FAQ

  • Solar Instruments

    • How does instrument temperature effect radiometer accuracy?

      • The temperature dependence of the sensitivity is a function of the individual CHP 1. For a given instrument the response lies in the region between the curved lines in Error! Reference source not found. The temperature dependence of each pyrheliometer is characterized and supplied with the instrument. Each CHP 1 has built-in temperature sensors to allow corrections to be applied if required.

        Typical Radiometer temperature dependence

    • RaZON+

      • Pyranometers

        • How can I check if there are interferences from the cable?

          • When we calibrate the sensors there is no signal bounce other than the time that the pyranometer needs to reach its final value (time constant) if however there are electrical inferences and the shielding of the cable and data logger is not good then you can expect noise. A good way of testing this is by connecting a dummy pyranometer with the same cable (length and position) to the data logger. (Dummy pyranometer is a 1 kOhm resistor) This will show any interference coming from the cable.

        • 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.

        • Solar radiation at the site was greater than 1400 W/m²! Is this reasonable?

          • It is indeed possible to reach a value of 1400 W/m² or slightly higher. The maximum radiation from the sun above the atmosphere is 1367 W/m². However at high altitudes with a clear sky and some bright white cumulus clouds (not covering the sun) it is possible to get above the 1400 W/m². These clouds will act like a mirror and reflect (extra) solar radiation to the sensor and through this effect reach these high values. So it is possible, but only under these extreme conditions. Under a clear sky without clouds the radiation is definitely below the 1367 W/m².

        • What is the directional or cosine response?

          • Radiation incident on a flat horizontal surface originating from a point source with a defined zenith position will have an intensity value proportional to the cosine of the zenith angle of incidence. This is sometimes called the ‘cosinelaw’ or ‘cosine-response’ and is illustrated in figure 11. Ideally a pyranometer has a directional response which is exactly the same as the cosine-law. However, in a pyranometer the directional response is influenced by the quality, dimensions and construction of the domes. The maximum deviation from the ideal cosine-response of the pyranometer is given up to 80° angle of incidence with respect to 1000 W/m2 irradiance at normal incidence (0°).

        • 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

        • 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.

        • 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).

             

        • What is the calibration frequency of a pyranometer?

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

        • 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.

            spectral range

        • 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

        • 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.

        • 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

            Solar Irradiance Spectrum 

             

        • 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.

             

             

        • 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.

        • 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.

            Output signal pyranometer

        • 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.

        • 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.

        • 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.

        • Is there a Pyranometer available that has the same spectral characteristics as a PV panel?

          • Yes, we do have a Pyranometer with the same spectral characteristics as a PV panel. This is the SP Lite(2) Pyranometer.

            Our SP-Lite is based on a silicon diode which has a response from 400 – 1100 nm.
            The advantage is the response time, which is as fast as any PV panel ( milli seconds).
            The disadvantage is that not all PV panels have the same spectral range. 
            A thermopile pyranometer covers the full spectral range of the sun and will give a more accurate measurement of the total (global) solar radiation.

        • Is it possible to connect the Pyranometers to a computer? That way, I could, using software (if there is any available), measures solar radiation all the time, non-stop.

          • The output from thermopile Pyranometers, such as our CMP Series, is very low – typically around 10 milli-volts on a clear sunny day. To resolve changes of 1 W/m2 requires an ADC with an accuracy and resolution of around 5 micro-volts. These PC interfaces are very expensive and difficult to find in a form that is easily interfaced to the PC. This is why meteorological data loggers are normally used that can cope with the low signal levels.

            Kipp & Zonen has solutions like handheld- or fixed location data loggers.

        • 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.

        • Do the pyranometers come with a calibration certificate, NIST traceable?

          • NIST in the USA supplies calibration services to industry – in case of light they characterise sensors, detectors and lamps for use in manufacturing and for luminance measurement (LUX).

            They are not set up for the calibration of sensors for solar radiation and they are not a traceable reference. 

