Pyrheliometer

Example of a pyrheliometer on a solar tracker which keeps the instrument pointed at the sun. A black shadow band keeps the pyranometer shaded, so that it measures diffuse radiation only. The global solar radiation is then calculated from direct and diffuse radiation.

A research grade pyrheliometer

Pyrheliometer: (1) protection cap, (2) window with heater, (3) sight, (5) sensor, (7) humidity indicator, (10) cable for heater

A pyrheliometer is an instrument for direct measurement of solar irradiance. Sunlight enters the instrument through a window and is directed onto a thermopile which converts heat to an electrical signal that can be recorded. The signal voltage is converted via a formula to measure watts per square metre. It is used with a solar tracking system to keep the instrument aimed at the sun. A pyrheliometer is often used in the same setup with a pyranometer.

Standards

Pyrheliometer measurement specifications are subject to International Organization for Standardization (ISO) and World Meteorological Organization (WMO) standards.

Applications

Typical pyrheliometer measurement applications include scientific meteorological and climate observations, material testing research, and assessment of the efficiency of solar collectors and photovoltaic devices.

See also

• Actinometer
• Pyrometer

References

Specifications, drawings and pictures courtesy of Hukseflux Thermal Sensors, www.Hukseflux.com