net thermal radiation)
Zero Offset B ≤ ± 2 W/m2 (response to 5 K/h change in ambient temperature)
Non-Stability ≤ ± 0.5% change per year
Non-Linearity ≤ ± 0.2% (100 to 1000 W/m2)
Directional Response < ± 10 W/m2
Spectral Selectivity < ± 3% (0.35 to 1.5 x 10-6 m)
Temperature Response < ± 0.4% (-30° to +50°C)
Tilt Response < ± 0.2% (0 to 90° at 1000 W/m2)
Heater No heater available
Steady-state Zero Offset
  • < ± 0.5 W/m2 (at +20°C)
  • < ± 0.8 W/m2 (-40° to +80°C)
Calibration Uncertainty < 1.2% (k=2)
Level Accuracy < 0.1° (bubble entirely in ring)
Operating Temperature Range -40° to +80°C
Field of View (FOV) 180°
Measurement Range -400 to 4000 W/m2
Spectral Range 285 to 3000 x 10-9 m (20% transmission points)
Sensitivity Digital output
Output Definition Running average over 4 measurements (refreshed every 0.1 s)


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Mounting Equipment

Compatible Note
CM255LS (retired)

Additional Compatibility Information

Compatible with all data loggers that support Modbus.

Listed Under

Common Accessory for the following products: