Instruments for measuring the solar Radiations :
Following instruments are used for measurements of Solar Radiations.
1) Pyranometer
2) Pyreheliometer
3) Sunshine recorder
4) Photo voltaic solarimeter
1) Pyranometer :-
A Pyranometer is a radiation measuring instruments. It measures total broadband Solar irradiation i. e. Beam Radiations and diffused radiations together. It can measure diffused radiations when shading ring is used to prevent Beam Radiations falling on it. It is called as Eppley Pyranometer.
Construction and working of Pyranometer:-
 |
| Pyranometer |
It is provided Thermopile sensor with a black and white a black and white coating. This sensor absorbs all Solar Radiations which have a flat spectrum covering the 300 to 50,000 nanometers wave length range. It has Glass dome which controls spectral response from 300 to 2800 nanometers while keeping 180 degree field of view. Glass dome also prevents leakage of heat radiations From the sensor .
Black coating of sensors absorb all heat Energy incidental on it. The heat energy flows through Thermopile sensor with genenrate output signal in millivolt. This signals is then calibrated in terms of watts per Sq.meter output to measure the value directly in terms of energy units.
2) Pyreheliometer :-
Pyreheliometer is used of measure Direct Beam Radiations.
Principle of operation of Pyreheliometer :
It is also working on similar principle as Pyranometer. Temperature difference between Black and White radiation absorption surfaces produces EMF Proportional to the energy incidental on the surface.
Construction and working of Pyreheliometer :-
 |
| Pyreheliometer |
It is in the shape of collimator tube which can be adjusted straight in the direction of solar rays so that Beam Radiations can directly fall on the sensor plate.
Thermopile junction are provided at the backside of the sensor plate. The cone angle is kept at 50 so that sensor receive only direct beam Radiations cutting off the diffused radiations.
The Pyreheliometer is used in metrological and Solar research laboratories to measure the intensity of solar Radiations.
3) Sunshine recorder :-
The Sunshine recorder is used to measure the duration of the day when there was Bright sunshine giving beam Radiations. It is measured continuously through out the day on the card pepar kept in the Groves provided on the instruments.
Construction and working of Sunshine recorder :-
 |
| Sunshine recorder |
It can made up of transparent glass sphere mounted on table with heavy base. Bowl is provided just below just the glass sphere. It is with a Grove to insert a Paper which receive concentrate beam of sun light. The Paper is chemically treated so that heat in the sun Beam lives burn mark on the paper giving as indication that were was sunshine during the period.
0 Comments