Category Archives: Calibration of Pyranometer

Recalibrate pyranometer every 2 years……….

Recalibrate pyranometer every 2 years……….

It is advised to recalibrate Pyranometer after every two years as the sensitivity of pyranometer slightly changes. The recalibration provides the proof of correct irradiance measurements. It also increases the confidence on the stability of the equipment. On re calibrating pyranometer and recieving new sensitivity certificate , one gets sure of the reliability and correctness of the instrument.

There are two methods to calibrate pyranometers . Either using Laboratory sources (Indoor) or  using the sun (Outdoor) In both methods, the testing pyranometer and a reference standard pyranometer are exposed under the same conditions. ITC India Pvt Ltd has adopted the first method i.e. using Laboratory Sources and is explained below.   Both the pyranometers  reference and the pyranometer that has to be calibrated are exposed to a stabilized tungsten-filament lamp installed at the end of an optical bench. A practical source for this type of work is a 0.5 to 1.0 kW halogen lamp mounted in a water-cooled housing with forced ventilation and with its emission limited to the solar spectrum by a quartz window. This kind of lamp can be used if the standard and the instrument to be calibrated have the same spectral response. For general calibrations, a high-pressure xenon lamp with filters to give an approximate solar spectrum should be used. When calibrating pyranometers in this way, reflection effects should be excluded from the instruments by using black screens. The usual procedure is to install the reference instrument and measure the radiant flux. The reference is then removed and the measurement repeated using the testing instrument.

ITC India Pvt Ltd is calibrating pyranometer providing accurate and reliable results. So, do not delay in sending it to the Lab or calibrate  it on site. For any qyery write us t info@itcindia.org or visit www.itcindia.org 

Thermopile Pyranometer calibration by ITC India Pvt Ltd

Thermopile Pyranometer calibration by ITC India Pvt Ltd

ITC India has diversify in Thermopile pyranometer calibration as per ISO 9847 standards . So, lets connect with us to calibrate your pyranometer.

Before the calibration of pyranometer let us discuss about

Why Thermopile pyranometer ?

Here is the table that makes the clear difference why thermipile is best of three.

S.NoSpecificationThermipile PyranometerPhotodiode PyranometerPhotovoltic Pyranometer
1Main ComponentThermocouplePhotodiodePV cell
2Sensitivity Range300nm to 2800nm400nm to 900 nm350 nm to 1150 nm
3CostExpensiveReliableModerate
4AccuracyHighestModerateHigh

What is a thermopile pyranometer ?

What is a thermopile pyranometer?
What is a thermopile pyranometer?

A thermopile pyranometer is a sensor based on thermopiles designed to measure the broadband of the solar radiation flux density from a 180° field of view angle.The first generation of thermopile pyranometers had the Hot junction of the sensor equally divided in black and white sectors. Irradiation was calculated from the differential measure between the temperature of the black sectors, exposed to the sun, and the temperature of the white sectors, sectors not exposed to the sun or better said in the shades.
In all thermopile technology, irradiation is proportional to the difference between the temperature of the sun exposed area and the temperature of the shadow area.

What is the design of thermopile pyranometer?

Thermopile Pyranometer is basically consist of two components.

Thermopile sensor: It has black coating and has a flat spectrum with
ability to absorb all the solar radiations. There are two junction one is active (hot) and one is passive (cold). the active junction is placed below the black coating and the passive junction is protected from solar junction and in thermal contact with the heat sink. The thermopile generates a small voltage in proportion to the temperature difference between the black coating surface and the instrument housing

Glass dome: It protects the thermopile sensor from convection. For first class and secondary standard pyranometers an another glass dome is used. It provides better thermal equilibrium between the sensor and inner dome, compared to using a single dome.

What is its working principal of thermopile pyranometer?

