CMP21 Pyranometer
The CMP21 pyranometer is designed for measuring the irradiance which results from direct solar radiation and from diffuse radiation. Fully compliant with ISO 9060:2018 spectrally flat Class A specifications, it provides solar irradiance measurements with the highest accuracy and reliability, and is a sensor of choice for renowned research institutes around the world.
- Classification to ISO 9060:2018
- Spectrally Flat Class A
- Sensitivity
- 7 to 14 µV/W/m²
- Impedance
- 10 to 100 Ω

Overview
In detail
Detector and calibration
CMP21 has the same detector as the CMP11 and individually optimised temperature compensation. A standard thermistor sensor is fitted to monitor the housing temperature. Each instrument is supplied with its own temperature and directional (cosine response) test data.
Class A performance
Fully compliant with ISO 9060:2018 spectrally flat Class A specifications, the CMP21 is an extremely robust pyranometer designed to fulfill the highest requirements of scientific research, with applications including the Baseline Surface Radiation Network.
Passive analogue output
The CMP21 does not require any power. Incoming solar radiation generates a continuous millivolt output, which is converted in a data logger to irradiance in W/m² using the calibrated sensitivity.
Maintenance and warranty
The CMP21 has an easy-to-remove drying cartridge filled with easy-to-replace desiccant that is supplied in convenient refill packets. All pyranometers from Kipp & Zonen come with a 5-year warranty, with service and calibration centers around the world.
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Specifications
Technical specifications
- Classification to ISO 9060:2018
- Spectrally Flat Class A
- Sensitivity
- 7 to 14 µV/W/m²
- Impedance
- 10 to 100 Ω
- Expected output range (0 to 1500 W/m²)
- 0 to 21 mV
- Maximum operational irradiance
- 4000 W/m²
- Response time (95%)
- < 5 s
- Spectral range (20% points)
- 270 to 3000 nm
- Non-stability (change/year)
- < ±0.5%
- Non-linearity (100 to 1000 W/m²)
- < ±0.2%
- Directional response (up to 80° with 1000 W/m² beam)
- < ±10 W/m²
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