            The only accepted world standards for the calibration of radiometers for the measurement of global or direct broadband solar radiation are as below:

            • ISO 9059 Calibration of Field Pyrheliometers by Comparison to a Reference Pyrheliometer

            • ISO 9060 Specification and Classification of Instruments for Measuring Hemispherical Solar and Direct Solar Radiation

            • ISO 9846 Calibration of a Pyranometer Using a Pyrheliometer Guide to Meteorological Instruments and Methods of Observation, Fifth ed., WMO-No. 8

             

        • What does Zero Offset A mean?

          • By physical laws any object having a certain temperature will exchange radiation with its surroundings. The domes of upward facing radiometers will exchange radiation primarily with the relatively cold atmosphere. In general, the atmosphere will be cooler than the ambient temperature at the Earth’s surface. For example, a clear sky can have an effective temperature up to 50°C cooler, whereas an overcast sky will have roughly the same temperature as the Earth’s surface. Due to this the Pyranometer domes will ‘lose’ energy to the colder atmosphere. This causes the dome to become cooler than the rest of the instrument. This temperature difference between the detector and the instrument housing will generate a small negative output signal which is commonly called Zero Offset type A. This effect is minimized by using an inner dome. This inner dome acts as a ‘radiation buffer’.

            The Zero Offset A can also be reduced by using a Ventilation Unit CVF 3.

        • Are there any accessories needed with the Pyranometer to avoid reflected radiation from the surface?

          • No, all the Pyranometers have a 180 degree field of view. When mounted horizontally, they cannot see light reflected from the ground due to its design.

        • What is the big difference between CMP 11 and CMP 21?

          • The CMP 11 uses a default temperature compensation setting and the dependency is ±1% from -10 to +40°C.

            The CMP 21 is individually tested and the temperature compensation is optimised.  It is ±1% from -20 to +50°C. However, from -10 to +40°C it is within ± 0.5%, typically ± 0.3%. In addition a temperature sensor is fitted and the temperature response curve is supplied. Each CMP 21 has the directional (cosine) response tested, and this is also supplied. This means that for the serious scientist the irradiance values can be corrected for temperature and solar elevation – increasing the accuracy. This is not possible with the CMP 11.

            BSRN requirements state that the solar radiometers must be fitted with an internal temperature sensor and the data recorded, so CMP 21 is compliant to this, but CMP 11 is not. 

        • Does a Pyranometer require any power?

          • Our thermopile-based instruments, including the CMP range of pyranometers and the CH(P) 1 pyrheliometer, do not require power to operate. They generate a small voltage output in response to the solar radiation.

        • Pyrgeometers

          • Why is the Pyrgeometer from Kipp & Zonen so much better than those from the competition?

            • The CGR 4 differs from all other Pyrgeometers in that it allows accurate daytime measurements on sunny days without the need for a shading device. Due to the unique construction of the CGR 4, solar radiation of up to 1000 W/m² induces window heating of less than 4 W/m² in the overall calculated downward radiation. In the Baseline Surface Radiation Network (BSRN) manual (WMO/TD-No.897) an extended formula is described. This formula corrects for window heating and so called “solar radiation leakage”. Due to the very low window heating offset and optimal spectral cut-on wavelength, these corrections are not necessaire for the CGR 4.

          • What is the calibration interval of a pyrgeometer?

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

              More information about our calibration service can be found here.

          • I am using a Ventilation unit on the Pyrgeometer. Do I need to put this on 5W or 10W?

            • If the CVF 3 is used for a Pyrgeometer the effect of sunrise is not valid and continuous 5 Watt is preferred. In extreme cold climates , polar / mountain tops, the 10 Watt heater can be used continuously.

          • Sun Tracker

            • Is it possible to mount 4 pyreliometers plus an extra sun sensor?

              • Yes. Normally 4 of these side-mounted sensors is the maximum, however we are able to make an extension on one pyrheliometer mount for the extra sun-sensor.

            • How much power is needed for the 2AP?

              • The power use of the 2AP itself is about 1.5 A to 2 Amps. (internal fuse is 3 Amps slow)

            • What power supply is needed when heaters are used?

              • The power use of the 2AP itself is about 1.5 A to 2 Amps. (Internal fuse is 3 Amps slow)

                Part number for the 24V heater kit is: 12136346.
                This kit contains two 50 Watt heaters.
                So the current for these heaters is 4.2 A (at 24V), fuse is 5 A slow blow.

