Solar energy how is it obtained

Department of Energy Solar Energy Technologies Office is driving innovative research and development in these areas.

Solar radiation is light — also known as electromagnetic radiation — that is emitted by the sun. Solar technologies capture this radiation and turn it into useful forms of energy. There are two main types of solar energy technologies—photovoltaics PV and concentrating solar-thermal power CSP. You're likely most familiar with PV, which is utilized in solar panels. When the sun shines onto a solar panel, energy from the sunlight is absorbed by the PV cells in the panel. This energy creates electrical charges that move in response to an internal electrical field in the cell, causing electricity to flow.

Concentrating solar-thermal power CSP systems use mirrors to reflect and concentrate sunlight onto receivers that collect solar energy and convert it to heat, which can then be used to produce electricity or stored for later use.

It is used primarily in very large power plants. These solar energy systems must be integrated into homes, businesses, and existing electrical grids with varying mixtures of traditional and other renewable energy sources. A number of non-hardware costs, known as soft costs, also impact the cost of solar energy. Yet this amount of energy is enormous. Every day enough energy strikes the United States to supply the nation's energy needs for one and a half years!

Where does all this energy go? About 15 percent of the sun's energy that hits the earth is reflected back into space. Another 30 percent is used to evaporate water, which, lifted into the atmosphere, produce's rain-fall. Solar energy also is absorbed by plants, the land, and the oceans. The rest could be used to supply our energy needs.

History of Solar Energy. People have harnessed solar energy for centuries. As early as the 7th century B. Over years ago in France, a scientist used heat from a solar collector to make steam to drive a steam engine. In the beginning of this century, scientists and engineers began researching ways to use solar energy in earnest. One important development was a remarkably efficient solar boiler invented by Charles Greeley Abbott, an American astrophysicist, in The solar water heater gained popularity at this time in Florida, California, and the Southwest.

The industry started in the early s and was in full swing just before World War This growth lasted until the mid- s when low-cost natural gas became the primary fuel for heating American homes. The public and world governments remained largely indifferent to the possibilities of solar energy until the oil shortages of the s. Today people use solar energy to heat buildings and water and to generate electricity.

Solar Collectors and Solar Space Heating. Heating with solar energy is not as easy as you might think. Capturing sunlight and putting it to work is difficult because the solar energy that reaches the earth is spread out over a large area. The sun does not deliver that much energy to any one place at any one time.

How much solar energy a place receives depends on several conditions. These include the time of day, the season of the year, the latitude of the area, and the clearness or cloudiness of the sky. A solar collector is one way to collect heat from the sun. A closed car on a sunny day is like a solar collector.

As sunlight passes through the car's glass windows, it is absorbed by the seat covers, walls, and floor of the car. The light that is absorbed changes into heat. The car's glass windows let light in, but don't let all the heat out. This is also why greenhouses work so well and stay warm year-round. Space heating means heating the space inside a building. Today many homes use solar energy for space heating. There are two general types of solar space heating systems: passive and active.

A "hybrid" system is a mixture of the passive and active systems. In a passive solar home, the whole house operates as a solar collector. A passive house does not use any special mechanical equipment such as pipes, ducts, fans, or pumps to transfer the heat that the house collects on sunny days.

Instead, a passive solar home relies on properly oriented windows. Since the sun shines from the south in North America, passive solar homes are built so that most of the windows face south.

They have very few or no windows on the north side. A passive solar home converts solar energy into heat just as a closed car does.

Sunlight passes through a home's windows and is absorbed in the walls and floors. To control the amount of heat in a passive solar house, the doors and windows are closed or opened to keep heated air in or to let it out. At night, special heavy curtains or shades are pulled over the windows to keep the daytime beat inside the house.

In the summer, awnings or roof overhangs help to cool the house by shading the windows from the high summer sun. Heating a house by warming the walls or floors is more comfortable than heating the air inside a house. It is not so drafty. And passive buildings are quiet, peaceful places to live. Fortunately, DC electricity can easily be changed into AC electricity by a gadget called an inverter.

In modern solar systems, these inverters can be configured as one inverter for the entire system or as individual microinverters attached behind the panels. A solar microinverter. Once the solar energy has been converted from DC to AC electricity, it runs through your electrical panel and is distributed within the home to power your appliances.

It works exactly the same way as the electrical power generated through the grid by your electric utility company, so nothing within the home needs to change. Since you still remain connected to your traditional power company, you can automatically draw additional electricity to supplement any solar shortages from the grid.

A smart electric meter. On cloudy days and overnight, your solar shingles or panels may not be able to capture enough sunlight to use for energy; conversely, in the middle of the day when nobody is home, they may collect surplus energy—more than you need to operate your home. Your utility company will often provide credits for any surplus power you send back to the grid. This is known as net metering.

It may not be rocket science—but it definitely is human ingenuity at its best. Interested in solar roofing for your home? Explore our solar products or find a credentialed solar installer in your area.