Pyrheliometer and pyranometer

The terms "pyrheliometer" and "pyranometer" both refer to instruments used for measuring solar radiation, but they serve slightly different purposes.

Pyranometer:

A pyranometer is a device used for measuring the total solar radiation flux density (in watts per square meter) on a horizontal surface. It is sensitive to solar radiation from all directions, providing a measure of the total sunlight (direct, diffuse, and reflected) that reaches a specific location. 

Pyrheliometer:

On the other hand, a pyrheliometer is specifically designed to measure direct beam solar irradiance, or the solar radiation received from the direction of the sun. Unlike a pyranometer, which measures total solar radiation, a pyrheliometer is oriented towards the sun and measures only the direct component of solar radiation. Pyrheliometers are often used in solar energy research, atmospheric science, and in applications requiring precise measurements of direct solar radiation, such as concentrating solar power systems.

Differences in application scenarios of the pyranometer and pyranometer:

- Application Scenarios for Pyranometers: Pyranometers are widely used in meteorology, climatology, solar energy research, and agriculture to measure the total solar radiation flux density on a horizontal plane, i.e., the total amount of solar radiation received from all directions.  

- Application Scenarios for Pyrheliometers: Pyrheliometers are mainly used in scenarios that require accurate measurement of direct solar radiation from the direction of the sun, such as solar energy research, atmospheric sciences, and applications that require high-precision measurements of direct solar radiation, such as concentrating solar power systems.

Pyrheliometer and pyranometer work on different principles:

- Pyranometer's working principle: The Pyranometer's sensor surface is covered with a black absorbing layer. When sunlight hits the sensor, the absorbing layer converts the light energy into heat energy and generates an electrical signal corresponding to the intensity of solar radiation. This electrical signal is converted into units of solar radiation flux density (watts per square metre).

- How the Pyrheliometer works: The Pyrheliometer remains aligned with the sun and therefore only receives direct solar radiation from the direction of the sun.Sensors inside the Pyrheliometer measure and record the intensity of the sun's radiation, usually through a sun tracking system, to ensure that it remains aligned with the sun and provides accurate data on direct solar radiation.

In summary, while both pyranometers and pyrheliometers are used to measure solar radiation, pyranometers measure the total solar irradiance, including both direct and diffuse radiation, while pyrheliometers specifically measure the direct solar radiation.

Pyranometer Solar Radiation Sensors data sheet

NBL-W-HPRS-Solar-Radiation-Sensor-Instruction-Manual-V3.0.pdf

NBL-W-SRS-Solar-radiation-sensor-instruction-manual-V4.0.pdf