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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 must have reflected and absorbed some solar energy.
Solar Radiation Map: Global Horizontal Irradiation in Europe

Solar energy is the transformation of heat, the energy that comes from the sun. It has been used for thousands of years in many different ways by people all over the world. The oldest uses of solar energy is for heating, cooking, and drying. Today, it is also used to make electricity where other power supplies are not there, such as in places far away from where people live, and in outer space.

It is becoming cheaper to make electricity from solar energy. Because the Sun always gives heat and light, solar energy can be considered a renewable energy and an alternative to non-renewable resources like coal and oil.

Energy uses

Solar energy is used today in a number of ways:

Energy from the Sun

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 off fossil fuels, or when simply eating plants, fish and animals.

Solar radiation reaches the Earth's upper 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 the 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

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

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 power plants

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]


World's largest photovoltaic power stations
Photovoltaic power station Country Site co-ordinates Nominal
Notes and references
Topaz Solar Farm[4] USA 35°23′N 120°4′W / 35.383°N 120.067°W / 35.383; -120.067 (Topaz Solar Farm) &&&&&&&&&&&&0500.&&&&&0500 installed capacity as of June 2019.
Desert Sunlight Solar Farm USA 33°49′33″N 115°24′08″W / 33.82583°N 115.40222°W / 33.82583; -115.40222 (Desert Sunlight Solar Farm) &&&&&&&&&&&&0500.&&&&&0500 Commissioned since November 2013 toward final capacity 550 MW
Longyangxia Dam Solar Park[5] China 36°07′20″N 100°55′06″E / 36.12222°N 100.91833°E / 36.12222; 100.91833 (Longyangxia Dam Solar Park) &&&&&&&&&&&&0320.&&&&&0320 Completed December 2013
Solar Star I and II[6] USA &&&&&&&&&&&&0309.&&&&&0309 Under construction, 579MW when completed[7]
California Valley Solar Ranch[8] USA 35°20′N 119°55′W / 35.333°N 119.917°W / 35.333; -119.917 (California Valley Solar Ranch) &&&&&&&&&&&&0292.&&&&&0292[9][10] 399 First 130MW connected Feb 2013.[11]
Agua Caliente Solar Project[12] USA 32°57.2′N 113°29.4′W / 32.9533°N 113.4900°W / 32.9533; -113.4900 (Agua Caliente) &&&&&&&&&&&&0290.&&&&&0290[13][14] 626 completed April 2014[15]
Antelope Valley Solar Ranch[12][16][17] USA 34°46′N 118°25′W / 34.767°N 118.417°W / 34.767; -118.417 (Antelope Valley Solar Ranch) &&&&&&&&&&&&0266.&&&&&0266[18] 230 MWAC. Has received government loan guarantee

Concentrated solar thermal


Rank 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 [19]
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 [20]
3 Solana  United States 32°55′N 112°58′W / 32.917°N 112.967°W / 32.917; -112.967 (Solana Generating Station) 280 [21]
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 [22]
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 / 37.41667°N 6.28889°W / 37.41667; -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 [23][24]
6 Extresol  Spain 38°39′N 6°44′W / 38.650°N 6.733°W / 38.650; -6.733 (Extresol Solar Power Station) 150 [25][26]
9 Palma del Rio  Spain 37°38′N 5°15′W / 37.633°N 5.250°W / 37.633; -5.250 (Palma del Rio Solar Power Station) 100 [25]
9 Manchasol  Spain 39°11′N 3°18′W / 39.183°N 3.300°W / 39.183; -3.300 (Manchasol Power Station) 100 [25]
9 Valle  Spain 36°39′N 5°50′W / 36.650°N 5.833°W / 36.650; -5.833 (Valle Solar Power Station) 100 [25][27]
View of Ivanpah Solar Electric Generating System from Yates Well Road, San Bernardino County, California. The Clark Mountain Range can be seen in the distance.

Solar cooker

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 cookers are covered with a glass plate. They achieve a higher temperature by using mirrors to focus the rays of the sun.

Solar heater

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."[28] Both air and liquid systems can supplement forced air systems.

Solar cells

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. A large no. of solar cells are combined in an arrangement called solar cell panel that can deliver enough electricity for practical use. Electricity produced by solar panels can be stored in rechargeable solar batteries, which is then drawn upon when required.[29]

Related pages


  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. SolarServer: CPI completes massive hybrid solar PV/hydro plant in Western China
  6. Solar Star Project, Japan DG Demand Drive SunPower's Q3, Forbes, 10/31/2014
  7. [1]
  8. Energy Division Resolution E-4229
  9. U.S. Solar Market Trends 2013, IREC, July 2014
  10. Meza, Edgar (27 June 2013). NRG Energy completes 250 MW California Valley Solar Ranch. Solar Energy Industry Association. Retrieved 5 July 2013. 
  11. "130MW energized". California Valley Solar Ranch. Retrieved Feb 2013. 
  12. 12.0 12.1 "RPS Project Status Table - February Update". 
  13. "World's Largest Operational Solar PV Project, Agua Caliente, Achieves 250 Megawatts of Grid-Connected Power". 
  14. "First Solar Stops Installation at Agua Caliente Project". Bloomberg. 
  15. World’s Biggest Solar PV Plant a Feather in DOE’s Cap, Pete Danko, greentechmedia, May 2, 2014
  16. "AV Solar Ranch One". NextLight Renewable Power LLC. 2009. Retrieved 2009-06-06. 
  17. Project Overview
  18. Hill, Joshua (22 Feb 2013). Antelope Valley Solar Ranch One Achieves 100 Megawatt Milestone. Retrieved Feb 2013. 
  19. Ivanpah Solar Electric Generating System,, retrieved 2014-02-18 
  20. SEGS Power Stations,, retrieved 2010-03-20 
  21. "Abengoa Solar: Abengoa’s Solana, the US’s first large-scale solar plant with thermal energy storage system, begins commercial operation". 
  22. "CSP World". 
  23. Andasol Solar Power Station,, retrieved 2010-03-20 
  24. Andasol Solar Power Station,,lang2,109,155.html, retrieved 2010-03-20 
  25. 25.0 25.1 25.2 25.3 (in Spanish) Lokalizacion de Centrales Termosolares en Espana Archived 2013-03-10 at the Wayback Machine
  27. "VALLE 1 and VALLE 2". 
  28. "Active Solar Heating". 
  29. "Solar Batteries | Natural Solar" (in en-US). Natural Solar. Retrieved 2018-11-01. 

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