CMP21 Pyranometer to measure solar irradiance

The CMP21 is a high-performance research-grade pyranometer and is fully compliant with all ISO 9060:1990 Secondary Standard Instrument performance criteria (highest possible ISO pyranometer performance category).

  • 5-year warranty
  • ISO 9060 spectrally flat Class A
  • Research grade performance
  • Verified cosine response
  • Verified temperature dependence
  • Internal desiccant – minimal maintenance


CMP21 Pyranometer

The CMP21 pyranometer is designed for research grade applications. Being compliant with all ISO 9060 spectrally flat Class A Instrument performance criteria the CMP21 meets the highest possible ISO pyranometer standards.

CMP21 has the same detector as the CMP11 and individually optimised temperature compensation. A  thermistor sensor is installed to monitor the housing temperature. Each instrument is supplied with its own temperature and directional (cosine response) test data.

It is the choice for scientific use and in high-grade solar radiation monitoring networks such as the Baseline Surface Radiation Network of WMO.

A waterproof socket is fitted for the signature yellow signal cable, which is available in a range of lengths pre-wired to the waterproof plug. The integral bubble level is raised to the top of the housing and can be viewed without removing the redesigned snap-on sun shield, which also covers the connector. The screw-in drying cartridge is easy to remove and the replacement desiccant is supplied in convenient refill packets.

The pyranometer does not require any power, it supplies a low voltage of 0 to 20mV in relation to the amount of incoming radiation. When a higher voltage level or a 4 to 20mA signal is required, the AMPBOX is the perfect solution.


Spectral range (50% points) 285 to 2800 nm
Sensitivity 7 to 14 µV/W/m²
Response time 5 s
Zero offset A < 7 W/m²
Zero offset B < 2 W/m²
Directional response (up to 80° with 1000 W/m² beam) < 10 W/m²
Temperature dependence of sensitivity (-20 ºC to +50 ºC) < 1 %
Operational temperature range -40 °C to +80 °C
Maximum solar irradiance 4000 W/m²
Field of view 180 °

CMP21 Pyranometer Accessories.

  • AMPBOX – Boosts the pyranometers output signal
  • Ventilation unit – Maintains the pyranometer temperature. Prevents dew, dust, frost, and snow build-up.
  • Mounting plate (unventilated) – One or two (albedometer) pyranometers can be mounted.
  • Mounting plate (ventilated) – One or two (albedometer) pyranometers with ventilation units can be mounted.
  • Mounting brackets – For fixing the mounting plate to the appropriate wall or pole.
  • Shadow Ring – Blocks direct radiation.
  • Adjustable tilt kit – Allows precise alignment of the pyranometer’s angle. Ideal for Plane of Array studies.
  • Cable lengths – Various cable lengths available 10, 25, 50 and 100m.