R.sun
Encyclopedia
r.sun is a solar irradiance and irradiation model for GRASS
, which is a is a free
, open source
geographical information system (GIS) capable of handling raster
, topological vector, image processing
, and graphic
data.
r.sun computes direct (beam
), diffuse and reflected solar irradiation raster
maps for given day, latitude
, surface and atmospheric conditions. This is useful in several areas of solar energy including solar thermal heating and photovoltaics
. Several solar parameters are saved in the map history file including:
Alternatively, r.sun enables users to specify a local time to compute solar incidence angle and/or irradiance raster maps, and the shadowing effect of the topography. It has recently begun to be used with GRASS
for estimating potential solar photovoltaic yields.
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
, which is a is a free
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
, open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
geographical information system (GIS) capable of handling raster
Raster graphics
In computer graphics, a raster graphics image, or bitmap, is a data structure representing a generally rectangular grid of pixels, or points of color, viewable via a monitor, paper, or other display medium...
, topological vector, image processing
Image processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...
, and graphic
Computer graphics
Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....
data.
r.sun computes direct (beam
Beam
Beam may refer to:*Beam , a construction element*Beam , the most extreme width of a nautical vessel, or a point alongside the ship at the mid-point of its length*A narrow, propagating stream of particles or energy:...
), diffuse and reflected solar irradiation raster
Raster
Raster may refer to:* Raster graphics, graphical techniques using arrays of pixel values* Raster graphics editor, a computer program* Raster scan, the pattern of image readout, transmission, storage, and reconstruction in television and computer images...
maps for given day, latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, surface and atmospheric conditions. This is useful in several areas of solar energy including solar thermal heating and photovoltaics
Photovoltaics
Photovoltaics is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material...
. Several solar parameters are saved in the map history file including:
- sunriseSunriseSunrise is the instant at which the upper edge of the Sun appears above the horizon in the east. Sunrise should not be confused with dawn, which is the point at which the sky begins to lighten, some time before the sun itself appears, ending twilight...
, - sunsetSunsetSunset or sundown is the daily disappearance of the Sun below the horizon in the west as a result of Earth's rotation.The time of sunset is defined in astronomy as the moment the trailing edge of the Sun's disk disappears below the horizon in the west...
times, - declinationDeclinationIn astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
, - extraterrestrial irradiance,
- daylightDaylightDaylight or the light of day is the combination of all direct and indirect sunlight outdoors during the daytime. This includes direct sunlight, diffuse sky radiation, and both of these reflected from the Earth and terrestrial objects. Sunlight scattered or reflected from objects in outer space is...
length
Alternatively, r.sun enables users to specify a local time to compute solar incidence angle and/or irradiance raster maps, and the shadowing effect of the topography. It has recently begun to be used with GRASS
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
for estimating potential solar photovoltaic yields.