A Heliostat is a device that tracks the movement of the sun. It is typically used to orient a mirror, throughout the day, to reflect sunlight in a consistent direction. When coupled together in sufficient quantities, the reflected sunlight from the heliostats can generate an enormous amount of heat if all are oriented towards the same target. It was originally developed as an instrument for use in surveying, allowing the accurate observation of a known point from a distance. The Sun is the star of our solar system. ... A mirror is a surface with good specular reflection that is smooth enough to form an image. ... Surveyor at work with a leveling instrument. ...

Its name comes from helios, the Greek word for sun (see also: Helios), and stat, as in stationary. Helios in his chariot In Greek mythology the sun was personified as Helios or Helius (Greek Ἥλιος / ἥλιος). Homer often calls him Titan and Hyperion. ...

Heliostats have been used for sunlight-powered interior lighting, solar observatories, and solar power generation. Mirrors and reflective surfaces used in solar power that do not track the sun are not heliostats. Solar power describes a number of methods of harnessing energy from the light of the sun. ...

The simplest heliostat devices use a clockwork mechanism to turn the mirror in synchronisation with the rotation of the Earth. More complex devices need to compensate for the changing elevation of the Sun throughout a Solar year. Even more advanced heliostats track the sun directly by sensing its position throughout the day.

A siderostat is a similar device which is designed to track a fainter star, rather than the Sun. The Pleiades, an open cluster of stars in the constellation of Taurus. ...

Use in power production

A photo of one of Solar Two's heliostats taken in 2003. The solar power tower can be seen in the background.

Using the experience from Solar One and Solar Two, the Solar Tres project in Spain is building a 15MW solar power plant with a 16 hour, 600 MWh thermal power storage system based on molten sodium nitrate salt. Some have criticized the use of this salt because of its safety and environmental hazards. Others believe that it is relatively safe compared to the other chemicals used in the electrical industry, especially if handled properly. ImageMetadata File history File links Download high resolution version (2048x1536, 1911 KB) Description: This is a photograph of one of Solar Twos heliostats, which directs sunlight onto a central receiver on top of a tower. ... ImageMetadata File history File links Download high resolution version (2048x1536, 1911 KB) Description: This is a photograph of one of Solar Twos heliostats, which directs sunlight onto a central receiver on top of a tower. ... A solar power tower is a solar power station based on a tower. ... Solar One is a pilot solar-thermal project in the Mojave Desert near Barstow, California. ... Sodium nitrate (not to be confused with sodium nitrite) is a type of pepper(NaNO3) which has long been used as an ingredient in explosives and in solid rocket propellants, as well as in glass and pottery enamel, and as a food preservative (such as in hot dogs), and has...

Sandia National Laboratory also has a heliostat array. It is used for experiments in electricity production, industrial processes requiring high temperatures and waste disposal. Sandia National Laboratories is a major United States Department of Energy research and development national laboratory with two locations, one in Albuquerque, New Mexico and the other in Livermore, California. ...

Use in interior lighting

The heliostat reflects the sunlight onto the transmission system. This is typically a set of mirrors that direct the reflected sunlight into the building or, alternatively, a light tube. Fiber optic cabling has also been used as a transfer mechanism. Various forms of commercial products have been designed for the point of termination (the "light bulb"). Light tubes or light pipes are used for transporting or distributing natural or artificial light. ...

Calculating the position of the sun in an "open loop" heliostat

Since the path of the sun across the sky varies through the year, a completely automatic heliostat must be guided by continuous calculations. The National Renewable Energy Laboratory has released its Solar Position Algorithm (SPA) with complete documentation. Another resource is the libnova Celestial Mechanics and Astronomical Calculation Library, which also calculates variables such as apparent position and rise, set and transit times among many others of astronomical objects. See also the "References" section of the Seasons" article. The National Renewable Energy Laboratory (NREL), located in Golden, Colorado, as part of the U.S. Department of Energy, is the United Statess primary laboratory for renewable energy and energy efficiency research and development. ... This article is about divisions of a year. ...

See also

• Renewable energy
• Solar cell
• Solar power
• Solar power tower
• Solar thermal energy
• Solar tracker

Renewable energy is energy which can be replenished at the same rate it is used. ... A solar cell, made from a monocrystalline silicon wafer A solar cell (or a photovoltaic cell) is a semiconductor device that converts photons from the sun (solar light) into electricity. ... Solar power describes a number of methods of harnessing energy from the light of the sun. ... A solar power tower is a solar power station based on a tower. ... The major applications of solar thermal energy at present are heating swimming pools, heating water for domestic use, and space heating of buildings. ... A solar tracker is a device for orienting a solar photovoltaic panel or concentrating solar reflector toward the sun. ...

External links

• Field of 63 heliostats at the Odeillo Solar Furnace
• Solar Furnaces at Odeillo
• A large field of heliostats were used at the Solar One and Solar Two experimental solar power plant in Barstow, CA. Includes video.
• The Solar Tres project.
• BOTLIGHT.COM
• Heliotrack.com