What is the Difference Between Pyranometer and Pyrheliometer?

The main difference between a pyranometer and a pyrheliometer is that a pyranometer measures the total amount of solar radiation received by a surface, including both direct and diffuse radiation, while a pyrheliometer measures only direct solar radiation. Here are some key differences between the two instruments:

Measurement: Pyranometers measure global solar radiation, which includes both direct and diffuse radiation, while pyrheliometers measure direct solar irradiance.
Accuracy: Pyrheliometers are typically more accurate than pyranometers but are more expensive and more difficult to operate.
Calibration: Pyranometers should be calibrated every 2 years to ensure accurate measurements, while pyrheliometers may not require as frequent calibration.
Spectral Response: Both instruments should have a spectral response that matches the solar spectrum to ensure accurate measurements, but pyranometers are more sensitive to diffuse radiation, whereas pyrheliometers are more sensitive to direct radiation.
Sensor Type: Different sensor types offer different advantages and disadvantages for each instrument, and the sensor type should be chosen based on the specific application.

In summary, pyranometers and pyrheliometers are both used to measure solar radiation, but they measure different aspects of it. Pyranometers measure total solar radiation, while pyrheliometers measure direct solar radiation. Understanding these differences can help choose the appropriate device for a specific application.