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  • Publicado : 7 de marzo de 2010
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* 1 Energy from the Sun
* 2 Applications of solar technology
* 2.1 Electrical generation
* 2.1.1 Photovoltaics
* 3 Development, deployment and economics
* 4.Propuesta para ponerlo en practica

Solar energy
Solar energy is the light and radiant heat from the Sun thatinfluences Earth's climate and weather and sustains life. Solar power is sometimes used as a synonym for solar energy or more specifically to refer to electricity generated from solar radiation. Since ancient times solar energy has been harnessed by humans using a range of technologies. Solar radiation along with secondary solar resources such as wind and wave power, hydroelectricity and biomassaccount for most of the available renewable energy on Earth.
Solar energy technologies can provide electrical generation by heat engine or photovoltaic means; space heating and cooling in active and passive solar buildings; potable water via distillation and disinfection, daylighting, hot water, thermal energy for cooking, and high temperature process heat for industrial purposes.
Applications of solartechnology

Average insolation showing land area (small black dots) required to replace the total world energy supply with solar electricity. Insolation for most people is from 150 to 300 W/m^2 or 3.5 to 7.0 kWh/m^2/day.
Solar energy refers primarily to the use of solar radiation for practical ends. All other renewable energies other than geothermal derive their energy from the sun.
Solartechnologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position ofa building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologie.

A solar cell, or photovoltaic cell (PV), is a device that converts light into direct current using the photoelectric effect. Thefirst solar cell was constructed by Charles Fritts in the 1880s. Although the prototype selenium cells converted less than 1% of incident light into electricity, both Ernst Werner von Siemens and James Clerk Maxwell recognized the importance of this discovery. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell in1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4.5–6%.
The earliest significant application of solar cells was as a back-up power source to the Vanguard I satellite in 1958, which allowed it to continue transmitting for over a year after its chemical battery was exhausted. The successful operation of solar cells on this mission was duplicated in many other Soviet andAmerican satellites, and by the late 1960s, PV had become the established source of power for them. Photovoltaics went on to play an essential part in the success of early commercial satellites such as Telstar, and they remain vital to the telecommunications infrastructure today.
The high cost of solar cells limited terrestrial uses throughout the 1960s. This changed in the early 1970s when pricesreached levels that made PV generation competitive in remote areas without grid access. Early terrestrial uses included powering telecommunication stations, off-shore oil rigs, navigational buoys and railroad crossings. These off-grid applications have proven very successful and accounted for over half of worldwide installed capacity until 2004.
Concentrating solar power

Solar troughs are the...
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