CMP3 Pyranometer

CMP3 Pyranometer

The CMP3 pyranometer is an instrument for measuring the solar irradiance. The thermopile sensor construction measures the solar energy that is received from the total solar spectrum and the whole hemisphere (180 degrees field of view). The output is expressed in Watts per meter square. The CMP3 pyranometer is designed for continuous indoor and outdoor use.

The CMP3 pyranometer (ISO 9060 spectrally flat Class C) is intended for shortwave global solar radiation measurements in the spectral range from 300 to 2800 nm. The thermopile detector measures irradiance up to 2000 W/m² with a response time of less than 20 seconds and a temperature response of less than 4% within the range of -10 ºC to +40 ºC.

Operating temperature range is -40 ºC to +80 ºC and the non-stability is less than 1% per year.

The CMP3 pyranometer features a snap-on white sun shield, integrated leveling and a weatherproof connector which is supplied pre-wired with 10 m of signal cable for simple installation. An optional mounting rod and longer cable lengths are available. Two CMP3s can easily be mounted back-to-back to make a low-cost albedometer.

The Pyranometer does not require a dedicated power supply. It generates a low voltage output in the estimated range of 0 to 48 mV relative to an irradiance measurement range of 0 to 1500 W/m2. When a higher voltage output or a 4 to 20 mA signal is required, the AMPBOX is the perfect solution.

For instruction on the installation of the CMP3 pyranometer, please watch this video.

 

 

 

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Specifications

Spectral range (50% points)	300 to 2800 nm
Sensitivity	24 to 32 µV/W/m²
Response time	< 20 s
Zero offset A	< ±15 W/m²
Zero offset B	< ±5 W/m²
Directional response (up to 80° with 1000 W/m² beam)	< ±20 W/m²
Temperature dependence of sensitivity (-10 ºC to +40 ºC)	< ±4 %
Operational temperature range	-40 °C to +80 °C
Maximum solar irradiance	2000 W/m²
Field of view	180 °

Downloads

Technical info

• Pyranometer versus Reference Cell
• Technical Advise - Desiccant replacement interval

Brochures

• KippZonen_Pyranometer_Calibrations_Infographic
• Brochure - Pyranometers
• Interface options for Kipp & Zonen Pyranometers
• Brochure - Solar Irradiance Monitoring in Solar Energy Projects
• Brochure - Solar Monitoring Stations
• Solar Energy Guide - Russian
• Solar Energy Guide - English

Datasheets

• Datasheet - CMP3 - SMP3 pyranometers - EN
• Datasheet - Albedometers - EN

STEP files

• CMP3 pyranometer - universal CAD drawing (STEP)

Declarations

• Declaration of Conformity Pyranometer

Newsletters

• Newsletter 36 - April 2016
• Newsletter 44 - April 2018
• Newsletter 43 - January 2018
• Newsletter 38 - October 2016
• Newsletter 37 - July 2016
• Newsletter 40 - April 2017
• Newsletter 39 - January 2017
• Newsletter 42 - October 2017
• Newsletter 41 - July 2017

Manuals

• Manual - Pyranometers - CMP series - English

FAQ

• Can I use a pyranometer under water?

  • The CMP series can also be used under water, the depth is limited to 1 meter and can only be used for short measurements.

    It is advisable not to keep the Pyranometer of the CMP series under water for longer than 30 minutes.

    The SP Lite2 pyranometer and the PQS 1 PAR Quantum Sensor can be used for a longer period under water, the depth is limited to 2 meters. Please also take  “breaking of light on the water surface” in consideration.

    

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• What parameters or errors should we take into account if the source of light comes from a certain angle?

  • If the Pyranometer remains horizontal the error involved is the directional error listed in the Pyranometer brochure.

    For CMP 3 < 20 W/m²  and for CMP 22 < 5 W/m²

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• If I use a pyranometer under water, can I connect a data logger to it ?

  • Yes, however the data logger needs to be placed on the surface (it is weather resistant, but cannot be lowered into the water).

     

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• What is the calibration frequency of a pyranometer?

  • We advise to re-calibrate the Pyranometer every two years. 

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• What does spectral range of 310 – 2800 nm (50% points) mean?

  • The 50 % points are the wavelengths where the output of the instrument is 50 % reduced with 100 % input.

    

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• What is the WMO standard for the pyranometers?

  •  

    	CMP 3	CMP 6	CMP 11	CMP 21	CMP 22
    WMO	Moderate quality	Good quality	High quality	High quality	High quality
    ISO	Spectrally Flat Class C	Spectrally Flat Class B	Spectrally Flat Class A	Secondary Standard	Secondary Standard

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• What is the resolution of a pyranometer?

  • The instrument has an analog output, therefore the resolution is infinite. Every change is noticed, no matter how small it is.

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• What is the bandwidth of a pyranometer?

  • The bandwidth of most pyranometers is 285 to 2800 nm. This covers the full solar spectrum as shown below.