                If we add up the total power we have:
                5A (heaters) + 3.15 (2AP)= 8.15 A

                Normal conditions:
                4.2 A (heaters) + 1.25A (2AP) = 5.5 A normal

                Therefore a 5 Amp power supply will not survive very long.
                We recommend to take a power supply that can deliver the 8.15 A. (when heaters are used)

            • Does the 2AP work autonomously?

              • The 2AP works fully autonomously, after the setup. Setup is done in combination with a PC. (Entering Longitude, Latitude etc.) Indeed a data logger is needed to collect data from the sensors, but this logger has no (hardware) connection with the 2AP.

            • Can the tracker be connected to a PC at 30 m distance?

              • To connect the 2AP with a PC for communication, a 3-wire cable is used (or 2 wires plus shield) as described on page 5 of the manual.
                Advised is a shielded cable, where the shield can be the ground connection.

                • On the 2AP side the wires are connected to the communication board.
                • On the PC side a 9 or 25 pin Sub D connector is used for the serial port.

                This cable length can be 30 meter. We can supply this cable, but it can be bought "around the corner".

                The communication software is included with the 2AP.

            • Why does the COM port of my Pentium not address the 2AP like my old 4.86?

              • The CMD and sun tracker software will work on COM1 or COM2 only, specified as the first parameter after the program name in the command line. Make sure the 2AP is connected to one of these two ports. Problems can also occur if another program has taken over the COM port and will not give it up. Also, some Compaq computers have non-standard COM ports, which the CMD and sun tracker programs cannot communicate through. The solution for this problem could be found in a simple add-on card with a standard extra serial port, if it can be set as COM 1 or 2.

            • What is the range of the temperature?

              • The temperature range for the 2AP tracker is:

                Standard temp range: 0 - 50 degrees Celsius
                With cold cover: -20 - 50 degrees Celsius
                With cold cover and heater -50 - 50 Degrees Celsius

                Normally the heater is built in, in the factory. However we can supply you with a kit plus instructions to do it yourself.

            • What is the accuracy of the 2AP tracker in combination with a sun sensor?

              • The 2AP has the following errors:

                • Time
                • Setup (leveling)
                • Calculation (algorithm according to Michailsky error max. is 0.025 degree)
                • Mechanical (BD = 0.09 and GD =0.045 degree max.)

                The first 2 are user controlled and the last 2 are fixed.

                Assuming that the leveling is done optimal the only error remaining that can be corrected is time. If we assume that the clock is reset every 1,000,000 seconds (11.5 days) there will be an expected error of 5 seconds. If we assume that the sun rotates 360 degrees in 24 hour then RMS 0.72 * 5 seconds = an actual time error of 3.6 seconds. For a period of 11.5 days the total time error contribution is 0.015 degrees (the diameter of the solar disk is 0.25 degrees). Per year this would result in 0.5 degree.

                If this time correction and the check on leveling are done on a regular interval there is no need for a sun sensor. If however this interval can or will not made, the sun sensor will correct for both (leveling and time).

                The sun sensor is normally used for first checking the tilt error. Assuming that there is sunshine for at least 2 full days over the full day. This information is stored in an internal log file and used to correct (in combination with PC). Over this period the user has to correct time. (if more than 2 weeks). After this initial run and correction for tilt, the sun sensor is used for time correction. This means that optimal accuracy is maintained without user (time) correction. This means that the 2AP is within specs the whole year without intervention.

                Please note that the sensors used on the 2AP also need maintenance on a regular base (drying cartridge and dirt on domes).

                Better than giving an error in percentage we would like to show the benefit of not having to correct to clock. The 2AP error in degrees can be calculated as percentage of 360 degrees, but the error in sensor reading depends on the type of sensor.

            • Is there a compensation for temperature drift?

              • The controller board has a temperature compensated oscillator module for the microprocessor. While power is applied the firmware keeps accurate time and updates the real time clock (which is not very accurate) every 8 hours.

