Pyranometer: Working, Types, Advantages & Disadvantages

As we know scientists and meteorologists study different aspects of our atmosphere with the help of different electrical and electronic equipments. While thermometers measure heat and barometers measure air pressure, scientists also use a tool which measures intensity of sunlight. This tool is known as Pyranometer. In this guide, we will learn different types of pyranometers such as thermopile and photodiode sensor based and their working principles. We will also explore their comparison and will touch upon advantages and disadvantages of pyranometers in general.

Pyranometer Types and Working

A pyranometer can be classified into two main types based on sensing technology used. Both the types measure solar radiation but use different principles and have different accuracy levels.

1. Thermopile Pyranometer: It measures solar radiation using thermoelectric sensor. It operates based on thermoelectric effect. It offers higher accuracy, wider spectral response and used in professional solar radiation measurements. Let us understand its working.

Solar radiation passes through glass dome and strikes black absorbing surface connected to thermopile. The absorbed energy increases temperature of hot junctions. The difference in temperature between the hot and cold junctions generate small electrical voltage which is proportional to solar radiation.

2. Photodiode Pyranometer: It measures solar radiation using semiconductor sensor. It operates on photoelectric effect. It offers fast response time, lower cost and suitable for simple solar monitoring systems. Let us understand its working.

In this type, when sunlight falls on silicon photodiode sensor, photons generate electron-hole pairs in the semiconductor. This produces small electric current proportional to light intensity. The signal is converted into solar radiation values.

Comparison between Thermopile and Photodiode Pyranometer

Advantages of Pyranometer

Following are some of the generic benefits of Pyranometer.

1. It offers high accuracy for solar energy measurements.
2. It offers reliable measurements.
3. It supports wide spectral response close to solar spectrum.
4. It works on simple operating principle.
5. It measures total solar radiation including both direct and diffuse radiation.

Disadvantages of Pyranometer

Following are some of the generic drawbacks of Pyranometer.

1. Higher precision models are expensive.
2. Requires regular calibration for accurate readings.
3. Sensitive to dirt, dust and moisture on the dome.
4. Requires proper leveling and installation for correct measurement.
5. Thermopile type sensor based pyranometer offers slower response time.

Summary

A Pyranometer (thermopile or photodiode) is an essential instrument used to measure global solar radiation for solar energy systems, meteorology and climate studies. Despite requiring calibration and maintenance, its accuracy and reliability make it crucial for evaluating solar energy resources and system performance.