Solar energy

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At the equator, the Sun provides approximately 1000 watts per square meter on Earth's surface.
The top diagram shows how the strength of sunlight is less nearer the Earth's poles. The lower map shows how much solar energy hits the Earth's surface after clouds and dust have reflected and absorbed some solar energy.
Solar Radiation Map: Global Horizontal Irradiation in Europe

Solar energy is energy that is present in sunlight. It has been used for thousands of years in many different ways by people all over the world. As well as its traditional human uses in heating, cooking, and drying, it is used today to make electricity where other power supplies are absent, such as in remote places and in space. It is becoming cheaper to make electricity from solar energy and in many situations it is now competitive with energy from coal or oil.

Energy use[change | change source]

Solar energy is used today in a number of ways:

Energy from the Sun[change | change source]

After passing through the Earth's atmosphere, most of the Sun's energy is in the form of visible light and infrared light radiation. Plants convert the energy in sunlight into chemical energy (sugars and starches) through the process of photosynthesis. Humans regularly use this store of energy in various ways, as when they burn wood or fossil fuels, or when simply eating plants, fish and animals.

Solar radiation reaches the Earth's upper Earth's atmosphere with the power of 1366 watts per square meter (W/m2). Since the Earth is round, the surface nearer its poles is angled away from the sun and receives much less solar energy than the surface nearer the equator.

At present, solar cell panels convert, at best, about 15% of sunlight hitting them into electricity.[1] The dark disks in the third diagram on the right are imaginary examples of the amount of land that, if covered with 8% efficient solar panels, would produce slightly more energy in the form of electricity than the world needed in 2003. [2]

Types of technologies[change | change source]

Many technologies have been developed to make use of solar radiation. Some of these technologies make direct use of the solar energy (e.g. to provide light, heat, etc.), while others produce electricity.

Solar energy absorbing panels on the sound barrier next to the Munich airport.

Solar power plants[change | change source]

Solar power plants convert sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). Concentrated solar power systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. Photovoltaics converts light into electric current using the photoelectric effect.[3]

Photovoltaics[change | change source]

Rank Station Country Location Capacity (MW) Ref
1 Topaz  United States 35°23′N 120°4′W / 35.383°N 120.067°W / 35.383; -120.067 (Topaz Solar Farm) 300[note 1] [4][5]
2 Agua Caliente  United States 32°57′20″N 113°29′40″W / 32.95556°N 113.49444°W / 32.95556; -113.49444 (Agua Caliente) 251.3 [6][7]
3 California Valley Solar Ranch  United States 35°20′N 119°55′W / 35.333°N 119.917°W / 35.333; -119.917 (California Valley Solar Ranch) 250 [8][9][10]
4 Charanka  India 23°54′00″N 71°11′00″E / 23.9°N 71.1833333°E / 23.9; 71.1833333 (Charanka Solar Park) 214
5 Huanghe Hydropower Golmud  China 36°22′00″N 95°15′00″E / 36.3666667°N 95.25°E / 36.3666667; 95.25 (Golmud Solar Park) 200 [11][12][13]
  1. Installed capacity as of January 2014. The final capacity will be 550 MW.

Concentrated solar thermal[change | change source]

Rank[change | change source]

! Station Country Location Capacity (MW) Ref
1 Ivanpah  United States 35°34′N 115°28′W / 35.567°N 115.467°W / 35.567; -115.467 (Ivanpah Solar Power Facility) 377 [14]
2 SEGS  United States 35°01′54″N 117°20′53″W / 35.03167°N 117.34806°W / 35.03167; -117.34806 (Solar Energy Generating Systems) 354 [15]
3 Solana  United States 32°55′N 112°58′W / 32.917°N 112.967°W / 32.917; -112.967 (Solana Generating Station) 280 [16]
4 Genesis  United States 33°38′38″N 114°59′17″W / 33.64389°N 114.98806°W / 33.64389; -114.98806 (Genesis Solar) 250 [17]
5 Solaben  Spain 39°13′29″N 5°23′26″W / 39.22472°N 5.39056°W / 39.22472; -5.39056 (Solaben Solar Power Station) 200
6 Solnova  Spain 37°25′00″N 06°17′20″W / 37.4166667°N 6.28889°W / 37.4166667; -6.28889 (Solnova Solar Power Station) 150
6 Andasol  Spain 37°13′43″N 03°04′07″W / 37.22861°N 3.06861°W / 37.22861; -3.06861 (Andasol Solar Power Station) 150 [18][19]
6 Extresol  Spain 38°39′N 6°44′W / 38.65°N 6.733°W / 38.65; -6.733 (Extresol Solar Power Station) 150 [20][21]
9 Palma del Rio  Spain 37°38′N 5°15′W / 37.633°N 5.25°W / 37.633; -5.25 (Palma del Rio Solar Power Station) 100 [20]
9 Manchasol  Spain 39°11′N 3°18′W / 39.183°N 3.3°W / 39.183; -3.3 (Manchasol Power Station) 100 [20]
9 Valle  Spain 36°39′N 5°50′W / 36.65°N 5.833°W / 36.65; -5.833 (Valle Solar Power Station) 100 [20][22]