                We enter a room temperature correction, which compensates for initial calibration of the oscillator module. The oscillator module can drift up to ±11 ppm over the 0 °C to 70 °C temperature range. The module can also drift up to ±2 ppm in a year.

                The temperature drift is different for each oscillator so cannot be compensated for in firmware.

            • Is compensation for pressure variations needed?

              • The air pressure that is required should be an average value for the site the instrument is operated. It does not need to be updated over time. The meaning of it is to correct for (a small) optical shift due to atmospheric pressure. A normal value depends of course on the heath of operation. A value of 1000 mBar is typical for sea level.

            • Is there a way to fix a tracker via remote PC?

              • You can try the following:
                If you send the command “CO”, the 2AP will cold start. This means ignore all present settings and start without using any previous (possibly wrong) settings.

                If you then start the sun tracker program, it will start up with the message “”recovering from cold start””

                Then longitude and latitude etc. will be recovered from the .ini file, the time and date of course cannot be stored and has to be entered again. If no further error message is given, the 2AP is most likely operational again.

                This could solve the problem, if not please contact us and we will discuss further options.

            • Why is the altitude limited to 2000 m?

              • The 2AP BD altitude specification (2000m) is limited by the CE and CSA (Canadian Standards Association) recommendation for main power board design. CSA recommends that AC boards have certain spacings between the board tracings for various elevation (pressures). As the pressure decreases there is more probability for arcing when the wires are close. Unfortunately there is not enough room internally, in the 2AP BD, to increase the size of this board (to make the spacings bigger).

                The best solution is to sell/quote a 2AP Gear Drive with 24VDC, as this would eliminate the altitude restrictions associated with high voltage AC.

            • How many (CHP 1) pyrheliometers can be mounted?

              • Standard one CHP 1 mount is included. An extra mounting clamp can be added on top of this CHP 1 mounting. The same can be done on the other side. So standard, 4 CHP 1’s is possible.

                The SOLYS Gear Drive can easily handle more, but for mounting more instruments (e.g. 8 pyrheliometers) a larger mounting plate is required.

            • What about the pointing accuracy?

              • Pointing accuracy is better than 0.02°, when active tracking, under all conditions.

            • Can the PMO-6 be mounted?

              • Yes, like on the SOLYS 2 a special mounting clamp is available for the PMO-6.

            • Is there any altitude limit in this as in 2AP?

              • The power supplies used in the SOLYS have EN60950-1 approvals. This means approved up to 5000m. If higher altitudes are required we can check or test if this is feasible.

            • How long takes the night time rewinding?

              • It takes a few minutes for the SOLYS to return to its home position. Then the SOLYS goes to sleep mode (for power reduction).

            • Are the Zenith/Azimuth Positions of tracker available in log file?

              • Yes, both the Solar Zenith and Azimuth positions and the SOLYS motor Zenith and Azimuth positions are available in the log file.

            • What is the power requirement for AC and DC?

              • The power requirement is for both AC and DC is 25 Watt during operation and 13 Watt at night. For the SOLYS “night” is from ~ 5 minutes after sunset to ~ 5 minutes before sunrise.

                When used in cold climates, the heater switches on to keep the interior above -20°C

                This is switched automatically and only used when powered from AC.

                The cold cover can be used to reduce the required heating power.

            • Is there any option for Sun sensor, can we remove from tracker?

              • The Sun Sensor is supplied as standard with the SOLYS Gear Drive. It can be removed (or not mounted) then the SOLYS will follow the sun based on its internal calculation.

                This is normally accurate enough, but does not correct for any misalignment or unstable mounting.

            • How well does the SOLYS work in salty air that is close to the ocean?

              • Like our radiometers, the SOLYS’s are made of anodised aluminium. Until now we did not see any effect on the functioning of the trackers that are mounted on the sea shore.

                The SOLYS has in addition to the radiometers a paint coating to further protect it.

            • Do you recommend the SOLYS Gear Drive in polar conditions?

              • Absolutely! Great care has been put in extending the temperature range and minimising the possible disturbance from dry air (ESD) to make the SOLYS Gear Drive suitable for this climate.

