Our CMP series pyranometers are well known around the world for their high quality, durability and accuracy. The instruments do not require any power and are ideal for remote sites with limited power availability or for field studies. Each has an individual calibration factor / sensitivity.

However, the signal output is a very low voltage, typically around 10 millivolts on a bright sunny day. To measure 1 W/m2 of irradiance requires a data logger ‘accuracy’ of better than 10 microvolts. This normally means a specialised meteorological data logger. Industrial type analogue inputs do not usually have sufficient sensitivity and the SMP series should be used.

CMP3 and CMP10 have internal desiccant that lasts for at least 10 years to reduce maintenance costs. The other CMP models have self-indicating desiccant in an easily accessed drying cartridge that should be inspected monthly and the desiccant changed when necessary.

Technical data

ISO classification Recommended applications
CMP22 Secondary StandardScientific research requiring the highest level of measurement accuracy and reliability
CMP21 Secondary Standard Meteorological networks, PV panel and thermal collector testing, materials testing
CMP10 & CMP11 Secondary Standard Meteorological networks, PV panel and thermal collector testing, materials testing
CMP6 First Class Good quality measurements for hydrology networks, greenhouse climate control
CMP3 Second Class Economical solution for routine measurements in weather stations, field testing

CM121B/C Shadow Ring

The CM121B/C Shadow Ring is designed to be connected to a Kipp & Zonen pyranometer to shield the pyranometer sensor from direct radiation. The combination of a pyranometer and the CM121B/C offers a simple solution for measuring diffuse solar radiation from the sky. It does not require any power, but the ring requires a simple adjustment every few days to ensure that the shadow covers the pyranometer dome completely as the sun declination changes during the year.


  • Suitable for all latitudes and all tilted surfaces
  • Correction factors are given in the manual
  • The shadow from the ring covers the pyranometer dome completely
  • The ring will not need adjustment for several days