Solar cooking[change | change source]

Solar cooking

Solar cooking uses the sun as the source of energy instead of standard cooking fuels such as charcoal, coal or gas. Solar cookers are an inexpensive and environmentally sound alternative to traditional ovens. They are becoming widely used in areas of the developing world where deforestation is an issue, financial resources to purchase fuel are limited, and where open flames would pose a serious risk to people and the environment.

Solar heating[change | change source]

House with solar panels for heating and other needs in Jablunkov, Czech Republic.

The sun may be used to heat water instead of electricity or gas. There are two basic types of active solar heating systems based on the type of fluid — either liquid or air — that is heated in the solar energy collectors. (The collector is the device in which a fluid is heated by the sun.)

Liquid-based systems heat water or an antifreeze solution in a "hydronic" collector, whereas air-based systems heat air in an "air collector."[23] Both air and liquid systems can supplement forced air systems.

Solar cells[change | change source]

Photo of 4 inch by 4 inch cell.

Solar cells can be used to generate electricity from sunlight. It is a device that converts light energy into electrical energy. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified.

Solar cells have many applications. They have long been used in situations where electrical power from the grid is unavailable, such as in remote area power systems, Earth-orbiting satellites and space probes, consumer systems, e.g. handheld calculators or wrist watches, remote radiotelephones and water pumping applications.

Related pages[change | change source]

References[change | change source]

  1. A solar panel in the contiguous United States on average delivers 19 to 56 W/m² or 0.45 - 1.35 (kW·h/m²)/day."us_pv_annual_may2004.jpg". National Renewable Energy Laboratory, US. Retrieved 2006-09-04.
  2. International Energy Agency - Homepage
  3. Technologies: From silicon to the solar cell.
  4. The Tribune: California Valley's Topaz Solar Farm now producing electricity
  5. Steve Leone (7 December 2011). "Billionaire Buffett Bets on Solar Energy". Renewable Energy World.
  6. First Solar’s Agua Caliente project hits 250MW milestone
  7. "First Solar Stops Installation at Agua Caliente Project". Bloomberg.
  8. Energy Division Resolution E-4229
  9. Meza, Edgar (27 June 2013). "NRG Energy completes 250 MW California Valley Solar Ranch". Solar Energy Industry Association. Retrieved 5 July 2013.
  10. "130MW energized". California Valley Solar Ranch. Retrieved Feb 2013.
  11. Enbridge Huanghe Company: Golmud 200MW PV Station Connected to Gridm
  12. CCTV: China-PV Power Station
  13. Samil Power: Utility Scale Projects
  14. Ivanpah Solar Electric Generating System,, retrieved 2014-02-18
  15. SEGS Power Stations,, retrieved 2010-03-20
  16. Abengoa Solar: Abengoa’s Solana, the US’s first large-scale solar plant with thermal energy storage system, begins commercial operation
  17. CSP World
  18. Andasol Solar Power Station,, retrieved 2010-03-20
  19. Andasol Solar Power Station,,lang2,109,155.html, retrieved 2010-03-20
  20. 20.0 20.1 20.2 20.3 (Spanish) Lokalizacion de Centrales Termosolares en Espana
  22. VALLE 1 and VALLE 2
  23. Active Solar Heating

Other websites[change | change source]