            • Solar Instruments Accessories

              • UV Radiometers

                • Net Radiometers

                  • What color code is used when there is an extended cable on the NR LITE?

                    • Sometimes it happens that the colors of the cables are different when you order extended cables. Usually there is added a page in the manual where this is mentioned.

                      Standard = extended
                      White = white
                      Green = blue
                      Black = black

                  • For the NR Lite, we want to use wind correction, but we don't understand the manual

                    • The correction factor in the manual could indeed be written more carefully. It says dividing by (1+x.V3/4) this refers to the calibration factor. Better is to say the output should be multiplied with a factor (1+x.V3/4).

                  • For the CNR 1, what is the ideal constant current source for the PT-100?

                    • There is no general value to use but some criteria to keep in mind to select a Pt-100 current.

                      Because the Pt-100 (unlike a thermocouple) needs current, it is advised to keep this current as low as possible to avoid self-heating of the Pt-100 by its own current. The Pt-100 measuring device (like our data loggers CC 48, CR10X) has a fixed current, in such a way that the voltage over the Pt-100 is matched with the Pt-100 (voltage) measuring input of these loggers.

                      In general the current for a Pt-100 is indeed between 0.1 and 1 mA. This would result (@ 0ºC) in a voltage over the Pt-100 of 10 mV or 100 mV. Therefore the current can also be selected depending on the available input range of the measuring device. The error introduced by self-heating, when using a 1 mA current, is quite low (< 0.2ºC) also because the Pt-100 is very well connected to the body of the CNR1. When the heater of the CNR1 is on, the error introduced by the heater in measuring the body temperature is typical 2ºC (see manual).

                      The benefit of a larger current (1 mA) is that electrical disturbances have less effect when the current is larger.

                      To summarize these facts I would say, 1 mA measuring current is accurate enough, but the output voltage in this case (0.1 Volt) has to match the measuring input range.

                  • What is the response time for CNR 1 sensors?

                    • Response time for CNR1 sensors: 5 s (63%) en 18 s (95%)

                  • Does the CNR 2 use the same sensor as the NR Lite(2) without wind-breaking domes? Or does it have separate thermopiles for short and long wave radiation?

                    • Both instruments use thermopiles, but the dome over the thermopile determines what kind of radiation passes through and reaches the thermopile. A  thermopile  is normally protected by a single or double dome to reduce offsets caused by sudden temperature changes like wind.

                      The CNR 2 uses two glass domes to cover the pyranometer and two silicon domes to cover the pyrgeometers. It uses TWO thermopile detectors (1 for each of the two pyranometers and 1 for each of the two pyrgeometers) and provides two separate outputs. One NETTO for short wave (solar spectrum) and one NETTO for long wave radiation.(Far Infrared spectrum).

                      So yes, the CNR 2 has separate thermopiles to measure Far Infrared and Solar radiation and so do the other CNR net radiometers.

                      The detector from the NR Lite(2) is not protected and I sin direct contact with the weather conditions. Therefore it cools down a lot faster by the wind, which effects the accuracy of the measurements. The NR Lite(2) uses NO dome. It uses only TWO detectors with a PTFE coating and provides ONE single output for NETTO short wave- and long wave radiation.  It uses one thermopile to measure the full spectrum of Far Infrared and solar radiation.

                  • How come the NR Lite(2) specs refer to a continuous range between 200 and 100,000 nm, while the CNR 2 specs refer separately for the short and long wave radiation ranges?

                    • The difference between the NR Lite(2) and CNR 2 lies in the material used to cover the thermopiles.

                      CNR 2 uses glass domes for the pyranometers (that measure short wave radiation) that have a bandwidth of 300 nm to 2800 nm. It uses silicon domes for the pyrgeometers (that measure long wave radiation) that have a bandwidth of 4500 nm to 42000 nm. This leaves a gap between 2800 nm and 4500 nm. This is the so called atmospheric window where very little radiation comes in (see picture below).

                       

                      The NR Lite(2) uses NO domes. It uses two detectors with a PTFE coating which have a bandwidth of 200 nm to 100.000 nm.

                  • Horticultural Sensors

                    • Data Loggers

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