A pyrheliometer is a device that measures solar irradiance coming directly from the sun. The SI units of irradiance are watts per square metre (W/m²). ... Figure 1 A pyrheliometer is pointed at the sun to measure the solar irradiance coming directly from the sun.

What is the function of a pyrheliometer?

A pyrheliometer is an instrument designed specifically to measure the direct beam solar irradiance with a field of view limited to 5°, also known as DNI: direct normal incidence. This is achieved by the shape of the collimation tube, with precision apertures, and the detector design.

What is pyrheliometer and pyranometer?

Pyrheliometer is for measuring direct sunbeam whereas pyranometer is for measuring diffused sunbeam.