HIM - A pyranometer is an electronic sensor used to measure solar irradiance on a flat surface. It is used to measure the solar radiant flux density from the hemisphere above within a wavelength range.
A pyranometer (from Greek πῦρ pyr "fire" and οὐρανός ouranós "sky") is used to measure the incoming global solar radiation. In other words, a pyranometer is a sensor for measuring the irradiance of the sun (in watts per square metre) with a field of view of 180 degrees.