Measurement and analysis of circumsolar radiation

Technical Report · Mon Oct 01 04:00:00 EDT 1979

OSTI ID:5626701

Grether, D F; Evans, D; Hunt, A; Wahlig, M

Four instrument systems called Circumsolar Telescopes are used to measure the solar and circumsolar radiation for application to solar energy systems that employ lenses or mirrors to concentrate the incident sunlight. circumsolar radiation results from the scattering of direct sunlight through small angles by atmospheric aerosols (dust, water droplets or ice crystals in thin clouds, etc.). The solar energy system will typically collect all of the direct solar radiation (that originating from the disk of the sun) plus some fraction of the circumsolar radiation. The exact fraction depends upon many factors, but primarily upon the angular size (field-of-view) of the receiver. A knowledge of the circumsolar radiation can be used as a factor in the optimization of a receiver design, as one measure of the suitability of a geographic region for concentrating systems, or as input to comparison studies of competing designs at a particular location. Each measuring system has a scanning telescope mounted on a precision solar tracker. The telescope is mechanically scanned thru an arc of 6/sup 0/ with the sun at the center of the arc. A digitization of the brightness of the sun or circumsolar radiation is taken every 1.5' of arc, with a complete scan taking one minute of time. Auxiliary instruments include a pyrheliometer and two pyranometers, one mounted in the usual horizontal position and one tracking the sun. The telescope and pyrheliometer have batched ten position filter wheels: one open position, eight interference filters that divide the solar spectrum into eight intervals of roughly equal energy content, and one opaque filter to monitor detector noise. The data are recorded on magnetic tape, with one tape holding one week's worth of data per telescope. The tapes are shipped to LBL for computer processing. (WHK)

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5626701
• Report Number(s): LBL-10243
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140100* -- Solar Energy-- Resources & Availability
CLOUDS
DATA ANALYSIS
DATA PROCESSING
DIFFUSE SOLAR RADIATION
EQUIPMENT
FILTERS
MEASURING INSTRUMENTS
MEASURING METHODS
OPERATION
OPTICAL FILTERS
PROCESSING
PYRANOMETERS
PYRHELIOMETERS
RADIATIONS
SOLAR EQUIPMENT
SOLAR FLUX
SOLAR RADIATION
SOLAR TRACKING
TELESCOPES