Apogee Instruments SP-212 Manuale d'uso - Pagina 4

Sfoglia online o scarica il pdf Manuale d'uso per Strumenti di misura Apogee Instruments SP-212. Apogee Instruments SP-212 20. Pyranometer

Solar radiation at Earth's surface is typically defined as total radiation across a wavelength range of 280 to 4000

nm (shortwave radiation). Total solar radiation, direct beam and diffuse, incident on a horizontal surface is defined

as global shortwave radiation, or shortwave irradiance (incident radiant flux), and is expressed in Watts per square

-2

meter (W m

, equal to Joules per second per square meter).

Pyranometers are sensors that measure global shortwave radiation. Apogee SP series pyranometers are silicon-cell

pyranometers and are only sensitive to a portion of the solar spectrum, approximately 350-1100 nm

(approximately 80 % of total shortwave radiation is within this range). However, silicon-cell pyranometers are

calibrated to estimate total shortwave radiation across the entire solar spectrum. Silicon-cell pyranometer

specifications compare favorably to specifications for World Meteorological Organization (WMO) moderate and

good quality classifications and specifications for International Organization of Standardization (ISO) Class C

classification, but because of limited spectral sensitivity, they do not meet the spectral specification necessary for

WMO certification.

Typical applications of silicon-cell pyranometers include incoming shortwave radiation measurement in

agricultural, ecological, and hydrological weather networks, and solar panel arrays.

Apogee Instruments SP series pyranometers consist of a cast acrylic diffuser (filter), photodiode, and signal

processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor to a

measurement device. Sensors are potted solid with no internal air space and are designed for continuous total

shortwave radiation measurement on a planar surface in outdoor environments. SP series sensors output an

analog voltage that is directly proportional to total shortwave radiation from the sun. The voltage signal from the

sensor is directly proportional to radiation incident on a planar surface (does not have to be horizontal), where the

radiation emanates from all angles of a hemisphere.