    There are some exceptions:

    • CMP22 has a bandwidth of 200-3600nm (Quartz glass )
    • SP Lite  has a bandwidth of 400-1100nm (silicon photo diode)
    • CMP3 has a bandwidth of 300-2800nm

     

     

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• In our PV application the cable from the CMP 11 (50 meters) will go along other cables that come from the PV panels in which there is a DC voltage and around 100 Amps. Will these cables affect the measurement?

  • The disturbance on the cables on the CMP 11 is difficult to judge from a distance. A test would give the best criteria in this case.

    Simply cover the CMP 11 so it is fully dark (in box with cloth etc.) Log the data over a period that disturbance is expected, at least one day.

    If the data is zero no problem is to be expected.

     

     

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• Do you have filters that can be used to verify spectral distribution over the following wave lengths? Ultraviolet - B 280-320 Ultraviolet - A 320-360 and 360-400 Visible 400-520, 520-640 and 640-800 Infrared 800-3000nm.

  • No, we do not have filters for any of our pyranometers. The only way to do this in a correct way is to use a filter dome. Otherwise the directional response would be affected.

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• Is there a standard product that converts the pyranometer output signal to 0-5V or 0-2V?

  • The AMPBOX is the best solution.

    You will need a suitable PSU and a shunt resistor of 500 Ω to convert the current output (4..20mA) to a voltage output of 2-10V , or you will need a shunt resistor of 50 Ω to convert the current to a voltage output of 0.2-1V.

    

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• What kind of pyranometer do you suggest for usage inside a greenhouse?

  • CMP 6 in combination with PQS1 PAR Quantum Sensor is advised.  CMP 6 for outside usage to measure Global solar radiation. PQS1 to measure  PAR radiation inside which is most sensitive for plants and crops.

    

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• What type of pyranometer can I use for my fixed PV panels farm?

  • For this application the CMP10 and SMP10 are advised as they have an internal drying cartridge that will last for at least 10 years.

    Please note that the pyranometer needs to be mounted in the same angle (POA) as the PV panel. 

     

    

    For users that prefer the desiccant visible Kipp & Zonen offers the CMP11 and SMP11 with visible and user changeable desiccant.

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• What type of pyranometer can I use for my solar concentrators farm?

  • None, solar concentrators are reflecting the direct solar radiation  to a concentrator and are tracking the sun. You will need a pyrheliometer on a sun tracker to measure direct solar radiation.

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• I would like to know what kind of output the CMP 6 Pyranometer has (analog or digital)? What voltage range do you have?

  • The CMP 6, as with all our solar radiometers based on thermopiles has a continuous small analoge voltage output. For CMP 6 an irradiance of 1 W/^m2 generates an output signal in the region of 5 to 15 micro-volts. We have additional solutions to increase this voltage.

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• Negative output during nighttime measurements?

  • This error is related to the zero offset type A. Normally this zero offset is present when the inner dome has a different temperature from the cold junctions of the sensor. Practically this is always the case when there is a clear sky. Because of the low effective sky temperature (<0 °C) the earth surface emits roughly 100 W/m2 longwave infrared radiation upwards. The outer glass dome of a pyranometer also has this emission and is cooling down several degrees below air temperature (the emissivity of glass for the particular wavelength region is nearly 1). The emitted heat is attracted from the body (by conduction in the dome), from the air (by wind) and from the inner dome (through infrared radiation). The inner dome is cooling down too and will attract heat from the body by conduction and from the sensor by the net infrared radiation. The latter heat flow is opposite to the heat flow from absorbed solar radiation and causes the well known zero depression at night. This negative zero offset is also present on a clear day, however, hidden in the solar radiation signal.
    
    Zero offset type A can be checked by placing a light and IR reflecting cap over the pyranometer. The response to solar radiation will decay
    with a time constant (1/e) of 1 s, but the dome temperature will go to equilibrium with a time constant of several minutes. So after half a minute the remaining signal represents mainly zero offset type A.
    
    Good ventilation of domes and body is the solution to reducing zero offsets even further. Kipp & Zonen advises the CVF 3 Ventilattion Unit for optimal ventilation and suppression of zero offset type A. Using the CVF 3 zero offset type A will be less than 3 W/m2.

    

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Accessories

	Accessory	Description
	CM121B/C Shadow Ring More information	To be used with Kipp & Zonen pyranometers, smart pyranometers, pyrgeometers and UV radiometers to shield the instrument from direct radiation.	Add To Basket
	METEON Data Logger More information	METEON is a hand-held device for use with Kipp & Zonen passive radiometers to display real-time irradiation values and has an integrated data logging function to store up to 3500 samples. METEON will operate for up to 7 weeks on 2 x AA batteries.	Add To Basket
	AMPBOX Amplifier More information	AMPBOX is a current loop amplifier for the complete range of solar radiometers.	Add To Basket
	Adjustable Tilt Radiometer Mounting Kit More information	Mount a radiometer at a desired solar zenith angle between 0° and 90° to measure tilted global or diffuse radiation.	Add To Basket

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