SMP21: Spectrally Flat Class A Pyranometer

The SMP21 pyranometer from Kipp & Zonen is a Spectrally Flat Class A pyranometer that integrates CMP21’s sensor technology with analog output, the RS-485 Modbus® interface, low maintenance and a five-year warranty.

The internal desiccant of the SMP21 pyranometer can last for a minimum of 10 years, thus considerably reducing the need for maintenance. The SMP21 can be fitted with the CVF4 ventilation unit to extend the interval for dome cleaning and to optimize the measurement quality.

The SMP21 features Modbus® RTU interface, individual temperature-corrected measurement data, improved response time and amplified analog output. The instrument comes with individual measured cosine response data. Thanks to the low and wide power supply range of 5–30 VDC, the SMP21 pyranometer can be easily integrated into meteorological and solar energy stations.

The SMP21 has been designed such that it is safeguarded against short-circuiting, over-voltage and reversed polarity. The standardized output and connections of each SMP21 make the exchange of instruments for recalibration simple. Modbus® address setting, SmartExplorer Windows™ software for data logging and data display all come with the instrument as standard.


ISO/IEC Classification

The SMP21 pyranometer belongs to ISO 9060 spectrally flat Class A, with ISO/IEC 17025 calibration.

Smart Interface

The SMP21 pyranometer includes a Modbus RTU interface and offers very low power consumption and a wide temperature correction range. The instrument offers both digital and analog outputs. The data logger does not need to be adjusted after recalibration.

Minimized Maintenance

There is no need to change the desiccant for 10 years, which makes SMP21 the best MTBF with a warranty of five years.


Technical Attributes. Source: Kipp & Zonen

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Analog Outputs 0 - 1 V (V-model) or 4 - 20 mA (A-model)
Cable Length 33, 82, 164, 330 ft (10, 25, 50, 100 m)
Classification Spectrally Flat Class A (ISO 9060:2018)
Digital Outputs Modbus RTU 2-wire RS-485
Directional Response ˂10 W/m² (up to 80 ° with 1000 W/m² beam)
Drying Cartridge and Maintenance
Internal, lasts for 10 years, replaced with
every recalibration
IP Rating IP68
Irradiance Saturation 4000 W/m² (Max.)
Material Enclosures Aluminum, anodized
Non-linearity ˂0.5% (0 - 100 W/m²)
Non-stability ˂0.5% (change/year)
Operating Humidity 0 - 100%
Operating Temperature Range -40 - +176 °F (-40 - +80 °C)
Response Time ˂0.7 s (63 %), ˂2 s (95%)
Sensitivity N.A.
Spectral Accuracy 285 - 2800 nm
Temperature Correction ˂0.3 %: -4 - +122 °F (-20 - +50 °C)
Weight 1.3 lb (600 g)
Zero offset A ˂7 W/m²
Zero offset B ˂2 W/m²

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