Solar energy | Definition, Uses, Advantages, & Facts

The most common devices used to collect solar energy and convert it to thermal energy are flat-plate collectors. Another method of thermal energy conversion is found in solar ponds, which are bodies of salt water designed to collect and store solar energy. Solar radiation may also be converted directly into electricity by solar cells, or photovoltaic cells, or harnessed to cook food in specially designed solar ovens, which typically concentrate sunlight from over a wide area to a central point.

Solar energy is commonly used for solar water heaters and house heating. The heat from solar ponds enables the production of chemicals, food, textiles, warm greenhouses, swimming pools, and livestock buildings. Cooking and providing a power source for electronic devices can also be achieved by using solar energy.

Solar energy is the radiation from the Sun capable of producing heat, causing chemical reactions, or generating electricity. The total amount of solar energy received on Earth is vastly more than the world's current and anticipated energy requirements. If suitably harnessed, solar energy has the potential to satisfy all future energy needs.

The potential for solar energy is enormous, since about 200,000 times the world’s total daily electric-generating capacity is received by Earth every day in the form of solar energy. Unfortunately, though solar energy itself is free, the high cost of its collection, conversion, and storage still limits its exploitation in many places. Solar radiation can be converted either into thermal energy (heat) or into electrical energy , though the former is easier to accomplish.

The Sun is an extremely powerful energy source, and sunlight is by far the largest source of energy received by Earth , but its intensity at Earth’s surface is actually quite low . This is essentially because of the enormous radial spreading of radiation from the distant Sun. A relatively minor additional loss is due to Earth’s atmosphere and clouds , which absorb or scatter as much as 54 percent of the incoming sunlight. The sunlight that reaches the ground consists of nearly 50 percent visible light , 45 percent infrared radiation , and smaller amounts of ultraviolet and other forms of electromagnetic radiation .

Reflection and absorption of solar energy. Although some incoming sunlight is reflected by Earth's atmosphere and surface, most is absorbed by the surface, which is warmed.

Reflection and absorption of solar energy. Although some incoming sunlight is reflected by Earth's atmosphere and surface, most is absorbed by the surface, which is warmed. (more)

solar energy , radiation from the Sun capable of producing heat , causing chemical reactions , or generating electricity . The total amount of solar energy incident on Earth is vastly in excess of the world’s current and anticipated energy requirements. If suitably harnessed, this highly diffused source has the potential to satisfy all future energy needs. In the 21st century solar energy is expected to become increasingly attractive as a renewable energy source because of its inexhaustible supply and its nonpolluting character, in stark contrast to the finite fossil fuels coal , petroleum , and natural gas .

Thermal energy

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Among the most common devices used to capture solar energy and convert it to thermal energy are flat-plate collectors, which are used for solar heating applications. Because the intensity of solar radiation at Earth’s surface is so low, these collectors must be large in area. Even in sunny parts of the world’s temperate regions, for instance, a collector must have a surface area of about 40 square metres (430 square feet) to gather enough energy to serve the energy needs of one person.

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solar heating

A building roof with flat-plate collectors that capture solar energy to heat air or water.

The most widely used flat-plate collectors consist of a blackened metal plate, covered with one or two sheets of glass, that is heated by the sunlight falling on it. This heat is then transferred to air or water, called carrier fluids, that flow past the back of the plate. The heat may be used directly, or it may be transferred to another medium for storage. Flat-plate collectors are commonly used for solar water heaters and house heating. The storage of heat for use at night or on cloudy days is commonly accomplished by using insulated tanks to store the water heated during sunny periods. Such a system can supply a home with hot water drawn from the storage tank, or, with the warmed water flowing through tubes in floors and ceilings, it can provide space heating. Flat-plate collectors typically heat carrier fluids to temperatures ranging from 66 to 93 °C (150 to 200 °F). The efficiency of such collectors (i.e., the proportion of the energy received that they convert into usable energy) ranges from 20 to 80 percent, depending on the design of the collector.

Another method of thermal energy conversion is found in solar ponds, which are bodies of salt water designed to collect and store solar energy. The heat extracted from such ponds enables the production of chemicals, food, textiles, and other industrial products and can also be used to warm greenhouses, swimming pools, and livestock buildings. Solar ponds are sometimes used to produce electricity through the use of the organic Rankine cycle engine, a relatively efficient and economical means of solar energy conversion, which is especially useful in remote locations. Solar ponds are fairly expensive to install and maintain and are generally limited to warm rural areas.

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solar-powered cookstove

A solar-powered cookstove in the Potala Palace, Lhasa, Tibet.

On a smaller scale, the Sun’s energy can also be harnessed to cook food in specially designed solar ovens. Solar ovens typically concentrate sunlight from over a wide area to a central point, where a black-surfaced vessel converts the sunlight into heat. The ovens are typically portable and require no other fuel inputs.

Since the beginning of time, people have been fascinated by the sun. Ancient civilizations personified the sun, worshipping it as a God or Goddess. Throughout history, farming and agriculture efforts have relied upon the sun’s rays to grow crops and sustain populations.

Only recently, however, have we developed the ability to harness the sun’s awesome power. The resulting technologies have promising implications for the future of renewable energy and sustainability. Below, we’ve given a brief on solar power, how it works, and what may be in store for the future of solar.

What is Solar Power?

Solar power is a form of energy harnessed from the power and heat of the sun’s rays. It is renewable, and therefore a “green” source of energy.

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How Does Solar Power Work?

The most common way of harnessing energy from the sun is through photovoltaic (PV) panels – those large, mirror-like panels you’ve likely seen on rooftops, handheld solar devices, and even spacecrafts. These panels operate as conductors, taking in the sun’s rays, heating up, and creating energy (and electricity).

On a larger scale, solar thermal power plants also harness the power of the sun to create energy. These plants utilize the sun’s heat to boil water and, in turn, power steam turbines. These plants can supply power to thousands of people.

There are other ways we harness solar power. Read more about these various methods utilized today here via National Geographic.

How is Solar Power a “Greener” Option?

Just like wind power, solar power is a virtually unlimited and inexhaustible resource (unlike power produced from expendable fossil fuels). As technologies improve and the materials used in PV panels become “greener,” the carbon footprint of solar power becomes smaller and smaller and the technique becomes more accessible to the masses.

Why Isn’t Solar Power More Prevalent?

Similarly to wind power, solar power is contingent upon the weather and the amount of sunshine present in a specific location. This means that geographical areas lacking in sunlight, or areas that frequently experience cloudy weather, may have difficulty utilizing solar power effectively.

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Additionally, solar power is an expensive endeavor. The technologies often require a large amount of land, and they can be extremely costly. Scientists are hard at work to find an affordable, efficient solution for harnessing solar power.

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Facts About Solar Power:

Did You Know?

• Every hour, the sun beats down with enough power to provide global energy for an entire year.
• It takes an average of eight minutes for energy to travel from the sun to the Earth.
• Scientists have used solar energy to power spaceships since 1958.
• Most solar panels used today have an average life expectancy of between 20-40 years.

Let the sunshine in! Interested in solar power for your home? There are a number of resources, projects, and products available online for families interested in going solar. To get the best bang for your buck, be sure to conduct thorough research before beginning any new effort.

Questions about solar power or other renewable energy sources? Ask us on Just Energy Facebook or Twitter

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Resources:

http://environment.nationalgeographic.com/environment/global-warming/solar-power-profile/
http://eco.allpurposeguru.com/2011/06/ten-interesting-facts-about-solar-power/