The thermoelectric detection principle is used, incoming radiation is almost completely absorbed by a horizontal blackened surface, over a very wide wavelength range. The resulting increase of temperature is measured via thermocouples connected in series or series-parallel to make a thermopile.
The thermopile is used to measure this temperature difference. The potential difference created in the thermopile owing to the temperature gradient between the two surfaces is used for measuring the amount of solar radiation. However, the voltage produced by the thermopile can be measured using a potentiometer. Radiation data needs to be integrated by means of an electronic integrator or planimetry.

What are its applications ?

They are widely used in …
Metrology
Climatology
Buliding engineering physics
Photovoltic systems

How it is advantages ?

Maximum senstivity range 285 nm to 2800 nm
Fast response time
Calibrated to ISO 9060 standards
Highest accurate than photodiode and photovoltic pyranometer.
Highest lineraity

To maintain performance, recalibration is usually recommended every two years, and a high-quality water-proof connector for the signal cable greatly simplifies the process.

ISO 9847 Calibration of Field Pyranometers

ISO 9847 Calibration of Field Pyranometers by Comparison to a Reference Pyranometer.

ISO 9847 Calibration of Field Pyranometers
ISO 9847 Calibration of Field Pyranometers

Are you looking for your pyranometer to be calibrated, ITC India Pvt Ltd has the facility to calibrate thermopile pyranometer at Lab and onsight. You are most welcome in ITC India Pvt Ltd for Pyranometer calibration. Either you can send the Pyranometer in the Lab or onsight calibration can be facilitated. Write to us at info@itcindia.org URL www.itcindi.org 

The calibration method is performed by our highly trained engineers and complies with type IIc Direct beam calibration of pyranometer as per international standard ISO 9847. 

Indoor calibration of field pyranometer is better as compared to outdoor in the following ways.

  • User control of test conditions
  • Results are independent of outdoor conditions
  • User convenience

The precision of the outdoor determination of the calibration factor of a field pyranometer is particularly dependent on sky conditions and solar elevation when performing measurements at low angles. Repeatability within any 21 points or more set of values of the same test scan performed at or near solar noon under stable irradiance conditions should be less than ± 0.5 % of the calibrated value of the instrument. If this requirement cannot be met, indoor calibration should be considered

To maintain performance, recalibration is usually recommended every two years, and a high-quality water-proof connector for the signal cable greatly simplifies the process.

Calibration of Pyranometer

Calibration of Pyranometer

ITC is active member in calibration of pyranometer. We are capable of calibrating multiple brands and works as per established and traceable standards. ITC is here to calibrate your pyranometer.

Pyranometer is a scientific instrument used to measure solar irradiance on plane finish and even measure the solar flux density in w/sq m. It In simple words, total radiation = direct (from sun) + diffused radiation (scattered by dust, air etc).

There are 2 kinds of pyranometers:-thermopile, photodetector.

In Thermopile pyranometer the thermoelectric detection principle is used, whereby incoming radiation is almost completely absorbed by a horizontal blackened surface, over a very wide wavelength range. The resulting increase of temperature is measured via thermocouples connected in series or series-parallel to make a thermopile.

Working of Thermopile Pyranometer

Details of the high-quality pyranometer that uses a thermopile to measure solar radiation:

  1. Outer dome made from a hemisphere of optical-quality glass.
  2. Inner dome made from a smaller hemisphere of optical glass.
  3. Black carbon disk (illuminated by the Sun) absorbs a broad range of wavelengths of solar radiation and acts as the sensing element.
  4. Second, control disk (not illuminated by the Sun) acts as a comparison and compensating element. Any sources of temperature rise other than solar heat (perhaps an air-conditioning unit positioned nearby) will warm both disks equally, so we can be reasonably confident that the difference between the two disks (and the temperature rise we’re measuring) is caused only by the Sun.
  5. Thermopile temperature sensor compares the temperature rise of the two disks.
  6. Output lead (usually about 10m or 30ft long).
  7. Replaceable silica gel cartridge absorbs moisture to prevent dew forming inside on cold nights.
  8. Adjustable screw legs let you level the pyranometer using its built-in, high-precision spirit level, which is sensitive to a fraction of a degree (not shown on this diagram).