The Pyranometer is an electronic device that is used for measuring solar irradiance on a planar surface. It is also a type of actinometer, which is designed for measuring the solar radiation flux density.

The Pyranometers can operate on their own and does not require a power for operating. The word Pyranometer was derived from the Greek words “pyr,” which means fire and “ano,” which refers to the sky.

The Pyranometer covers the solar radiation spectrum, extending from 300 to 2800 nm approximately, with an as flat as possible spectral sensitivity. As per the theory goes “the response to “beam” radiation varies with the cosine of the angle of incidence” while measuring the flux density or irradiance. This means that there is a full response when the sensor is hit by the solar radiation perpendicularly, when the sun at 90 degrees angle of incidence there is 0 responses, and when the sun is at degrees angle of incidence there are 0.5 responses.

Therefore following the definition it can be stated that the Pyranometer should have “directional response” or “cosine response” to come closer to the cosine characteristic. The Pyranometer has the following segments:

The thermopile sensor has a black coating. This absorbs the solar radiation has a near-perfect cosine response. The Pyranometer are broadly used in the fields of climatology, meteorology, building physics, and solar energy studies.